Evaluation of extracts of wild Cannabis sativa L. for genotoxicity and phytochemical composition

Abstract

Cannabis sativa L. is used as medicine and narcotic in Lesotho. Phytochemical composition and total phenolics content (TPC) for hexane, chloroform, ethyl acetate and methanol extracts of aerial parts of C. sativa were determined. Ethyl acetate extract (0.1875, 0.375 and 0.75 mg mL-1) and methanol extract (0.75, 1.5 and 3.0 mg mL-1) were evaluated for cytotoxicity, genotoxicity and modulation of cyclophosphamide (CP, 1.25 mg mL-1)- and ethylmethane sulphonate (EMS, 0.25 mg mL-1)-induced genotoxicity using Allium cepa root meristem assay. CP or EMS did not reduce mitotic index (MI) of cells, hence not cytotoxic when compared with negative control using the t-test (p>0.05), but genotoxic. Both extracts were genotoxic with methanol extract also being cytotoxic. Genotoxicity was the number of aberrant cells per 100 mitotic cells. Modulatory effect (ME) was obtained by comparing mutagen-induced genotoxicity with mixture-induced genotoxicity and expressed as the number of units of mutagen-induced genotoxicity that equalled the mixture-induced genotoxicity. ME was either positive or negative and significant only if ME = ≥ 2. Both extracts were genotoxic with methanol extract also being cytotoxic. Aberrations observed were sticky chromosomes, c-metaphase, anaphase and telophase bridges, chromosome fragments and laggards. Mixture of methanol extract with CP or EMS was more genotoxic (+ME range = 1.61-11.89) than the mutagen or extract alone which suggested synergistic interaction. Mixture of ethyl acetate extract with CP induced insignificant +ME. Mixture of ethylacetate extract with EMS was significantly more genotoxic (+ME = 2.20) than EMS only at high extract concentration. The methanol and ethylacetate extracts of C. sativa were not anti-genotoxic to CP- or EMS- induced genotoxicity. TPCs for hexane, chloroform, ethyl acetate and methanol extracts were 39831.46, 2544.94, 2438.20 and 56601.12 mg GAE/gram dry weight respectively. The differences in the cytotoxicity and MEs of the extracts were attributed to differences in phytochemical composition of extracts.