ABSTRACT
Objective: To evaluate the anticancer activity of crude acetone and water leaf extracts of Tulbaghia violacea on a human oral cancer cell line (KB). Methods: The antioxidant activity of the leaf extracts was evaluated by using the DPPH assay while the anti-proliferative activity was assessed by using the MTT assay. The morphological characteristics of apoptotic cells were examined by using the dual acridine orange/ethidium bromide staining. Flow cytometry was used to evaluate the induction of multi-caspase activity and changes in the cell cycle. Results: The acetone and water extracts exhibited antioxidant activity in a concentration dependent manner. The extracts inhibited the growth of the KB cell line with IC50 values of 0.2 mg/mL and 1 mg/mL, respectively for acetone and water. Morphological changes such as cell shrinkage, rounding and formation of membrane blebs were observed in the treated cells. In acridine orange/ethidium bromide staining, the number of apoptotic cells increased as the concentration of the extracts increased. The activation of multi-caspase activity in KB cells treated with Tulbaghia violacea extracts was concentration dependent, leading to cell death by apoptosis and cell cycle arrest at the G2/M phase. Conclusions: The acetone and water extracts of Tulbaghia violacea appear to have anti-cancer activity against human oral cancer cells and need to be investigated further.