Free radical scavenging effect of Pu-erh tea extracts and their protective effect on oxidative damage in human fibroblast cells

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.