CASSIA SENNA INHIBITS MUTAGENIC ACTIVITIES OF BENZO[A]-PYRENE, AFLATOXIN B-1, SHAMMA AND METHYL METHANESULFONATE

Ethanol extract of Senokot tablets (Cassia senna concentrate used as v egetable laxative), was found to be non-mutagenic while it inhibited t he mutagenicity of benzo[a]pyrene, shamma, aflatoxin B-1 and methyl me thanesulfonate in the Ames histidine reversion assay using the Salmone lla ty phimurium tester strain TA98. While the Senokot extract complet ely inhibited the mutagenicity of promutagens (i.e. metabolic activati on dependent) like benzo[a]pyrene and shamma, it reduced the mutagenic activity of the direct acting mutagen methyl methanesulfonate by only 58%. The mutagen aflatoxin B-1 showed a 25-fold increase in the numbe r of histidine revertants per plate at low concentrations (1.0-4.0 mu g/plate) in the presence of metabolic activation system while at high concentrations (10.0-30.0 mu g/plate) it proved to be weakly mutagenic (with a 5-fold increase in the number of histidine revertants/plate) without metabolic activation. The Senokot extract completely inhibited the mutagenic effect of low concentrations of aflatoxin B-1 in the pr esence of metabolic activation but not that resulting from higher conc entrations without metabolic activation. The results obtained with ben zo[a]pyrene, shamma and aflatoxin B-1 indicated that the antimutagenic effects of Senokot extract could be largely due to an interaction wit h the metabolic process involved in the activation of procarcinogens. However, the results obtained with methyl methanesulfonate suggested t hat factors in Senokot may also interact with direct mutagens to produ ce some antimutagenic effects. An ethanol extract of crude senna leave s found to be weakly mutagenic also inhibited (though less than Senoko t) the mutagenic effect of benzo[a]pyrene suggesting that the antimuta genic principle is present in the complex plant material itself.