OBJECTIVETo investigate the AAPH scavenging activities of 22 flavonoids and phenolic acids and 9 extracts of Chinese materia medica.

METHODThe antioxidant activities of the samples were evaluated by an oxygen radical absorbance capacity method (ORAC), at the same time, the total contents of flavonoids and phenolic the 9 herb extracts were analyzed by Folin-Ciocalteu method, and the active components were qualitatively and quantitatively analyzed by an HPLC method.

RESULTIt was found that the tea extract showed the strongest AAPH activity with the ORAC value of 4786.40 micromol x g(-1) whereas safflower demonstrated the weakest activity with the ORAC value of 784.04 micromol x g(-1). As for compounds, quercetin had the strongest AAPH activity with the ORAC value of 12.90 while ( - )-EGC had the weakest activity with the ORAC value of 2.47. A quantitative relationship was obtained to describe the AAPH scavenging activity of the herb extracts: Y = 1844.8 lnX-3577.5, r = 0.8675, where Y stands for the ORAC vaule, and X stands for the concentration of total phenolic acids.

CONCLUSIONFlavonoids and phenolic acids are the AAPH scavenging active ingredients in the Chinese herb extracts. It's a good way to study the antioxidant activity of Chinese herb extract and its chemical composition by combing ORAC method and HPLC method.