Hoechst staining of cell to detect BT induced apoptosis. Ovarian cancer cell lines were treated with 100 μM BT for 24 hrs. Treated/untreated cells were stained with Hoechst 33258 and visualized by fluorescence microscopy. Representative images were taken with an inverted microscope (Olympus H4-100, CCD camera) and 20× objective. Graph: Quantification of percent of apoptosis in terms of DNA fragmentation using Trevigen’s TACS® 2 TdT in Situ Apoptosis Detection Kit (TUNEL assay). Cells were treated with BT as explained earlier. At the end of the treatment time, labelled nucleotides were added and detected with HRP – HRP substrate (TACS-Sapphire) system. The absorbance was measured at 450 nm using a microplate reader, Multiskan (Thermo Scientifics). Experiments were performed in duplicate. Data was expressed as mean ± SD of duplicate experiments.