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Complexes of diphenylarsinic acid and phenylarsonic acid with thiols: a 1 H and 13 C NMR study
Author(s) -
Nakayama Takashi,
Isobe Tomohiko,
Nakamiya Kunichika,
Edmonds John S.,
Shibata Yasuyuki,
Morita Masatoshi
Publication year - 2005
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1585
Subject(s) - chemistry , adduct , glutathione , nuclear magnetic resonance spectroscopy , thiol , carbon 13 nmr , proton nmr , medicinal chemistry , organic chemistry , nuclear chemistry , enzyme
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 1 H and 13 C 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 1 H and 13 C 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 1 H and 13 C 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. Copyright © 2005 John Wiley & Sons, Ltd.