Inhibitory Effects of (—)‐Epigallocatechin Gallate on Spontaneous Hepatoma in C3H/HeNCrj Mice and Human Hepatoma‐derived PLC/PRF/5 Cells

The inhibitory effect of (—)‐epigallocatechin gallate (EGCG), a main constituent of Japanese green tea, on spontaneous hepatoma in C3H/HeNCrj mice was investigated. A total of 72 mice were divided into three groups; the control group without EGCG, and two experimental groups receiving 0.05% (w/w) or 0.1% EGCG in drinking water. EGCG reduced the incidence of hepatoma‐bearing mice from 83.3% (control) to 56.0% (0.05% EGCG) and 52.2% (0.1% EGCG), and also reduced the average number of hepatomas per mouse from 1.83 (control) to 0.72 (0.05% EGCG) and 0.91 (0.1% EGCG) at week 65. Ridit analysis of the distribution of the number of hepatomas in each group revealed that EGCG significantly increased the rate of mice without hepatoma in the two EGCG groups as compared to the control. EGCG did not affect body weight gain, food consumption or any serum biochemical parameter. EGCG inhibited the growth and secretion of α‐fetoprotein by human hepatoma‐derived PLC/PRF/5 cells without decreasing their viability. These results indicate that EGCG may be a practical, nontoxic preventive agent against human hepatoma.