Abstract: The crude extract, fractions and subfractions derived from RPV were evaluated for the DPPH radical scavenging ability, the inhibition ability of bleaching β-carotene and the reducing power. The EAF (ethyl acetate-soluble fraction) and EAF6 (a subfraction derived from EAF) were the most valuable fraction and subfraction, respectively. Furthermore, bioactivity-guided chromatographic fractionation revealed that four pure compounds greatly contributed to the antioxidant activities. Qualitative and quantitative analyses of the major antioxidant constituents in the extract were systematically conducted by NMR, Mass spectra and RP-HPLC. The results demonstrated that gallic acid, (+)catechin, galloyl-paeoniflorin and galloyl-oxypaeoniflorin were the major antioxidative constituents in RPV. These compounds showed stronger activity than the BHT in four tested concentration levels. The results from this study indicate that RPV extract as well as isolated compounds are promising antioxidants which can be used as food additives.

Key words: radix Paeonia veitchii, antioxidant activity, antioxidative constituents, structure determination, quantification