ANTIOXIDATIVE EFFECTS OF PHENYLETHANOIDS FROM CISTANCHE DESERTICOLA

The acetone-H2O (9:1) extract from the stem of Cistanche deserticola s howed a strong free radical scavenging activity, Nine major phenyletha noid compounds were isolated from this extract. They were identified b y NMR as acteoside, isoacteoside, 2'-acetylacteoside, tubuloside B, ec hinacoside, tubuloside A, syringalide A 3'-alpha-rhamnopyranoside, cis tanoside A and cistanoside F. All of these compounds showed stronger f ree radical scavenging activities than alpha-tocopherol on 1,1-dipheny l-2-picrylhydrazyl (DPPH) radical and xanthine/xanthine oxidase (XOD) generated superoxide anion radical (O-2-radical-anion). Among the nine compounds, isoacteoside and tubuloside B, whose caffeoyl moiety is at 6'-position of the glucose, showed an inhibitory effect on XOD. We fu rther studied the effects of these phenylethanoids on the lipid peroxi dation in rat liver microsomes induced by enzymatic and non-enzymatic methods. As expected, each of them exhibited significant inhibition on both ascorbic acid/Fe2+ and ADP/NADPH/Fe3+ induced lipid peroxidation in rat liver microsomes, which were more potent than alpha-tocopherol or caffeic acid. The antioxidative effect was found to be potentiated by an increase in the number of phenolic hydroxyl groups in the molec ule.