title: Interaction of O,O,S-trimethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate, the impurities of malathion with supercoiled PM2 DNA.
abstract: The interaction of O,O,S-trimethyl phosphorothioate and O,S,S-trimethyl phosphorodithioate, the impurities found in malathion, with DNA at pH 8.0, was investigated. Supercoiled PM2 DNA was incubated with these compounds at pH 8.0 at 37 degrees C and then the superhelicity of the modified DNA was determined by gel electrophoresis. Both compounds caused unwinding of supercoiled DNA in dose- and incubation time-dependent manner. O,S,S-trimethyl phosphorodithioate was a more potent agent than O,O,S-trimethyl phosphorothioate. At 37 degrees C following 2.0 hours incubation, 100 mM O,S,S-trimethyl phosphorodithioate produced fully unwound DNA, whereas at 200 mM O,O,S-trimethyl phosphorothioate produced 80% unwound DNA following 12 hours' incubation. At the same condition, 5 mM methyl methanesulfonate, a potent alkylating mutagen, produced fully unwound DNA following 1 hour incubation at 5 mM. These results indicated that there were chemical interactions between these agents and DNA. The possibility of the interaction of OOS-TMP being as a covalent intercalation as well as strand nicking was discussed.
mesh_terms: D000818:Animals; D002417:Cattle; D004278:DNA, Superhelical / Q000378:metabolism*; D004587:Electrophoresis, Agar Gel; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D008294:Malathion / Q000633:toxicity; D009691:Nucleic Acid Denaturation / Q000187:drug effects; D063086:Organothiophosphates / Q000378:metabolism*; D009946:Organothiophosphorus Compounds / Q000378:metabolism*; D051381:Rats; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D004278:DNA, Superhelical; D063086:Organothiophosphates; D009946:Organothiophosphorus Compounds; C019123:O,O,S-trimethyl phosphorothioate; C033125:O,S,S-trimethyl phosphorodithioate; D008294:Malathion