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 Phenolic is an adjective and a substantive (noun) that may apply to : * Phenol (or carbolic acid), a colorless crystalline solid and aromatic compound * Phenols, a class of chemical compounds that include phenol * Phenolic content in wine * Phenol ...

-OH groups. They are distinct from

flavanol Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compo ...

s (with "a") such as catechin, another class of flavonoids. 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 the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

(due to

excited state intramolecular proton transfer Excited state intramolecular proton transfer (ESIPT) is a process in which photoexcited molecules relax their energy through tautomerization by transfer of protons. Some kinds of molecules could have different minimum-energy tautomers in different ...

or ESIPT) is induced by

tautomerism Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hyd ...

of flavonols (and glucosides) and could contribute to plant

UV protection Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

and

flower colour Biological pigments, also known simply as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective Absorption (electromagnetic radiation), color absorption. Biological pigments include plant ...

. Besides being a subclass of

flavonoids 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 ...

, flavonols are suggested by a study of cranberry juice to play a role along with proanthocyanidins, 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 Inhibitor or inhibition may refer to: In biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotra ...

CYP2C9 Cytochrome P450 family 2 subfamily C member 9 (abbreviated CYP2C9) is an enzyme protein. The enzyme is involved in metabolism, by oxidation, of both xenobiotics, including drugs, and endogenous compounds, including fatty acids. In humans, the prote ...

and

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine. It oxidizes small foreign organic molecules (xenobiotics), such as toxins or drugs, so that they can be removed from t ...

, which are

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

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.

References

External links

* {{flavonol