Everything about Quercetin totally explained
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Quercetin is a
flavonoid and, to be more specific, a
flavonol.
Chemical structure
It is the
aglycone form of a number of other flavonoid
glycosides, such as
rutin and
quercitrin, found in
citrus fruit & onions. Quercetin forms the
glycosides
quercitrin and
rutin together with
rhamnose and
rutinose, respectively.
Medicinal properties
Quercetin is found to be the most active of the flavonoids in studies, and many medicinal plants owe much of their activity to their high quercetin content. Quercetin has demonstrated significant
anti-inflammatory activity because of direct inhibition of several initial processes of
inflammation. For example, it inhibits both the manufacture and release of
histamine and other
allergic/inflammatory
mediators. In addition, it exerts potent
antioxidant activity and
vitamin C-sparing action.
Quercetin also shows anti-tumour properties. A study in the
British Journal of Cancer showed that, when treated with a combination of quercetin and
ultrasound at 20 kHz for 1 minute duration,
skin and
prostate cancers show a 90% mortality within 48 hours with no visible mortality of normal cells. Note that ultrasound also promotes
topical absorption by up to 1,000 times making the use of topical quercetin and ultrasound wands an interesting proposition.
Recent studies have supported that quercetin can help men with
chronic prostatitis, and both men and women with interstitial cystitis, possibly because of its action as a
mast cell inhibitor.
Quercetin may have positive effects in combating or helping to prevent
cancer,
prostatitis,
heart disease,
cataracts,
allergies/
inflammations, and
respiratory diseases such as
bronchitis and
asthma. It also has been claimed to have antidepressant properties, however any claim of quercetin action against neurological diseases should be treated with skepticism due to the fact that quercitin is a neurotoxin in vitro.
Occurrence
Foods rich in quercetin include
capers (1800mg/kg),
lovage (1700mg/kg),
apples (440mg/kg),
tea (
Camellia sinensis),
onions (higher concentrations of quercetin occur in the outermost rings),
red grapes,
citrus fruits,
broccoli and other
leafy green vegetables,
cherries, and a number of berries including
raspberry,
bog whortleberry (158 mg/kg, fresh weight),
lingonberry (cultivated 74mg/kg, wild 146 mg/kg),
cranberry (cultivated 83 mg/kg, wild 121 mg/kg),
chokeberry (89 mg/kg),
sweet rowan (85 mg/kg),
rowanberry (63 mg/kg),
sea buckthorn berry (62 mg/kg),
crowberry (cultivated 53mg/kg, wild 56 mg/kg), and the fruit of the
prickly pear cactus. A recent study found that
organically grown tomatoes had 79% more quercetin than
"conventionally grown".
A study by the
University of Queensland,
Australia, has also indicated the presence of quercetin in varieties of
honey, including honey derived from
eucalyptus and
tea tree flowers.
In plants, it's a naturally-occurring
polar auxin transport inhibitor.
It also may be found in
dietary supplements.
Drug interactions
Quercetin is contraindicated with antibiotics; it may interact with
fluoroquinolones (a type of medicinal
antibiotic), as quercetin competitively binds to bacterial DNA
gyrase. Whether this inhibits or enhances the effect of fluoroquinolones isn't entirely clear.
Quercetin is also a potent
inhibitor of
CYP3A4, an
enzyme that breaks down most
drugs in the body. As such, quercetin would be expected to increase serum levels, and therefore effects, of drugs metabolized by this enzyme.
Further Information
Get more info on 'Quercetin'.
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