The toxicity profile of medicinal plants is an important preclinical requirement in the development of phytomedicines. The cytotoxic and genotoxic effects of the leaf of Uvaria chamae P. Beauv (Annonaceae) and stem bark of Morinda lucida Benth (Rubiaceae) were investigated in order to provide information on their safety as antimalarial plants. The methanol extract of U. chamae and ethanol (70%) extract of M. lucida were separately orally administered (125, 250, and 750 mg/kg/day) to mice for 10 consecutive days. Cyclophosphamide (50 mg/kg, single dose) and distilled water were used as positive and negative controls, respectively. The mice were injected with colchicine (0.04%) intra-peritoneally 24 h after the last administration of the extracts and the bone marrows harvested. Giemsa-stained slides of bone marrow cells were microscopically assessed for dividing cells to determine the mitotic index (MI) and scored for chromosomal aberrations (CA) according to standard methods. chamae exhibited dose-dependent cytotoxicity. At 750 mg/kg, the MI was significantly (p < 0.05) lower (1.81 ± 0.04) than that of cyclophosphamide (5.83 ± 0.04). The lower the MI, the higher the cytotoxicity. The activity of M. lucida was not significantly different (p > 0.05) from that of the negative control. The total CA observed from treatment with both plants at all doses were significantly (p < 0.05) greater than that of control. This study concluded that U. chamae showed both cytotoxicity and genotoxicity while M. lucida exerted only genotoxic effect. Nevertheless, the two plants should be used with caution in antimalarial therapy.
Keywords: Chromosome aberration; Morinda lucida; Uvaria chamae; cyclophosphamide; mitotic index.