Antioxidant effects of diarylheptanoid derivatives from Alnus japonica on human LDL oxidation

Abstract

Two diarylheptanoids, oregonin (1) and hirsutanone (2), were isolated by bioassay-guided fractionation of the methanol extracts of the leaves of Alnus japonica Steud and their structures were elucidated from their spectroscopic data. Compounds 1 and 2 exhibited significant low-density lipoprotein (LDL)-antioxidant activities, e.g., thiobarbituric acid-reactive substances (TBARS) assay (1: IC50 = 3.2 μM, 2: IC50 = 1.5 μM), lag time (1:162 min, 2:230 min at 2.0 μM, control: 63 min), relative electrophoretic mobility (REM, inhibition of 1:71%, 2:75% at 10 μM), apoB-100 fragmentation (inhibition of 1:27.3%, 2:40.3% at 10 μM) and macrophage-mediated LDL oxidation (inhibition of 1:82%, 2:84% at 1 μM).