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p>Flavonoids are natural antioxidants derived from plant pigments and commonly found in agricultural produce such as fruits, vegetables, and also in beverages like tea and wine. Quercetin is the most important flavonoid which belongs to the class of flavonol. Quercetin is a vital biologically active compound, which is present in many products, such as onion ( Allium cepa ), black tea ( Camellia sinensis ), Broccoli ( Brassica oleracea var . italic ), and also in red wine and green tea, It is widely used in medicine and pharmaceutics. In particular, it is used for cancer treatment; as it restrains the growth of cancer cells. Earlier some of computational investigations of this molecule were reported in literature, but they were made at low theory level. Quercetin provided many health promoting benefits, like cardiovascular properties, cancer reducing agent, Anti-inflammatory, asthma and many more. That is why the further investigation of this molecule is important. The main important of this review is to understanding of the structure of quercetin and corresponding biological properties of quercetin expressed in vitro studies, absorption is critical, but in vivo studies, better absorbed antioxidant were observed like vitamin C, further reported studies on effect of food processing, health benefits, storage effects, and evaluate its safety and dosage.</p
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Flavonoids involve an important group of naturally
occurring, bioactive polyphenolics, popular in plants of
higher generation1. Currently, the interest and awareness on
avonoids have largely focused on two different benecial
aspects. First, for their biological activities, and second for its
anti carcinogenic properties. The anti carcinogenic property of
avonoids is most frequently attributed to their anti oxidant
Flavonoids are said to be highly effective as an anti-
proliferative agent against lymphoid, colorectal, ovarian, and
breast cancer cells. Similarly, they are identied to induce
chromatin condensation and apoptosis in some cancer cells.
The mechanisms of avonoid induced cytotoxicity are not yet
established, but it is said to inuence the sequential occurrence
of apoptosis2.
Quercetin is a most abundant poly phenolic bioavonoid or
avonoid, which is generally classied as a avonol. Quercetin
is also classied as water-soluble pigments, which cannot be
produced by human. It is also known as a phytoestrogens.
Quercetin, comprising 3 rings and 5 hydroxyl groups, has
many health benecial effects, including improvement of
cardiovascular health and reducing the risk for cancer.
Quercetin, present in fruits and vegetables, is identied
to occur in various forms of glycosides; although its skin
is found to posses quercetin aglycone structure and are in
higher concentration. It is also naturally present as glycone
or carbohydrate conjugates in plants. It is one of the most
profusely present dietary avonoids that are present in apples
(Malus domestica); black and green tea (Camellia sinensis)
onions (Allium cepa) (predominantly in the outer rings);
broccoli (Brassica oleracea).
Quercetin glycosides in the onion extracts were converted
to quercetin and sugars by thermo-stable β-glucosidase enzyme.
It is found to posses several benecial biological activities,
like antioxidant, anti-inammatory, anti-cancer, and anti-
viral properties. The benecial effects of quercetin are limited
due to its sparingly soluble nature in water, which makes its
absorption limited.
2.1 Structure
The International Union of Pure and Applied Chemistry
(IUPAC)) nomenclature for quercetin is 3,3’,4’,5,7-
pentahydroxyavanone (or) 3,3’,4’,5,7-pentahydroxy-2-
phenylchromen-4-one with a molecular formula C15H10O7. The
presence of ve hydroxyl groups, at positions 3, 5, 7, 3’, and 4’
in quercetin molecule as shown in Fig. 1, leads to the formation
of and pentamethyl derivatives. It is also commonly termed as
quercetine, sophretin, meletin3.
Quercetin is acts as a building block for other avonoids.
Quercetin is commonly present as an aglycone in food. On
hydrolysis with acid, quercitrin is converted to quercetin and
rhamnose as shown in Fig. 2.
2.2 Chemical and Physical Properties of Quercetin
Quercetin with its high molecular weight (302.24),
Health Benets of Quercetin
R. Kumar*, S. Vijayalakshmi, and S. Nadanasabapathi
Food Engineering and Packaging Division, Defence Food Research Laboratory, Mysuru 570 011, India
Flavonoids are natural antioxidants derived from plant pigments and commonly found in agricultural produce
such as fruits, vegetables, and also in beverages like tea and wine. Quercetin is the most important avonoid
which belongs to the class of avonol. Quercetin is a vital biologically active compound, which is present in many
products, such as onion (Allium cepa), black tea (Camellia sinensis), Broccoli (Brassica oleracea var. italic), and
also in red wine and green tea, It is widely used in medicine and pharmaceutics. In particular, it is used for cancer
treatment; as it restrains the growth of cancer cells. Earlier some of computational investigations of this molecule
were reported in literature, but they were made at low theory level. Quercetin provided many health promoting
benets, like cardiovascular properties, cancer reducing agent, Anti-inammatory, asthma and many more. That is
why the further investigation of this molecule is important. The main important of this review is to understanding of
the structure of quercetin and corresponding biological properties of quercetin expressed in vitro studies, absorption
is critical, but in vivo studies, better absorbed antioxidant were observed like vitamin C, further reported studies on
effect of food processing, health benets, storage effects, and evaluate its safety and dosage.
Keywords: Quercetin; Flavonoids; Health benets; Food processing; Safety
Defence Life Science Journal, Vol. 2, No. 2, April 2017, pp. 142-151, DOI : 10.14429/dlsj.2.11359
Received : 16 February 2017, Revised : 13 March 2017
Accepted : 21 April 2017, Online published : 12 May 2017
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
melting point (316.5 °C) and poor water-solubility makes
it a big challenge for being available for biologically. The
presence of ve hydroxyl groups in the quercetin molecule
makes it lipophilic nature. The Table 1 represents the physical
properties of quercetin. Quercetin derivatives can be lipophilic
or hydrophilic in nature based on the type of substituents in
the molecule. In general, O-methyl, C-methyl and prenyl
derivatives of quercetin are lipophilic in character. They are
synthesised by the glands present on the surface of leaves,
owers and fruits. They can be easily isolated by immersing
the plant tissue in acetone4. The structural decomposition of
quercetin occurs when heated at higher temperatures, wherein
it emits acrid smoke and irritating fumes5.
4-OH-3-methoxy-phenylacetic acid; thereby nally quercetin
formed is absorbed from the small intestine to colon6.
From various studies it was found that 0.07 per cent
to 17.4 per cent of the amount of quercetin consumed was
excreted as quercetin or its conjugates. But the quercetin in
form glycosides was reported to absorb in the rat stomach.
Walgren7, et al, established from his study with invitro studies
of Caco-2 cells, that lack of absorption of the quercetin
glucosides, happens primarily due to the effective efux by
the multi-drug resistance protein 2 transporters. In succeeding
studies conducted with human subjects, it was observed that
the quercetin glucosides were hydrolysed by bacterial enzymes
in the small intestine.
In another study, it was reported that the absorption of
quercetin and quercetin aglycone ranged from 36 per cent to
53 per cent and 65-81 per cent respectively. It was found that
absorption of quercetin in ileostomists, as quercetin glucosides,
quercetin rutinoside and quercetin aglycone was 52±5%, 17
±15% and 24±9%, respectively8-13.
3.1 Thermal Processes on Quercetin
Thermal processes have a great inuence on the
availability of avonoid from foods, based on their magnitude
and duration of exposure. Various thermal processes like
drying, microwaving, heating by an autoclave, roasting,
pasteurisation, blanching have been used and their respective
impact on the avanoid was analysed. The Table 2 listed a few
studies where the effect of heat treatment on the degradation of
quercetin in foods was reported. The authors have reported that
Figure 1. Structure of quercetin (pubchem).
Figure 3. Proposed pathways of quercetin absorption (Source: Wu
et al, 2002) extraction and analysis of quercetin.
C21H20O11 + H2O HCl C15H10O7 + CH3 (CHOH) 4 CHO
Quercetin Quercetin Rhamnose
Figure 2. Hydrolysis of quercetin.
Boiling point Sublimes
Melting point 316.5 °C
(a) Very soluble
(b) Soluble
(c) Water
Less than 1 mg/mL at 70 °C
Ether, methanol
Ethanol, acetone pyridine, acetic acid
60 mg/mL at 16 °C
Table 1. Physical properties of quercetin
2.3 Absorption and Metabolism of Quercetin
Initially it was assumed that quercetin is absorbed in
the small intestine following the cleavage of ß-glucoside
linkage by colonic micro ora found in humans, but later on it
was concluded that its absorption was improved by conjugation
with glucose as shown in Fig. 3. It is proposed that quercetin-
3-glucoside on reacting with bacterial enzyme results in the
formation quercetin, which further reacts with colon and tissues
to give 3,4-diOH-phenylacetic acid and isorhamnetin. 3,4-
diOH-phenylacetic acid which is produced, further interacts
with colon and tissues to give 3-OH-phenylacetic acid and
Table 2. Effect of heat treatment on quercetin content
Heat treatment
Food product/avonoids Processing conditions Impact on avonoids content
Grapefruit juices Pasteurisation (95 °C, 80 s) Decrease of quercetin
Bean (quercetin) Atmospheric (100 °C) and pressure boiling (121 °C) with and without
soaking and draining Increases of 1-90% of quercetin
Strawberry juices (quercetin) High intensity pulsed electric elds Pasteurisation (90 °C, 60 s) Stability of quercetin
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
that quercetin was labile to heat degradation.
Ranilla14, et al, reported that boiling and
soaking of Brazilian beans at 100 °C along with
or without draining, induced a loss percentage
of 1-90 per cent of quercetin. Thermal
pasteurisation of strawberry juices when
performed at 90 °C for 60 s was reported to
have no effect on detrimental effect on quercetin
contents15, whereas it was proved to reduce
quercetin content in grapefruit juices16,17. The
avonoids in aqueous solutions have showed
to posses different degrees of sensitivity to
heat treatment based on their structures. The degradation of
avonoids may also be inuenced by other parameters such as
pH, phytochemicals and their structure and also by the presence
or absence of oxygen18.
3.2 Mechanical Processes on Quercetin
The commonly processes like peeling, trimming, and
cutting has been studied for its effect on bioactive compounds in
avonoid-rich foods; which is expected to inuence the content,
activity and availability of those bioactive compounds19. High
proportions of avonoids are lost during the pre-processing
step when undesired parts of the product was removed or cut
off. For instance, during peeling and trimming of onions it said
to result in 39 per cent of avonoids to lose20 and great losses
were noticed while peeling and dicing of tomatoes21. However,
in another study, it was reported that cutting increased avonol
content in fresh-cut potatoes22 and onions23.
3.3 Domestic Processes on Quercetin
Several studies were investigated to nd out the effects on
avonoid degradation under simulated home food preparation
conditions as shown in Table 3. Common domestic processes
methods like boiling, frying, baking, sautéing were performed.
Boiling was reported to result in avonoids losses of 43.9 per
cent for asparagus spears and 20.5 per cent for onions, due
to leaching of avanoids into the cooking water24. Similarly,
avanoid losses in onions were reported25-27. Lombard28, et al.
reported that sautéing resulted in a 25 per cent increase in the
avonoid content of onion. But the frying process was reported
to decrease about 25-33 per cent of avonoid content in
onion25,27. Conversely, baking was found to increase the amount
of quercetin conjugate and total avonol content (7 per cent)
in onions, due to the loss of water and other volatiles during
cooking and thereby making these compounds concentrated in
the tissues25,26.
The effect of storage conditions on the nutritional quality
of food can be a limiting step28. The degradation of avanoid is
inuenced by the storage duration, temperature and the presence
and intensity of light. The inuence of storage temperature and
time need to be controlled to reduce the effect on the avanoid
degradation. The quality degradation has been found to vary
with state of food (fresh or processed) when evaluated for the
effect of storage temperature (0 °C and 20 °C) under dark or
light exposure conditions as shown in Table 4.
The lower temperature storage of fresh has been reported
to result in minimal effect on the avanoid degradation. Price27,
et al. reported that nil effect was acquired in onion quercetin
conjugate content when stored under dark condition at 4°C
temperature for 6 months. Lopez-Rubira29, et al. reported
the effect on the antioxidant activity was insignicant in the
pomegranates stored at 1 °C for 13 days. In contrary to this,
Vina and Chaves30 reported 47 per cent loss in total avanoid
content of pre-cut celery, when stored at 0 °C for 21 days. An
increase in the avanoid content was reported22,31. The potato
strips when stored at 4 °C and exposed to light, was reported
to have a higher avanoid accumulation rate22. Wang31, et al.
reported that storage of raspberries 16 °C/24 °C for 4 days
induced an increase in it’s the phenolic content.
The quercetin content of strawberry juices was found to
decrease progressively on storage at 4 °C in darkness for 56
days15. In another study on raspberry jams, 40 per cent loss
of quercetin 3-glycoside was reported when it was stored in
dark at 20 °C for a period of 6 months32. Though the studies
have proved the effect of storage conditions such as time,
Table 3. Effects of domestic treatment on quercetin content
Domestic processes
Food product Processing condition Impact on avonoid content
Onions Sautéing (5 min),
baking (15 min, 176 °C) Increase of quercetin conjugates
Brown skinned
Boiling (20 min) A 14.3% loss of quercetin conjugates
Frying (5 min, 15 min) 23-29% Losses of quercetin conjugates
Red skinned
Boiling (20 min) A 21.9% loss of quercetin conjugates
Frying (5 min, 15 min) 23-29% Losses of quercetin conjugates
Effect of storage conditions
Food product/ avonoids Storage conditions Impact on avonoids content
Fresh foods pomegranate Storage (13 days, 1°C) No effect on antioxidant activity
Fresh-cut potatoes (avonols) onions
(quercetin conjugates)
Storage at 4 °C under light Long-term
storage in darkness (6 months,4 °C)
A 100% increase of avonol content
and no effect on quercetin conjugates
Enriched tea drink
Strawberry juice (quercetin)
Storage (6 months, 4 °C) Refrigeration in
darkness (56 days, 4 °C) Decrease of quercetin
Raspberry jams (quercetin 3-glycoside) Storage (6 months, 20 °C) 40% loss of quercetin3-glycoside
Table 4. Effect of storage conditions on quercetin
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
temperature and lighting, on the degradation of the avanoids,
the effect cannot generalised, as the degree or type of inuence
varies with the type of product and its nature, and with storage
The photodegradation of avanoid has been investigated
earlier33-35. The photodegradative effect on the avanoids was
reported to either increase or decrease, based on the state of
the food (fresh or processed foods). The stress signal caused
by the light exposure enhances the avanols in fresh foods56
such as fresh-cut potatoes and onions22,25. In a study on the
effect of illumination on fresh cut onons, 8 per cent increase
in the quercetin was reported. The exposure of the blueberries
to UV-C increased the avonoid content and the antioxidant
activity as well. Wang31, et al. reported an increase in the
phenolic content of the raspberries when exposed light.
The effect of light, primarily on the photodegradation of
phenols was reported to be dependent on various variables like
wavelength of light, pH, concentration and its structure, based
which positive or negative effects were obtained.
According to Tommasini36, et al. structural rearrangement
of 3-hydroxyavone, occurred rapidly when irradiated at 254
nm than when it was exposed at 350 nm. It was also reported
to be highly inuenced by the physicochemical properties
of the solvent, which played a vital in determination of the
occurrence of a photo-oxidation or photo-induced molecular
The versatile nature of quercetin contributes too many
benecial biological properties such as antioxidant action,
canker sores, neurological effect, antiviral activity, anti-
inammatory, asthma, cardiovascular properties and as a
anticancer agent.
6.1 Antioxidant Action
The antioxidant property of the avanoids principally
neutralises the free radicals by donating hydrogen atoms to it.
Pietta37, et al. observed that difculty aroused on correlating
the structure of avonoids and their accountability for radical-
The formation of reactive oxygen species (ROS) has
been reported to contribute to the diabetes, atherosclerosis,
hypertension, ischemic heart disease and heart failure. Quercetin
acts as an antioxidant by preventing oxidative stress, the major
cause for generation of ROS. The avonoids comprising 3-OH
and 3`, 4`-catechol were known to be ten times more effective
towards peroxynitrite than ebselen, a RNS scavenger38.
Quercetin is widely known for its antioxidant property that
is for its ability to scavenge free radicals and bind transition
metal ions. The ultimate effects on the humans by quercetin for
its antioxidant property need to streamline to obtain signicant
impact on the biomarkers/ indices to be measured. In a study, the
consumption of a test meal of fried onions was reported to have
signicantly increased the plasma quercetin levels. Though
an increase in the total antioxidant activity of the plasma was
noted, not much difference occurred in the oxidation of the
plasma or isolated low density lipoprotein (LDL) over the 48-h
period following the consumption of the fried onions. The
two weeks supplementation of quercetin in healthy subjects
(150 mg/day) was reported to have minimal inuence on the
plasma, its antioxidant capacity, oxidised LDL, or alpha- or
6.2 Neurological Effects
Quercetin has been proved to be neuroprotective as well
as neurotoxic. Joseph34, et al. reported to be neuroprotector
in rat brain when used in combination to sh oil, where it
benecial effects against neurodegenerative diseases (e.g.
Alzheimer’s disease). Choi40, et al. showed inhibitory effects
against acetylcholinesterase. Quercetin was reported to have
decreased the 6-hydroxydopamine induced oxidative stress in
the neurons of brain striatum of rats56. In another study, it was
reported that the quercetin treatment affected the working of
the nervous system by depleting the intracellular glutathione
contents41. On the other hand, whether the prolonged usage
of antioxidant supplements can be considered safe for human
health is still a big question.
6.3 Antiviral Activity
Quercetin has been reported to be effective against viruses
i.e. it posses antiviral activity against enveloped viruses such
as herpes simplex type I, parainuenza type 3, respiratory
syncytial, pseudorabies, and Sindbis. It was also proved to
be protecting from the cardio virus42. The antiviral activity of
quercetin was due to its ability to bind to viral coat protein
and polymerases and also to damage DNA. The mutagenic,
carcinogenic, and anti carcinogenic activity of quercetin was
found to be related to its ability to impose or prevent damage
to DNA. It was reported that on stabilisation of Quercetin with
ascorbate it enhances its antiviral activity, which was similar
to the effect induced by ascorbate enhanced antiproliferative
effect on squamous cell carcinoma43. Quercetin was also proved
to have enhance the antiviral activity of agents like interferon
and 5°ethyl-2’-deoxyuridine.
6.4 Anticancer Agent
Quercetin and other avonoids, derived from fruits and
vegetables have been marked important compounds as it was
considered to positively help in preventing cancer. Various
studies has been performed to evaluate the anti-carcinogenic
effect of quercetin on cell cultures, where it was found that
slow the growth of cancer cells was effected and it also helped
to foster apoptosis. The induction of apoptosis in cancer cells
has been proved to be an vital step in the development of novel
anticancer drug44. Some animal studies conducted have shown
that quercetin helps in the protecting form certain type of
cancers, especially colon cancer45.
6.5 Canker Sores
Small and shallow lesions known as the canker sores
(aphthous ulcers), occur on the soft tissues in mouth or at the
base of gums. Sharma45, et al. proved that quercetin reduced
the occurrence of mouth sores and also helps to induce mild
symptomatic relief.
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
6.6 Cardiovascular Properties
Heart diseases have been identied to be the primary and
leading cause of mortality in the developed countries. Though
the exact reason for the cause and the mechanism involved
in the occurrence of heart disease still remains a mystery,
oxidative stress and inammation has been identied to play
a vital role. Quercetin has been investigated for its possible
utilisation as a safe alternative to the antioxidant and anti-
inammatory drugs used for conditions like cardiovascular
disease. The studies have revealed that, both preclinical and
clinical study, quercetin positively reduced several of the risk
factors related with heart disease, including blood pressure and
cytokine-induced C-reactive protein (CRP) expression. It has
also been identied as a potent vasodilatory agent.
6.7 Anti-inflammatory
The normal biological process in response to injuries,
microbial infection or intoxication and chemical irritation
was known as inammation. Inammation was generally
considered to be initiated by the migration of immune cells
from blood vessels to the infected/ injured area and discharge
of mediators to combat the infection/injury.
Quercetin has been widely known for its anti-inammatory
activity. During a in vivo study conducted by Lin46, et al., when
the rats were treated with quercetin mixed with polysorbate 80,
it resulted in the inhibition of edema in the paw of the rats. The
applications of quercetin glycoside through the skin surface
were found to be ineffective against inammation due to low
absorption value. The quercetin pentamethylether formulation
was highly absorbed through the skin route in rat, and it was
found to be effective against inammation, therby proving it to
be a potent anti-inammatory agent.
6.8 Asthma
Asthma is a chronic lung-disease that swells and narrows
the airways, thereby causing difculty in breathing. Quercetin
was found to ease the symptoms of asthma. It was found to
induce reduction in the inammatory immune cells number
and activation, cuts off the histamine level and also eases the
airway smooth muscle. Rigolin47, et al. reported that even at
the minimum concentration, quercetin was effective against
asthma, in comparison to the standard asthma maintenance
medications and steroid inhalers that reduces the resistance to
air ow.
Quercetin was also reported to reduce pathologies of
asthma, such as eosinophil and neutrophil enrollment, bronchial
epithelial cell activation, mucus and collagen production and
airway hyperactivity. The dietary intake levels of quercetin
were reported to inuence the asthma symptoms. The clinical
studies performed revealed the possible application of quercetin
to prevent or treat asthma in human patients.
Quercetin which was generally considered to be safe was
reported to result in few side effects like headache and discomfort
of stomach. A preliminary study conducted, suggested that the
byproduct of quercetin leads to the loss of protein function.
It has also been reported that very high doses of quercetin
may harm the kidneys and thereby it was suggested to take
intermittent breaks during the consumption of quercetin. It was
advised that pregnant and breastfeeding women and people
with kidney disorder should avoid quercetin. Consumption
of doses greater than 1 g per day, have been reported to have
caused damage to the kidneys.
In a four-week rat study performed by Azuma48, et al.
increase in the ratio of weight of liver and kidney to the body
weight ratios was observed when fed with more than 314 mg
and 157 mg quercetin/kg body weight/day, respectively. The
consumption of doses above 157 mg quercetin/kg body weight/
day resulted in a pro-oxidant effect.
In human studies, it was seen that the quercetin content has
commonly been well tolerated. It was proved that consumption
of doses up to 1,000 mg/day for several months have not
induced any adverse effects on blood parameters of liver and
kidney function, hematology, or serum electrolytes. At present,
the principal concern for toxicity was the co-administration of
high quercetin doses with digoxin. Though it has been proved
to be toxic, until more studies pertaining to the safe dosage
level determination, it suggested to avoid consumption of
quercetin along with digoxin31.
Several studies, have shown that the higher doses of
quercetin more than 200 μm reduced the cell viability49; but
low doses of quercetin (<200 μm) was reported to increase the
cell viability and to be xed as therapeutic dose. It was reported
that a low dose of quercetin also resulted in the inhibition of
the proliferation of breast cancer cells, mild cytotoxic effect,
and also induce mild DNA damage. The fruit and vegetable
consumption was reported to contribute to an average of 15 mg
to 40 mg of quercetin per day from the diet. It was suggested
that an increase in quercetin intake could be accomplished
by increasing the consumption of more fruit and vegetables.
Therapeutic dosages of quercetin intake were denoted to range
from 250 mg to 500 mg three times per day. Quercetin was
generally available, in the form of capsules or tablets ranging
in doses from 50 mg to 500 mg, as dietary supplements. The
dosage of quercetin has been recommended based on the health
condition to be treated and no standard dose for quercetin has
been suggested. According to Werbach50, et al, for allergic
conditions and for chronic hives, a dose of 250 mg - 600 mg
per day and 200 mg - 400 mg has been recommended. It was
reported that a low dose of quercetin was sufcient to inhibit
the proliferation of breast cancer cells, mild cytotoxic effect,
and to induce mild DNA damage51.
Scientists have involved in the process of identication
and quantication of quercetin from various food sources.
It was reported that on comparing the quercetin content in
onion peel with that in its esh, the highest concentration was
found in the peels of onion52. It has been normally found in
a variety of foods like onions, apples, berries, tea, tomatoes,
grapes, shallots, brassica vegetables, many seeds, nuts,
owers, barks, leaves and also in some medical plants (ginkgo
biloba, cranberries and St. John’s wort). The aglycone form
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
of quercetin was found in much lesser amounts in the diet
generally consumed. Hollman8, et al. analysed the glycoside
and aglycone form of quercetin extracted from plants, and
quantied using High-performance Liquid Chromatography
(HPLC). The Table 5 represents the list of items and their
quercetin content as reported by the United States Department
of Agriculture53.
Quercetin, a avonoid has been proved to be a powerful
antioxidant which can be derived from raw foods such as fruit
and vegetables, cocoa, tea, coffee, etc. Quercetin was also
known to provide various benecial properties for human health
as a anti-oxidant, anti-inammatory agent, antiviral activity,
cardiovascular properties and anticancer properties. The health
benets of quercetin can be preserved in the processed foods by
adapting less intense and non-aggressive processes. However,
providing the consumers, antioxidants enriched food products
may not be an easy task, despite the several studies conducted
on the effect of food processes on the degradation of quercetin
and their functional activities, it has been difcult to generalize
the results and adapt. Many factors such as:
(i) The type of raw food
(ii) Standardisation of processing and analytical methods
(iii) The inuence of the food matrix, affect the quercetin
content extraction, analysis and it properties as well.
The usage of quercetin for its anti-oxidative and anti-
inammatory property has been well established. Interestingly,
these were the two effects of quercetin which has been widely
dealt to combat the oxidative stress and inammation proving
it to be a major source of supplementation for those who have
been suffering from this problem.
The major toxicological work related to the quercetin and
its by product has been widely studied with the in vitro studies.
The formation of toxic compounds from quercetin upon
oxidation, during its ROS scavenging activities were likely
to occur. The primary oxidation product of quercetin formed
was found to be orthoquinone, which has been proved to be
toxic. As a result, the supplementation of quercetin during the
in vivo studies has to be done with utmost care, considering
the possibility of toxic compounds/ metabolite formation,
especially in the treatment of chronic ailments.
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Food source Quercetin content (mg/100g)
Raw onions 13.27
Black tea 1.99
Apple, with skin 4.42
Green tea 2.69
Broccoli, raw 3.21
Red wine 0.84
Spinach, raw 4.86
Cocoa powder, unsweetened 20.10
Cranberries, raw 14.00
Table 5. Quercetin content in foods
Extraction method Solvents Temperature (oC) Pressure Time
Ultrasonication CH3OH, C2H5OH Above room temperature 120 Watt 1 h
Microwave assisted extraction CH3OH, C2H5OH 60 15 Watt 2 min
Shaking-water bath 60% aqueous CH3OH 30 60 min
Ultrasonication using a ultrasonic liquid processor 60% aqueous CH3OH Room temperature 10 Watt 30 s
Accelerated solvent extraction 60% aqueous CH3OH 40 1500 psi 2 min
Table 6. Experimental conditions for the extraction of quercetin
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The Raman spectrum analysis of quercetin in the ethanol
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The bands obtained were at 600 cm-1 and 1616 cm-1, appeared
without interference from the solvent peak. The quantitative
measurement and conrmation of quercetin was done using
with HPLC and UV-Vis absorption spectrometry. The HPLC
analysis of quercetin was performed with a UV detector at
254 nm. The UV-Vis absorption spectra were determined by
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Dr R. Kumar, obtained his MSc (Food Science & Nutrition)
from Tamil Nadu Agricultural University, Coimbatore and
PhD (Food Science) from Bharathiyar University, Coimbatore.
Presently working as Scientist ‘F’ in DFRL, Mysuru. He has 65
research papers and 10 patents to his credit. He has received
many awards including DRDO Performance Excellence Award
and Thomson Edition Award. He has research experience in
thermal, non-thermal food processing technologies and food
Contribution in the current study, he did collection of relevant
literature, preparation of manuscript and correction.
KUMAR, et al.: DEF. LIFE SCI. J., VOL. 2, NO. 2, APRIL 2017, DOI : 10.14429/dlsj.2.11359
Ms S. Vijayalakshmi obtained her MSc (Food Science and
Technology) from Pondicherry University. Presently she is
working as Senior Research Fellow in DFRL, Mysuru. She
has published more than 10 research and review papers. Her
research interest includes: Reduction of Aflatoxin contamination
by the use o f pulsed e le ct rical field ( PE F) proce ss in g and
combination processing.
Contribution in the current study, she is involved in writing
of manuscript.
Dr S. Nadanasabapathi obtained his MSc (Chemistry) from
Annamalai University and PhD (Chemistry) from University
of Mysuru. Presently working as Scientist ‘G’ and Head,
Food Engineering & Packaging in DFRL, Mysuru. He has 95
research papers and 15 patents to his credit. He has received
DRDO Performance Excellence Award, Thomson Edition Award,
Technology Group Award, and Laboratory Scientist of the Year
Award. He has research experience in the : Food packaging,
thermal and non thermal food processing technologies.
Contribution in the current study, he is involved in final
correction and editing of the manuscript.
... As an anti-oxidant and anti-inflammatory, quercetin is widely used. These two quercetin effects have been commonly employed to cope with oxidative stress and inflammation and are shown to be the major source of supplements for individuals suffering from this condition [146]. ...
... Various preclinical pharmacological studies have been performed to investigate the anticancer effects of quercetin, which has been shown to reduce the growth rate of cancer cells and also to induce apoptosis [177]. Inducing apoptosis in cancer cells is a vital step to develop a new anticancer drug [146]. In addition, in vivo studies have shown that quercetin is involved in the prevention of several types of cancer, especially colon cancer [178]. ...
Full-text available
Over the past few years, the cancer-related disease has had a high mortality rate and incidence worldwide, despite clinical advances in cancer treatment. The drugs used for cancer therapy, have high side effects in addition to the high cost. Subsequently, to reduce these side effects, many studies have suggested the use of natural bioactive compounds. Among these, which have recently attracted the attention of many researchers, quercetin has such properties. Quercetin, a plant flavonoid found in fresh fruits, vegetables and citrus fruits, has anti-cancer properties by inhibiting tumor proliferation, invasion, and tumor metastasis. Several studies have demonstrated the anti-cancer mechanism of quercetin, and these mechanisms are controlled through several signalling pathways within the cancer cell. Pathways involved in this process include apoptotic, p53, NF-κB, MAPK, JAK/STAT, PI3K/AKT, and Wnt/β-catenin pathways. In addition to regulating these pathways, quercetin controls the activity of oncogenic and tumor suppressor ncRNAs. Therefore, in this comprehensive review, we summarized the regulation of these signalling pathways by quercetin. The modulatory role of quercetin in the expression of various miRNAs has also been discussed. Understanding the basic anti-cancer mechanisms of these herbal compounds can help prevent and manage many types of cancer.
... In fruits, they are present mainly as quercetin [50]. For instance, elderberry contains a significant amount of quercetin derivatives, and quercetin is reported to have positive benefits on health; typically, they are well-known for their antioxidant, anti-obesity, and anti-inflammatory properties, and can be used in preventing cardiovascular illnesses [51,52]. Apple pomace is typically discarded as waste material in processing industries after the juice has been extracted. ...
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The fruit production and processing sectors produce tremendous amounts of by-products and waste that cause significant economic losses and an undesirable impact on the environment. The effective utilization of these fruit wastes can help to reduce the carbon footprint and greenhouse gas emissions, thereby achieving sustainable development goals. These by-products contain a variety of bioactive compounds, such as dietary fiber, flavonoids, phenolic compounds, antioxidants, polysaccharides, and several other health-promoting nutrients and phytochemicals. These bioactive compounds can be extracted and used as value-added products in different industrial applications. The bioactive components extracted can be used in developing nutraceutical products, functional foods, or food additives. This review provides a comprehensive review of the recent developments in fruit waste valorization techniques and their application in food industries. The various extraction techniques, including conventional and emerging methods, have been discussed. The antioxi-dant and antimicrobial activities of the active compounds extracted and isolated from fruit waste have been described. The most important food industrial application of bioactive compounds extracted from fruit waste (FW) has been provided. Finally, challenges, future direction, and concluding remarks on the topic are summarized.
... In fruits, they are present mainly as quercetin [50]. For instance, elderberry contains a significant amount of quercetin derivatives, and quercetin is reported to have positive benefits on health; typically, they are well-known for their antioxidant, anti-obesity, and anti-inflammatory properties, and can be used in preventing cardiovascular illnesses [51,52]. Apple pomace is typically discarded as waste material in processing industries after the juice has been extracted. ...
The fruit production and processing sectors produce tremendous amounts of by-products and waste that cause significant economic losses and an undesirable impact on the environment. The effective utilization of these fruit wastes can help to reduce the carbon footprint and greenhouse gas emissions, thereby achieving sustainable development goals. These by-products contain a variety of bioactive compounds, such as dietary fiber, flavonoids, phenolic compounds, antioxidants, polysaccharides, and several other health-promoting nutrients and phytochemicals. These bioactive compounds can be extracted and used as value-added products in different industrial applications. The bioactive components extracted can be used in developing nutraceutical products, functional foods, or food additives. This review provides a comprehensive review of the recent developments in fruit waste valorization techniques and their application in food industries. The various extraction techniques, including conventional and emerging methods, have been discussed. The antioxidant and antimicrobial activities of the active compounds extracted and isolated from fruit waste have been described. The most important food industrial application of bioactive compounds extracted from fruit waste (FW) has been provided. Finally, challenges, future direction, and concluding remarks on the topic are summarized.
... oleracea var. italica Plenck) (Kumar et al., 2017). In a mice model of lethal sepsis, quercetin significantly attenuated LPS-induced production of TNF-α and IL-1β in RAW264.7 macrophages, and also inhibited the LPSstimulated phosphorylation of the inhibitors of κB kinase (IKKs), Akt, and JNK. ...
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Sepsis is a severe inflammatory response to systemic infection and is a threatening cause of death in intensive care units. In recent years, a number of studies have been conducted on the protective effect of natural products against sepsis-induced organ injury. However, a comprehensive review of these studies indicating the mechanisms of action of the bioactive compounds is still lacking. In this context, this review aimed to provide an updated analysis of the mechanism of action of plants’ secondary metabolites in the management of sepsis. Scopus, Science Direct, Google Scholar, and PubMed were searched from inception to July 2022. A variety of secondary metabolites were found to be effective in sepsis management including allicin, aloin, cepharanthine, chrysin, curcumin, cyanidin, gallic acid, gingerol, ginsenoside, glycyrrhizin, hesperidin, kaempferol, narciclasine, naringenin, naringin, piperine, quercetin, resveratrol, rosmarinic acid, shogaol, silymarin, sulforaphane, thymoquinone, umbelliferone, and zingerone. The protective effects exerted by these compounds can be ascribed to their antioxidant properties as well as induction of endogenous antioxidant mechanisms, and also via the downregulation of inflammatory response and reduction of biochemical and inflammatory markers of sepsis. These findings suggest that these secondary metabolites could be of potential therapeutic value in the management of sepsis, but human studies must be performed to provide strength to their potential clinical relevance in sepsis-related morbidity and mortality reduction.
... These polyphenolics are very well-known for their antioxidant activity, and they have been proven to have a role in many different types of diseases/disorders, such as cardiovascular disease, hepatic disorder, diabetes, allergies, infection, inflammation, and cancer, to name a few [61][62][63]. The anti-cancer effect of flavonoids is due to the antioxidant effect, which, in turn, is dependent on a number of phenolic hydroxyl groups in their structure [64,65]. Similarly, many reports are available that show anti-cancer properties of terpenoids [66,67], as well as anti-inflammatory properties [68]. ...
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The primary objective of this research was to use flow cytometry to gain mechanistic insights into the cytotoxic effects of Tribulus terrestris extracts on breast cancer (MCF7) and lung cancer (A549) cell lines. T. terrestris was extracted using a Soxhlet apparatus in a progressive process. GC–MS was used to establish the phytochemical constituents. The amounts of phenolic compounds and flavonoids in the plant extracts were calculated using spectrophotometric analysis. The cytotoxicity of plant extracts was initially evaluated in non-malignant L929 cells, then in carcinogenic MCF-7 and A549 cell lines. Then, we performed an Annexin V assay, an anti-Bcl-2 assay, a Caspase-3 assay, and a DNA fragmentation (TUNEL) assay, using flow cytometry to investigate the underlying molecular processes. Based on the data, the methanolic extract of T. terrestris contained the highest amounts of phenolic compounds and flavonoids, with values of 169.87 µg GAE/g dwt and 160.12 µg QE/g dwt, respectively. Analysis by GC–MS revealed the presence of bioactive phytochemicals with proven cytotoxicity. Based on the MTT experiment, we determined that the IC50 values for the methanol extract’s effect on the viability of the MCF-7 and A549 cell lines were 218.19 and 179.62 µg/mL, respectively. The aqueous and methanol extracts were less cytotoxic when tested against the cancer-free L929 cell line (IC50 = 224.35 µg/mL). In both breast and lung cancer cells, the methanolic extract was found to activate caspase-3 and inhibit the Bcl-2 protein, resulting in early and late apoptosis and cell death via DNA damage. These findings point to cytotoxic effects of T. terrestris methanol extract against breast and lung cancer cell lines. Due to its potential as a source of anti-cancer chemotherapeutic medicines, T. terrestris warrants further investigation.
There is a diverse array of berries found wild in tropical, temperate and arid ecosystems or cultivated in both field and control environments across the globe. It is evident berry genetics, species, growth environment, cultivation techniques, postharvest management practices, packaging and processing affect the nutritional and functional properties of berries. The level and composition of functional and nutritional compounds in berries are primarily responsible for their health promotive properties. In particular, anthocyanins and flavonoids are shown to be very effective in managing, treating and reducing CVD risks in humans; and the effects are even more pronounced when combined with personalized nutrition or diets and physical activities. Globally, there is a steady increase in CVD incidences and associated deaths. There is a need for interventive strategies to reduce these CVD incidences and associated deaths. Personalized nutrition and diets containing increase levels or consumption of fresh berries, berry-based functional foods, nutritional products, or nutraceuticals could be an effective long-term strategy to reduce CVD disease risks, as well as improve population health globally.
Astringency is a feeling of dryness in the mouth. Microscopically, it is manifested in the diversity of ingredients and mechanisms that can cause astringency, astringent components are mainly flavonoids, phenolic acids, tannin and other polyphenols components. Macroscopically, it is manifested in the rich variety of foods with astringent taste, because polyphenols are common secondary metabolites of plants. With the improvement of people's living standards, the demand for reducing or removing astringency in food and medicine is also increasing, and polysaccharides, as commonly used flavoring agents and food additives, have become the ideal choice for decreasing astringency. In this paper, the material basis, molecular mechanism, possible pathways and related cases of polysaccharides moderating of astringency are mainly reviewed, so as to illustrate the feasibility of polysaccharides decreasing of astringency and provide a reference for reducing the astringency of food and drugs.
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Objective: The aim: This research aims to analyze the challenges we came across due to the rapid spread among the population (including young people) of tobacco heating devices. Patients and methods: Materials and methods: Analysis of 20 literature sources containing information about tobacco heating systems was performed. The search for literary sources was carried out in two main scientific databases: Scopus and PubMed. The review included original articles, research, and official recommendations from medical associations. Conclusion: Conclusions: Tobacco heaters reduce harmful substances in the inhaled air compared to conventional tobacco cigarettes, but these new devices provide effective nicotine absorption, which prolongs a person's nicotine dependence and prevents smoking cessation. The main problem we face due to the rapid spreading of these devices - potentially tobacco heating systems can pose health risks and further research on such risks, especially long - term, are needed. Tobacco heating devices, regardless of their manufacturer and design, should be subject to restrictions similar to traditional cigarettes.
Objective: The aim: To improve the effectiveness of treatment of patients with hypertension using metabolic therapy based on the evaluation of endothelial dysfunction indicators, markers of inflammation, and blood lipid spectrum. Patients and methods: Materials and methods: A clinical study was performed with 72 patients (34 male and 38 female) with stage 2 arterial hypertension of 2-3 degrees, admitted to the cardiology department of the municipal non-profit enterprise "Lviv Emergency Clinical Hospital". The mean age of patients was 44.8±8.5 years. Patients were divided into 2 groups: Group I was taking quercetin in addition to basic therapy (Ramipril/Amlodipine in individually adjusted dose); Group II - had basic therapy following the clinical protocol. The level of nitric oxide, IL-1, IL-6, TNF-a, CRP, seromucoid, blood lipid spectrum was determined. Results: Results: There is a significant decrease in the NO and CRP levels. There is a decrease in the TNF-a level by 31.27±2.13 (p<0.01) after the treatment of patients with hypertension. The TNF-a level decreased by 22.2±1.13 (p<0.01) with the use of basic therapy. IL-1 decreased significantly in the two groups, but it was more pronounced in group I, by 40.68±1.67 (p<0.01) and 21.4±2.1 in group II (p<0.05). There is a positive change in the blood lipid spectrum, but the changes were more pronounced in the group of patients receiving metabolic therapy. Conclusion: Conclusions: The use of quercetin (Corvitin, Quertin) in combination therapy with the combined antihypertensive drug containing ramipril/amlodipine (Egis-Hungary) significantly reduces the levels of nitric oxide, CRP, IL-1, and blood lipid spectrum, which reduces the incidence of complications and progression of hypertension.
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Objective: The aim: To review the available results for genetic influences on pain syndrome development. Patients and methods: Materials and methods: In the period from 2009 to 2020, a total of 45 research papers describing the key points of genetic influences on pain mechanisms in both adults and children were published in Ukrainian and English and they are now included in the PubMed, EMBASE, Cochrane, and Google Scholar research databases. Conclusion: Conclusions: Pain is a comprehensive characteristic of a person; therefore, it is inevitable that several genes with little individual effect interact with each other and environmental factors, influencing pain susceptibility and chronic pain syndrome manifestation. This requires searching for biomarkers for diagnosing and predicting the development of acute and chronic pain syndromes, especially in pediatric practice.
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Allergic asthma is a complex inflammatory disorder characterized by airway hyperresponsiveness, eosinophilic inflammation and hypersecretion of mucus. Current therapies include β2-agonists, cysteinyl leukotriene receptor 1 antagonists and corticosteroids. Although these drugs demonstrate beneficial effects, their adverse side effects limit their long-term use. Thus, the development of new compounds with similar therapeutic activities and reduced side effects is both desirable and necessary. Natural compounds are used in some current therapies, as plant-derived metabolites can relieve disease symptoms in the same manner as allopathic medicines. Quercetin is a flavonoid that is naturally found in many fruits and vegetables and has been shown to exert multiple biological effects in experimental models, including the reduction of major symptoms of asthma: bronchial hyperactivity, mucus production and airway inflammation. In this review, we discuss results from the literature that illustrate the potential of quercetin to treat asthma and its exacerbations.
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The oxidative degradation of quercetin and rutin in phosphate buffer solutions, pH 8.0, at 97 degrees C, was studied by means of UV-vis spectroscopy and reversed-phase high-performance liquid chromatography (HPLC). The effect of the transition metal ions Fe(2+) and Cu(2+) On degradation rate and browning development was also assessed. It was shown that both flavonols are very labile to thermally induced degradation under oxidative conditions. Fe(2+) and Cu(2+) caused an increase in the degradation rate, as well as an increase in browning (A(420)) Significant differences were observed in the degradation mechanisms, as implied by HPLC analyses. It is postulated that metal ions promote flavonol oxidation through reactive oxygen species formation, whereas increases in browning could be ascribed to oxidation and metal-polyphenol interactions.
Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.
Onions contain large quantities of quercetin, known to be active as an antioxidant. Also, welsh onion belong to the group of leafy vegetables, and the leaf sheaths contain large quantities of ascorbic acid. So, we tried to enhance the contents of these compounds in allium vegetables through postharvest management. We take an interest in the biological action of UV reviewed in various plant tissue and cells, especially the induction of oxidative stress defense systems in living body. From the information that UV could not penetrate deeply in the plant tissue, we used onion slices for this study. We showed that UV-A radiation increased the content of quercetin in bulbs, and reached its maximum during the end of dormancy at regrowth. In addition, UV radiation also caused an increase in the amount of ascorbic acid in the leaf sheath of welsh onion after the harvest. From these results, UV radiation was considered one possible means of postharvest managements to enhance the functional compounds in these vegetables.
The effect of conventional and microwave pasteurization on the main flavonoids present in grapefruit juice and their stability throughout 2 months of refrigerated and frozen storage was evaluated. Individual flavonoids were analyzed by HPLC. The results showed that naringin, narirutin, quercetin and naringenin were the most abundant flavonoids in grapefruit juice. In general, although every pasteurization treatment caused a significant reduction in the content of all the studied flavonoids, the treated samples were more stable during storage. While fresh squeezed juice (FS) and conventional pasteurized juice (CP) were better preserved under refrigeration conditions, microwave pasteurized juice (MP) conserved better when frozen stored. In fact, after 2 months, frozen MP samples showed the greatest flavonoid retention. From this point of view, microwave treatment can be considered a good alternative to conventional pasteurization.
To investigate the anti-amnesic effect of quercetin by using in vivo Y-maze and passive avoidance tests, the learning and memory impairment in ICR mice was induced by neurotoxic trimethyltin. Quercetin pre-administration attenuated TMT-induced memory injury in both in vivo tests. Acetylcholinesterase (AChE), prepared from mice brain tissues, was inhibited by quercetin in a dose-dependent manner. Malondialdehyde generation in the brain homogenate of mice treated with quercetin decreased, indicating that peroxidation of polyunsaturated fatty acids was inhibited by the cellular membrane. In addition, potent antioxidant capacity of quercetin was confirmed through various antioxidative assays. Our findings suggest that the quercetin may improve cognitive ability against TMT-induced neuronal deficit and also have an inhibitory action against AChE. Consequently, these results demonstrate that the quercetin could possess a wide range of beneficial activities for neurodegenerative disorders, notably Alzheimer’s disease (AD).
In this study, the usefulness of different mathematical models to predict the retention of ascorbic acid (AA), total phenols (TP) and DPPH radical scavenging activity (SA) of pasteurized pineapple juices during storage has been evaluated. The results indicate that first-order kinetic model provided the best prediction of the degradation of AA (MAE = 0.0059; MRE = 0.0117; MSE = 0.0001; R2 = 0.9995) whereas Weibull model provided the less satisfactory prediction (MAE = 0.2387; MRE = 0.2911; MSE = 0.0769; R2 = 0.9993). In addition, zero-order (MAE = 0.0016; MRE = 0.0017; MSE = 0.0000; R2 = 0.9992) and first-order (MAE = 0.0027; MRE = 0.0029; MSE = 0.0000; R2 = 0.9989) kinetic models are adequate models for application in the prediction of TP loss, and first-order kinetic (MAE = 0.0294; MRE = 0.0549; MSE = 0.0015; R2 = 0.9845) and Weibull (MAE = 0.0533; MRE = 0.0881; MSE = 0.0044; R2 = 0.9823) models are recommended to predict the change of SA. These results show that the behaviors of AA, TP and SA during storage of juices can be accurately described by different prediction models. Therefore, the selection of the most adequate model is of great importance to predict nutritional deterioration in food products during storage.
Quercetin content in onion (Allium cepa L.), represented mainly by 3,4′-O-quercetin diglucoside (3,4′-Qdg) and 4′-O-quercetin glucoside (4′-Qmg), was examined in five cultivars before and after three cooking treatments (sautéing, baking, and boiling). Baking and sautéing produced a 7–25% gain in quercetin concentration, while boiling produced an 18% decrease in quercetin concentration. Ratios of 3,4′-Qdg to 4′-Qmg in tissues ranged from 1:1.3 and 1:1.7, and combined the two conjugates represented 89–90% of total flavonol content in treatment and raw control means indicating heat stability of the flavonols. Changes in flavonol concentrations as a result of cooking method were consistent across all five cultivars.