Epigallocatechin gallate, a constituent of green tea, regulates high glucose-induced apoptosis.

A high concentration of glucose has been implicated as a causal factor in initiation and progression of diabetic complications, and there is evidence to suggest that hyperglycemia increases the production of free radicals and oxidative stress. Therefore, compounds that scavenge reactive oxygen species may confer regulatory effects on high glucose-induced apoptosis. Epigallocatechin gallate (EGCG), the major polyphenolic of green tea, is reported to have an antioxidant activity. We investigated the effect of EGCG on high glucose-induced apoptosis in U937 cells. Upon exposure to 35 mM glucose for 2 days, there was a distinct difference between untreated cells and cells pre-treated with 1 microM EGCG for 2 h in regard to cellular redox status and oxidative DNA damage to cells. EGCG pre-treated cells showed significant suppression of apoptotic features such as DNA fragmentation, damage to mitochondrial function, and modulation of apoptotic marker proteins upon exposure to high glucose. This study indicates that EGCG may play an important role in regulating the apoptosis induced by high glucose presumably through scavenging of reactive oxygen species.