Abstract: Jussiaea repens L.(JRL) was extracted with chloroform-methanol(1:2,V/V) in a ultrasonator,and the extract was then partitioned with petroleum ether,EtOAc and BuOH successively. Antioxidant activities(AA) of the three corresponding extracts were evaluated by Schaal method,and compared with that of BHT. The ethyl acetate-soluble fraction(EAF) exhibits the highest AA among the three fractions,which is higher than that of BHT. Furthermore,bioactivity-guided chromatographic fractionation of the EAF was conducted by repeated column chromatography of silica gel,RP-18 and Sephadex LH-20,and three pure antioxidant compounds were obtained. Their structures were determined by interpretation of the 1D and 2D NMR,as well as mass spectral data. The results showed that rosmarinic acid,quercetin 3-O-β-D-glucopyranoside and kaempferol 3-O-β-D-glucopyranoside are the major antioxidant constituents in JRL. The antioxidant activities of the compounds decrease in the following order:rosmarinic acid > quercetin 3-O-β-D-glucopyranosid > kaempferol 3-O-β-D-glucopyranoside > EAF> BHT. The antioxidant activities of phenolic compounds are closely correlated to their chemical structures. In general,the antioxidant activities of phenolics depend mainly on the number of hydrogen-donating hydroxyl groups on the aromatic ring of the phenolic molecules.

Key words: Jussiaea repens, edible oil and fat, antioxidant activity, antioxidant constituents