Sarcostemma viminale: a potential anticancer therapy

There is a need for cancer treatments to be selectively cytotoxic to cancer cells so as to reduce adverse side effects. In this study, a cancer cell line (HeLa cells) and a non-cancer cell line (HF-32) were exposed to an extract from the plant Sarcostemma viminale. Cytopathic effects and apoptosis were measured by morphological changes, annexin V/propidium iodide (PI) and 4′,6-diamidino-2-phenylindole (DAPI) staining assays. Also, a novel mixed culture flow cytometry assay was performed exploiting the overexpression of p16INK4a in HeLa cells to demonstrate the change in numbers of HeLa and HF-32 cells post-exposure to the extract. At 1 % (v/v) after 48 h of exposure, HeLa cells showed >75 % cytopathic effect, 77 % were in apoptosis or dead by the annexinV/PI assay, and 100 % had nuclear changes by DAPI staining; there was a reduction of 76 % in the number of cells by mixed culture assay. In contrast, for the HF-32 cells, only 5 % showed any cytopathic effect, there were no more cells in apoptosis or dead (34 %) than in the control by the annexinV/PI assay, <1 % of cells had nuclear changes by DAPI staining, and there was a slight increase in cell numbers by the mixed culture assay. Results from these assays clearly demonstrate that the extract from S. viminale destroyed the cancer HeLa cells quickly and at a low concentration, whilst the non-cancer HF-32 cells survive. This study indicates that extracts from S. viminale may be a specific anticancer agent.