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