Antioxidative Effects of Phenylethanoids from Cistanche deserticola

摘要

The acetone-H20 (9:1) extract from the stem of Cistanche deserticola showed a strong free radical scavenging activity. Nine major phenylethanoid compounds were isolated from this extract. They were identified by NMR as acteoside, isoacteoside, 2'-acetylacteoside, tubuloside B, echinacoside, tubulosidc A, syringalide A 3'-a-rhamno-pyranoside, cistanoside A and cistanoside F. All of these compounds showed stronger free radical scavenging activities than a-tocopherol on l,l-diphenyl-2-picrylhydrazyl (DPPH) radical and xanthine/xaiithine oxidase (XOD) gene-rated supcroxide anion radical (OJ). 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 further studied the effects of these phenylethanoids on the lipid peroxidation in rat liver microsomes induced by enzymatic and non-enzymatic meth-ods. 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 a-tocopherol or caffeic acid. The antioxidative effect was found to be potentiated by an increase in the number of phenolic hydroxyl groups in the molecule.