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Oxidation of a cysteine‐derived nucleophilic reagent by dimethyl sulfoxide in the amino acid derivative reactivity assay
Author(s) -
Akimoto Miyuki,
Yamamoto Yusuke,
Watanabe Shinichi,
Yamaga Hiroaki,
Yoshida Kousuke,
Wakabayashi Koji,
Tahara Yu,
Horie Nobuyuki,
Fujimoto Keiichi,
Kusakari Kei,
Kamiya Kohei,
Kojima Kohichi,
Kawakami Tsuyoshi,
Kojima Hajime,
Ono Atsushi,
Kasahara Toshihiko,
Fujita Masaharu
Publication year - 2020
Publication title -
journal of applied toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.784
H-Index - 87
eISSN - 1099-1263
pISSN - 0260-437X
DOI - 10.1002/jat.3948
Subject(s) - chemistry , reactivity (psychology) , nucleophile , reagent , dimethyl sulfoxide , acetonitrile , cysteine , solvent , sulfoxide , nucleophilic addition , derivative (finance) , thiol , organic chemistry , combinatorial chemistry , medicinal chemistry , catalysis , medicine , alternative medicine , pathology , financial economics , economics , enzyme
Abstract The amino acid derivative reactivity assay (ADRA), which is an in chemico alternative to the use of animals in testing for skin sensitization potential, offers significant advantages over the direct peptide reactivity assay (DPRA) in that it utilizes nucleophilic reagents that are sensitive enough to be used with test chemical solutions prepared to concentrations of 1 m m , which is one‐hundredth that of DPRA. ADRA testing of hydrophobic or other poorly soluble compounds requires that they be dissolved in a solvent consisting of dimethyl sulfoxide (DMSO) and acetonitrile. DMSO is known to promote dimerization by oxidizing thiols, which then form disulfide bonds. We investigated the extent to which DMSO oxidizes the cysteine‐derived nucleophilic reagents used in both DPRA and ADRA and found that oxidation of both N ‐(2‐(1‐naphthyl)acetyl)‐ l ‐cysteine (NAC) and cysteine peptide increases as the concentration of DMSO increases, thereby lowering the concentration of the nucleophilic reagent. We also found that use of a solvent consisting of 5% DMSO in acetonitrile consistently lowered NAC concentrations by about 0.4 μ m relative to the use of solvents containing no DMSO. We also tested nine sensitizers and four nonsensitizers having different sensitization potencies to compare NAC depletion with and without 5% DMSO and found that reactivity was about the same with either solvent. Based on the above, we conclude that the use of a solvent containing 5% DMSO has no effect on the accuracy of ADRA test results. We plan to review and propose revisions to OECD Test Guideline 442C based on the above investigation.