Coumarins from branch of Fraxinus sieboldiana and their antioxidative activity

Objective:To investigate the chemical constituents from the branch of Fraxinus s/ebo/d/ana,and evaluate their an- tioxidative activity.Method:The chemical constituents were isolated and purified by chromatographic techniques over silica gel, macroporous adsorbent resin,Sephadex LH-20,and preparative HPLC.Structures of the compounds were identified by spectroscopic methods.The antioxidant activity was evaluated by Fe~(+2)-cystine induced rat liver microsomal lipid peroxidation.Result:Eight couma- rins were obtained and their structures were elucidated as esculin(1),esculetin(2),fraxin(3),fraxetin(4),6,7-di-O-β-D-gluco- pyranosylesculetin(5),scopoletin(6),cleomiscosin D(7)and cleomiscosin B(8).At a concentration of 10~(-6)mol·L~(-1),com- pound 4 showed antioxidative activity inhibiting Fe~(+2)-cystine induced rat liver microsomal lipid peroxidation with inhibitory rate of 60%.Conclusion:Compounds 5,7 and 8 were obtained from the genus Fraxinus for the first time.Compound 4 showed remarkable antioxidative activity,which was higher than that of VE(35%).