title: Development of micellar reactive oxygen species assay for photosafety evaluation of poorly water-soluble chemicals.
abstract: A reactive oxygen species (ROS) assay was previously developed for photosafety assessment; however, the phototoxic potential of some chemicals cannot be evaluated because of their limited aqueous solubility. The present study was undertaken to develop a new micellar ROS (mROS) assay system for poorly water-soluble chemicals using a micellar solution of 0.5% (v/v) Tween 20 for solubility enhancement. In repeated mROS assay, intra- and inter-day precisions (coefficient of variation) were found to be below 11%, and the Z'-factors for singlet oxygen and superoxide suggested a large separation band between positive and negative standards. The ROS and mROS assays were applied to 65 phototoxins and 18 non-phototoxic compounds for comparative purposes. Of all 83 chemicals, 25 were unevaluable in the ROS assay due to poor solubility, but only 2 were in the mROS assay. Upon mROS assay on these model chemicals, the individual specificity was 76.5%, and the positive and negative predictivities were found to be 93.9% and 86.7%, respectively. The mROS assay provided 2 false negative predictions, although negative predictivity for the ROS assay was found to be 100%. Considering the pros and cons of these assays, strategic combined use of the ROS and mROS assays might be efficacious for reliable photosafety assessment with high applicability and predictivity.
authors.affiliation: Department of Pharmacokinetics and Pharmacodynamics, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Seto
authors.forename: Masashi
authors.initials: M
authors.lastname: Kato
authors.forename: Shizuo
authors.initials: S
authors.lastname: Yamada
authors.forename: Satomi
authors.initials: S
authors.lastname: Onoue
mesh_terms: D001681:Biological Assay; D008823:Micelles; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000633:toxicity*; D011136:Polysorbates / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*; D012995:Solubility; D013481:Superoxides / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D008823:Micelles; D017319:Photosensitizing Agents; D011136:Polysorbates; D014867:Water; D013481:Superoxides; D026082:Singlet Oxygen
keywords: CV; DMSO; Micellar solution; NBT; NaPB; OECD; PABA; Photoreactivity; Photosafety assessment; Phototoxicity; Poorly water-soluble chemicals; ROS; Reactive oxygen species; SD; SDS; UV; coefficient of variation; dimethyl sulfoxide; mROS assay; micellar reactive oxygen species assay; nitroblue tetrazolium; p-aminobenzoic acid; reactive oxygen species; sodium dodecyl sulfate; sodium phosphate buffer; standard deviation; the Organisation for Economic Co-operation and Development; ultraviolet