Cytotoxicity of sanguinarine in primary rat hepatocytes is attenuated by dioxin and phenobarbital

Putative interactions between quaternary benzo[ c ]phenanthridine alkaloid sanguinarine (SA) and aryl hydrocarbon receptor/cytochrome P450 CYP1A (AhR/CYP1A) regulatory pathway are the subject of perpetual disputations. The role of CYP1A enzymes and AhR receptor in SA cytotoxicity was anticipated. In this paper, we tested, whether selected inducers of CYP enzymes modulate cytotoxicity of SA in primary cultures of rat hepatocytes. Cells were challenged 48 h with dioxin (TCDD; 5 nM), phenobarbital (PB; 500 μM) or DMSO prior to the treatment with SA. SA itself displayed time- and dose-dependent cytotoxicity as revealed by lactate dehydrogenase leakage into the medium and MTT test. Pre-treatment of hepatocytes with TCDD and/or PB significantly attenuated SA cytotoxicity, the effects being more pronounced at lower concentrations of SA and shorter periods of incubation. We assumed involvement of CYP1A enzymes in diminution of SA cytotoxicity. Surprisingly, co-treatment with SA and furafylline, an inhibitor of CYP1A enzymes, further attenuated SA cytotoxicity instead of expected reversal of this effect. We conclude that TCDD- and PB-inducible genes attenuate cytotoxicity of SA in rat hepatocytes. CYP1A enzymes are not involved in this attenuation, but they rather augment SA cytotoxicity. Future research should focus on analyses of the involvement of other CYPs in SA cytotoxicity and on identification of TCDD-/PB-controlled genes responsible for observed phenomenon.