Antimutagenic activity of flavonoids from the heartwood of Rhus verniciflua.

Pretreatment of the methanolic extract of the heartwood of Rhus verniciflua (Anacardiaceae) to rats prevented the activation of hepatic microsomal cytochrome p(450) enzymes, inhibition of hepatic glutathione S-transferase by bromobenzene treatment, respectively, and therefore significantly decreased malondialdehyde content in the rat. The Ames test showed that the addition of 1.0 mg/plate of the methanolic extract or the EtOAc fraction of the Rhus verniciflua heartwood extract potentially inhibited the mutagenicity by aflatoxin B(1). Column chromatography of the EtOAc fraction yielded four flavonoids, garbanzol (1), sulfuretin (2), fisetin (3), fustin (4), mollisacasidin (5). When these components were subjected to the Ames test, it was found that sulfuretin might effectively prevent the metabolic activation or scavenge electrophilic intermediates capable of causing mutation. In contrast, fustin showed a dose-independent antimutagenic activity and it has mutagenic/antimutagenic activity. However, a mixture of sulfuretin and fustin (1:1) exhibited dose-dependent antimutagenicity indicating that sulfuretin inhibited the mutagenicity of fustin. These results suggest that the extract of Rhus verniciflua heartwood containing flavonoid complex could be a potent anticarcinogen.