Inhibition of early 3-methyl-4-dimethylaminoazobenzene-induced hepatocarcinogenesis by gomisin A in rats.

The effects of gomisin A, a lignan component of Schizandra fruits, on hepatocarcinogenesis caused by 3'-methyl-4- dimethylaminoazobenzene (3'-MeDAB) in male Donryu rats were investigated. Gomisin A significantly inhibited the appearance of foci stained for glutathione S-transferase placental form (GST-P) in the liver of rats given feed with 0.06% 3'-MeDAB. Gomisin A (30 mg/kg/daily, po) decreased the concentration of 3'-MeDAB-related azo dyes in the liver, and increased their excretion in the bile. The ratio of diploid to tetraploid nuclei increased during ingestion of 3'-MeDAB, but gomisin A delayed the increase. After the withdrawal of 3'-MeDAB, carcinogen-related azo dyes were not detected in the liver or bile, but the proportion of diploid nuclei remained high, although it decreased with a 0.03% gomisin A diet. The results suggested that the effects of gomisin A are related to improved liver function and reversal of abnormal ploidization.