Low Density Lipoprotein (LDL)-Antioxidant Flavonoids from Roots of Sophora flavescens

Abstract

Oxidation of low density lipoprotein (LDL) is strongly implicated as a key process in the onset of atherosclerosis. In this study, nine alkylated (C₁₀–C₅) flavonoids from Sophora flavescens were examined for their inhibitory effects on copper-induced LDL oxidation. Of the flavonoids tested, sophoraflavanone G (1), kurarinone (2), kurarinol (3), norkurarinol (4), and kuraridin (9) inhibited the generation of thiobarbituric acid reactive substances (TBARS) with IC₅₀s of 7.9, 14.5, 22.0, 26.9, and 17.5 μM, respectively. The most potent inhibitor, compound 1, also demonstrated significant activities in complementary in vitro investigations, such as lag time (130 min at 5 μM), relative electrophoretic mobility (REM) of ox-LDL (80% inhibition at 20 μM), and fragmentation of apoB-100 (inhibition of 71% at 20 μM). Analysis of the structures of these compounds reveals that a resorcinol moiety in the B-ring is strongly correlated with protection of LDL-oxidation.