Cell Proliferation and Cytotoxic Studies of Vernonia amygdalina on Vascular Smooth Muscle Cells and HT 29 Cell Lines

The antiproliferative effects of the methanol leaf extracts of Vernonia amygdalina (V. amygdalina) Del (Asteraceae) on Vascular Smooth Muscle Cells (VSMC) and Human Colorectal Adenocarcinoma Cell line (HT 29) were investigated using the Cell Titer 96 MTT Proliferation Assay where the viable cells were seeded at a density of 5 × 104 (100 μL/well). For VSMC, log concentrations of the extract at 200 and 800 μg/mL were added and incubated for 24 and 48 h time points. Incubation of the extracts in the presence of VEGF and ET-1 (the mitogens) was also conducted at different time points. Concentrations of the extract (200, 400 and 700 μg/mL) were also added and incubated with the HT 29 cell line for 24, 48 and 72 h time points. The result showed that after 24 hours, the effect of the extract of the plant on the VSMC alone and in the presence of the mitogens was more of proliferation except the 200 μg/mL in which there was no proliferation in the presence of ET-1. At 48 hrs, the proliferation was even more marked. For instance, the 800 μg/mL of V. amygdalina in the presence of VEGF caused 153.3% increase. In the case of HT 29 cytotoxic study, the extract at all doses used caused cytotoxic effect. For instance, the 200 μg/mL concentration of V. amygdalina caused 69.2% cell inhibition at 72 hours time point. It must however be noted that it was at 24 hrs time point that the effect of the extract was most pronounced and consistent. It could be concluded from this study that while the extract has proliferative effects on the VSMCs, the reverse is the case for the HT 29 cell line. It thus showed that the extract caused inhibitory effects on HT 29 cell line indicating that the extract exhibits cytotoxic effect and could then serve as lead agents in the search for anticancer drug from natural products.