title: Preparation, analysis, and anticholinesterase properties of O,O-dimethyl phosphorothioate isomerides.
abstract: Previous studies have shown that impurities in commercial organophosphorus insecticides induce a variety of toxicological manifestations. Few studies have contrasted common impurity types and their comparative chemical and biochemical properties. In this study, five O,O-dimethyl phosphorothioate compounds were converted to their corresponding O,S-dimethyl phosphorothioates (isomerides) by a stepwise dealkylation-alkylation process (yields 58-76%). The O,S-isomerides and parent material were characterized by reverse-phase high-performance liquid chromatography (RPHPLC) and phosphorus (31P) nuclear magnetic resonance (NMR) spectroscopy. Methanol-water mixtures were found to adequately separate isomeride from parent structure with the isomeride eluting first. In general, the O,S-isomerides were found to be shifted about 40 ppm upfield relative to the O,O material. Isomerides were also determined to be significantly more potent as anticholinesterases (rat brain), with ki values approximating 1000-fold those of the parent material.
authors.affiliation: Department of Chemistry, Loyola University of Chicago, Illinois 60626.
authors.forename: C M
authors.initials: CM
authors.lastname: Thompson
authors.forename: J A
authors.initials: JA
authors.lastname: Frick
authors.forename: B C
authors.initials: BC
authors.lastname: Natke
authors.forename: L K
authors.initials: LK
authors.lastname: Hansen
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002800:Cholinesterase Inhibitors / Q000032:analysis / Q000138:chemical synthesis*; D002851:Chromatography, High Pressure Liquid; D066298:In Vitro Techniques; D007536:Isomerism; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008743:Methyl Parathion / Q000031:analogs & derivatives / Q000737:chemistry; D009946:Organothiophosphorus Compounds / Q000032:analysis / Q000138:chemical synthesis* / Q000494:pharmacology; D010759:Phosphorus Isotopes; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002800:Cholinesterase Inhibitors; D008055:Lipids; D009946:Organothiophosphorus Compounds; D010759:Phosphorus Isotopes; D008743:Methyl Parathion; C072329:S-methyl-methylparathion