Effects of the lignan, arctiin, on 17-beta ethinyl estradiol promotion of preneoplastic liver cell foci development in rats.

Anti-promotional effects of arctiin, a lignan with antiestrogenic action, against 17-beta ethinyl estradiol (EE) and 2-acetylaminofluorene (2-AAF) were examined using a medium-term liver bioassay based upon the induction of glutathione S-transferase placental form (GST-P) positive foci in rat liver. Male F344 rats were initially injected with diethylnitrosamine (DEN, 200 mg/kg body weight) intraperitoneally and two weeks later were treated with arctiin (1%), EE (1.5 ppm or 5 ppm), 2-AAF (20 ppm), arctiin + EE (1.5 ppm or 5 ppm), or arctiin + 2-AAF (20 ppm) in the diet for 6 weeks and then killed, all rats being subjected to partial hepatectomy at week 3. EE and 2-AAF clearly increased the development of GST-P foci. Antipromotional effects of arctiin were observed only for 2-AAF. These findings provide experimental evidence that arctiin exerts weak-protective potential against hepatocarcinogenesis in rats.