Prenylated Flavonoids from the Roots of<i>Sophora flavescens with</i>Tyrosinase Inhibitory Activity

Abstract

Prenylated flavonoids containing the resorcinol moiety were isolated as tyrosinase inhibitors from the roots of Sophora flavescens by activity-guided fractionation. Among the 12 compounds isolated, kuraridin, kurarinone and norkurarinol showed stronger inhibitory potencies (IC 50 = 1.1, 1.3 and 2.1 microM, respectively) than that of kojic acid (IC 50 = 11.3 microM), a well known tyrosinase inhibitor. Substitution of a lavandulyl or hydroxylavandulyl group at the C-8 position and a methoxy or hydroxy group at the C-5 position are essential for the inhibitory effect.