Context: Melastomastrum capitatum is indicated in traditional herbal medicine as one of the plant used in treatment of cancer and tumor as well as other diseases in Mambila plateau Taraba State Nigeria. The plant is unique for its sour-to-sweet taste of the leaves.

Aim: To evaluate the preliminary cytotoxic and growth inhibitory effects of M. capitatum leaf methanol extract.

Methods: Cytotoxic and growth inhibitory effects of the methanol extract of leaf was evaluated using tadpoles (Raniceps ranninus) and the radicle length of guinea corn (Sorghum bicolor) seeds respectively.

Results: M. capitatum leaf methanol extract (MCE) produced 20 % (2.3±0.2) mortality at a concentration of 20 μmg/mL and was eventually increased to 100 % mortality at the concentration of 320 μg/mL over a period of 2 h in the tadpoles. The extract displayed a concentration-dependent cytotoxic effect on the tadpoles. In the growth inhibitory study, an average growth length of 64.97±8.1 mm was produced by the radicle in the control seeds after 96 h with percentage growth inhibitory effect of 0 %. At MCE concentration of 16μg/mL, the extract showed growth inhibitory percentage of 87.87 % on the length of the radicle, and lowest at 1μmg/mL concentration of the extract. In all the studies, cytotoxic and growth inhibitory effects were showed by the plant extract in a concentration-dependent fashion.

Conclusion: The study showed that M. capitatum leaf possessed cytotoxic and growth inhibitory effects, thus can act as a cytotoxic and growth inhibitory agent to cancer and tumor cells respectively in traditional medicine.