Study on Antioxidative Polyphenol Compounds in Pu’er Tea

Eleven phenolic compounds were isolated from the Pu’er tea, which was produced in the post-fermentated process by using the crude green tea prepared from the leaves of Camellia sinensis var. assamica as raw materials. Their structures were identified as gallocatechin(1), (-)-epicatechin(2), (+)-catechin(3), myricetin(4), gallic acid(5), kaempferol(6), kaempferol-3-O-β-D-glucopyranoside(7), kaempferol-3-O-rutinoside(8), quercetin(9), quercetin-3-O-β-D-glucopyranoside(10), 2,5-dihydroxy-benzoic acid(11). This is the first time that compounds 6~11 were found from Pu’er tea. All of isolated compounds were tested for their antioxidative activities by DPPH radical scavenging assay. It was found that compounds 2, 3 and 5 showed antioxidative activity close with that of positive control, L-ascorbic acid, and the flavonoids(5, 6 and 9) are more active than the flavonoid glycosides(7, 8 and 10)and compound 11.