Fisetin

Fisetin is a plant flavonol: 3,3',4',7-tetrahydroxyflavone, C15H10O6, molecular weight 286.24, CAS 528-48-3, PubChem CID 5281614. Structurally it is a flavonoid aglycone — a 4H-chromen-4-one core carrying a catechol B-ring plus hydroxyls at the 3 and 7 positions, with no sugar attached. It occurs as a yellow pigment in several plant families, including Cotinus coggygria, Rhus and other sumacs, Acacia greggii and Acacia berlandieri, Butea frondosa, Gleditsia triacanthos and quebracho colorado, and it is the colouring principle of "young fustic", the historic yellow dye extract taken from smoketree wood. In foods it is a minor constituent: reported highest in strawberries at about 160 µg/g, with apples near 26 µg/g and persimmon near 10.6 µg/g, and smaller amounts in grapes, onions, tomatoes and cucumber. Those are trace dietary quantities compared with the inclusion levels used in supplement formats, which is why the isolate exists as a traded ingredient at all. Thovek supplies fisetin at NLT 98.0% by HPLC as the standard article, extracted from Cotinus coggygria Scop. (syn. Rhus cotinus, Anacardiaceae) wood and purified by recrystallisation; Toxicodendron succedaneum (L.) Kuntze, syn. Rhus succedanea L., the wax tree, is the other commercial feedstock and the species actually used is named on every lot certificate. The powder is yellow to greenish-yellow, melts at 330 °C, and is practically insoluble in water — a formulation constraint to design around rather than a defect. Two-piece hard capsules and direct-compression tablets accept the neat powder without difficulty; anything aqueous needs a phospholipid, cyclodextrin or lipid dispersion, and we supply those at 10% and 20% fisetin. Lower-strength standardised smoketree wood extracts at 20%, 50% and 90% are made to order for cost-led blends. The pigment is strong, so plan for colour carry-over into tablet coatings, clear capsule shells and any light-coloured powder base. On origin and allergens: the material is vegan and vegetarian, wood-derived and non-GMO, with no milk, egg, soy, fish, crustacean, gluten, sesame, peanut or tree-nut input. The source genera sit in Anacardiaceae, the family that also contains cashew, pistachio and mango, but none of those nuts or fruits is a raw material and none is present in the extract — worth stating plainly on your allergen matrix, because the family name alone sometimes triggers questions from retail buyers. Where Toxicodendron (formerly Rhus) wood is the feedstock we run urushiol-type alkylcatechol screening and report the result. Because the isolated compound is not covered by the food history of the fruits that contain it, buyers selling into the EU or UK should confirm novel food status under Regulation (EU) 2015/2283 before launch. Thovek describes composition and specification only and makes no therapeutic or disease claim; finished-label copy remains the brand owner's responsibility in its own market.