title: Cytotoxicity and superoxide anion generation by some naturally occurring quinones.
abstract: Four naturally occurring quinones, mansonone-D (MD), mansonone-H (MH), thespone (TP) and thespesone (TPE), extracted from the heartwood of Thespesia populnea have been tested for their cytotoxic action by aerobic incubation with human breast adenocarcinoma (MCF-7) cells. Toxicity of the quinones follows the order MD > TP > MH approximately TPE. EPR spectrometric and Clark electrode oximetric studies indicate that redox cycling of these quinones produce superoxide anion radical (O2*-) and H2O2 on aerobic incubation with NADH:cytochrome c reductase. Generation of superoxide radical during enzymatic reduction of quinones, was confirmed by EPR spin trapping experiment using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap. Cyclic voltammetric studies show reversible redox couples for MD and TP whereas TPE and MH show irreversible redox couple. The electrochemical results indicate that MH and TPE are more difficult to reduce than TP and MD.
authors.affiliation: School of Chemistry, Madurai Kamaraj University, India.
authors.forename: J
authors.initials: J
authors.lastname: Johnson Inbaraj
authors.forename: R
authors.initials: R
authors.lastname: Gandhidasan
authors.forename: R
authors.initials: R
authors.lastname: Murugesan
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D006801:Humans; D009285:Naphthoquinones / Q000737:chemistry / Q000494:pharmacology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D011809:Quinones / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013481:Superoxides / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D009285:Naphthoquinones; D010936:Plant Extracts; D011809:Quinones; C112690:mansonone D; C121002:mansonone H; C121004:thespesone; C121003:thespone; D013481:Superoxides