title: Complexes of diphenylarsinic acid and phenylarsonic acid with thiols: a 1H and 13C NMR study.
abstract: The high toxicity of diphenylarsinic acid, found in ground water and well water as a probable consequence of the inappropriate disposal of warfare agents, prompted us to study the reaction, monitored by 1H and 13C NMR spectroscopy, of the compound and its monophenyl analogue, phenylarsonic acid, with cellular thiols as represented, in particular, by glutathione. Glutathione reduced the phenylarsenic acids to trivalent forms and complexed them: diphenylarsinic acid to a monoglutathione adduct and phenylarsonic acid to a diglutathione adduct. The complexes were characterized by 1H and 13C NMR spectroscopy and mass spectrometry. The NMR spectra showed the diastereotopic nature of the two phenyl groups in the diphenylarsinic acid-glutathione compound, and of the two glutathione residues in the phenylarsonic acid-diglutathione complex. The stereochemistry of thiol compounds of phenylarsonic acid was further explored by 1H and 13C NMR spectroscopy of the L-cysteine complex. The diphenylarsinic acid-glutathione complex was stable below pH 12 but at higher pH the complex dissociated into diphenylarsinous acid and reduced glutathione. The released diphenylarsinous acid then oxidized to diphenylarsinic acid with a half-life of about 7 h at pH 13 and at room temperature.
authors.affiliation: National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakayama
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Isobe
authors.forename: Kunichika
authors.initials: K
authors.lastname: Nakamiya
authors.forename: John S
authors.initials: JS
authors.lastname: Edmonds
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shibata
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Morita
mesh_terms: D001152:Arsenicals / Q000032:analysis / Q000737:chemistry*; D002247:Carbon Isotopes; D046911:Macromolecular Substances / Q000032:analysis / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010084:Oxidation-Reduction; D011522:Protons; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D001152:Arsenicals; D002247:Carbon Isotopes; D046911:Macromolecular Substances; D011522:Protons; D013438:Sulfhydryl Compounds; D014874:Water Pollutants, Chemical; C020979:benzenearsonic acid; C493087:diphenylarsinic acid