Sintesis 7-Hidroksiflavonol dan Fisetin

Abstract

Fisetin (7,3’,4’-trihydroxyflavonol) is commonly found in fruits and vegetables. It is potential as antioxidant, anti-inflammation, and antidiabetic. In this study, fisetin was synthesized by following 7-hydroxyflavonol synthesis method. 7-Hydroxyflavonol was succesfully synthesized from resacetophenone and benzaldehyde. Both starting materials were protected by tetrahydropyranyl (THP) group and then condensed with 60% KOH as catalyst forming THP-protected chalcone. Cyclization of the chalcone into THP-protected 7-hydroxyflavonol was carried out by using Algar-Flynn-Oyamada oxidative cyclization. Deprotection of the THP protecting group with p-toluenesulfonic acid resulted 7-hydroxyflavonol. The overall yield was 22% with total synthesis time of 7 days, faster than isolation from natural products. However, development of this method to synthesize fisetin from resacetophenone and 3,4-dihydroxybenzaldehyde as starting materials only gave 1% yield. Further study with other protecting groups for 3,4-dihydroxybenzaldehide as well as variation of reactants’ composition and reaction conditions are necessary in order to increase the fisetin yield. All synthetic products had been characterized by melting point and spectroscopy analysis