title: A novel in chemico method to detect skin sensitizers in highly diluted reaction conditions.
abstract: The direct peptide reactivity assay (DPRA) is a simple and versatile alternative method for the evaluation of skin sensitization that involves the reaction of test chemicals with two peptides. However, this method requires concentrated solutions of test chemicals, and hydrophobic substances may not dissolve at the concentrations required. Furthermore, hydrophobic test chemicals may precipitate when added to the reaction solution. We previously established a high-sensitivity method, the amino acid derivative reactivity assay (ADRA). This method uses novel cysteine (NAC) and novel lysine derivatives (NAL), which were synthesized by introducing a naphthalene ring to the amine group of cysteine and lysine residues. In this study, we modified the ADRA method by reducing the concentration of the test chemicals 100-fold. We investigated the accuracy of skin sensitization predictions made using the modified method, which was designated the ADRA-dilutional method (ADRA-DM). The predictive accuracy of the ADRA-DM for skin sensitization was 90% for 82 test chemicals which were also evaluated via the ADRA, and the predictive accuracy in the ADRA-DM was higher than that in the ADRA and DPRA. Furthermore, no precipitation of test compounds was observed at the initiation of the ADRA-DM reaction. These results show that the ADRA-DM allowed the use of test chemicals at concentrations two orders of magnitude lower than that possible with the ADRA. In addition, ADRA-DM does not have the restrictions on test compound solubility that were a major problem with the DPRA. Therefore, the ADRA-DM is a versatile and useful method.
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Yusuke
authors: Y
authors: Yamamoto
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Haruna
authors: H
authors: Tahara
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Ryota
authors: R
authors: Usami
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Toshihiko
authors: T
authors: Kasahara
authors: FUJIFILM Corporation, Synthetic Organic Chemistry Laboratories, Shizuoka, Japan.
authors: Yoshihiro
authors: Y
authors: Jimbo
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Takanori
authors: T
authors: Hioki
authors: FUJIFILM Corporation, Safety Evaluation Centre, Kanagawa, Japan.
authors: Masaharu
authors: M
authors: Fujita
mesh_terms: D000826:Animal Testing Alternatives / Q000379:methods*; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry; D016208:Databases, Factual; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry; D009281:Naphthalenes / Q000633:toxicity*; D010455:Peptides / Q000737:chemistry*; D015203:Reproducibility of Results; D012867:Skin / Q000187:drug effects* / Q000378:metabolism
chemical_list: D009281:Naphthalenes; D010455:Peptides; C031721:naphthalene; D008239:Lysine; D003545:Cysteine
keywords: ADRA-DM (ADRA-dilutional method); NAC; NAL; amino acid derivative reactivity assay (ADRA); direct peptide reactivity assay (DPRA); prediction; skin sensitization