(-)-Epicatechin gallate (ECG) is a catechin compound abundant in green tea displaying bioactivity to modulate cell proliferation apoptosis and gene expression pathways In colon HCT-116 cells ECG induces apoptosis through activating transcription factor 3 (ATF3) regulated via activation of early growth response protein 1 (EGR-1) In these cancer cells ECG upregulates apoptotic factor NAG-1 and increases caspase-3 activity at concentrations around 150 M ECG s cytotoxic potency differs among cell types with an NR50 (midpoint cytotoxic concentration) of approximately 67 M in HSC-2 oral cancer cells while normal human fibroblast HGF-2 cells show greater resistance with an NR50 near 100 M ECG metabolites identified in rat urine include various O-methylated derivatives useful as biomarkers for metabolism studies ECG serves as a research tool for oncology mechanisms and apoptosis signaling pathways