GA 2017

The possibility of moderating the response of cells to a particular mutagen by phytomedicines opens new horizons in cancer control. On this basis, the research for antimutagens presents many possibilities for the discovery of new anticarcinogenic substances^1,2. The methanol extract of C. microphyllum was evaluated for antimutagenicity in the Ames/microsome assay using Salmonella typhimurium TA98, TA100 and TA102 without metabolic activation. A bioassay-guided fractionation of the crude extracts led to the isolation of three compounds: n-tetracosanol, eicosanoic acid and arjunolic acid. Arjunolic acid was the most active in all three tested strains with percentage antimutagenicity of up to 41.92 ± 9.59%, 35.84 ± 1.45% and 43.78 ± 0.18% in S. typhimurium TA98, TA100 and TA102 respectively at the highest concentration tested, followed by eicosanoic acid and lastly n-tetracosanol. The compounds were assessed for antioxidant activity using the quantitative 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical scavenging method. Arjunolic acid was the only compound with pronounced antioxidant activity (measured as DPPH-free scavenging activity) with EC₅₀ value of 0.51 µg/ml. Furthermore, the isolated compounds were assessed for their potential toxic effects in the MTT assay using human hepatocytes. All three compounds were not toxic with LC₅₀ values >200 µg/ml for n-tetracosanol and eicosanoic acid and 106.39 µg/ml for arjunolic acid. Based on findings from this study, compounds from C. microphyllum protect against 4-NQO and MMC induced mutations as evident in the Ames test. Taking into account that genotoxicity involving gene mutations plays a major role in cancer initiation³, C. microphyllum has potential in cancer prevention as it inhibits these genotoxic end-points. The antimutagenic activity of arjunolic acid, at least in part, may be attributed to its antioxidant activity which results in the detoxification of reactive oxygen species produced during mutagenesis.