Polyphenols - Flavanols Part 3 Flashcards
What are Flavonols?
Flavonols - also yellow
* They have a ketone ( –one) and hydroxyl ( –ol) groups on unsaturated central ring.
* Quercetin - which is the most researched and found in a LOT of veg and herbs like fennel.
* Isorhamnetin, yellow or red onions and sea buckthorn.
* Kaempferol in apples, onions, leeks, capers, kale, broccoli, citrus fruits, grapes, red wines, ginkgo, rosemary and St. John’s wort.
Epidemiological studies and flavonols
* Lower mortality from ischaemic heart disease (quercetin, kaempferol, naringenin and
hesperetin).
* Reduced lung cancer incidence (quercetin) and lower prostate cancer risk (myricetin).
* Asthma incidence lower (quercetin, naringenin and hesperetin).
* Reduction in risk type 2 diabetes (quercetin and myricetin) and hypercholesterolaemia.
* Anti-inflammatory activity in patients with
osteoarthritis (citrus flavonoids).
What are some major sources of Flavonols?
Sources of quercetin and its glycosides
* Many different glycosides of quercetin in plants e.g. hyperin in Crataegus spp and also in ginko
* Antioxidant, anti-inflammatory activity and
anti cancer properties
* Hyperin (quercetin 3-galactoside)
* Protects against cataract development via inhibition of lens aldose reductase.
* In vitro antiviral hep B, antidepressant
activity and enhances the bioavailability of other constituents.
* Inhibits mast cell degranulation (antiallergic and anti-inflammatory effect).
** Quercetin studies show:**
* Inhibits prostate cancer via various mechanisms.
* Metabolites of quercetin accumulates in human arterial tissue when atherosclerosis threatens, acting as localised vascular
antioxidants.
* Lack of in vivo toxicity, lack of carcinogenic properties and concluded safety of
quercetin.
What is Rutin?
Rutin
* Rutin or rutoside, is a glycoside of quercetin found in fruits and fruit rinds (especially citrus fruits) and berries, cranberry and mulberry.
* Also in asparagus, buckwheat, butchers broom, horse chestnut, St. John’s
wort, rue, and Rheum species.
* Rutin has been shown to strengthen the capillaries and is venotonic.
* A study showed it has beneficial effects on varicose veins, spider veins, leg oedema and haemorrhoids.
What are the other Flavonols, Isorhamnetin and Kaempferol?
Isorhamnetin
* In vitro and in vivo studies show sea buckthorn to have antioxidant, anticancer and
cardioprotective effects.
* Ginkgo contains this - and is used in the prevention and treatment of cardiovascular diseases.
Kaempferol
* We find this in berries, broccoli, capers and dark greens, wine, rosemary, ginkgo and hawthorn.
* It is antioxidant and anti-inflammatory; also inhibits a recpetor which is activated by smoke and air pollution, blocking the ability of these to support the development of cancer
Ginkgo
* Has many active compounds are flavonol glycosides - quercetin, kaempferol, myricetin, and isorhamnetin, terpene lactones (terpenoids), bilobalide, ginkgolides, biflavonoids and procyanidins.
* Antioxidant, anti-inflammatory and neuroprotective - protects against dementia.
Hawthorn
* Active compounds include quercetin glycosides along with the oligomeric
procyanidins.
* Antioxidant and increases coronary blood flow and improves revasculisation.
* Positively inotropic (flavonoids, OPC), and negatively chronotropic.
