Hibernation, reversible cell growth inhibition by epigallocatechin-3-O-gallate

Epigallocatechin-3-O-gallate (EGCg) and related polyphenolic compounds found in tea are known to have antioxidative activities. However, they also have pro-oxidative activities such as generation of hydrogen peroxide. In this report, we investigated the effect on cells and showed the potential usage of EGCg in cell preservation. H2O2 was generated from EGCg at concentrations of more than 300 μg/mL for 6 h at 37 °C, and high cytotoxicity for L929 cells were shown. In contrast, in the presence of 1 μg/mL catalase, the amount of generated H2O2 was significantly low and cytotoxicity decreased markedly. This indicates that catalase eliminated H2O2 generated by degradation of EGCg. Although H2O2 generation was prevented, L929 cell proliferation was slightly inhibited in proportion to the concentrations of EGCg. L929 was exposed able to be 300 μg/mL to EGCg and 1 μg/mL catalase for maximum 18 days. EGCg inhibited the growth of L929 cells, and cell proliferation was restarted immediately after medium change for removing EGCg. We concluded that EGCg had a reversible growth inhibition when H2O2 was eliminated from cell cultures.