Journal of Agricultural and Food Chemistry. 2006, 54 (21), pp 8058-064

Free Radical Scavenging Effect of Pu-erh Tea Extracts and Their Protective Effect on Oxidative Damage in Human Fibroblast Cells

Guoliang Jie, Zhi Lin, Longze Zhang, Haipeng Lv, Puming He, and Baolu Zhao

Zhejiang University Tea Research Institute, 268 Kaixuan Road, Hangzhou 310029, People's Republic of China, Tea Research Institute of Chinese Academy of Agricultural Sciences, Key Laboratory of Tea Chemical Engineering, Ministry of Agriculture, 1 Yunxi Road, Hangzhou 310008, People's Republic of China, and State Key Laboratory of Brain & Cognitive Science, Institute of Biophysics, Academia Sinica, Beijing 100101, People's Republic of China

In the present study, we successively extracted the Pu-erh tea with acetone, water, chloroform, ethyl acetate, and n-butanol, and the extracts were then isolated by column chromatography. Our study demonstrates that the Pu-erh tea ethyl acetate extract, n-butanol extract, and their fractions had superoxide anion and hydroxyl radical scavenging activity: fractions 2 and 8 from the ethyl acetate extract and fractions 2, 4, and 5 from the n-butanol extract showed protective effects against hydrogen peroxide-induced damage in human fibroblast HPF-1 cells and increased the cells' viability under normal cell culture conditions. In addition, it is found that these fractions, except fraction 5 from the n-butanol extract, decreased the accumulation of intracellular reactive oxygen species in hydrogen peroxide-induced HPF-1 cells. Interestingly, the antioxidant effect of fraction 8 from the ethyl acetate extract on the above four systems was much stronger than that of the typical green tea catechin (-)-epigallocatechin-3-gallate, but there were almost no monomeric polyphenols, theaflavins, and gallic acid in fraction 8.

Keywords: Pu-erh tea; tea extraction; free radicals; oxidative damage; natural antioxidants; human fibroblast; HPF-1