Cassia Senna Inhibits Mutagenic Activities of Benzo[a]-pyrene,Aflatoxin B1, Shamma and Methyl Methanesulfonate

Abstract: Ethanol extract of Senokot tablets (Cassia senna concentrate used as vegetable laxative), was found to be non-mutagenic while it inhibited the mutagenicity of benzoa]pyrene, shamma, aflatoxin B₁ and methyl methanesulfonate in the Ames histidine reversion assay using the Salmonella typhimurium tester strain TA98. While the Senokot extract completely inhibited the mutagenicity of promutagens (i.e. metabolic activation dependent) like benzoa]pyrene and shamma, it reduced the mutagenic activity of the direct acting mutagen methyl methanesulfonate by only 58%. The mutagen aflatoxin B₁ showed a 25-fold increase in the number of histidine revertants per plate at low concentrations (1.0–4.0 μg/plate) in the presence of metabolic activation system while at high concentrations (10.0–30.0 μg/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 B₁ in the presence of metabolic activation but not that resulting from higher concentrations without metabolic activation. The results obtained with benzoa]pyrene, shamma and aflatoxin B₁ indicated that the antimutagenic effects of Senokot extract could be largely due to an interaction with the metabolic process involved in the activation of procarcinogens. However, the results obtained with methyl methanesulfonate suggested that factors in Senokot may also interact with direct mutagens to produce some antimutagenic effects. An ethanol extract of crude senna leaves found to be weakly mutagenic also inhibited (though less than Senokot) the mutagenic effect of benzoa]pyrene suggesting that the antimutagenic principle is present in the complex plant material itself.