
Flavonols are a class of
flavonoid
Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.
Chemically, flavonoids ...
s that have the
3-hydroxyflavone backbone (IUPAC name: 3-hydroxy-2-phenylchromen-4-one). Their diversity stems from the different positions of the
phenolic –OH groups. They are distinct from
flavanols (with "a") such as
catechin, another class of flavonoids, and an unrelated group of metabolically important molecules, the
flavins (with "i"), derived from the yellow B vitamin
riboflavin
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
.
Flavonols are present in a wide variety of fruits and vegetables. In Western populations, estimated daily intake is in the range of 20–50 mg per day for flavonols. Individual intake varies depending on the type of diet consumed.
The phenomenon of dual
fluorescence
Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with colore ...
(due to
excited state intramolecular proton transfer or ESIPT) is induced by
tautomerism of flavonols (and glucosides) and could contribute to plant
UV protection and
flower colour.
Besides being a subclass of
flavonoids, flavonols are suggested by a study of cranberry juice to play a role along with
proanthocyanidin
Proanthocyanidins are a class of polyphenols found in many plants, such as cranberry, blueberry, and grape seeds. Chemically, they are oligomeric flavonoids. Many are oligomers of catechin and epicatechin and their gallic acid esters. More complex ...
s, in the juice's ability to block bacterial adhesion, demonstrated by the compressing the
fimbria of ''E. coli'' bacteria in the urinary tract so as to greatly reduce the ability of those bacteria to stay put and initiate an infection. Flavonol aglycones in plants are potent antioxidants that serve to protect the plant from
reactive oxygen species (ROS).
Flavonols
Flavonol glycosides
Drug interactions
Flavonoids have effects on CYP (
P450) activity. Flavonols are
inhibitor of
CYP2C9 and
CYP3A4
Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine, which in humans is encoded by ''CYP3A4'' gene. It organic redox reaction, oxidizes small foreign organic molecules ( ...
,
[ which are ]enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
s that metabolize most drugs in the body.
Technological uses
A 2013 study showed that it is possible by optical methods to quantify the flavonol accumulation in some fruit and thus to sort fruit according to fruit quality and storage durability.
Effects on health
A 2022 study indicated an association between consumption of flavonols (found in food) and a lower rate of decline of cognitive ability, including memory.
See also
* Phenolic compounds in wine
* Algar–Flynn–Oyamada reaction
References
External links
*
{{flavonol