Tamarindus indica bark extract and a bioactive fraction induce apoptosis in HeLa and PA-1 cells

Abstract

The aim of the current study was to evaluate the anticancer potential of tamarind bark and its bioactive fraction on HeLa and PA-1 cell lines. Tamarind bark extract was prepared with dichloromethane as the solvent using Soxhlet apparatus and treated on HeLa and PA-1 cell lines to determine the anticancer potential by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Further, bioassay guided fractionation of the extract was carried out using thin layer chromatography. In vitro assays like fluorescence microscopy, DNA fragmentation analysis, caspase-9 activity assay and flow cytometry analyses were carried out to determine the mechanism of anticancer activity of the selected bioactive fraction. The fraction was further characterized by gas chromatography-mass spectrometry. Tamarind bark dichloromethane extract was found to be cytotoxic to HeLa and PA-1 cells. Bioassay guided fractionation indicated that the fourth fraction of the extract possessed the bioactive component. Further, in vitro assays demonstrated that the bioactive fraction induced caspase-9-mediated apoptosis in the cells and was able to reduce the total cell count as evidenced by flow cytometry analyses. The gas chromatography-mass spectrometry analysis of the bioactive fraction indicated the presence of cantharidin, an anticancer compound earlier reported from the blister beetles. It can be concluded that the presence of cantharidin might be responsible for inhibition of proliferation and induction of apoptosis in the cancer cells.