Fisetin (7,3′,4′-flavon-3-ol) is a plant flavonol from the flavonoid group of polyphenols.[1] It occurs in many plants where it serves as a yellow pigment. It is found in many fruits and vegetables, such as strawberries, apples, persimmons, onions, and cucumbers.[2][3][4]
Its chemical formula was first described by Austrian chemist Josef Herzig in 1891.[5]
Many fruits and vegetables contain fisetin.[2] In one study, fisetin content was highest in strawberries, with content also observed in apples, grapes, onions, tomatoes, and cucumbers.[2] Fisetin can be extracted from fruit juices, wines,[8] and teas.[3] It is also present in Pinophyta species such as the yellow cypress (Callitropsis nootkatensis).
The average intake of fisetin from foods in Japan is about 0.4 mg per day.[1]
Fisetin is a flavonoid, which is a polyphenol subgroup.[10] Flavonoid synthesis begins with the phenylpropanoid pathway, in which phenylalanine, an amino acid, is transformed into 4-coumaroyl-CoA.[10] This is the compound that enters the flavonoid biosynthesis pathway. Chalcone synthase, the first enzyme of this pathway, produces chalcone from 4-coumaroyl-CoA. All flavonoids are derived from this chalcone backbone (this family being the so-called chalconoids).[citation needed] The activity of different enzymes, including isomerases and hydroxylases, alter the backbone depending on the subclass of the flavonoid being produced.
Research
Although fisetin has been under laboratory research over several decades for its potential role in senescence or anticancer properties, among other possible effects, there is no clinical evidence that it provides any benefit to human health, as of 2018.[1]
^De Santi C, Pietrabissa A, Mosca F, et al. (2002). "Methylation of quercetin and fisetin, flavonoids widely distributed in edible vegetables, fruits and wine, by human liver". International Journal of Clinical Pharmacology and Therapeutics. 40 (5): 207–212. doi:10.5414/cpp40207. PMID12051572.
