Abstract

Hyraceum (HM) is used in traditional medicine in Southern Africa. Three concentrations of HM (mg/ml in distilled water) (0.0156, 0.03125 and 0.0625) were assessed for cytotoxicity (CT), genotoxicity (GT) and modulation of cyclophosphamide (CP)- and ethyl methanesulfonate (EMS)-induced GT using the Allium cepa assay following 24 h treatment.  CP (1.00 mg/ml) and EMS (0.0375 mg/ml) were not cytotoxic but genotoxic. HM (0.03125, 0.0625 mg/ml) and its mixtures with CP or EMS induced significant reduction (p <0.05) of the mitotic index (MI) and were adjudged cytotoxic. HM alone and its mixtures with CP or EMS induced statistically significant genotoxicity (p < 0.05). Mixture of HM (0.016 mg/ml) with CP was not significantly more genotoxic than CP alone (ME 0.57). Each mixture of HM (0.03125, 0.0625 mg/ml) with CP was insignificantly less genotoxic than CP alone with modulatory effect (ME) of -0.14 and -0.01, respectively, which suggested no interaction between HM and CP. Mixtures of HM with EMS induced positive and significant (>2-fold) MEs and each mixture was significantly (p < 0.05) more genotoxic than HM or EMS alone which indicated a synergistic interaction. Sticky chromosomes, chromosome laggards, chromosome fragments, anaphase and telophase bridges, binucleate interphase cells were observed.

Key words: Cytotoxicity, cyclophosphamide, ethyl methanesulfonate (EMS), Genotoxicity; anti-genotoxicity.