Extraction and identification of antioxidative components of Hsian-tsao (Mesona procumbens Hemsl.)

The antioxidative activities of various solvent extracts of Hsian-tsao (Mes ona procumbens Hemsl) were investigated. The results showed that for the sa me concentration 0.2 g/kg, the antioxidative activities of various Hsian-ts ao extracts, especially the ethyl acetate extract, which exhibited 93% inhi bition of peroxidation of linoleic acid, were greater than those of BHA and alpha-tocopherol. When the ethyl acetate extract of Hsian-tsao (EEHT) was separated into nine fractions by silica gel chromatography fraction II show ed high yield and high antioxidative activity. Fraction II was further sepa rated into five subfractions using silica gel chromatography. Subfraction I IC was then isolated by preparative HPLC equipped with a silica column and four components were identified as stigmasterol, beta-sitosterol, oleanolic acid, and ursolic acid by UV, EI-MS, H-1-, and C-13-ArMR. The descending o rder of antioxidative activity for those compounds was: EEhT > BHA > alpha- tocopherol > ursolic acid > oleanolic acid > beta-sitosterol > stigmasterol .