Theaflavin-3-gallate is a polyphenolic compound found in black tea. The theaflavins are formed during the enzymatic oxidation of catechins, which happens during processing of the fresh tea leaves. Theaflavin-3-gallate has been shown to have inhibitory effects on ovarian cancer cells OVCAR-3 and A2780/CP70 by inducing apoptosis and impairing tumor angiogenesis. In addition, theaflavin-3-gallate was found to give stronger reactive oxygen species scavenging activity than theaflavin by a chemiluminescence assay. Exposure of CAL27 and HSC-2 carcinoma cells to theaflavin-3-gallate demostrated cytotoxic and antiproliferative properties of the compound.