Premium
Cause of and countermeasures for oxidation of the cysteine‐derived reagent used in the amino acid derivative reactivity assay
Author(s) -
Fujita Masaharu,
Yamamoto Yusuke,
Watanabe Shinichi,
Sugawara Tsunetsugu,
Wakabayashi Koji,
Tahara Yu,
Horie Nobuyuki,
Fujimoto Keiichi,
Kusakari Kei,
Kurokawa Yoshihiko,
Kawakami Tsuyoshi,
Kojima Kohichi,
Kojima Hajime,
Ono Atsushi,
Katsuoka Yasuhiro,
Tanabe Hideto,
Yokoyama Hiroshi,
Kasahara Toshihiko
Publication year - 2019
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.3707
Subject(s) - reactivity (psychology) , chemistry , reagent , cysteine , nucleophile , sensitization , derivative (finance) , metal ions in aqueous solution , combinatorial chemistry , metal , organic chemistry , catalysis , medicine , immunology , alternative medicine , pathology , financial economics , enzyme , economics
The amino acid derivative reactivity assay (ADRA) is an in chemico alternative to animal testing for skin sensitization that solves certain problems found in the use of the direct peptide reactivity assay (DPRA). During a recent validation study conducted at multiple laboratories as part of the process to include ADRA in an existing OECD test guideline, one of the nucleophilic reagents used in ADRA— N ‐(2‐(1‐naphthyl)acetyl)‐ l ‐cysteine (NAC)—was found to be susceptible to oxidation in much the same manner that the cysteine peptide used in DPRA was. Owing to this, we undertook a study to clarify the cause of the promotion of NAC oxidation. In general, cysteine and other chemicals that have thiol groups are known to oxidize in the presence of even minute quantities of metal ions. When metal ions were added to the ADRA reaction solution, Cu 2+ promoted NAC oxidation significantly. When 0.25 μ m of EDTA was added in the presence of Cu 2+ , NAC oxidation was suppressed. Based on this, we predicted that the addition of EDTA to the NAC stock solution would suppress NAC oxidation. Next, we tested 82 chemicals used in developing ADRA to determine whether EDTA affects ADRA's ability to predict sensitization. The results showed that the addition of EDTA has virtually no effect on the reactivity of NAC with a test chemical, yielding an accuracy of 87% for predictions of skin sensitization, which was roughly the same as ADRA.