In vitro antioxidant and cytotoxic activity of the root extract of Aspilia mossambicensis (Oliv) Wild (Asteraceae)

Aspiliamossambicensis(Oliv) Wild is used by Traditional Health Practitioners in northeastern Tanzania, for treatment of cancers. In order to evaluate these claims root powder of the plant was extracted with dichloromethane: methanol (1:1), followed by vacuum liquid chromatography fractionation to obtain dichloromethane, ethyl acetate and methanol fractions which were screened for brine shrimp toxicity and antioxidant activity using DPPH and FRAP assays. The ethyl acetate fraction exhibited higher toxicity on brine shrimp larvae (LC50 = 12.87 µg/ml) than cyclophosphamide (LC50 = 16.12 µg/ml), and antioxidant activity with an EC50 of 200 µg/ml for DPPH and 53.92 μM ECGC equivalent/g dry weight for FRAP assay. The ethyl acetate fraction was cytotoxic against HeLa cancer cells (IC50 50.77 ± 1.69 µg/ml), causing cell cycle arrest at the M phase, phosphatidylserine (PS) externalization and activation of caspase 3 and 8. Four compounds were isolated from this fraction; (-)-Angeloylgrandifloric acid and 16α–hydroxykauran-19-oic acid, which were cytotoxic to the HeLa cervical cancer cells with IC50 = 27.75 and 40.19 μg/ml, respectively, and 16αHydroxy-9(11)-kauren-19-oic acid and grandifloric acid which were non-toxic to the HeLa cells. Further research is recommended to establish the clinical significance of the current findings. Key words: Aspiliamossambiscensis, cytotoxic activity, brine shrimp toxicity, antioxidant