Inhibitory effect of coumarins from Weigela subsessilis on low density lipoprotein oxidation

Oxidation of low density lipoprotein (LDL) is thought to be a major factor in the pathophysiology of atherosclerosis. In the present study, we found that coumarins isolated from Weigela subsessilis (Caprifoliaceae) inhibited LDL oxidation mediated by either catalytic copper ions (Cu2+) or free radicals generated with the azo compound 2,2'-azobis-(2-amidinopropane)dihydrochloride (AAPH). Of the coumarins tested, scopoletin (1) and cleomiscosin A (2) increased the lag time of conjugated diene formation and inhibited the generation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. In addition, it was found that compounds 1 and 2 had the capacity to protect the fragmentation of apolipoprotein B-100 (apoB-100). These results suggest that W. subsessilis and its active coumarins, 1 and 2, may have a role to play in preventing the LDL oxidation involved in atherogenesis.