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Nutritional value and pharmacological importance of citrus species grown in Iraq

August 2016
IOSR Journal of Pharmacy (IOSRPHR) 06(08):76-108

Authors:

University of Thi-Qar

Citrus fruits contained many phytochemicals including essential oils, alkaloids, flavonoids, coumarins, psoralens, carotenoids with a wide range of nutritional components including vitamins, minerals and trace elements. The previous pharmacological studies revealed that citrus fruits possessed antimicrobial, anthelmintic, insect repellent, antioxidant, anticancer, cardiovascular, central nervous, anti-inflammatory, analgesic, antidiabetic, reproductive, gastrointestinal, immunological, respiratory and many other pharmacological effects. This review was designed to highlight the chemical constituents, nutritional value and pharmacological activities of citrus fruits

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IOSR Journal Of Pharmacy www.iosrphr.org

(e)-ISSN: 2250-3013, (p)-ISSN: 2319-4219

Volume 6, Issue 8 Version. 1 (Aug 2016), PP. 76-108

Nutritional value and pharmacological importance of citrus

species grown in Iraq

Dr Ali Esmail Al-Snafi

Department of Pharmacology, College of Medicine, Thi qar University, Iraq

Abstract:- Citrus fruits contained many phytochemicals including essential oils, alkaloids, flavonoids,

coumarins, psoralens, carotenoids with a wide range of nutritional components including vitamins, minerals

and trace elements. The previous pharmacological studies revealed that citrus fruits possessed antimicrobial,

anthelmintic, insect repellent, antioxidant, anticancer, cardiovascular, central nervous, anti-inflammatory,

analgesic, antidiabetic, reproductive, gastrointestinal, immunological, respiratory and many other

pharmacological effects. This review was designed to highlight the chemical constituents, nutritional value and

pharmacological activities of citrus fruits.

Keywords: constituents, nutritiona, pharmacology, citrus fruits, Citrus aurantifolia, Citrus medica,

Citrus medica var. limetta, Citrus sinensis

Introduction

Medicinal plants are the Nature’s gift to human beings to help them pursue a disease-free healthy life.

Plants are a valuable source of a wide range of secondary metabolites, which are used as pharmaceuticals,

agrochemicals, flavours, fragrances, colours, biopesticides and food additives(1-50). Citrus contained nutrients

and phytochemicals that were beneficial for health. Citrus fruits and juices contain a wide range of substances

including carbohydrates, fibre, vitamin C, potassium, folate, calcium, thiamine, niacin, vitamin B6, vitamin A,

phosphorus, magnesium, copper, riboflavin, pantothenic acid and a variety of phytochemicals. These substances

are necessary for proper functioning of the body but some confer additional protection against chronic disease

over and basic nutrition. Citrus fruits are also low in fat and in overall dietary energy – a major consideration

given the increasing rate of obesity in both adults and children. It also has a relatively low glycaemic index

which helps in maintaining a more stable blood glucose level and generally healthier carbohydrate metabolism.

Citrus fruits also contained many phytochemicals including essential oils, alkaloids, flavonoids, coumarins,

psoralens and carotenoids. The previous pharmacological studies revealed that citrus fruits possessed

antimicrobial, anthelmintic, insect repellent, antioxidant, anticancer, cardiovascular, central nervous, anti-

inflammatory, analgesic, antidiabetic, reproductive, gastrointestinal, immunological, respiratory and many other

pharmacological effects. This review will highlight the chemical constituents, nutritional value and

pharmacological activities of citrus fruits.

Plants profile:

Synonyms(53):

Any botanical classification of citrus fruit faces several difficulties. All citrus types hybridise easily.

New hybrids are continuously developed to obtain desired qualities such as seedlessness, juiciness and fresh

taste. New hybrids spontaneously arise by cross-pollination. The most modern methods of molecular research

are sometimes needed to distinguish citrus types from each other. However, the synonyms of citrus species

were:

Citrus aurantifolia

Limonia aurantifolia Christre. & Panzer, Citrus javanica Blume, Citrus notissima Blanco, Citrus acida

Roxb., Citrus hystrix ssp. acida (Roxb.) Engl., Citrus lima Lunan, Citrus limetta var. aromatica Wester, Citrus

medica var. acida (Roxb.) Hook. f., Limonia aurantiifolia Christm., Citrus acida Pers., Citrus alata (Tanaka)

Yu.Tanaka, Citrus amara Link, Citrus articulata Willd. ex Spreng. Citrus assamensis R. M. Dutta &

Bhattacharya, Citrus aurantiaca Swingle, Citrus aurantiifolia var. latifolia Yu. Tanaka, Citrus aurantiifolia

subsp. murgetana García Lidón & al., Citrus aurantium var. amara L., Citrus aurantium subsp.

aurantiifolia (Christm.) Guillaumin, Citrus aurantium var. crassa Risso, Citrus

aurantium var. daidai Makino, Citrus aurantium var. decumana L. Citrus aurantium f. deliciosa, (Ten.)

M. Hiroe, Citrus aurantium f. grandis (L.) M. Hiroe, Citrus aurantium subsp. ichangensis,

Citrus aurantium f. intermedia, Citrus aurantium var. japonica, Citrus aurantium subsp. junos, Citrus

aurantium var. limetta, Guillaumin.

Nutritional value and pharmacological importance of citrus species

Citrus limonum

Citrus aurantium subsp. bergamia (Risso & Poit.) Engl., Citrus aurantium subsp. bergamia (Risso)

Wight & Arn., Citrus aurantium var. bergamia (Risso) Brandis, Citrus aurantium var. mellarosa (Risso)

Engl., Citrus bergamia Risso & Poit., Citrus bergamia subsp. mellarosa (Risso) D.Rivera & al.,

Citrus bergamota Raf., Citrus limodulcis D.Rivera, Obón & F.Méndez, Citrus limonelloides Hayata, Citrus

limonia Osbeck, Citrus limonia var. digitata Risso, Citrus limonum Risso, Citrus medica var. limon L.,

Citrus medica f. limon (L.) M.Hiroe, Citrus medica subsp. limonia (Risso) Hook. f.,

Citrus medica var. limonum (Risso) Brandis, Citrus medica subsp. limonum (Risso) Engl.,

Citrus medica var. limonum (Risso) Brandis, Citrus mellarosa Risso, Citrus meyeri Yu.Tanaka, Citrus

vulgaris Ferrarius ex Mill., Limon vulgaris Ferrarius ex Miller.

Citrus medica

Aurantium medicum (L.) M. Gómez, Citrus alata (Tanaka) Yu.Tanaka, Citrus alata (Tanaka) Tanaka,

Citrus aurantium var. medica (L.) Wight & Arn., Citrus aurantium var. proper Guillaumin, Citrus

aurantium var. tamurana Yu.Tanaka, Citrus balotina Poit. & Turpin, Citrus bicolor Poit. & Turpin, Citrus

bigena Poit. & Turpin, Citrus cedra Link, Citrus cedrata Raf., Citrus crassa Hassk., Citrus fragrans Salisb.,

Citrus gongra Raf., Citrus grandis var. pyriformis (Hassk.) Karaya, Citrus hassaku Yu.Tanaka,

Citrus hiroshimana Yu.Tanaka, Citrus kizu Yu. Tanaka, Citrus kwangsiensis Hu, Citrus limetta Risso, Citrus

limetta subsp. murcica S.Ríos & al., Citrus limonia var. limetta (Risso) Engl., Citrus limoni medica Lush.,

Citrus lumia Risso, Citrus medica var. alata Yu.Tanaka, Citrus medica subsp. Bajoum H. Perrier,

Citrus medica var. digitata Risso ex Guillaumin, Citrus medica var. dulcis Risso & Poit.,

Citrus medica var. ethrog Engl., Citrus medica var. limetta (Risso) Engl., Citrus medica var. medica, Citrus

medica var. nana Wester, Citrus medica var. proper Hook.f., Citrus medica var. sarcodactylus, Citrus

medica f. sudachi (Shirai) M.Hiroe, Citrus medica var. tarung Yu.Tanaka, Citrus nana (Wester)

Yu.Tanaka, Citrus odorata Roussel, Citrus pyriformis Hassk., Citrus sarcodactylus Siebold ex Hoola van

Nooten.

Citrus medica var. limetta It is a synonym of Citrus medica L.

Citrus sinensis

Citrus sinensis (L.) Osbeck, Citrus sinensis var. brassiliensis Tanaka, Citrus sinensis subsp. crassa (Risso)

D.Rivera & al., Citrus sinensis subsp. fetifera (Risso) D.Rivera & al., Citrus sinensis subsp.

hierochuntica (Risso) D. Rivera & al., Citrus sinensis subsp. lusitanica (Risso) D.Rivera & al., Citrus sinensis

var. Sanguinea (Engl.) Engl., Citrus sinensis f. sekkan Hayata, Citrus sinensis var. sekkan Hayata,

Citrus sinensis subsp. suntara (Engl.) Engl.

Taxonomic classification:

Kingdom: Plantae; Subkingdom: Tracheobionta; Superdivision: Spermatophyta; Division: Magnoliophyta;

Class: Magnoliopsida; Subclass: Rosidae; Order: Sapindales; Family: Rutaceae; Genus: Citrus(53-54).

Common names(53):

Citrus aurantiifolia:

Arabic: laimon helo; Chinese: lai meng; English: Egyptian lime, Indian lime, Key lime, lime, Mexican lime,

sour lime, lime; French: citron vert, citronnier gallet, lime acid, limettier, limettier des Antilles, limettier

mexicain; German: Limette, Limettenbaum, Limone, saure Limette; India: kagzi nimboo, kagzi nimbu;

Italian: lima; Portuguese: limão-galego, limão-tahiti; Spanish: limón agrio, limón ceutí, lima, lima

mejicana, limero.

Citrus limonum

Arabic: laimon hamidh; Chinese: li meng, ning meng; English: lemon; French: Citronnier, lemonier; German;

Zitrone; Italian: limone; Portuguese: Limão, limoeiro-azedo, limão-eureka, limão-gênova, limão-siciliano,

limão-verdadeiro, limoeiro; Spanish: limón, limonero.

Citrus medica

Arabic: Raranj, Trunj; Chinese: fo shou gan, xiang yuan; English: Buddha's-Hand, citron, etrog

citron, finger citron flesh-finger citron, small citron; French; cédrat, cédratier, main de Bouddha, sarcodactyle;

German: Buddhafinger, gefingerte Zitrone, medischer Apfel, Zitronatzitrone; Italian: cedrato; Japanese:

bushukan; Portuguese: cidra, cidreira; Spanish: cidro; toronja; Swedish: etrogcitron, fingercitron,

suckatcitron.

Citrus medica var limetta

Arabic: noomi helo, laimon helo; English: Mediterranean limetta, Mediterranean lumia, Mediterranean sweet

lemon, Sweet lemon, Sweet lime; French: Limette à mamelon, Limette d'Italie, Limette douce de Tunisie,

Limettier à fruits doux, Limettier doux, Limonette; German:: Süße Zitrone; Italian: Limetta, Limetta, dolce

Nutritional value and pharmacological importance of citrus species

romana Limoncella patriarca; Japanese: Suiito remon, Rimetta, Rimetta oodineeru. Portuguese: Lima de

bico; Spanish: Limeta dulce de Túnez, Limón dulce, Limonero dulce.

Citrus sinensis:

Arabic: Burtaqal; Chinese: tian cheng English: blood orange, navel orange, orange, sweet orange, Valencia

orange; French: Navel, orange douce, oranger, oranger doux, sanguine; German: Apfelsine, Apfelsinenbaum,

Orange, Orangenbaum; Italian: arancio dolce; Portuguese: laranja-doce, laranjeira, laranjeira-doce, laranja-

amarga, laranja-azeda, laranja-bigarade, laranja-da- terra, laranja -de-sevilha; Spanish: naranja, naranjo

duce.

Distribution:

The primitive center of origin of citrus species has been a subject of speculation and discussion for

some time. The most recent research indicates an origin in Australia, New Caledonia and New Guinea. Some

researchers believe that the origin is in the part of Southeast Asia bordered by Northeast

India, Burma (Myanmar) and the Yunnan province of China(3-4). Now, a worldwide cultivation and high-

demand production for citrus fruit make it stand high among fruit crops. Growth of the citrus industry,

including rapid development of the processing technology of frozen concentrated orange juice after World War

II, has greatly expanded with international trade and steadily increased consumption of citrus fruits and their

products during the past several decades. Because of distinct aroma and delicious taste, citrus fruits have been

recognized as an important food and integrated as part of our daily diet, playing key roles in supplying energy

and nutrients and in health promotion. Citrus fruits are characterized by low protein and very little fat content,

citrus fruits supply mainly carbohydrates, such as sucrose, glucose, and fructose. Fresh citrus fruits are also a

good source of dietary fiber, which is associated with gastrointestinal disease prevention and lowered

circulating cholesterol. In addition to vitamin C, which is the most abundant nutrient, the fruits are a source of B

vitamins (thiamin, pyridoxine, niacin, riboflavin, pantothenic acid, and folate), and contribute phytochemicals

such as carotenoids, flavonoids, and limonoids. These biological constituents are of vital importance in human

health improvement due to their antioxidant properties, ability to be converted to vitamin A (for example, β-

cryptoxanthin), and purported protection from various chronic diseases. All these characteristics enhanced

worldwide citrus fruit cultivation (53).

Traditional uses:

Citrus aurantifolia

Citrus aurantifolia was used traditionally as laxative, appetizer, stomachic, digestive, anthelmintic,

dyspepsia, flatulence and helmenthiasis(55). Citrus aurantifolia was also used for cold fevers, sore throats,

sinusitis and bronchitis, as well as helping asthma. Its oil is mainly used as antidepressant because it promoted

refreshment to the tide mind. It can be helpful for rheumatism arthritis, obesity and has an astringent and toning

action to clear oily skin and acne, in the treatment of herpes, cuts and insect bites(56-57).

Citrus limonum

Lemon juice is widely known as diuretic, antiscorbutic, astringent, and febrifuge. In Italy, the

sweetened juice is given to relieve gingivitis, stomatitis, and inflammation of the tongue. Lemon juice in hot

water has been widely advocated as a daily laxative and preventive of the common cold, but daily doses have

been found to erode the enamel of the teeth. Prolonged use will reduce the teeth to the level of the gums. Lemon

juice and honey, or lemon juice with salt or ginger, is taken as a cold remedy(58).

Citrus medica

In traditional medicine, ripe fruits were used in sore throat, cough, asthma, thirst, hiccough, earache,

nausea, vomiting, anti scorbutic, stomachic, tonic, stimulant, expellant of poison, correct fetid breath; distilled

water of the fruit was sedative, fruits and seeds were cardiac tonic and used in palpitation, fruit decoction is

analgesic. Roots, flowers, seeds, peels and leaves were used in many ailments. The fruit wrapped in cloth was

used to protect clothes from moths indicating its insect repellent activity. In ancient literature, citron was

mentioned as an antidote for various kinds of poison(58-62).

Citrus medica var limetta

Citrus medica var limetta fruit and leaves were used for healing of common cold, control of blood lipids, for

the treatment of fever, regulation of inflammatory and digestive disorders and as a blood pressure modulator(63-

64).

Citrus sinensis

Oranges were eaten to allay fever and catarrh. The roasted pulp was prepared as a poultice for skin

diseases. An infusion of the immature fruit was taken to relieve stomach and intestinal complaints. The flowers

were employed medicinally by the Chinese people living in Malaya. Orange flower water, made in Italy and

Nutritional value and pharmacological importance of citrus species

France as antispasmodic and sedative. A decoction of the dried leaves and flowers was given in Italy as an

antispasmodic, cardiac sedative, antiemetic, digestive and remedy for flatulence. The inner bark, macerated and

infused in wine, was taken as a tonic and carminative. Decoction of husked orange seeds was prescribed for

urinary ailments in China and the juice of fresh orange leaves or a decoction of the dried leaves was taken as a

carminative or emmenagogue or applied on sores and ulcers. An orange seed extract was given as a treatment

for malaria in Ecuador but it was known to cause respiratory depression and a strong contraction of the

spleen(58,65).

Description:

Tree growth and form varies depending on the species and genetic background and whether

the tree was established by seed or grafting. Trees produced from seed tend to have more thorns and

upright branch growth than trees produced from grafting.

Flowers are 2–4 cm (0.8–1.6 in) in diameter, axillary, fragrant, single, few or cymose, and often

perfect (having both functional stamens and pistils) or staminate. The calyx is 4–5 lobed and there are

usually five petals with oil glands. Stamens number between 20 and 40. Petal colors range from white

to pinkish in Kafr lime to pinkish to purplish externally in citron and reddish in lemon varieties. The

subglobose ovary is superior, with 8–18 locules (cavities), with 4–8 ovules per locule in two rows.

Leaves are entire, 4 to 8 cm (1.6–3.2 in) in length, unifoliate, fairly thick, with winged

petioles. Leaves are ovate, oval or elliptical, with acute to obtuse tips, and glands containing oils in

glands, which are released when crushed. Young twigs are angled in cross-section, green, and axillary

single-spined, while older twigs and branches are circular in cross-section and spineless.

The fruit is a hesperidium, a feshy, indehiscent berry that ranges widely in size, color,

shape, and juice quality. Citrus fruit range in size from 4 cm (1.6 in) for lime to over 25 cm

(10 in) in diameter for pummelo. Fruits are globose to ovoid in shape. The feshy endocarp is divided

into 10–14 sections containing the stalked pulp and separated by thin septa. Each section contains pulp

(juice vesicles) that contains a sour or sweetish watery juice.

Seeds are pale whitish to greenish, fattened, and angular. The seeds are usually polyembryonic,

meaning they have multiple embryos that can germinate. The embryos are either (zygotic) or (nucellar).

The zygotic embryos are derived from pollination of the ovary, sexual reproduction. The nucellar

embryos are derived wholly from the mother plant and display very similar characteristics to the parent

plant(66-68).

Chemical constituents:

Citrus essential oils were obtained from the citrus fruits peel’s sacks. They were used by the food

industry to give flavor to drinks and foods. They were also used in the pharmaceutical industry for the

preparation of drugs, soaps, perfumes and other cosmetics as well as for home cleaning products(69-70). The

pericarp (rind) of Citrus aurantiifolia contained 7 percent essential oil. The major compounds were D-

limonene, D-dihydrocarvone, verbena, β-linalool, α-terpinol, trans- α –bergamotene, citral, fenchon , as well

as terpineol, bisabolene, and other terpenoids(71-72). However, a total of 46 compounds were identified from

the Citrus aurantiifolia oil. Most of these were terpenes, which were found in greater amounts than

sesquiterpenes, aldehydes, ketones, phenols, and free acids. Alcohols and some terpenes show higher

percentage areas in the maturity stages. D-limonene showed a concentration level higher than 70%, followed by

bergamol (8%), β-pinene (7.62%), linalool (2.89%), α-pinene (0.82%). The isolated compounds were

included, α-Pinene, Camphene, β-Pinene, Sabinene, β-Myrcene, d-Limonene, Nonanal, (Z) Sabinene hydrate,

Nonane, Undecanal, Linalool, Camphor, Bergamol, Trans-α-bergamotene, Aromadendrene, Terpinen-4-ol,

Epi-β-santalene, Trans-sabinene hydrate, Farnesol, Isopinocarveol, Terpineol acetate, α-Terpineol, Neryl

acetate, Neral, Geranyl acetate, Geranial, Cis-geraniol, 1-Cyclohexen-1, -methanol 4-1 methylenil acetate, Octal

cyclopropene, Cis-myrtanol, Perillal, 2-Tridecen-1-ol, 3-Cyclohexen-1-ol, Cyclohexyl-dodecane, Bicyclo(2,2,1)

Heptane, 2,2diethyl-3-methyl P-menth-1-en-8-ol, β-Bisabolol, Carveol, α-Farnesene, α-Bisabolol, β-Farnesene,

Trans-β-santalol, α-Santalol, Isopropyl palmitate, β-Santalene and Cyclopropamethanol(73).

Constituents of leaf essential oil of Citrus medica L. and their percentage were:

Limonene 18.36, 7-Oxabicyclo[4.1.0] heptane, 1-methyl-4-(1-methylethenyl)- 1.18, 6-Octenal, 3,7-

dimethyl- 4.39 Cyclohexanone, 2-methyl-5-(1-methylethenyl)- 2.24, 1-Monolinoleoylglycerol trimethylsilyl

ether 0.86, 6-Octen-1-ol, 3,7-dimethyl- 1.72, n-pentyl(1-propenyl)dimethylsilane 0.82, citral 12.95, 2-Octen-

1-ol, 3,7-dimethyl-, isobutyrate, (Z)- 1.10, 2-Oxocycloheptyl acetate 0.87, 2,4-Dodecadienoic acid, 11-

methoxy-3,7,11-trimethyl-, methyl ester, (E,E)- 1.22, Methoprene 3.51, Geranyl methyl ether 1.42, 13-

Heptadecyn-1-ol 1.05, 1,2-Cyclohexanediol, 1-methyl-4-(1-methylethenyl)- 3.98, 2,6-Octadien-1-ol, 3,7-

dimethyl-, acetate, (Z)- 5.23, Mehp 8.96, 3,7-Nonadien-2-ol, 4,8-dimethyl- 1.16, Erucylamide 28.43. While,

the constituents of peel essential oil of Citrus medica L. and their percentage were: (1R)-2,6,6-

Nutritional value and pharmacological importance of citrus species

Trimethylbicyclo[3.1.1]hept-2-ene 0.14, α-Pinene 0.41, 3-Octyn-2-ol 0.10, β-Myrcene 2.70, 2-Acetyl-5-

methylfuran 0.05, Cyclooctyl alcohol 0.17, Limonene 21.78, Isolimonene 39.37, 1,3,6-Octatriene, 3,7-

dimethyl-, (Z)- 0.43, 1-Heptanol, 3-methyl- 0.04, Linalool 0.94, Nonanal 0.25, trans-p-Mentha-2,8-dienol

0.04, 7-Oxabicyclo[4.1.0]heptane, 1-methyl-4-(1-methylethenyl)- 0.41, citral 23.12, 6-Octenal, 3,7-dimethyl-

0.29, cis-Verbenol 0.09, Carane, 4,5-epoxy-, trans 0.30, 1,2-Cyclohexanediol, 1-methyl-4-(1-methylethyl)-

0.03, 4-Terpineol 0.08, Terpinyl acetate 0.16, β-Terpinyl acetate 0.52, Decanal 0.33, Neryl acetate 2.51,

Neryl Alcohol 2.25, Undecanal 0.10, Neryl acetate 0.60, Dodecanal 0.08, (Z,E)-α-Farnesene 0.05,

Caryophyllene 0.59, α-Bergamotene 0.48, 1,6,10-Dodecatriene, 7,11-dimethyl-3-methylene-, (Z)- 0.04,

Tetrakis(trimethylsiloxy)silane 0.04, α-Caryophyllene 0.08, Germacrene D 0.05, cis-.α-Bisabolene 0.07, γ-

Elemene 0.05, β-Bisabolene 0.71, δ-Cadinene 0.05, Tetradecanal 0.10, Neoisolongifolane, hydroxy- 0.07, β-

Bisabolol 0.12 and n-Hexadecanoic acid 0.12(74). The volatile fraction of every sample of Citrus medica oil

characterized by a high content of limonene, γ-terpinene, and monoterpene aldehydes and a lower content of α-

and β-pinene and myrcene, sesquiterpenes, and aliphatic aldehydes. GC analysis of the extracts allowed the

determination of the enantiomeric distribution of five terpenoid compounds; a prevalence of four dextrorotatory

isomers was observed. Oxypeucedanin was the main component of the oxygenated heterocyclic fraction in the

extracts of green fruits, while citropten was the major oxygenated compound in the oil obtained from yellow

citron(75).

Eleven constituents were identified from Citrus limonum leaves essential oils. Citronellal ( 29.31

%), limonene (17.59 %), (E)-citral (12.71 %), 1,6-octadien-3-ol,3,7- dimethyl (10.91 %), biocyclo [3.1.0]

hexane, 4-mehylene-1-(1-methyl) (8.80 %), 6-octen-1-ol,3,7-dimethl (7.95 %), 2,6-octadien-1-ol,3,7-dimethyl-,

acetate, (Z) (6.29 %), 1,3-cyclohexadiene,5-(1,5-dimethyl-4-hexenyl)-2-methyl, [S(R,S)] (2.81 %),

cyclohexene,3-(1,5-dimethyl-4-hexenyl)-6-methylene-, [S-(R,S)](1.64 %), bezene,1-(1,5-dimethyl-4-hexenyl)-

4-methyl (1.10 %) and cyclohexene,1-methyl-4-(5-methyl-1-methyl-1-methylene-4-hexenyl)-,(s) (0.88 %)(75-77).

Hydro distillation of the peels of Citrus limetta yielded 0.313% oil. Gas chromatographic analysis

identified 17 constituents among which limonene (95.98 %) was found as major component followed by

camphene (1.79 %), while the remaining terpenes were less than 1%. However, the chemical composition of

essential oil of Citrus limetta and their percentage were: α-hujene 0.0688, α -pinene, 0.0381, β-pinene 0.0299,

ρ-cymene 0.3861, Camphene 1.7865, Limonene 95.9768, α -terpinene, 0.3337, Neral 0.2907, Geraniol

0.3641, Geranial 0.0315, Citronellal 0.0951, α - terpinol, 0.3191, α -humulene, 0.0511, β-bisabolene 0.1276

and β-sinesol 0.0268(78-80).

Citrus sinensis fruit contains 1.5% essential oil. The components of fruit peel of Citrus sinensis and their

percentage were: Octane 8.37 , 4-Methylthiazole 0.14 , n-Nonane 0.2, α-Pinene 6.65, Sabinene 6.50,

Myrcene 17.55, n-Octanal 0.19, α-Phellandrene 0.33, iso-Sylvesteren 1.14, Limonene 61.34, E-β-Ocimene

0.5, γ-Terpinene 0.5, Linalool 1.84, α-Thujene 2.31, trans-Limonene oxide 0.18, Citronellal 0.29, Decanal

1.40, β-Elemene 0.08, Tetradecane 0.2 1, β-Caryophyllene 0.1, Valencene 0.48, Pentadecane 0.2 and

Hexadecane 0.2(80-81).

Nutritional analysis of Citrus aurantifolia, Citrus limonum, Citrus sinensis and Citrus medica (per 100g of

edible portion) showed that they contained: moisture: 84.6, 85.0, 88.4, 87.1 g, protein: 1.5, 1.0, 0.8, 0.081 g ,

fat: 1, 0.9, 0.3, 0.04 g, fiber: 1.3, 1.7, 0.5, 1.1 g, carbohydrates: 10.9, 11.1, 9.3, 6.9 g, minerals:0.7, 0.3, 0.7,

0.3 g, Iron: 0.3, 2.3, 0.7, 0.55 mg, Carotene 15,0, 0, 0.009 μg, and Energy, 59,57, 43 and 30 Kcal

respectively(58,69,82).

Phytochemical analysis showed that Citrus aurantifolia, Citrus limonum and Citrus sinensis fruits

contained: alkaloids: 0.33 ±0.11, 0.54 ±0.20, 0.62 ±0.10; flavonoids: 0.29 ±0.20, 0.57 ±0.10, 0.19 ±0.20;

tannins: 0.04 ±0.11, 0.01 ±0.10, 0.04 ±0.11; phenols: 0.02 ±0.10, 0.05±0.11, 0.01 ±0.10; and saponins: 0.22

±0.30, 0.42 ±0.10, 0.08 ±0.10 mg/ 100g dry weight respectively(69,83).

Citrus flavonoids, coumarins, psoralens and carotenoids composition were:

Citrus sinensis flavonoids: [Flavanones (Didymin 1.89%, Eriocitrin 0.31%, Hesperidin 28.6%, Narirutin

5.2%); Flavones (Neoeriocitrin 0.59%, Poncirin 1.04%, 6,8-di-C-Glu-Apigenin 5.72%, 6,8-di-C-Glu-

Diosmetin 0.35%, Rhoifolin 0.05%, Isorhoifolin 0.07%, Diosmin 0.09%, Neodiosmin 0.08%);

Polymethoxyflavones (Heptamethoxyflavone 0.08%, Nobiletin 0.33%, Sinensetin 0.37%, Tangeretin 0.04%)

and Aglycones( Taxifolin 0.03%, Acacetin 0.03%)]. Coumarins and psoralens: (auraptenol, scoparon,

xanthyletin). carotenoids: (Phytoene, phytofluene, β -carotene, β -carotene, cryptoxanthin, lutein,

antheraxanthin, mutatoxanthins, violaxanthin, luteoxanthins, auroxanthins).

Citrus limon flavonoids: [Flavanones (Eriocitrin 16.7%, Hesperidin 20.5%); Flavones (6,8-di-C-Glu-

Apigenin1.17%, 6,8-di-C-Glu-Diosmetin 4.95%, 7-O-Rut-Luteolin 3.93%, Diosmin 3.12%),

Aglycones (Luteolin 0.08%)].Coumarins and psoralens: (Bergapten, bergamottin, byakangelicin, citropten,

imperatorin, isoimperatorin, isopimpinellin, phellopterin, prangol, scoparon, scopoletin, umbelliferone,

umbelliprenin, xanthyletin). Carotenoids: (Phytofluene, β-carotene, cryptoxanthin, violaxanthin, auroxanthin).

Nutritional value and pharmacological importance of citrus species

Citrus medica flavonoids: (hesperidin, eriocitrin, rutin and diosmin and naringin). Coumarins and psoralens:

(citrumedin-B, bergapten and citropten). Citrus medica also contained 5-methoxy furfural, 5-hydroxy-2-

hydroxymethyl-4H-pyran-4-one, diosmetin, diosmin, obacunone, aviprin, 3-(3-methoxy-4-hydroxyphenyl)-

acrylic acid, vanillic acid and 3,4-dihydroxy-benzoic acid.

Citrus limmeta flavonoids: (hespiridin, naringin). However, peels of Citrus limmeta contained eighty-five

compounds, including three abscisic acid derivatives, five limonoid glycosides, twenty-six dihydro-cinnamic

and cinnamic acid glycosides, eleven flavanone glycosides, seven flavone glycosides, seventeen flavonol

glycosides, including limocitrol and limocitrin derivatives.

Citrus aurantifolia flavonoids: [Flavanones (Eriocitrin 0.29%, Hesperidin 1.77%, Neoeriocitrin 0.01%);

Flavones (Diosmin 0.08%), Polymethoxyflavones (Heptamethoxyflavone 0.12%, Natsudaidain 0.04%,

Nobiletin 0.52%, Tangeretin 0.18%); Aglycones (Taxifolin 0.04%, Luteolin 0.61%)] (69,84-89).

The favonoids contents of Citrus juice were included: Flavonoid composition of Citrus aurantifolia juice

(mg/100 ml): Flavanones (Eriocitrin 0.29, Hesperidin 1.77, Neoeriocitrin 0.01); Flavones (Diosmin 0.08);

Polymethoxyflavones (Heptamethoxyflavone 0.12, Natsudaidain 0.04, Nobiletin 0.52,Tangeretin 0.18);

Aglycones (Taxifolin 0.04, Luteolin 0.61). Flavonoid composition of Citrus limon juice (mg/100 ml):

Flavanones (Eriocitrin16.7, Hesperidin 20.5); Flavones ( 6,8-di-C-Glu-Apigenin 1.17, 6,8-di-C-Glu-Diosmetin

4.95, 7-O-Rut-Luteolin 3.93, Diosmin 3.12); Aglycones (Luteolin 0.08). Flavonoid composition of Citrus

sinensis juice (mg/100 ml): Flavanones ( Didymin 1.89, Eriocitrin 0.31, Hesperidin 28.6, Narirutin 5.2);

Flavones (Neoeriocitrin 0.59, Poncirin 1.04, 6,8-di-C-Glu-Apigenin 5.72, 6,8-di-C-Glu-Diosmetin 0.35,

Rhoifolin 0.05, Isorhoifolin 0.07, Diosmin 0.09, Neodiosmin 0.08); Polymethoxyflavones

(Heptamethoxyflavone 0.08, Nobiletin 0.33, Sinensetin 0.37, angeretin 0.04); Aglycones (Taxifolin 0.03,

Acacetin 0.03)(34).

Flavonoid content of Citrus aurantifolia roots, stem, stem bark, leaves and peels were 0.64±0.40,

0.33±0.01, 0.42±0.01, 0.06±0.07 and 0.51±0.02 % respectively. While, the flavonoid content of Citrus limon

roots, stem, stem bark, leaves and peels were 0.60±0.01, 0.34±0.02, 0.47±0.01, 0.65±0.03 and 0.48±0.01%

respectively. Citrus sinensis roots, stem, stem bark, leaves and peels showed 0.63±0.01, 0.29±0.01, 0.38±0.05,

0.63±0.03 and 0.35±0.01% flavonoids content respectively(90).

Although pectin occurs in a majority of plant cell walls, it was most abundant in citrus (lime, lemon,

grapefruit, and orange) fruits. The structure of pectin was primarily composed of repeating units of galacturonic

acid joined by a 1→ 4 glycosidic linkages, which create a linear polymer. The regular linear structure was

interrupted by the presence of neutral sugar side chains. Furthermore, the carboxyl groups of galacturonic acid

may either remain as free acids, be esterified with methanol, or be neutralized with cations. The chemical

structure of pectin varies by fruit species and also during the different developmental stages of the fruit(91).

Mineral contents of Citrus aurantifolia, Citrus limonum and Citrus sinensis were: phosphorus

0.29,0.38, 0.41; potassium 1.0, 0.37, 0.82; magnesium 0.36, 0.33, 0.33; sodium 0.36, 0.33, 0.33 and calcium

2.81, 2.0 and 0.2 g/100g respectively(83).

Vitamin contents of Citrus aurantifolia, Citrus limonum, Citrus sinensis and C. medica fruits were: ascorbic

acid: 22.88, 61.60, 19.36, 368; thiamin: 0.11, 0.88, 0.06, 0.052; riboflavin: 0.04, 0.02,0.11, 0.029 and niacin:

0.03, 0.14, 0.38 and 0.125 mg/ 100g respectively(58, 82-83).

In citrus species, limonoids, limonoids were produced in leaves and transported to fruit and seeds,

with limonoid concentration highest in the earliest stages of growth of leaves and fruit and highest in seeds

during fruit growth and maturation. In leaves and fruit, total limonoid content increases during growth and

maturation and decreases after maturation. In contrast, limonoid concentration does not decrease in seeds after

fruit maturity, indicating that seeds act as storage tissues for these compounds(92).

Although pectin occurs in a majority of plant cell walls, it was most abundant in citrus (lime, lemon,

grapefruit, and orange) fruits. The pectin was composed of repeating units of galacturonic acid joined by a 1→

4 glycosidic linkages, which create a linear polymer. The regular linear structure is interrupted by the presence

of neutral sugar side chains. Furthermore, the carboxyl groups of galacturonic acid may either remain as free

acids, be esterified with methanol, or be neutralized with cations. The chemical structure of pectin varies by

fruit species and also during the different developmental stages of the fruit(91).

Organic acid contents of Citrus aurantifolia, Citrus limonum and Citrus sinensis juices were: oxalic acid:

0.109, 0.094, 0.110; tartaric acid 0.336, 0.073, 0.012; malic acid 1.516, 1.465, 5.183; lactic acid: 1.857, 1.545,

0.915; citric acid 13.918, 73.936, 61.497 and ascorbic acid 0.636, 0.718 and 0.354 g/l respectively(93).

Pharmacological effects:

Citrus fruits, are one of the main fruit tree crops grown throughout the world. Although sweet orange

(Citrus sinensis) is the major fruit in this group accounting for about 70% of citrus output. The group also

encompasses other citrus fruits such as Citrus reticulata, Citrus vitis, Citrus aurantifolia, Citrus medica and

Citrus limonum(69).

Nutritional value and pharmacological importance of citrus species

Antimicrobial effect:

The antibacterial potential of the leaf essential oil and petroleum ether, chloroform, ethyl acetate and

methanol extracts of the leaves of Citrus aurantifolia were studied against human pathogenic bacteria (Bacillus

cereus, Enterobacter faecalis, Salmonella paratyphi, Staphylococcus aureus, Escherichia coli, Proteus vulgaris,

Klebsiella pneumoniae, Pseudomonas aeruginosa and Serratia marcescens) by agar well diffusion method.

Leaf essential oil as well as ethyl acetate, chloroform and methanol extracts of Citrus aurantifolia leaves

exhibited pronounced activity against Gram-positive and Gram-negative bacteria and their activity was quite

comparable with the standard antibiotics such as tobramycin, gentamicin sulphate, ofloxacin and ciprofloxacin

screened under similar conditions(94).

Studying of the antibacterial effect of varieties of citrus available in Malaysian (Citrus aurantifolia,

Citrus reticulata, Citrus microcarpa, Citrus limon and Citrus sinensis) against Streptococcus pyogenes,

Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa showed that the methanol extract of

the five varieties of citrus exerted no inhibition at 5 and 10 mg/ml. The methanol extract of Citrus microcarpa,

Citrus reticulata and Citrus sinensis at 20 mg/ml showed better inhibition compare to Citrus aurantifolia and

Citrus limon against Staphylococcus aureus and Escherichia coli(95).

Citrus sinensis, Citrus limon, and Citrus aurantifolia fruit peel extracts were investigated against

gastrointestinal pathogens. Citrus aurantifolia and Citrus limon showed high zone of inhibition against

Shigella Spp., and E. coli strains. Whereas Citrus aurantifolia was effective against Salmonella Spp(96).

The antimicrobial potency of Citrus aurantifolia was studied against many bacterial and fungal pathogenes, in

the different forms [juice of the fruit, burnt rind of the fruit commonly known as (epa-ijebu) in the Yoruba

dialect, and the oil obtained from steam distillation of the fruit]. Antimicrobial activity was carried out by the

agar well diffusion. The clinical isolates used included Anaerobic facultative bacteria, namely: Staphylococcus

aureus ATCC 25213, Staphylococcus aureus, Salmonella paratyphi, Shigella flexnerii, Streptococcus faecalis,

Citrobacter spp, Serratia spp, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli ATCC

25922, and Escherichia coli; Fungi such as Aspergilus niger and Candida albicans; and Anaerobes which

includes Bacteroides spp, Porphyromonas spp, and Clostridium spp. Crude extracts of all solvents used varied

in zones of inhibition. The anaerobes and the Gram-positive bacteria were susceptible to all the extracts with

minimum inhibitory concentration (MIC) ranging from 32mg/ml-128g/ml. The antifungal study showed that

only the oil extract was potent against A. niger, while Candida albicans was susceptible to all the extracts with

MIC ranging from 256mg/ml-512mg/ml. The Gram-negatives showed MIC ranging from 64mg/ml-512mg/ml.

Minimum bactericidal concentration (MBC) ranged between 32mg/ml to 512mg/ml depending on isolates and

extracting solvent. The oil and palm-wine extract showed greater activity than the other extracts(97).

The antimicrobial efficacy of leaf extract of Citrus aurantifolia Linn (CA) was evaluated against

some microorganisms - bacteria and fungus (Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia,

Pseudomonas spp, Aspergillus niger, Aspergillus fumigates, Mucor Spp and Pencillium Spp). 100 µl of 10 mg

CA were assessed against eight test microorganisms by agar well diffusion method. A different solvent was

used to obtain CA leaf extract using maceration technique. Due to its high yield value, hydroalcoholic extract of

CA was used for estimating the antimicrobial activity. The study demonstrates that the hydroalcoholic extract of

CA leaf exhibit antibacterial activity on Klebsiella pneumonia, Pseudomonas sp, Staphylococcus aureus and

antifungal activity among Aspergillus niger, Aspergillus fumigates and Mucor species(98).

Citric acid extracted from Citrus aurantifolia was tested as antimicrobial agent. The largest inhibition area of

citric acid was obtained against Escherichia coli, 3.92 cm, and the smallest inhibition area is obtained against

Lactobacillus acidophilus, 2.16 cm(99).

Citrus aurantifolia oils were tested against Mycobacterium tuberculosis. The saturated fatty acid

palmitic acid exhibited higher activity against multidrug-resistant M. tuberculosis strains (MICs = 50 µg/ml)

than the unsaturated fatty acids oleic acid and linoleic acid, which showed less activity (MICs = 100 µg/ml)(100).

The antibacterial activity of Lemon, lime and sudachi juices was studied against seven strains of Vibrio species.

All juices were effective in inhibiting the growth of the Vibrio strains. Citric acid, the major organic acid in

these juices, were found to be responsible for inhibiting the growth of Vibrio parahaemolyticus, whereas the

sauce adjusted to higher pH values had no bacterial activity. Diluted sudachi juice or citric acid solution also

had antibacterial activity independently. The results suggest that citrus fruit juices were effective in preventing

infection with Vibrio species(101).

The effect of essential oils, natural and concentrated lemon juice and fresh and dehydrated lemon peel

was studied against V. cholerae O1 biotype Eltor serotype Inaba tox+. Products were used at different dilutions,

when V. cholerae present at concentrations of 102, 104, 106 and 108 colony forming units (CFU) /ml, and after

different exposure times. Concentrated lemon juice and essential oils inhibited V. cholerae completely at all

studied dilutions and exposure times. Fresh lemon peel and dehydrated lemon peel partially inhibited growth of

V. cholerae. Freshly squeezed lemon juice, diluted to 10-2, showed complete inhibition of V. cholerae at a

concentration of 108 CFU/ ml after 5 min of exposure time; a dilution of 2 x 10-3 produced inhibition after 15

min and a dilution of 10-3 after 30 min(102).

Nutritional value and pharmacological importance of citrus species

The antibacterial activity of crude extracts (aqueous and ethanolic) of Citrus limonum fruits against

four wound isolates Staphylococcus sp, Pseudomonas sp, Escherichia coli and Klebsiella sp. showed that they

exerted antibacterial activity with diameter of inhibition zone of 20, 18, 20 and 15 mm for ethanolic extract,

and 15, 20, 11, and 10 mm for aqueous extract respectively(103).

The potential inhibitory effect of Citrus lemon and Citrus sinensis on lipophilic, yeast like fungus Malassezia

furfur which causes Pityriasis versicolor, chronic superficial fungal disease of the skin have been studied using

two different methods (Disc diffusion and microdilution methods). In screening of lemon and orange oil by disc

diffusion method, the diameters of inhibition zone were found to be 50 and 20 mm which were greater than

inhibition zone of reference antibiotics, gentamycin 16.5mm and streptomycin 17 mm. Minimum inhibitory

concentrations (MIC) of lemon and orange oil against M. furfur were found to be 0.8 and 2.2 μl/ml(104).

The antimicrobial activity of Citrus lemon was studied in vitro. The citrus peel oils show strong

antimicrobial activity. The antimicrobial activity has been checked in terms of MIC by using different solvents

against microorganisms like Pseudomonas aeruginosa NCIM 2036 for which MIC was 1:20 by methanol

extract, for Salmonella typhimurium NCIM 5021 the observed MIC was 1:20 by acetone extract. While, for

Micrococcus aureus NCIM 5021 the observed MIC was 1:20 by ethanol extract(105).

The antimicrobial activity of different types and parts of lemon was evaluated against different

microbial isolates. The antimicrobial effects of aqueous extracts of peel and juice from fresh and dried citrus

and sweet lemon were evaluated against 6 Gram-positive and 8 Gram-negative bacterial and one yeast isolates,

including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Enterococcus faecalis,

Streptococcus pneumoniae, Streptococcus agalactiae, Pseudomonas aeruginosa, Enterobacter aerogenes,

Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, Proteus spp., Moraxella catarrhalis, Acinetobacter

spp. and Candida albicans.The water extracts of all the materials showed various inhibitory effects. The juice

of Citrus limon has antimicrobial activities more than other types of extracts. Escherichia coli, Staphylococcus

epidermidis, Streptococcus agalactiae and Candida albicans showed the highest resistance to these extracts.

Lemon species might have antimicrobial activity against different Gram-positive, Gram-negative and yeast

pathogens and could be used for prevention of various diseases caused by these organisms(106).

The effects of Citrus limonum essential oils (EO) compared to 0.2% chlorhexidine (CHX) and 1%sodium

hypochlorite (NaOCl) was studied in multispecies biofilms formed by Candida albicans, Enterococcus faecalis

and Escherichia coli. The biofilms were grown in acrylic disks immersed in broth, inoculated with microbial

suspension (106 cells/ml) and incubated at 37°C /48 h. After the biofilms were formed, they were exposed for 5

minutes to the solutions: Citrus limonum EO, 0.2% CHX, 1% NaOCl or sterile saline solution. The discs were

placed in sterile 0.9% NaCl and sonicated to disperse the biofilms. Tenfold serial dilutions were performed and

the aliquots were seeded onto selective agar and incubated at 37C / 48 h. Next, the number of colony-forming

units per milliliter was counted and analyzed statistically (Tukey test, p <0.05). Citrus limonum EO promoted a

100% reduction of C. albicans and E. coli, and 49.3%of E. faecalis. CHX was less effective against C. albicans

and E. coli, yielding a reduction of 68.8% and 86.7%, respectively. However, the reduction of E. faecalis using

CHX (81.7%) was greater than that obtained using Citrus limonum EO. Citrus limonum EO was effective in

controlling multi-species biofilms; the microbial reductions achieved by EO were not only similar to those of

NaOCl, but even higher than those achieved by CHX, in some cases(107).

The antibacterial activity of Citrus limon was studied against Acne vulgaris. Citrus limon juice was

used at different concentrations of (20%, 40%, 60%, 80% and 100%) on Propioni bacterium acne. The Citrus

limon juice was found to be effective at all concentrations used(108).

Essential oil from the fresh leaf of Citrus medica L. var. sarcodactylis possessed strong antimicrobial

activity against Staphylococcus aureus and Bacillus subtilis (MIC 2,500 ppm). However, the antimicrobial

efficiency of essential oil from this plant was much lower (about 40%) than that of tetracycline solution at the

same concentration(109).

The antibacterial effect of the peels of Citrus medica was evaluated on Staphylococcus aureus

MTCC96, Escherichia coli MTCC739, Proteus vulgaris MTCC426, Bacillus subtilis MTCC441, Klebsiella

pneumonia MTCC109 and Pseudomonas aeruginosa MTCC424. The solvent used for the extraction of plants

was water ethanol. The in vitro antibacterial activity was performed by agar cup method. The most susceptible

Gram-positive bacteria were Staphylococcus aureus while the most susceptible Gram-negative bacteria was

Klebsiella pneumonia and Pseudomonas aeruginosa. The antibacterial activity of active extract was compared

with the standard antibiotic, streptomycin (100 ppm)(110).

Antimicrobial activity of fruit juice and ethanolic extracts of root, leaf, bark, peel and pulp of Citrus medica

were examined against seven bacteria (Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis,

Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Proteus vulgaris), two fungi

(Aspergillus flavus and A. niger) and a yeast Candida albicans of clinical origin. The antimicrobial effects were

studied using an in vitro disc diffusion method; minimum inhibitory concentrations (MIC) and minimum

bactericidal concentrations (MBC) were determined by standard agar dilution method. All extracts and fruit

juice showed varied level of antibacterial activity against one or more test bacteria. Root, leaf and bark extracts

Nutritional value and pharmacological importance of citrus species

inhibited S. aureus, E. faecalis and P. vulgaris with maximum inhibition by root extract comparable to standard

antibiotic. Fruit peels have shown least activity among all extracts and slightly inhibited growth of S. aureus, K.

pneumoniae and P. vulgaris. The yeast C. albicans was not inhibited by any extract. Among bacteria S. aureus

and P. vulgaris were highly susceptible to all extracts while B. subtilis was highly resistant and inhibited by

only fruit juice. Root extract had the lowest MIC 0.5mg/ml and MBC 1mg/ml against S. aureus. The maximum

MIC of extracts was 50 mg/ml and MBC 75 mg/ml. The minimum MIC of juice was < 1% and MBC 1%

against P. vulgaris while maximum MIC was 3.5% and MBC 7%. Antifungal activity was shown by only root

extract and fruit juice while C. albicans was resistant to all tested samples(111).

The antimicrobial activity against the selected bacteria and fungi was observed for the alcoholic

extract of Citrus medica , it was found active against all the tested bacteria and fungi (Enterobacter aerogenes,

Staphylococcus aureus,Bacillus subtilis, Proteus vulgaris, Klebsiella pneumoniae, Shigella flexneri,

Chryseobacterium gleum and fungi Candida albicans, Aspergillus niger and Aspergillus flavus). The maximum

antibacterial activity was shown against Staphylococcus aureus (6.3 mm) by methanolic extract, whereas the

maximum antifungal activity was shown against A. niger (6.3 mm) and minimum activity was shown against

A. flavus (3 mm)(112).

The antibacterial investigation of crude extracts (aqueous and ethanolic) of fruits of Citrus medica

var limetta against four wound isolates Staphylococcus sp, Pseudomonas sp, Escherichia coli and Klebsiella

sp., showed that they exert antibacterial activity with diameter of inhibition zone of 10, 12, 10 and 10 mm for

ethanolic extract, and 8, 9, 8 and 9 mm for aqueous extract respectively(113).

The aqueous extract of the peels of C. limetta produced a good antimicrobial activity against 15

isolates, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Enterococcus faecalis,

Streptococcus pneumoniae, Streptococcus agalactiae, Pseudomonas aeruginosa, Enterobacter aerogenes,

Klebsiella pneumoniae, Escherichia coli, Salmonella typhi, Proteus spp., Moraxella catarrhalis, Acinetobacter

spp. and Candida albicans, with inhibition zones ranged (from 10 to 35mm) against Gram-positive or Gram-

negative bacteria with no activity against Candida(106).

The results of antimicrobial activity of peel essential oil of Citrus limetta var. Mitha tested by disc

diffusion method, against different against bacteria and fungi showed that it exhibited maximum zone of

inhibition against Bacillus cereus ATCC 14579 (28 mm) and Bacillus subtilis ATCC 6633 (26 mm) followed

by Staphylococcus aureus ATCC 25923 (21 mm), whereas the minimum zone of inhibition was shown by

Fusarium oxysporum ATCC 48122 (11 mm) after 48 h of incubation at their respective temperature (37°C for

bacteria and 25°C for fungi). The inhibition zones, measured after 48 and 96 h, showed that it was active against

all the tested bacteria and fungi(79).

The anti typhoid activity of aqueous extract of fruit peel Citrus sinensis was studied in vitro. The

aqueous extracts of fruit peel Citrus sinensis exhibited antityphoid activity against Salmonella typhi,

Salmonella paratyphi A and Salmonella paratyphi B(113).

The antibacterial activity of aqueous and ethanol extracts of Citrus sinensis leaves was evaluated

aginst Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus. The in

vitro antibacterial activity was performed by agar disc diffusion method. The aqueous extract showed a zone of

inhibition against Escherichia coli (7mm), while on the other organisms it showed little or no zones of

inhibition ranging from 0-3mm in diameter. The ethanol extract also showed little zones of inhibition against

the tested organisms ranging from 1-3mm in diameter(114).

The peels were air-dried and ground to powder, extracted with 95% ethanol. The extract was subjected

to antibacterial study against six Salmonella paratyphi B, one Salmonella typhi and three Aeromonas

hydrophila. Agar diffusion method was employed to test the antibacterial activity of the extract and the MIC

and MBC of the extract were determined by broth dilution technique. The results showed that the isolates were

sensitive to the extract, with MIC of 0.25-2.5mg/ml and MBC of 0.5-5.0mg/ml(115).

Peels of Citrus lemon, Citrus sinensis and Citrus limetta were dried and extracted by cold water, hot

water, methanol, ethanol, ethyl acetate and acetone. Extracts were subjected to antibacterial and antifungal

susceptibility assay against (Pseudomonas aeruginosa, Salmonella typhimurium, Micrococcus aureus,

Trichophyton mentagrophytes, Microsporum canis and Candida albicans) by agar well diffusion method. All

the extracts of Citrus lemon were found to be effective against the tested bacterial pathogens except hexane

extracts. Methanol and acetone extract showed maximum zone of inhibition of 18 mm. Only methanol extract

was effective against fungal pathogens showing a zone of inhibition of 18 mm. Hexane extract of Citrus

sinensis was found to be most effective against bacterial pathogens giving a zone of 13 mm. Only the cold water

extract of orange was effective against fungal pathogens. Acetone extract of Citrus limetta was most effective

giving a zone of 20 mm against bacterial pathogens. Only cold water and ethyl acetate extracts of Citrus limetta

were effective against fungal pathogens giving a zone of inhibition of 17mm and 15 mm respectively(116).

The antimicrobial activity of methanolic extract of C. sinensis fruit peel was tested against three bacterial and

two fungal strains using turbidimetric or tube dilution method and paper disc diffusion method. C. sinensis fruit

peel methanolic extract exhibited antibacterial activity against Escherichia coli with minimum inhibitory

Nutritional value and pharmacological importance of citrus species

concentration of 0.78 μg/ ml and minimum bactericidal concentration of 6.25 µg/ml, and appreciable antifungal

activity with minimum inhibitory concentration of 12.5 μg/ml(117).The dried peels of Citrus sinensis were

defated and then were subjected to the methanolic extraction. The methanolic extract obtained was dissolved in

various solvents such as water, methanol, ethanol, chloroform, diethyl ether and were subjected to evaluation of

antitubercular activity against Mycobacterium tuberculosis by Microplate Alamar Blue Assay (MABA) method.

The results concluded that the extract dissolved in water as solvent showed significant activity at 50μgm/ml(118).

The antimicrobial activity of petroleum ether extract of the peels of Citrus sinensis was studied against various

Gram positive organisms (Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis), Gram negative

organisms (Escherichia coli, Pseudomonas vulgaris, Salmonella typhi), and fungal strains (Aspergillus niger,

and Candida albicans). Antimicrobial activity was conducted by the agar well diffusion method. The extract

showed various levels of antimicrobial activity on the tested microorganisms. It was more effective against

Staphylococcus epidermidis, Micrococcus luteus and Pseudomonas vulgaris followed by Salmonella typhi,

Escherichia coli and Candida albicans, while it showed no activity against Bacillus subtilis and Aspergillus

niger(119).

The antmicrobial effects of aqueous extracts of peel, juice and leaves from fresh Citrus sinensis was

evaluated against 3 Gram-positive and 6 Gram-negative bacterial, including S. aureus, S. pyogenes, E. feacalis,

P. aeruginosa, K. pneumoniae, E. coli, S. typhi, Proteus spp., M. catarrhalis. Citrus juices showed the highest

antibacterial activity against most of the studied bacterial isolates. Moderate activity produced by the citrus

peels and the lowest effect was produced by the extract of the citrus leaves(120).

The antimicrobial activity of Citrus sinensis oil was studied by paper disc diffusion method against

Bacillus subtilis and Escherichia coli. Zones of inhibition of E. coli and B. subtilis were 13 and 17mm

respectively(121).

The antimicrobial potential and the minimum inhibitory concentration (MIC) of aqueous and ethanol (cold and

hot) extracts of Citrus sinensis peel extracts was investigated against Aggregatibacter

actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia, using agar well diffusion

method. The results showed that Prevotella intermedia and Porphyromonas gingivalis were resistant to

aqueous extracts while Aggregatibacter actinomycetemcomitans was inhibited at very high concentrations. Hot

ethanolic extracts showed significantly higher zone of inhibition than cold ethanolic extract. Minimum

inhibitory concentration of hot and cold ethanolic extracts of Citrus sinensis peel ranged between 12-15 mg/ml

against all three periodontal pathogens(122).

Citrus aurantifolia juice destroyed human immunodeficiency virus (HIV). Ten percent of Citrus

aurantifolia juice produced a 1000-fold reduction in HIV activity in a laboratory sample(123).

To evaluate the effect of extracts of peels of Citrus sinensis (Cs) on the replication of coronavirus (CoV) and

on the expression of TRP genes during coronavirus infection, HeLa-CEACAM1a (HeLa-epithelial

carcinoembryonic antigen-related cell adhesion molecule 1a) cells were inoculated with MHV-A59 (mouse

hepatitis virus-A59) at moi of 30. 1/50 dilution of the extracts was found to be the safe active dose. ELISA kits

were used to detect the human IL-8 levels. Total RNA was isolated from the infected cells and cDNA was

synthesized. Fluidigm Dynamic Array nanofluidic chip 96.96 was used to analyze the mRNA expression of 21

TRP genes and two control genes. Data was analyzed using the BioMark digital array software. Determinations

of relative gene expression values were carried out by using the 2(-∆∆Ct) method (normalized threshold cycle

(Ct) value of sample minus normalized Ct value of control). TCID50/ml (tissue culture infectious dose that will

produce cytopathic effect in 50% of the inoculated tissue culture cells) was found for treatments to determine

the viral loads. TRPA1, TRPC4, TRPM6, TRPM7, TRPM8 and TRPV4 were the genes which expression levels

changed significantly after Cs extract treatments. The virus load decreased when Cs extracts was added to the

CoV infected cells. Extract treatment had an effect on IL-8 secretion, TRP gene expression and virus load after

CoV infection(124).

Anthelmintic and repellent effects:

Methanolic extract of Citrus medica was evaluated for anthelmintic activity against Indian adult

earthworm Pheritima posthuma. Various concentrations of extract were tested and results were expressed in

terms of time for paralysis and time for death of worms. Piperazine citrate (10 mg/ml) was used as a reference

standard and distilled water as a control group. Dose dependent anthelmintic activity was possessed by the

methanolic extract of Citrus medica(125).

Petroleum ether extracts of Citrus medica leaves also possessed dose dependant anthelmintic activity against

the Indian adult earthworms (Pheretima posthumad). The effect which could be attributed to inhibition of

glucose uptake in the parasites and depletion of its glycogen synthesis. It also activated nicotinic cholinergic

receptor in the worms resulting in either persistent depolarization or hyperpolarization(126).

The anthelmintic activity of petroleum ether extract of the peels of Citrus sinensis was studied against Indian

adult earthworms, Pheretima posthuma, it exhibited a dose dependent inhibition of spontaneous motility

(paralysis), and evoked responses to pin-prick, and the effects were comparable with that of piperazine

Nutritional value and pharmacological importance of citrus species

citrate(119).The effect of aqueous extract of this Citrus medica on viability of the protoscolices of Echinococcus

granulosus in vitro, in a concentration of 90 mg/ml, the aqueous extract was effective in killing all

protoscolices after four days of incubation(127).

Alcoholic extracts of the rind of Citrus medica showed in vitro anthelmintic activity against human Ascaris

lumbricoides(128).The larvicidal potential of hexane and petroleum ether extracts of Citrus limetta peels was

assessed against dengue fever vector, Aedes aegypti, and malarial vector, Anopheles stephensi, by evaluating the

toxicity effects on early fourth instars. Both the extracts were found effective against both the species. The

bioassay with hexane extracts resulted in LC50 values of 132.45 and 96.15 ppm against A. stephensi and A.

aegypti, respectively; while the petroleum ether extracts from the C. limetta peels showed LC50 values of

244.59 and 145.50 ppm, respectively. It revealed that the hexane extracts possessed 1.9-fold more larvicidal

potential against A. stephensi and 1.5-fold more efficacy against A. aegypti as compared to the extracts obtained

using petroleum ether as solvent. The data further revealed that the extracts were 1.4-1.7 times more effective

against A. aegypti as compared to A. stephensi(129).

The mosquito repellent activity of extracts from Peels of five citrus fruit species, Citrus sinensis,

Citrus limonum, Citrus aurantifolia, Citrus reticulata and Citrus vitis, were studied using five different

concentrations, 5%, 10%, 15%, 20% and 25% (volume by volume). Topical application of the extract

concentrations on human volunteers revealed that 20% and 25% repelled mosquitoes 2 hours and 5 hours,

respectively. Short-lived and mild skin itching and sneezing reactions were observed as side effects(130).

Antioxidant effect:

The DPPH radical scavenging activities of the leaf extracts and leaf essential oil of Citrus aurantifolia

were investigated on 1, 1- diphenyl-2-picrylhydrazyl (DPPH) radical. Among the leaf extracts and leaf essential

oil of C. aurantifolia studied, leaf methanol and ethyl acetate extracts showed potent scavenging activity(94).

The antioxidant effects of fresh juice and peel extract of Citrus aurantifolia was evaluated. 5 μl of lime juice

didn't change LDL oxidation. 10 μl of juice inhibited LDL oxidation, and with increasing the juice

concentration, LDL was oxidized faster. Both juice and peel demonstrated antioxidant properties(131).

The antioxidant properties of Citrus aurantifolia peel and leaves from different areas were studied

using the diphenyl picryl hydrazyl, 2,2′-azino-bis(3-ethyl benzo thiazoline-6-sulfonic acid) and ferric reducing

ability of plasma assays, and the β-carotene bleaching test. Methanol extracts of the peel and leaves

demonstrated the strongest radical scavenging activity. A similar trend was observed with the reducing ability,

with values from 112.1 to 146.0 µmol/l Fe/ g (87).

The in vitro antioxidant activities of juices of both unripen and ripen Citrus aurantifolia was

investigated. Juices were extracted from fresh ripen and unripen fruits by mechanical squeezing and were used

for antioxidant study. The antioxidant activity of juice was evaluated by using the free radical scavenging

activity of 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH), total antioxidant capacity (TAC) by the

phosphomolybdenum method. Unripen juices showed more antioxidant scavenging activity as compared to

ripen juices. The lower antioxidant activity of ripe fruit juices could be due to the possible reduction in the

ascorbic acid and total phenolic content during ripening. The unripe juice showed a range of 3.45 to 28.23 % at

25 to 200 μl concentrations respectively. At the same concentration range the value for the ripe juice was found

to be 2.08 to 23.56 % respectively. The total antioxidant content in terms of ascorbic acid ( mg/ml ) was 0.178

and 0.127 mg/ml for unripe and ripen juices respectively(132).

Various in vitro and ex vivo studies were performed to estimate the polyphenols and flavonoids in the

Citrus limonum pulp and peel. The reducing power, free radical scavenging activity and lipid peroxide

inhibition were also investigated. The lemon peel was found to have a slightly greater contents of polyphenols

and flavonoids. The peel extracts also showed better reducing power and higher free radical scavenging activity.

The peel extracts gave 82.3% of inhibition towards lipid peroxidation, when compared to the pulp extracts

which showed an inhibition of 78.2%(133).

Citrus limon essential oil (EO) showed strong antioxidant activity in mice. Furthermore, it also

possessed scavenger activity in all in vitro tests(134).Essential oil of Citrus limon leaves reduced the lipid

peroxidation and nitrite content as well as increase the glutathione reduced (GSH) levels and enzymatic

antioxidant activities (super-oxide dismutase, catalase and glutathione peroxidase) in mice hippocampus. These

findings strongly support the hypothesis that oxidative stress in hippocampus might occur during

neurodegenerative diseases, proving that hippocampal damage induced by the oxidative process played a crucial

role in brain disorders, which implies that a neuroprotective effect could be achieved using Citrus limon

essential oil as antioxidant treatment(135). The action of Citrus limonum essential oil to control free radical-

induced lipid peroxidation and preventing tissue damage in skin was investigated. The superoxide anion

scavenging activity of essential oil was evaluated by the enzymatic hypoxanthine/xanthine oxidase system. The

same oil diluted in DMSO or grape-seed oil was spread on the face of human volunteers after UV exposition. A

sample of skin lipids was collected and the presence of peroxyl radicals was detected based on the measurement

of light emitted (chemiluminescence) when the excited carbonyl and singlet oxygen decay to ground state. Data

Nutritional value and pharmacological importance of citrus species

demonstrated that the lemon essential oil was more active than α- tocopherol against O2 - and peroxide free

radical inhibition at 1:100 dilution(136). The antioxidant activity of 70% aqueous methanol extract of the

defatted powdered leaves of Citrus medica was calculated to be 102.9μg/ml. It also exerted significant

reduction in blood glucose level to (105.2±8.35) in diabetic rats after one month of treatment with a dose of 200

mg/kg and to (87.4±6.30) with 400mg. The authors concluded that the methanol extract of the defatted

powdered leaves of Citrus medica exhibited significant antihyperglycemic activity which might be attributed to

the presence of flavonoid compounds(137).The extract of Citrus medica showed significant antioxidant activity

verified by different assays (DPPH test, β-carotene bleaching test and bovine brain peroxidation assay) in a dose

dependent manner as compared to ascorbic acid (138-139).

The antioxidant potential of ethanolic extract of Citrus medica L. peels (ECMP) extract was studied

on Thiobarbituric Acid Reactive Substances (TBARS) as index of lipid peroxidation and on the glycemic

control in streptozotocin induced diabetic rats. ECMP was used in as (200 and 400 mg/kg). The elevated level

of blood glucose, glycosylated hemoglobin, TBARS observed in diabetic rats were significantly decreased after

treatment with ECMP for 8 weeks in diabetic rats. From the results, the ethanolic extract of Citrus medica L.

peels possessed potent antioxidant and antidiabetic properties(140).

The results of antioxidant activity of peel essential oil of Citrus limetta var. Mitha showed that it was able to

reduce the stable radical 1- diphenyl-2-picrylhydrazyl (DPPH) to yellow-colored DPPH-H reaching 87.77% of

DPPH scavenging effect at its 100% concentration comparative to ascorbic acid as reference standard being a

strong antioxidant reagent(79).

The in vitro antioxidant activity of the methanol extracts of Citrus limetta fruit peel (MECL) was

evaluated in different models such as DPPH, superoxide radical and nitric oxide radical scavenging activity and

inhibition of lipid peroxidation. The total phenolic compounds present in the extracts were estimated by Folin-

Ciocalteu’s reagent. The extract showed good free radical scavenging activity in a dose dependent manner. The

IC50 values for DPPH, superoxide radical, nitric oxide radical inhibition and lipid peroxidation assays of MECL

were 7.36, 9.36, 136.45 and 111 respectively. Measurement of total phenolic compounds by Folin- Ciocalteu’s

reagent indicated that 1 mg extract contains 126.85 μg equivalent of pyrocatechol in MECL(141).

Extracts prepared from the Citrus limetta fruit peels were studied for antioxidant and anti- inflammatory activity

using in vitro bioassays. Among all extracts, ethanol extract of Citrus limetta fruit peels has shown promising

anti-oxidant and anti-inflammatory activity (142).

It was reported that juice and edible parts of Citrus sinensis of different origin and from different varieties

exerted antioxidant activity, while, the peel extracts were found to have a good total radical antioxidative

potential(143-144). Methanolic extracts of 6 citrus species (C. sinensis var. Washington Navel, C. sinensis var.

Valencia, C. reticulata var. Page, C. sinensis var. Sungin, C. paradise and C. aurantium) peels and tissues

growing in Pakistan were investigated for their antioxidant activity by DPPH method. IC 50 for antioxidant

activity ranged from 0.8- 4.7 mg/ml. Total phenolic content of the citrus spp. samples (based on folin Ciocalteu

method) varied from 99.4 to 229.5 mg gallic acid equivalent/g of extract and flavonoids content (based on

colorimetric AlCl3 method) varied from 0.2 to 25.7 mg quercetin equivalent/g of extract. There were no

correlation between the total phenolic and/ or flavonoids contents and antioxidant activity in tissues and/or

peels(145).

The in vitro antioxidant activity of Citrus sinensis peel extracts from different solvents were investigated.

Among the different solvent extracts methonolic extract exhibited the highest in vitro scavenging activity

followed by other solvent extracts which includes ethanolic, hexane, benzene, ethyl acetate, and chloroform

with IC50 values 65.44, 120, 138.45, 151.34, 170.34, 185.35 with 55.6 % inhibitory concentration for ascorbic

acid(146).

Hesperidin was extracted from the peel of Citrus sinensis, and its antioxidant capacity was evaluated.

Hesperidin was found to be moderately active as an antioxidant agent; its capacity reached 36%(147).

The antioxidant, protective and bioavailability of Citrus sinensis juice (poly)phenols were studied by

monitoring urinary flavanone metabolites and ring fission catabolites produced by the action of the colonic

microbiota. Twelve volunteers [6 men and 6 women; body mass index (in kg/m2): 23.9-37.2] consumed a low

(poly)phenol diet for 2 days before first drinking 250 ml pulp-enriched orange juice, which contained 584 μmol

(poly)phenols of which 537 μmol were flavanones. Urine collected for a 24-h period was analyzed qualitatively

and quantitatively. A total of 14 metabolites were identified and quantified in urine after orange juice intake.

Hesperetin-O-glucuronides, naringenin-O-glucuronides, and hesperetin-3'-O-sulfate were the main metabolites.

The overall urinary excretion of flavanone metabolites corresponded to 16% of the intake of 584 μmol

(poly)phenols. This bioavailability could be explain the antioxidant and protective effect of orange juice

(poly)phenols(148).

Cardiovascular effects:

According to World Health Organization's recent report, citrus fruits offer protection against

cardiovascular diseases by reducing levels of homocysteine. Orange fruit contained vitamin C, carotenoids and

Nutritional value and pharmacological importance of citrus species

flavonoids, which were cardio- protective. Cholesterol lowering effect of orange was produced by limonene.

Furthermore, polymethoxylated flavones (PMFs) were present in citrus fruit peel, which can lower cholesterol

more effectively than some prescription drugs, without showing any side effect. Although, a variety of citrus

fruits contain PMFs, the most common PMFs were tangeretin and nobiletin. PMFs work like statin drugs that

inhibit the synthesis of cholesterol and triglycerides inside the liver. However, a tablespoon or so of the peel of

orange each day, may be a practical way of achieving some cholesterol-lowering benefits(149).

Hesperidin, a bioflavonoid, was an abundant and inexpensive by-product of citrus cultivation. A

deficiency of this substance in the diet has been linked with abnormal capillary leakiness as well as pain in the

extremities causing aches, weakness and night leg cramps. No signs of toxicity have been observed with the

normal intake of hesperidin or related compounds(150).

The effect of drinking the juice of two different citrus fruits on vascular neointima formation was

studied using a cuff-induced vascular injury mouse model. Male C57BL6 mice were divided into five groups as

follows: 1) Control (water) (C), 2) 10% citrus unshiu (CU) juice (CU10), 3) 40% CU juice (CU40), 4)

10% citrus iyo (CI) juice (CI10), and 5) 40% CI juice (CI40). After drinking them for 2 weeks from 8 weeks of

age, cuff injury was induced by polyethylene cuff placement around the femoral artery. Neointima formation

was significantly attenuated in CU40, CI10 and CI40 compared with C. However, no remarkable preventive

effect was observed in CU10. The increases in levels of various inflammatory markers including cytokines such

as monocyte chemotactic protein-1, interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in response to

vascular injury did not differ significantly between C, CU10 and CI10. The increases in cell proliferation and

superoxide anion production were markedly attenuated in CI10, but not in CU10 compared with C. The increase

in phosphorylated ERK expression was markedly attenuated both in CU10 and CI10 without significant

difference between CU10 and CI10. Accumulation of immune cells did not differ between CU10 and CI10. The

results indicate that drinking citrus fruit juice attenuates vascular remodeling partly via a reduction of oxidative

stress(151).

The cardiovascular effects of Citrus aurantifolia fruit were studied experimentally. The anti-

hypertensive effect was tested on three experimental hypertensive models including cadmium induced

hypertensive model, glucose induced hypertensive model, Egg feed diet induced hypertensive model, and

normotensive model. The systolic pressure, diastolic pressure, mean blood pressure and heart rate of Spargue

Daweley rats were measured by tail cuff method from the tail of rats using non-invasive blood pressure

instrument and body weights were also measured. Three different doses were used for screening 0.25, 05, and

0.75g/kg, orally given and there effects on normotensive rats were observed at 2hr, 4hr and 6hr intervals. The

dose of 0.75g/kg was selected because it significantly reduced the mean blood pressure, systolic blood pressure,

diastolic blood pressure, and heart rate. The methanol extract of Citrus aurantifolia, administered at the dose of

0.75mg orally, significantly (p<0.01) reduced systolic blood pressure, mean blood pressure, diastolic blood

pressure, heart rate and body weight of Spargue Dawely rats in both normotensive and hypertensive

experimental models when compared to control groups(152).

The effects of an aqueous extract of Citrus aurantifolia on arterial blood pressure and on isolated heart

and aorta activities was evaluated experimentally. Rabbits were used for the study on the arterial blood pressure

using a Ludwig manometer. Albino Wistar rats were used for the isolated heart and aorta activities using

isolated organ bath systems. Aqueous extract of Citrus aurantifolia (4mg/kg-16mg/kg bw) produced a dose-

dependent and significant decrease in rabbit blood pressure (p<0.05). This hypotension was not prevented by

atropine (2 mg/kg bw, p>0.05). Aqueous extract (4mg/kg-16mg/kg bw) was dose-dependently reduced

hypertension evoked by adrenalin (30 μg/kg bw). The extract also induced both negative inotropic and

chronotropic effects on the heart contractile activity. The extract induced a dose dependent relaxation of

contractions produced by adrenalin or by KCl. Aqueous extract of Citrus aurantifolia evoked vasorelaxant

effects were totally abolished by removal of the endothelium layer or by a pretreatment with L-NAME (153).

In vitro / in vivo study was designed to determine the effect of Citrus limon on blood parameters, coagulation

and anticoagulation factors. In vitro tests revealed highly significant increase in thrombin time and activated

partial thromboplastin time by Citrus limon, whereas fibrinogen concentration was significantly reduced in

comparison to control, however prothrombin time was not affected significantly. In vivo testing of

Citrus limon was carried out at three different doses (0.2, 0.4 and 0.6ml/kg) in healthy rabbits. Significant

changes were observed in hematological parameters such as erythrocytes, hemoglobin and mean corpuscular

hemoglobin concentration. Bleeding time and thrombin time were significantly prolonged and there was

increase in protein C and thrombin antithrombin complex levels. These results may be due to inactivation of

thrombin because it significantly decreased fibrinogen concentration and inhibited platelet

aggregation. Citrus limon showed maximal anticoagulant effect at 0.4ml/kg, which suggest

that Citrus limon possessed an anti-thrombin component and could prevent thrombosis and playing a cardio-

protective role(154).

The protective effect of the ethanolic extract of Otroj, Citrus medica (EEOT) against isoproterenol

(ISO)-induced cardiotoxicity was evaluated in rats. Rats were administered EETO (250 and 500 mg/kg) or

Nutritional value and pharmacological importance of citrus species

vehicle orally for 15 days along with ISO (85 mg/kg, sc) on the 14th and 15th day. ISO induced cardiac

dysfunction, increased lipid peroxidation and alteration of myocyte-injury specific marker enzymes. ISO also

showed an increase in levels of plasma cholesterol, triglycerides (TG), LDL-C, and VLDL-C. Moreover, the

histological investigations showed myocardial necrosis and inflammation. EETO treatment brought the above

parameters towards normal level. Moreover, in vitro DPPH radical scavenging and β-carotene-linoleic acid tests

of the EEOT exhibited a notable antioxidant activity in both assays used. In addition, histopathological

examination reconfirmed the protective effects of EEOT. Accordingly C. medica alleviates myocardial damage

in ISO-induced cardiac injury and demonstrates cardioprotective potential(155).

The antihypertensive effect of C. medica limetta leaves was investigated against the acute response of

blood pressure to angiotensin II administration The results showed that different concentrations of the aqueous

extract prevented the raise of systolic blood pressure (p≤0.001 vs. vehicle), diastolic blood pressure (p ≤ 0.0002

vs. vehicle) and mean blood pressure (p ≤ 0.0000 vs. vehicle); with a dose dependent effect for diastolic

pressures at 125–500 mg/kg dosages. The 500 and 1000 mg/kg doses inhibited the action of Ang II in similar

extent to telmisartan. Toxic signs or deaths were not observed in mice treated with a dose of 2000 mg/kg(156).

Four-week consumption of orange juice in healthy middle-aged, normal-weight men reduced diastolic

blood pressure (DBP)(157). However, the effects of four-week intake of natural and commercial orange (Citrus

sinensis) juice (CSJ) on blood pressure was evaluated in healthy volunteers. 22 healthy subjects were included

and randomly divided into two groups. Group A consumed commercial CSJ during the first four-week period.

After a two-week washout period, they consumed natural CSJ for another four weeks. The procedure was

reversed in group B. The participants were asked to drink 500 ml/day of either natural or commercial CSJ twice

a day with breakfast and dinner. After drinking commercial CSJ, diastolic and systolic blood pressure were

significantly decreased (5.13%; P = 0.03 and -5.91%; P = 0.003, respectively). However, consumption of

natural CSJ did not have significant effects on either diastolic or systolic blood pressure. Higher flavonoid,

pectin, and essential oils content of concentrated products compared to natural juice might have been

responsible for this effect(158).

An attempt was made to isolate hypotensive substances from a hot water extract of Citrus unshiu. Six

flavonoid glycosides were isolated by repeated chromatography and gel filtration after extraction with butanol

and treatment with lead subacetate. Each component was intravenously injected into SHR-SP rats (1 mg/100g

body weight), 3,6-di-C-glucosylapigenin and rutin were found to lower their blood pressure(159).

Hypolipidemic effect:

The effect of Citrus aurantifolia peel essential oil was studied on serum triglyceride and cholesterols

in Wistar rats. Thirty Wistar rats were divided into 5 groups: control, sham, and 3 experimental groups. The

animals were treated in 2 phases: first, except for control group, which received normal saline, the rest of the

groups were fed with a high cholesterol regimen to induce hyperlipidemia; then, the 3 experimental groups were

treated with Citrus aurantifolia peel essential oil in 3 different doses: 25, 50, and 100 µl/kg. The sham group

demonstrated a significant rise in mean serum triglyceride, cholesterol, and LDL level in comparison with the

control group (p<0.05). The results of experimental groups treated with peel essential oil in 50 and 100 µl/kg

doses demonstrated a significant reduction in triglyceride, cholesterol, and LDL (p< 0.01) (160).

The effect of Citrus aurantifolia on hepatic lipidomics was studied in female albino rats, it was found

that the fresh juice of lime had different effects on cholesterol, riacylglycerol and phospholipid concentrations

of the liver. The low concentration of lime juice (30μl) did not showed considerable effect on cholesterol

concentration of the liver. Increase in cholesterol concentration was observed only after applying a

concentration of 60 μl. Beyond this concentration, cholesterol concentration was decreased. Therefore, it was

demonstrated that peak stimulation for lime juice is 60μl. Similar effect also occur for triacylglycerol

concentration. However, it caused dose-dependent increase in phospholipids concentration(161).

Eriocitrin (eriodictyol 7-rutinoside), a powerful antioxidative flavonoid in lemon with lipid-lowering

effects was evaluated in a rat model of high-fat diet to investigate its mechanism of action. A feeding

experiments was conducted in zebrafish with diet-induced obesity. Oral administration of eriocitrin (32

mg/kg/day for 28 days) improved dyslipidaemia and decreased lipid droplets in the liver. DNA microarray

analysis revealed that eriocitrin increased mRNA of mitochondrial biogenesis genes, such as mitochondria

transcription factor, nuclear respiratory factor 1, cytochrome c oxidase subunit 4, and ATP synthase. In HepG2

cells, eriocitrin also induced the corresponding orthologues, and reduced lipid accumulation under conditions of

lipid loading. Eriocitrin increased mitochondrial size and mtDNA content, which resulted in ATP production in

HepG2 cells and zebrafish(162).

Citrus medica cv Diamante peel extract lowered plasma cholesterol and triglycerides in mice(163).

Anticancer effect:

Epidemiological studies have shown that the consumption of fruits is associated with a decreased

risk of cancer. The ingestion of citrus fruit has been reported to be beneficial for the reduction of certain types

of human cancer(164).The in vitro effects of concentrated lime juice (CLJ) extract was evaluated on the

Nutritional value and pharmacological importance of citrus species

spontaneous proliferation of human breast carcinoma cell line (MDA-MB-453) and a human lymphoblastoid B

cell line (RPMI-8866). CLJ extract was prepared by freeze-drying fresh fruit juice and dialyzing the

concentrated extract against phosphate buffered saline in orderto deplete low molecular weight micronutrients

such as flavonoids as well as adjusting the pH of the extract to the physiological range. The effects of different

concentrations of the CLJ extract on the spontaneous proliferative responses of the cell lines were determined

by 3 H-thymidine incorporation after24 hrs of incubation. CLJ extract had no significant effect on MDA-MB-

453 cell line, however, using the concentrations of 125, 250, and 500 µg/ml of CLJ extract a significant

inhibition of the spontaneous proliferation of RPMI-8866 cell line was detected (P<0.05)(165).

The bioactive compounds isolated from of seeds of Citrus aurantifolia were found to posses the

potential of inhibiting human pancreatic cancer cells. While, the compounds purified from peel had the potential

of suppressing the colon cancer cells. The purified compounds from seeds exhibited significant inhibition of

Panc-28 cells with IC50 values in the range of 18.1-100 μM, which was confirmed by viable cell count. DNA

fragmentation and expression of proteins in cells treated with compounds showed the induction of apoptosis

through p53 and caspase-3 mediated pathway. The volatile oil showed 78 per cent inhibition of human colon

cancer cells (SW-480) with 100 μg/ml concentration at 48 h. Lime volatile oil showed DNA fragmentation and

induction of caspase-3 up to 1.8 and two folds after 24 and 48 h, respectively(71).

Citrus aurantifolia fruit volatile oil showed 78% inhibition of human colon cancer cells (SW-480) with 100

g/ml concentration at 48 h. Lime volatile oil showed DNA fragmentation and induction of caspase-3 up to 1.8

and 2- folds after 24 h and 48 h, respectively. Analysis of apoptosis-related protein expression further confirmed

apoptosis induction by lime volatile oil(166).

The genotoxic effect of the crude volatile oils (0.005, 0.010, 0.025, 0.050, 0.075, 0.1 ppm) of Citrus

limon fruit peels was investigated through estimation of mitotic index (MI) and blast index (BI) in human

lymphocytes after treatment with prepared concentrations. The results showed that volatile oils from maturated

and non maturated lemon peels possessed genetic effect by increasing MI and BI value of treated lymphocytes.

It also appeared that volatile oils stimulated increasing the production of lymphocytes but with more than

synergistic treatment with (PHA). Otherwise, It was also found that volatile oils exerted toxic effects against

lymphocytes viability(167).

The antimutagenicity and anticancer effect of Citrus medica fruit juice were evaluated on human

astrocytoma cancer cells cultured in DMEM (Gibco), cancer cell line were treated by half-ripe and ripe Citrus

medica fruit juice and cellular vital capacity was determined by MTT. The Citrus medica fruit juice was

subsequenthy evaluated in terms of antimutagenicity and anticancer properties by a standard reverse mutation

assay (Ames Test) which was performed with histidine auxotroph strain of Salmonella typhimurium (TA100).

By MTT, human astrocytoma cell line revealed a meaningful cell death when compared with controls (P<0.01).

In Ames Test, the fruit juice prevented the reverted mutations and the hindrance percent of half-ripe Citrus

medica was 71.7% and ripe Citrus Medica was 34.4% in antimutagenicity test and this value in anticancer test

was 83.3% and 50% in half-ripe Citrus medica and ripe Citrus medica respectively(168-169).

C. limetta root extract at the concentration of 500 μg/ml was found to be lethal towards the larvae of brine

shrimp (Artemia franciscana) in a study conducted in the Amazonas state of Brazil, which can serves as a pre-

screen to existing cytotoxicity and antitumor assays(170).

The antitumor activity of methanol extract of peel of Citrus limetta fruits (MECL) was evaluated

against Ehrlich ascites carcinoma (EAC) cell line in Swiss albino mice. Twenty-four hours after intraperitoneal

inoculation of tumor EAC cells in mice, MECL was administered at 200 and 400 mg/kg bw, ip daily for nine

consecutive days. On the 10th day, half of the mice were sacrificed for the estimation of tumor growth (tumor

volume, viable and non-viable tumor cell counts), and hematologic parameters (red blood cells, white blood

cells and hemoglobin). The rest animals were kept alive for assessment of survival parameters (median survival

time and percentage increase in life span of EAC bearing mice). Intraperitoneal administration of MECL at the

doses of 200 and 400 mg/kg for nine days to the carcinoma induced mice demonstrated a significant (P<0.001)

decrease in tumor volume, viable tumor cell count, tumor weight and a significant (P<0.001) improvement in

hematologica parameters and life span as compared to the EAC control mice. The results establishes marked

and dose dependant antitumor effect of Citrus limetta fruit peel against Ehrlich ascites carcinoma bearing Swiss

mice(171).

Limonene, one of the main constituents of citrus species fruit, reduces the risk of mouth, skin, lung, breast,

stomach and colon cancer. Hesperidin, and its flavone analogue, diosmin, also exerted anti-carcinogenic

activities in various in vivo studies. The polymethoxylated flavones have shown strong anti-proliferative action

against cancer cells and antigen activated T-lymphocytes. Beta-cryptoxanthin (an orange-red carotenoid)

inhibited development of lung cancer(172-173).

A study of the inhibitory effects of two limonoid aglycones (limonin and nomilin) on the formation of

benzo[a]pyrene induced neoplasia in the fore stomach of ICR/Ha mice showed that incidence of tumors was

reduced by more than 50% at 10mg/dose(174).

Nutritional value and pharmacological importance of citrus species

The cytotoxicity of hesperidin from the peel of Citrus sinensis was evaluated gainst different human

carcinoma cell lines (larynx, cervix, breast and liver carcinoma cell lines). The results revealed that hesperidin

exhibited pronounced anticancer activity against the selected cell lines. IC₅₀ were 1.67, 3.33, 4.17, 4.58 μg/ml,

respectively(147).

Central nervous effects:

Preliminary behavioral screening performed with the lemon fruit demonstrates that it promoted sleep

in dementia increasing motivational behaviour and improving disturbed behavior(175-176).

The central nervous system (CNS) depressant and anticonvulsant activities of Citrus limon essential oil (EO)

were investigated in animal models. The EO (50, 100 and 150 mg/kg) administered by oral route in mice

caused a significant decrease in the motor activity of animals when compared with the control group, up to

thirty days after the administration and the dose of 150 mg/kg significantly reduced the remaining time of the

animals on the Rota-rod apparatus. Additionally, C. limon essential oil was also capable to promote an increase

of latency for development of convulsions induced by pentylenetetrazole. The administration of flumazenil, (10

mg/kg, ip), GABAA-benzodiazepine (GABA-BZD) receptor antagonist, antagonized the effect of C. limon

essential oil at higher dose. C. limon essential oil was also capable to promote an increase of latency for

development of convulsions induced by picrotoxin at higher dose. In the same way, the anticonvulsant effect of

the EO was affected by pretreatment with flumazenil, a selective antagonist of benzodiazepine site of GABAA

receptor(177).

The effects of apigenin, a bioflavonoid widely found in citrus fruits, on behavioral changes and

inflammatory responses induced by chronic unpredictable mild stress (CUMS) was investigated in rats. When

GW9662, a selective peroxisome proliferator-activated receptor gamma (PPARγ) inhibitor, administered 30min

before apigenin, apigenin (20mg/kg, intragastrically) for three weeks remarkably ameliorated CUMS-induced

behavioral abnormalities, such as decreased locomotor activity and reduced sucrose consumption. In response

to oxidative stress, the NLRP3 inflammasome was activated and IL-1β secretion increased in the prefrontal

cortex (PFC) of CUMS rats. However, apigenin treatment upregulated PPARγ expression and downregulated

the expression of NLRP3, which subsequently downregulated the production of IL-1β. In addition, GW9662

diminished the inhibitory effects of apigenin on the NLRP3 inflammasome. Accordingly, the results

demonstrated that apigenin exhibited antidepressant-like effects in CUMS rats, possibly by inhibiting IL-1β

production and NLRP3 inflammasome expression via the up-regulation of PPARγ expression(178).

Anxiolytic and antidepressant effects and acute toxicity of ethanolic extract (EE) of the aerial parts of Citrus

limon were studied in mice. Anxiolytic activity was evaluated using open field and elevated plus-maze tests.

The antidepressant effect of the extract was studied by forced swimming test in mice. In the open field test, the

oral route administration of EE alone showed significant sedative and antidepressant activities in mice (p <

0.05). EE did not alter motor coordination. The EE, at three doses tested, showed antidepressant effect and

produced decrease in immobility time. The authors concluded that the EE of the aerial parts of C. limon have a

sedative effect, which may be mediated by benzodiazepine-type receptors, and also an antidepressant effect

where noradrenergic and serotoninergic mechanisms will probably play a role(179).

The effect of Citrus limon on memory of mice was studied using Harvard Panlab Passive Avoidance response

apparatus controlled through LE2708 Programmer. Passive avoidance was fear-motivated tests used to assess

short or long-term memory of small animals, which measures latency to enter into the black compartment.

Animals with Citrus limon treatment showed significant increase in latency to enter into the black compartment

after 3 and 24 hours than control(180).

The sedative, anxiolytic and antidepressant effects of essential oil (EO) of leaves from Citrus limon

were investigated in mice. The effects of EO were demonstrated by open-field, elevated-plus-maze, rota rod,

pentobarbital-induced sleeping time, and forced swimming tests in mice. In the open-field test, EO at the doses

of 50, 100 and 150 mg/kg, after oral administration, significantly decreased the number of crossings, grooming,

and rearing. In the elevated-plus-maze (EPM) test, EO increased the time of permanence and the number of

entrances in the open arms. On the contrary, the time of permanence and the number of entrances in the closed

arms were decreased. In the rota rod test, EO did not alter motor coordination and, thus, was devoid of effects,

as related to controls. In the pentobarbital-induced sleeping time test, EO at the same doses significantly

increased the animals sleeping time duration. Since EO, at the doses of 50, 100 and 150 mg/kg, did not show a

sedative effect in the open field test, these three doses when used in the forced swimming test, they were

producing a decrease in the immobility time, similarly to that of imipramine (positive control). However, the

antidepressant effects of EO were not altered by the previous administration of paroxetine. In addition, effects

of EO in the forced swimming test were totally blocked by reserpine pretreatment(181).

The behavioral effects of Citrus limon juice was studied in rats at three different doses (0.2, 0.4 and 0.6 ml/kg),

considered as low, moderate and high doses. Anxiolytic and antidepressant activities were specifically assessed

twice during 15 days using open field test, elevated plus maze and forced swimming test. In open field test

Nutritional value and pharmacological importance of citrus species

Citrus limon, revealed increase in distance travelled, number of central entries and number of rearing's at

moderate dose, while in the elevated plus maze, number of open arm entries were found to be increased.

Whereas in forced swimming test, there was decrease in duration of immobility and increase in duration of

climbing(182).

Factors that enhance the intrinsic growth potential of neurons play a major role in the regeneration and

repair of adult neurons following an injury. Fibroblast growth factor (FGF-2) is one of the key players in the

origin and growth of neuronal and glialcells through autocrine and paracrine signaling. Water extract of Citrus

medica var. sarcodactylis, was found to activate the FGF-2 promoter in transgenic luciferase expression

models. Citrus medica treatment on Schwann cells (RSC96) transfected with luciferase reporter plasmid under a

FGF-2 promoter, was found to induce the FGF-2 promoter and showed enhanced luciferase expression. The

FGF-2 expression was accompanied with an increase in the expression of proteins involved in cell migration

and cell proliferation in a dose dependent manner (183).

The effects of Citrus sinensis essential oil was evaluated in the elevated plus-maze followed by the

light/dark paradigm in rats. The animals were exposed to the orange aroma (100, 200 or 400 microl) for 5 min,

while in a Plexiglas chamber and were then immediately submitted to the behavioural tests. At all doses, C

sinensis oil demonstrated anxiolytic activity in at least one of the tests and, at the highest dose, it presented

significant effects in both animal models, as indicated by increased exploration of the open arms of the elevated

plus-maze (time: p=0.004; entries: p=0.044) and of the lit chamber of the light/dark paradigm (time: p=0.030).

In order to discard the possibility that this outcome was due to non-specific effects of any odour exposure, the

behavioural response to Melaleuca alternifolia essential oil was also evaluated, using the same animal models,

but no anxiolytic effects were observed(184).

Antidiabetic effect:

To study the hypoglycemic effect of hexane extract of Citrus limon peel, diabetes was induced in rats

by a single intraperitonial injection of alloxan (140mg/kg bw). Hexane extract (200mg/kg bw) of Citrus limon

peel was administered orally, while metformine hydrochloride (175 mg/kg bw) was used as a standard drug.

The results showed that hexane extract exerted significant hypoglycemic activity and the activity of extract was

comparable to that of standard drug(185).

The effect of oral treatment with citrus peel extracts on wound repair of the skin was studied in

diabetic rats. The extracts were estimated for vitamin C and total carotenoid contents prior to animal study.

Diabetes mellitus was induced in rats by intraperitoneal injection of a single dose of streptozotocin (STZ, 75

mg/kg bw). One week after diabetes induction, full thickness excision wounds were made in hyperglycemic

rats. The different test groups were treated with different citrus peel extracts orally at the dose of 400 mg/kg bw

daily for 12 days. The blood glucose, body weight and rate of wound closure of each rat were measured every

3rd day during the experimental period. At the end of experiment, granular tissues of wounds were removed and

estimated for hydroxylproline and total protein content. The results showed significant reduction in blood

glucose and time to wound closure. Tissue growth and collagen synthesis were significantly higher as

determined by total protein and hydroxylproline content(186).

Measurements of the effects of Citrus medica cv Diamante peel extract on the mouse insulinoma MIN6 β-

cells indicated that it exerted direct stimulatory effects on the exocytotic release of insulin in a concentration-

dependent manner. Citrus medica cv Diamante peel extract reduced plasma glucose concentration in mice

(163).

The antidiabetic and hypolipidemic activity of petroleum ether extract of Citrus medica seeds was

studied in streptozotocin (STZ) induced diabetic model in rats. Seed extract was given as (200 and 400 mg/kg,

po.) The petroleum ether extract of Citrus medica seeds induced significant reduction (p < 0.05) of fasting

blood glucose, serum cholesterol, serum triglycerides, LDL and VLDL in dose dependent manner after 15 days

of drug administration. However, 200 mg/kg/day seed extract for 15 days was not showing any change in HDL

level, while 400 mg/kg/day dose significantly increased HDL level in diabetic rats(187).

In vivo hypoglycemic, and antidiabetic activity of Citrus medica L. var. Sarcodactylis were confired in

Sprague-Dawley-SPF rats and Wistar DIO rats. Insulin secretagogue effect of Citrus medica L. var.

Sarcodactylis Hort fruits was confirmed by kinetic analysis on the hypoglycemic patterns of the intraperitoneal

glucose tolerance and the insulin-glucose tolerance tests(188).

The antihyperglycemic activity of methanol extract of Citrus limetta fruit peel (MECL) was

evaluated in streptozotocin-induced (STZ; 65 mg/kg bw) diabetic rats. Three days after STZ induction, diabetic

rats received MECL orally at 200 and 400 mg/kg bw daily for 15 days. Glibenclamide (0.5 mg/ kg po) was used

as reference drug. Blood glucose levels were measured on 0, 4th, 8th, and 15th days of study. Serum biochemical

parameters namely, SGOT, SGPT and ALP were also estimated. The TBARS and GSH levels of pancreas,

kidney, and liver were determined. MECL significantly (P<0.001) and dose dependently normalized blood

glucose levels and serum biochemical parameters, decreased lipid peroxidation, and recovered GSH as

compared to those of STZ control(189).

Nutritional value and pharmacological importance of citrus species

The inhibitory effect of the aqueous Citrus limetta peel extract on the metabolism of carbohydrates

was studied. The extract inhibited primarily the enzyme α-amylase by 49.6% at a concentration of 20 mg/ml

and to a lesser extent the enzyme α-glucosidase with an inhibition of 28.2% at the same concentration. This

inhibition was likely due to the high polyphenol content in the Citrus limetta peel (19.1 mg GAE/g).

Antioxidant activity of the Citrus limetta peel demonstrated dose-dependent antioxidant activity , varying from

6.5% at 1.125 mg/ml to 42.5% at 20 mg/ml. The results showed that these polyphenolic compounds having

both antihyperglycemic and antioxidant activities(190).

The anti-diabetic potential of orange peel and juice was attributed to anti peroxidation, inhibition of α-

amylase enzyme activity responsible for the conversion of complex carbohydrates to glucose, increased

hepatic glycogen content, stimulation of insulin secretion, and repair of secretory defects of pancreatic β-

cells(191-192).

The effects of four different concentrations of peel extract from Citrus sinensis (CS) were investigated

in male mice, the results revealed that they exerted glucose lowering and antiperoxidative activities. In a

separate experiment their potential was evaluated with respect to the regulation of alloxan induced diabetes

mellitus. While a single dose of alloxan (120 mg/kg) increased the serum levels of glucose and alpha-amylase

activity, rate of water consumption and lipid peroxidation (LPO) in hepatic, cardiac and renal tissues with a

parallel decrease in serum insulin level, administration of 25 mg/kg of CS was found to normalize all the

adverse changes induced by alloxan, revealing the antidiabetic and anti peroxidative potential of tested fruit peel

extracts(193).

Antiinflammatory and analgesic effects:

The inhibitory effect of pectin at different degrees of esterification (DEs) on the expressions of

inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-activated

macrophages was investigated. Western blot and RT-PCR analyses demonstrated that 30% esterified pectin

(DE30), DE60 pectin, and DE90 pectin significantly inhibited the protein and mRNA expressions of iNOS and

COX-2 in LPS-activated macrophages, and DE90 pectin was the most-potent inhibitor. To clarify the

mechanisms involved, DE90 pectin was found to inhibit the phosphorylation of MAPKs and IKK kinase

activity. In addition, DE90 pectin inhibited the activation of NF-kB and AP-1 by electrophoretic mobility shift

assay and transient transfection experiments. DE90 pectin bind with LPS, and might result in decreasing

binding of LPS to its receptor(194).

Orally, Citrus limon essential oil (EO) (50, 100, and 150 mg/kg) significantly reduced the number of

writhes, and, at highest doses, reduced the number of paw licks. Naloxone antagonized the antinociceptive

action of EO (highest doses), this suggested, at least, the participation of the opioid system(134).

The ethanolic extract of peels of Citrus limon (Burm) fruit was screened for its anti-nociceptive property

using both chemical and thermal methods of nociception in rats.

The extract at doses 250 and 500 mg/kg po, showed nociceptive property in both chemical and thermal

methods. The activity exhibited by the extract was comparable to that of the standard drug, diclofenac sodium

(15 mg/kg)(195).

The anti-inflammatory study of the stem and root barks of Citrus medica var. sarcodactylis Swingle

has led to the isolation of new anti-inflammatory compounds. The new anti-inflammatory components

included xanthyletin, nordentatin, atalantoflavon and lonchocarpol A, which displayed potent nitric oxide (NO)-

reducing activity in microglial cells(196).

The anti-inflammatory and analgesic activities of ethyl acetate extract of Citrus medica peel (EtCM)

(200, 300 and 400 mg/kg) were studied on carrageenan induced inflammatory pain in rats. Anti-inflammatory

activity was assessed by measuring paw volume in rats. Analgesic activity was evaluated for its central and

peripheral pharmacological actions by using hot plate, plantar, pin prick and mechanical allodynia tests in rats.

EtCM (400 mg/kg) produced significant analgesic and anti-inflammatory effects(138).

The analgesic effect of fresh decoction of Citrus medica fruits was studied in rats. The decoction was

prepared from fresh fruits in distilled water and the volume was reduced to 1/4th. Three doses of decoction (1,

2 and 4ml/kg po) were tested for analgesic activity using tail immersion method and hot plate method.

Diclofenac sodium (10mg/kg ip) was used as standard. The decoction at doses (2 and 4ml/kg) showed

significant increase in latency to flick compared to control in tail immersion method. Whereas the decoction of

Citrus medica at all three doses showed significant increase in the mean basal reaction time in hot plate

method. In both methods, analgesic effect of 4ml/kg decoction was observed comparable to the standard

drug(197).

Methanol extracts of peel of Citrus limetta fruits (MECL) were evaluated in two dose levels (200 and

400 mg/kg) in histamine, carrageenan and dextran induced acute rat paw oedema models for their anti-

inflammatory potential. MECL was able to significantly (p<0.001) reduce the inflammatory potential produced

by different inflammatory mediators in a dose dependant manner. MECL was able to produce significant anti-

inflammatory activity better than the reference drug used (phenylbutazone 100 mg/kg bw po)(198). Carotenoids,

Nutritional value and pharmacological importance of citrus species

zeaxanthin and beta-cryptoxanthin, were the phytonutrients of Citrus sinensis which reduce remarkably the risk

of rheumatoid arthritis. Persons consuming high amount of zeaxanthin and cryptoxanthin showed 52% less

chances of developing rheumatoid arthritis(65).

The effect of orange juice on cellular modifications induced by a fatty meal was investigated. 18

apparently healthy subjects consumed a fatty meal, during which they drunk orange juice, either blond or red, or

water, according to a randomized cross-over design. Two hours after the end of the fatty meal, both white blood

cell (WBC) and platelet counts significantly increased (12.5 and 5%, respectively), while mean platelet volume

decreased and a 25% release of myeloperoxidase (MPO) from polymorphonuclear leukocyte occurred. Both

juices significantly prevented WBC increase and MPO degranulation, in respect to control. Triglycerides

significantly increased (42%) after the fatty meal, but at a lower extent when red orange juice was consumed

with the meal (20%), in respect to blond orange juice or control. This effect was statistically significant in the

subgroup subjects with hypertriglyceridemia. Vascular stiffness (augmentation index), measured by Endo-

PAT2000, significantly decreased after the meal only in conjunction with red orange juice. Accordingly, in

healthy subjects the concomitant intake of orange juice may prevent the low-grade inflammatory reaction

induced by a fatty meal, at cellular and possibly at vascular function levels(199).

Ultraviolet light (UV) induced an inflammatory response in the skin by cyclooxygenase (COX)-2

expression and prostaglandin PGE2 production. Orange peel which contained polymethoxyflavonoids (PMFs) as

a major ingredient, which have anti-inflammatory activity, has been used as a natural medicine. The extract

suppressed UVB-induced COX-2 expression and PGE2 production in HaCaT cells. Furthermore, the extract

acted as a peroxisome proliferator-activated receptor (PPAR)-γ agonist. The suppression of UVB-induced

COX-2 expression by this extract was inhibited by GW 9662 and T0070907, which were both PPAR-γ

antagonists. It was therefore suggested that orange peel extract, containing high levels of PMFs, suppresses

UVB-induced COX-2 expression and PGE2 production through PPAR-γ (200).

Reproductive effects:

Studies have shown that lime juice destroys sperm cells, fifty percent of Citrus aurantifolia juice

wiped out 2000 of sperm cells in 30 seconds. The high acidity of Citrus aurantifolia juice may probably

responsible for this destruction(123). The effect of lime juice was studied on the fetal parameters of Sprague-

Dawley rats. The estrous cycles of the female rats were studied for the first 16 days to establish cyclicity. The

rats were mated with male SD rats of proven fertility on the estrous day (heat period) of estrous cycle. Rats in

group I received 1ml of undiluted lime juice while rats in group II received distilled water by gastric gavage.

The rats were sacrificed on the 20th day of gestation and fetal parameters were evaluated. There was a reduction

in the number of fetus of treated pregnant rats when compared to the control. There was a significant reduction

in the crown-rump length, weight and umbilical cord length of the fetus when compared with the control.

Accordingly, lime juice showed abortificient effect but no obvious teratogenic effect was observed(123).

The anti fertility effect of Citrus limonum seeds was studied on male rats. Male albino rats were

orally treated with alcoholic extract and its fractions for 30 and 60 days. Testis and epidadymis were removed

and tested for sperm count, sperm motility, sperm morphology in addition to histopathologcal examination.

sperm counts were also studied 90 days after discontinuation of the treatment to see reversibility of effect. 60

days treatment significantly decreased the sperm count. Size and weight of testis and epidadymis were reduced

indicating atrophic changes in testis and epididymis. It caused drastic effect on sperm motility and morphology

which decreased fertility. Sperm counts returned to normal after 90 days(201).

The petroleum ether, alcoholic and aqueous extracts of Citrus limonum seeds were investigated for

anti-fertility effect in female albino mice. The extracts were administered orally for 7 days after insemination

(i.e. post-ovulatory test). The control group received 4% gum acacia. The animals were examined for

implantation sites on 10th day of pregnancy. The number of pups delivered at term was recorded for each group.

The alcoholic extract showed significant anti-fertility effect as compared to petroleum ether and aqueous

extracts. The alcoholic extract was subjected for fractionation and the fractions were again tested for their anti-

fertility effect. The fraction of ethyl-acetate showed most encouraging anti-fertility activity. In second part of

the study, the alcoholic extract and its ethyl-acetate fraction were subjected to evaluation of their mechanism of

action and it was found that their principal mode of action is as an anti-zygotic agent. Withdrawal of the

treatment, resulted in complete restoration of fertility(202).

Estrogenic /anti-estrogenic activities of alcoholic extract of Citrus limonum seeds was studied in Albino rats.

The standard drug estrogen was given sub-cutaneiously and test drug, alcholic extract of lemon seeds was given

orally for 7 days from 8th to 14 th days of ovariectimised rats. The extract treated rats exhibited estrogenic

effect, which include vaginal epithelium cell cornification and increased in uterine weight. For further

supporting the estrogenic activity of the extract, isolated rats uterus preparation was mounted, and it showed

that alcoholic extract of lemon seeds produced the contraction as pretreatment with stelbistrol(203).

Three extracts of the peels of Citrus medica including oil, ethanolic and chloroform extract were

investigated for antifertility activity. The alcoholic extract at the dose of 2.5gm/kg and the chloroform extract at

Nutritional value and pharmacological importance of citrus species

dose of 1.0 gm/kg on female wistar rats on days 1-7 post-coital, exhibited significant anti-implantation activity.

While, the oil extract at the dose of 100mg/kg on days 1-7 didn’t exhibit significant anti-implantation

activity(204 Petroleum ether extract of Citrus medica seeds, was administered orally (400 mg/kg body weight)

for 30 days to study its effect on fertility in Wistar strain Albino rats. Animal were divided into 3 groups: Group

I, received 400mg petroleum ether extract/kg in 0.2ml Tween-80 (1%) orally for 30 days. Group-II, received

only 0.2ml Tween-80 (1%)/kg for 30 days and left untreated for another 30 days to served as control. Group-

III: received 400mg petroleum ether extract/kg in 0.2ml Tween-80 (1%) for 30 days and left untreated for next

30 days to see the withdrawal effects. The results were analysed depending on gravimetric, histological,

histometric and biochemical parameters. Histologically, ovary and uterus in extract treated rats showed reduced

number of healthy follicles, regressing follicles and also elevation in corpora lutea in the Group I and II. For the

study of withdrawal effects of this extract in Group III, the results indicated that the animals returned to normal

and regained gonadotrophin secretion similar to that of control rats(205).

Petroleum ether, benzene and ethanol extracts of the seeds of Citrus medica were administered orally

at the dose level of 200 and 400 mg/kg to adult female albino rats for 30 days. The estrous cycle of these rats

was irregular with prolonged proestrus and estrous, reduced metestrus and diestrus phase during the

experimental period. At autopsy on day 31st , petroleum ether extract treated rats showed reduced ovarian

weight, benzene extract treated rats showed increased ovarian weight and ethanol extract treated rats showed

non-significant change in the weight of ovary. Histological changes of the ovary indicated increases in the

number of atretic follicles but decreases in the number of healthy developing follicles, Graafian follicles and

corpora lutea. The total cholesterol, activity of acid and alkaline phosphatase and ascorbic acid content of the

ovary were increased, whereas, protein and glycogen content were decreased. The uterine weight and its

micrometric measurements in the treated rats were increased significantly. However, petroleum ether extract of

Citrus medica seeds was more effective in causing these changes comparing to other extracts(206).

Estrogenic/anti-oestrogenic activities of petroleum ether extract of Citrus medica seeds were studied in albino

rats. The extract at the dose level of 200 and 400 mg/kg body weight was administered for seven days to

immature ovariectomised rats, along with or without 1 μg ethinyl estradiol. The extract -treated rats exhibited

estrogenic effects, which included increase in uterine weight and vaginal epithelial cell cornification. The

micrometric measurements of the uterus and its components were increased and glands showed high secretory

activity. When the extract was tested in 30-day-old immature rats, they exhibited opening of vagina on the fifth

day and cornification of vaginal epithelial cells, which was about 10 days earlier compared to controls, which

further supporting the estrogenic activity of the extract. Hence, these results strongly indicate the potent

estrogenic nature of petroleum ether extract of Citrus medica seeds(207).

The estrogenic activity of petroleum ether extract of Citrus medica leaves was studied in immature female rats.

The petroleum ether extract proved to retain high estrogenic activity in immature female rats. Oral

administration of petroleum ether extract of Citrus medica in ovariectomized immature female Wistar rats for 7

days in a dose of 400 mg/kg resulted in significant increase in the uterine weight (g) (1.7±0.11) when compared

with ovariectomized control rats (1.3±0.07)(208).

Gastrointestinal effect:

The antiulcer activity of aqueous extract of the fruits of Citrus medica was evaluated against ethanol-

induced ulcers in rats. The rats were pretreated with the extract at two doses (250 and 500 mg/kg po) and the

antiulcer effect was compared with that of ranitidine (20 mg/kg po). The extract of both doses showed a

significant reduction in ulcer formation. Histopathological sections showed significant decrease in mucosal

ulceration, inflammatory mucosal changes and submucosal edema compared to ethanol treated group and the

ranitidine group. It was concluded that, the fruits of Citrus medica possesses significant antiulcer activity

against ethanol-induced ulcers in rats and the antiulcer activity could be due to the presence of flavonoids as

these compounds have well documented antiulcer activity(209).

Respiratory effect:

A study among British children found a positive association between fresh fruit consumption and the

level of forced expiratory volume in one second (FEV1). The association was more pronounced in wheezers

than non-wheezers(210).

An Italian study, followed over 18,000 children aged 6-7 years and found that those eating the most citrus fruit

(oranges, tangerines, and grapefruit), along with kiwifruit, had a reduced risk of wheezing. The protective effect

of citrus did not appear to be dose related. The authors attributed the lung health benefiting properties of citrus

and kiwifruit to their high concentration of vitamin C(211).

Dental effect:

The effects of Citrus aurantifolia (CA) extract was studied on smear layer removal in different parts

of root canals. Thirty-nine single-rooted human teeth were randomly divided into three experimental and one

Nutritional value and pharmacological importance of citrus species

control groups. Teeth were instrumented using MTwo rotary instruments. Root canals were irrigated with

NaOCl during instrumentation. The canals in each group were irrigated with one of the following: completed

mixture of Citrus aurantifolia extracts, 17% EDTA, and alcoholic extract of CA. Distilled water was used for

the control group. The irrigants were left within the canal for 20 minutes, and then rinsed with normal saline

solution. Teeth were subsequently split longitudinally into 2 halves, and the canals were examined by a

scanning electron-microscope. Cleanliness was evaluated using a five point scoring system. Statistical

significant difference was found between groups (P<0.05). The smear layer was more effectively removed with

17% EDTA compared to alcoholic CA extract. However, they were both able to remove the smear layer in the

coronal segment. Completed CA extract removed more smear layer in coronal and middle parts compared with

the alcoholic extract (P=0.001); however, there was no significant difference in the apical part(212).

Antiallergic and immunological effect:

Gencydo®, a combination of Citrus limon juice and aqueous quince (Cydonia oblonga) extract has

been used traditionally in anthroposophical medicine for treating patients with allergic rhinitis or asthma. The

anti-allergic effects of this preparation was investigated in vitro by using cell lines and primary cells in various

biological and immunological endpoints. The release of soluble mediators from basophilic cells, mast cells and

lung epithelial cells, which were essential for the initiation of early- and late-phase allergic reactions, was

analyzed in relation to the synthetic anti-allergic drugs azelastine and dexamethasone. In addition, the impact of

Gencydo® on the viability and activation of GM-CSF-activated eosinophil granulocytes was investigated.

Gencydo® reduced the degranulation and histamine release of IgE-activated basophilic cells and mast cells and

inhibited the IgE- and PMA/A23187-induced increases in IL-8, TNF-α and GM-CSF production in mast cells.

The effects were comparable to that of azelastine and dexamethasone. Furthermore, Gencydo® partially

blocked eotaxin release from human bronchial epithelial cells, but has no impact on the viability and activation

of GM-CSF-activated eosinophil granulocytes. The results gave a rational base for the topical use of Gencydo®

in treatment of allergic disorders through the down regulation of soluble mediators, which were essential for the

initiation and maintenance of allergic reactions(213).

The effects of the combined Citrus medica ssp. limonum /Cydonia oblonga (0.01 g/ml of each one), separate

products of Citrus medica ssp. limonum (0.01 g/ml) and Cydonia oblonga (0.01 g/ml) were investigated on the

immunological pathways involved in seasonal allergic rhinitis (SAR). Peripheral blood mononuclear cells

(PBMCs) from five healthy and five grass pollen allergic donors were isolated and analyzed in vitro after

polyclonal and allergen-specific stimulation of T cells in the presence of the three extracts. The analyses

demonstrated acceptable cell survival with no signs of toxicity. Citrus mainly had a selective effect on reducing

allergen-specific chronic inflammatory (TNF-α; Citrus compared to Cydonia and Citrus/Cydonia: −87.4 (P<

0.001) and −68.0 (P< 0.05), resp.) and Th2 pathway activity (IL-5; Citrus compared to Cydonia: −217.8

(P<0.01); while, both Cydonia and Citrus/Cydonia mainly affected the induction of the allergen-specific Th1

pathway (IFN-γ; Cydonia and Citrus/Cydonia compared to Citrus: 3.8 (P<0.01) and 3.0 (P<0.01), respectively).

Citrus and Cydonia demonstrated different working mechanisms in the treatment of SAR and the combination

product did not demonstrate larger effects than the separate preparations(214).

The immunomodulatory and antiallergic properties of preparations from lemon, Citrus medica L. (citrus),

and Cydonia oblonga , which were used in pharmaceutical products to treat patients suffering from allergic

disorders, were investigated. Preparations were analyzed with respect to their impact on the degranulation

capacity from basophilic cells as well as mediator release from activated human mast cells in vitro, including

IL-8 and TNF- α secretion. The results showed that the degranulation of basophilic cells was diminished only in

the presence of Citrus. Furthermore, Citrus and Cydonia both inhibited the production of IL-8 and TNF- α from

human mast cells, and at low concentrations additive effects were observed(215).

To compare the efficacy and safety of two routes of administration (nasal spray versus subcutaneous

injections) of Citrus/Cydonia in seasonal allergic rhinitis, a randomised, comparative clinical trial with two

parallel groups was carried out. After a one- or two-week wash-out period, 23 patients were randomized, to a 6-

week treatment period and the immunological and symptom severity changes and safety were evaluated. Both

routes of administration were safe, they demonstrate therapeutic immunological and clinical effects (216).

Effect on body weight:

The effects of Citrus aurantifolia essential oils in reducing body weight, individually and in co-

administration with ketotifen, an antihistaminic drug that causes weight-gain, has been investigated using mice

model. During the 45 days experimental period, the mice that received ketotifen demonstrated an enhancement

both in the amount of food intake and body weight compared to the control group. Groups treated with Citrus

aurantifolia essential oil displayed reduction in body weight and food consumption, possibly through promoting

anorexia which might have played a role in weight loss. Interestingly, co-administration of the Citrus

aurantifolia essential oil and ketotifen caused significant suppression in gaining weight, as well as decreased

Nutritional value and pharmacological importance of citrus species

body weights of mice. The results suggested that Citrus aurantifolia essential oil played an important role in

weight loss and could be useful in treatment of drug-induced obesity and related diseases(217).

Effect on bone loss:

The efficacy of Citrus aurantifolia cv. Swingle and Citrus sinensis cv. Liucheng against osteoporosis

was evaluated in an ovariectomized rat model. Administration of Citrus extracts increased trabecular bone

mineral content and bone mineral density of tibia, improved the levels of phosphorus and calcium. The results

demonstrated that Citrus extracts reduced bone loss in ovariectomized rats(218).

Anti-cholinesterase effect:

The anti-cholinesterase activity of Citrus aurantifolia peel and leaves from different areas of

growth, was studied. n-Hexane fractions of both peel and leaves showed a good acetylcholinesterase inhibitory

activity with IC50 values in the range 91.4-107.4 µg/ ml(87).

Xanthine oxidase inhibitory effect:

Among the many extracts tested, the Citrus limetta peel extract exhibited highest potency of xanthine

oxidase inhibition (IC50 = 40.16±0.88µg/ml)(219).

Decreasing the risk of renal stone:

It was recorded that when women drank 1/2 liter of orange juice daily, their urinary pH value and citric acid

excretion increased thereby diminishing the risk of forming calcium oxalate stones significantly(220).

Feeding value:

A feeding trial was conducted with thirty six mixed breeds of rabbits to assess the feeding value of

sun dried sweet orange (Citrus sinensis) fruit pulp meal (SOPM). The sweet orange peel meal was analyzed for

its proximate nutrients and its crude fiber constituents. The experimental rabbits were randomly assigned to six

dietary treatments: T0, T5, T10, T15, T20 and T25 in which SOPM replaced maize at 0, 5, 10, 15, 20 and 25%,

respectively. The rabbits were fed these diets for 84 days during which performance and nutrient digestibility

were evaluated. Experimental diets had significant effects (p<0.05) on the body weight gain, water intake,

water: feed ratio, protein efficiency ratio and final live weight. Coefficient of digestibility and nutrient

digestibility, were not adversely affected by the inclusion of SOPM in the diets. The results revealed the

possibility that sweet orange fruit pulp meal can be used as a replacement feedstuff for maize in the ration of

grower rabbit up to a level of 20%(221).

Effect on liver metabolism:

The possible action of the Citrus aurantium extract on liver metabolism was investigated on isolated

perfused rat liver. The isolated perfused rat liver was used to measure catabolic and anabolic pathways,

including oxygen uptake and perfusion pressure. The Citrus aurantium extract and p-synephrine increased

glycogenolysis, glycolysis, oxygen uptake and perfusion pressure. These changes were partly sensitive to α and

β- drenergic antagonists. p-Synephrine (200 µM) produced an increase in glucose output that was only 15%

smaller than the increment caused by the extract containing 196 µM p-synephrine. At low concentrations the

Citrus aurantium extract tended to increase gluconeogenesis, but at high concentrations it was inhibitory,

opposite to what happened with p-synephrine. The action of the Citrus aurantium extract on liver metabolism is

similar to the well known actions of adrenergic agents and can be partly attributed to its content of p-

synephrine. Many of these actions were catabolic and compatible with the weight-loss effects usually attributed

to Citrus aurantium(222).

Protective effect:

The cytoprotective effects of Citrus aurantifolia was evaluated against Aflatoxin B1 (AFB1)-

induced liver injury in rat model. Wistar albino rats were divided into five groups. Group I served as the

control. Group II treated with vehicle, dimethyl sulfoxide (DMSO) a single intraperitoneally intraperitoneally

on day 5. Group III received AFB1-alone (1mg/Kg body weight) intraperitoneally in DMSO as a single dose

on day 5. Group IV and V received Citrus aurantifolia methanolic extract (MeCA) and Citrus aurantifolia

aqueous extract (AqCA) (500mg/Kg body weight, per oral) for 5 days and AFB1 (1mg/kg body weight)

intraperitoneally in DMSO as a single dose on day 5. At the end of the 8th day, the livers were collected and

used to determine the hepatoprotective activity. Genomic DNA fragmentation was observed by agarose gel

electrophoretic pattern in the rat livers. The ultra-structure of the liver cells was studied by electron microscopy.

Citrus aurantifolia treatment significantly protected nucleic acid. The treatment was significantly inhibited

DNA fragmentation. Nucleus structures were well maintained. The results demonstrate that Citrus aurantifolia

has a cytoprotective effect against AFB1-induced liver injury(223).

Nutritional value and pharmacological importance of citrus species

The ethanol extract of Citrus limon fruits was evaluated for its effects on experimental liver damage

induced by carbon tetrachloride. The ethyl acetate soluble fraction of the extract of Citrus limon. fruits was

evaluated on HepG2 cell line. The ethanol extract normalized the levels of aspartate aminotransferase, alanine

aminotransferase, alkaline phosphatase, and total and direct bilirubin, which were altered due to carbon

tetrachloride intoxication in rats. In the liver tissue, treatment significantly raised the levels of antioxidant

enzymes superoxide dismutase and catalase. It improved the reduced glutathione (GSH) levels in treated rats in

comparison with CCl4-intoxicated rats. In the histopathologic studies, treated animals exhibited restoration of

the liver architecture toward normal. Three doses of ethanol extract (150, 300, and 500 mg/kg) were evaluated.

The results obtained were dose dependent, and the effect of the highest dose was almost equal to the standard

silymarin. Significant reduction in cell viability was observed in cells exposed to CCl4. A dose-dependent

increase in the cell viability was observed when CCl4-exposed HepG2 cells were treated with different

concentrations of ethyl acetate soluble fraction of the ethanol extract. The highest percentage viability of HepG2

cells was observed at a concentration of 100 µg/ml (224).

Ethylene glycol (0.75% v/v po in drinking water; 28 days) induced urolithiasis was used to study the

protective effect of flavanoid rich fraction of Citrus medica (FFCM) at three dose level (320, 380 and 440

μg/kg - 28 days; po) in male wistar albino rats. Cystone (750 mg/kg; po) was used as standard drug. After

completion of treatment period of 28 days, 24 hr urine sample and blood were collected. Various physical

parameters like body weight, diuresis, pH, kidneys weight (wet and dry) were measured. Various stone forming

inhibitors (magnesium and citrate) and promoters (oxalate, calcium, phosphate, uric acid and urea) were

analysed in urine, serum and kidney homogenate. Renal function test (BUN and creatinine clearance),

antioxidant parameters (MDA and catalase) and crystalluria were also evaluated. FFCM at all dose level

significantly prevented EG induced changes in calcium, inorganic phosphate, uric acid, oxalate, urea, citrate,

magnesium level; creatinine clearance and oxidative stress. FFCM possessed anti-lithiatic activity in

experimentally induced urolithiatic model that can be attributed to its diuretic action, decrease in promoters and

increase in inhibitors level as well as antioxidant potential(225).

The hepatoprotective activity of orange essential oils was evaluated in carbon tetrachloride-induced

hepatotoxicity in rats. Orange essential oils significantly reduced the serum ALT level when compared to CCl4

group, while it did not affect the serum AST level. The histopathological findings did not show any significant

difference between the orange essential oils treated and CCl4 groups(226).

Toxicity and side effects:

Citrus aurantifolia

All sources agree that citrus fruits contain d-limonene. Several sources demonstrate that oxided d-

limonene is allergenic, whereas information on unoxided d-limonene is conflicting. Several sources mention

that Citrus species contains 5-methoxypsoralene that is phototoxic(227).

The acute toxicity of Citrus aurantifolia indicated that doses up till 3g is safe (152). Acute and subchronic

toxicities of the water extract from the roots of Citrus aurantifolia were studied in both male and female rats.

Oral administration of the extract at a single dose of 5,000 mg/kg body weight did not produce signs of toxicity,

behavioral changes, mortality or differences on gross appearance of internal organs. The subchronic toxicity

was determined by oral feeding the test substance at the doses of 300, 600 and 1,200 mg/kg body weight for 90

days. The examinations of signs, animal behavior and health monitoring showed no signs of abnormalities in

the test groups as compared to the controls. The test and control groups (on the 90th day) and the satellite group

(on the 118th day) were analyzed by measuring their final body and organ weights, taking necropsy, and

examining hematological parameters, blood clinical chemistry and histopathology features. The oral

administration of 1,200 mg/kg/ day of the extract of Citrus aurantifolia in male and female rats caused a

increase in the liver enzymes, which remained within the normal range, but did not produce a significant

histopathological change in the internal organs. In conclusion, the extract from the roots of Citrus aurantifolia

administered orally did not cause acute or subchronic toxicities to male and female rats(228).

The subchronic toxicity of Citrus aurantium was evaluated in mice. Mice received for 28 consecutive days a

commercial Citrus aurantium dried extract (containing 7.5% p-synephrine) 400, 2000 or 4000 mg/kg and p-

synephrine 30 or 300 mg/kg by oral gavage. There was a reduction in body weight gain of animals treated with

both doses of p-synephrine. Organs relative weight, biochemical and hematological parameters were not altered

in all treated mice. There was an increase in reduced glutathione (GSH) concentration in groups treated with

Citrus aurantium 4000 mg/kg and p-synephrine 30 and 300 mg/kg. In glutathione peroxidase (GPx), there were

an inhibition of the activity in Citrus aurantium 400 and 2000 mg/kg and p-synephrine 30 and 300 mg/kg

treated animals, respectively, and there was no alteration in malondialdehyde (MDA) levels(229).

Citrus limonum

Essential oil of Citrus limonum is generally considered safe and devoid of adverse side effects when

administered in recommended doses. The potential capacity of causing sensitisation effects is very weak(230).

Nutritional value and pharmacological importance of citrus species

Acute toxicity study of n-hexane extract of C. limon peel at 2000mg/kg body weight in mice for 14 days did not

produce any mortality. There was no significant change in the body weight and food consumption of the

animals. The animals did not show any signs of toxicity and resembled the normal animals, which indicated the

safety of extract of C. limon peel in the experimental species(185).

Citrus medica

The toxicity of Citrus medica leaves essential oil was studied in rats. The effect of chronic ingestion

of a diet treated with different concentrations of essential oil of Citrus medica was studied on body weight, diet

consumption, haemoglobin, total and differential leucocyte count, blood glucose, protein, cholesterol, urea

levels and glutamic oxalacetic transaminase, glutamic pyruvic transaminase and alkaline phosphatase activity in

albino rats. It was found that the Citrus medica oil was nontoxic to test animals and did not induce any adverse

effects to the blood, liver function, kidney function, protein, carbohydrate and lipid metabolism of the

animals(231). The acute toxicity of the ethanol extract of the whole fruit of Citrus medica was evaluated in rats.

Female rats received a single high dose of ethanolic extract of Citrus medica (2 g/kg orally) by gavage. The

animals were observed for toxic symptoms continuously for the first 4 h after dosing. Finally, the number of

survivors was noted after 24 h and these animals were then maintained for a further 13 days with daily

observation. No toxicity symptoms (e.g., convulsions, myosis, mydriasis, diarrhea, increasing respiration,

urination, and muscle relaxation) were recorded. The LD50 value by oral route could not be determined as no

lethality was observed up to 2.0 g/kg of the Citrus medica in the animals(155).

Citrus sinensis

Essential oil of Citrus sinensis is generally considered as safe and devoid of adverse side effects when

administered in recommended doses. The potential capacity of causing sensitization and irritation effects is very

weak. Human patch tests with orange essential oil eight per cent in petrolatum had no irritant reaction after

48 hours, no sensitization, and no phototoxic effects(232).

Conclusion:

This review discuss the chemical constituent, pharmacological and therapeutic effects of Citrus fruits as

promising nutraceutical because of its safety and effectiveness.

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