Extraction and Identification of Antioxidative Components of Hsiantsao (Mesona procumbens Hemsl.)

The antioxidative activities of various solvent extracts of Hsian-tsao (Mesona procumbens Hemsl.) were investigated. The results showed that for the same concentration of 0.2 g/kg, the antioxidative activities of various Hsian-tsao extracts, especially the ethyl acetate extract, which exhibited 93% inhibition of peroxidation of linoleic acid, were greater than those of BHA and -tocopherol. When the ethyl acetate extract of Hsian-tsao (EEHT) was separated into nine fractions by silica gel chromatography, fraction II showed high yield and high antioxidative activity. Fraction II was further separated into five subfractions using silica gel chromatography. Subfraction IIC was then isolated by preparative HPLC equipped with a silica column and four components were identified as stigmasterol, -sitosterol, oleanolic acid, and ursolic acid by UV, EI-MS,1H-, and13SC-NMR. The descending order of antioxidative activity for those compounds was: EEHT>BHA> tocopherol>ursolic acid>oleanolic acid> -sitosterol>stigmasterol.