ith methanol at room temperature for 72 hours and filtered through Whatman No. 1 filter paper. The MeOH filtrate was collected and excess solvent was evaporated under reduced pressure using a rotary evaporator at 40uC to dryness producing 160.3 g of dark-greenish MeOH extract. Part of the MeOH extract was reserved for the assay while the remaining portion was further shaken vigorously with hexane until the resultant hexane became almost colorless. The hexane soluble solution was filtered and pooled, followed by concentration under reduced pressure by a rotary evaporator to yield 6.5 g of hexane extract. The remaining hexane insoluble was subjected to solvent-solvent extraction with a mixture of ethyl acetate and distilled water followed by fairly vigorous mixing. This mixture was then successively fractionated using a separating funnel in which two distinct layers formed. The bottom layer was discarded while the EtOAc phase was released into a clean beaker. This filtrate was concentrated under reduced pressure using a rotary evaporator to yield 9.7 g of EtOAc extract. In all experiments, extracts were dissolved in dimethylsulfoxide as stock solution and stored at 220uC. Prior to analysis, the final concentration of each sample was prepared by diluting the stock solution in 10% DMSO. The final concentration of DMSO in the cell culture was,0.5%. PW-M, PW-H and PW-E of P. watsonii were further subjected to Neutral Red Uptake assay according to the procedures described later. PW-H was found to exhibit strongest cytotoxicity when compared with PW-M and PW-E and warranted further investigation. Materials and Methods Ethics Statement All necessary permits and permission for collection of materials were obtained for the described field studies and the party involved is duly acknowledged. The species is located in the Endau Rompin National Park which belongs to the state government of Johor and managed by the Johor National Parks Corporation, Malaysia. The species is not endangered and the habitat is not threatened and it is also not listed in the Bioassay-guided Fractionation of PW-H The cytotoxically active fraction of PW-H was chromatographed on a column packed with silica gel 60 F254, 0.25 mm thickness . Gradient step elution began with 100% PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/22187495 hexane and polarity of eluting solvent was gradually RGFA-8 site increased using acetone and MeOH. Eluents of 25 mL volume were collected in numbered vials. The separation of each eluent was monitored on pre-coated thin layer chromatography silica gel 60 F254 plate using n-hexane/acetone as a developing solvent and the TLC zones were detected after spraying with p-anisaldehyde reagent and heating at 105uC for 5 10 min. The eluents were pooled according to the similarity of the chemical composition detected on TLC and the excess solvent was evaporated under reduced pressure using a rotary evaporator to yield a total of 10 fractions designated as PWH-1, PWH-2, PWH-3,…….,PWH-8, PWH-9 and PWH-10. Fractions PWH-9 and PWH-10 were found to contain silica gel and were further dissolved in chloroform and filtered through Whatman No. 1 filter paper Apoptosis Induction of Phyllanthus watsonii to remove the silica. Fractions PWH-9 and PWH-10 were obtained after 
removing the excess solvent by evaporation to dryness at 40uC under reduced pressure in a rotary evaporator. All the fractions were further subjected to Neutral Red Uptake assay and fractions PWH-4,…..,PWH-8 revealed as the most active fractions in cytotoxic activi
