Inhibition of green tea catechins against the growth of cancerous human colon and hepatic epithelial cells

The ability of (−)-epicatechin (EC), (−)-epigallocatechin (EGC) and (−)-epigallocatechin gallate (EGCG) to inhibit the growth of HCT 116 colorectal and Hep G2 hepatocellular carcinoma cells was examined by MTT and clonogenic assays (CA). The respective catechins inhibited the growth of HCT 116 more strongly than Hep G2. In MTT assay, IC50 values of EGC and EGCG against HCT 116 grew smaller on prolongation of the exposure times of the cells to the catechins. In CA, however, these two catechins had IC50 values ranging between 7.6±0.4 and 11.2±0.5 μM against the same cells regardless of the exposure times. EC showed much weaker growth inhibitions relative to the two aforementioned catechins.