title: Studies on cytotoxic, hydroxyl radical scavenging and topoisomerase inhibitory activities of extracts of Tabernaemontana divaricata (L.) R.Br. ex Roem. and Schult.
abstract: In the present investigation, the cytotoxic, hydroxyl radical scavenging and topoisomerase inhibition activities of Tabernaemontana divaricata (Apocynaceae) were evaluated. The extracts from leaves of the plant were prepared with different solvents viz. chloroform, methanol, ethyl acetate and hexane. In, in vitro cytotoxicity assay, with cell lines viz HCT-15 (Colon), HT-29 (Colon), 502713 (Colon), MCF-7 (Breast), PC- 3 (Prostrate), it was observed that the ethyl acetate extract was effective against only one colon cell line (502713) at the lowest dose i.e. 10 micro g/ml, whereas the chloroform extract was effective against all the three colon cancer cell lines, at 30 microg/ ml. In order to evaluate the mechanism of cytotoxicity of these extracts, they were assessed for their ability to scavenge hydroxyl radicals in plasmid nicking assay with pBR322. It was observed that all the extracts effectively inhibited the unwinding of supercoiled DNA except hexane extract, which showed the least effect. Since the expression of topo enzymes is linked with cell proliferation so the extracts were also checked for topo I and topo II inhibitory activities. It was noticed that ethyl acetate extract selectively showed inhibition of topo II in topoisomerase II relaxation assay.
authors.affiliation: Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar 143005, Punjab, India.
authors.forename: Tarunpreet Singh
authors.initials: TS
authors.lastname: Thind
authors.forename: Satyam Kumar
authors.initials: SK
authors.lastname: Agrawal
authors.forename: A K
authors.initials: AK
authors.lastname: Saxena
authors.forename: Saroj
authors.initials: S
authors.lastname: Arora
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004278:DNA, Superhelical / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000494:pharmacology*; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism*; D020287:In Situ Nick-End Labeling; D007194:India; D016877:Oxidants / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D010957:Plasmids / Q000187:drug effects / Q000235:genetics; D030014:Tabernaemontana / Q000737:chemistry*; D059004:Topoisomerase I Inhibitors
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D004278:DNA, Superhelical; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D016877:Oxidants; D010936:Plant Extracts; D059004:Topoisomerase I Inhibitors; D017665:Hydroxyl Radical