cis-Terpenones as an effective chemopreventive agent against aflatoxin B1-induced cytotoxicity and TCDD-induced P450 1A/B activity in HepG2 cells.

Aflatoxin B1 (AFB1) is a potent carcinogen, which can significantly increase the risk of hepatocellular carcinoma development through food contamination. In past decades, chemopreventive agents, such as oltipraz and chlorophyllins, have demonstrated that chemo-intervention is an effective approach to reduce hepatotoxicity by AFB1. However, because of the potential adverse effects of these agents, alternative novel mechanism-based chemopreventive agents are needed. We report here that novel cis-terpenones 1-3, which were synthesized as the precursors of natural product analogues in our laboratory, showed promising protective effects against AFB1-induced cytotoxicity in HepG2 cells. Chemo-protection was observed with increasing concentrations of cis-terpenones in the co-treatment of AFB1, and no cytotoxicity was observed with cis-terpenones alone. In addition, cis-terpenones 1-3 at 10 and microM effectively inhibited induced cytochrome P450 1A/1B activity by 50% in HepG2 cells, as indicated by an EROD assay. P450 1A/B is involved in the activation of many pre-carcinogens and is highly inducible in liver cells. These results suggested that novel terpenones 1-3 are candidates for the development of novel mechanism-based chemopreventive agents against AFB1 and other carcinogenic stimuli.