10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 3 2014 (July- September) The aim of this study was to investigate the apoptosis inducing property of methanolic extract of lessThan i greaterThan Phyllanthus polyphyllus lessThan /i greaterThan (MPP) lessThan i greaterThan in vitro lessThan /i greaterThan using human cervical cancer cells (HeLa) and human breast carcinoma cells (HBL-100). First, the anti-proliferative activity of MPP was determined using Tryphan blue dye exclusion method. Then, the apoptosis of cells was evidenced in MPP (500 µg/ml) by using propidium iodide (PI) staining and fluorescent microscopy. The Tryphan blue dye exclusion assay showed that MPP had induced a dose- dependent decrease in cell viability. The IC lessThan sub greaterThan 50 lessThan /sub greaterThan of MPP was found to be 340 and 250 µg/ml. Among the tested cell lines, MPP was more selective cytotoxic against HBL-100 than HeLa. Extensive apoptotic changes were found in HBL-100 and HeLa cells. The morphology of cancer cells induced by MPP after staining with PI and examined under a fluorescence microscope was condensed chromatin and fragmented nuclei. SWAPNA.G (SWAPNA GURRALA), B. RAJKAPOOR, BHARATHI KOGANTI AND K.V.S.R.G. PRASAD Cytotoxic potential, Phyllanthus polyphyllus, HeLa, HBL-100, Fluorescent microscopy, Apoptosis. 323-328