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Nutritional value and pharmacological importance of citrus species grown in Iraq



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
IOSR Journal Of Pharmacy
(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
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:
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
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
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,
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
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-
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
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 24 cm (0.81.6 in) in diameter, axillary, fragrant, single, few or cymose, and often
perfect (having both functional stamens and pistils) or staminate. The calyx is 45 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 818 locules (cavities), with 48 ovules per locule in two rows.
Leaves are entire, 4 to 8 cm (1.63.2 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 1014 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
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--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
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
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
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
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
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
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
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
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 (p0.001 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 125500 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
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,
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
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- 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-
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
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
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-
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
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
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).
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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