PARP16 and cancer: Compound 15 is epicatechin-3-gallate (ECG), the third major catechin component in green tea, which has been shown strong biological activity in some aspects, including apoptosis, cell growth inhibition in various cells.25 However, the most abundant and powerful antioxidant in green tea for cancer chemoprevention is EGCG.26 Interestingly, ECG and EGCG have very similar structures (Figure 3a), raising the possibility that EGCG may also inhibit the PARP16 activity.