Photosafety evaluations of chemicals used in consumer products, such as pharmaceuticals and cosmetics, are very important. Currently, two non‐animal tests for photosafety evaluations, the in vitro 3T3 neutral red uptake phototoxicity test (NRU PT) and the reactive oxygen species (ROS) assay, are used to detect photoreactive chemicals. However, these two tests are difficult to apply to hydrophobic chemicals. In the present study, we attempted to develop a new photosafety test method, named the electron spin resonance‐based photosafety test (ESR‐PT), that would be applicable even to hydrophobic chemicals based on the detection of singlet oxygen generation after irradiation using ESR spectroscopy with 4‐hydroxy‐2,2,6,6‐tetramethyl‐piperidine as a spin trap reagent. To achieve a quantitative evaluation, the singlet oxygen formation (SOF) value, which can be calculated as the increment in relative intensity after irradiation of the test mixture normalized by the increment in relative intensity after irradiation of the vehicle control solution, was calculated. The performance of the ESR‐PT was evaluated by testing all the proficiency chemicals of the ROS assay plus additional chemicals, including hydrophobic chemicals and chemicals that tested false negative in the 3T3‐NRU PT and ROS assay. SOF values were successfully calculated for all the chemicals tested including the hydrophobic chemicals, and the accuracy of the ESR‐PT using a tentative cutoff value of 2.8 against the photosafety information was 100%. Therefore, the SOF value could be an effective parameter for photosafety evaluations, suggesting that the newly developed ESR‐PT is a promising non‐animal test applicable even to hydrophobic chemicals.

中文翻译：

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基于使用电子自旋共振检测单线态氧产生的新光安全测试方法的开发。

消费品（如药品和化妆品）中使用的化学品的光安全评估非常重要。目前，两种用于光安全评估的非动物试验，即体外 3T3 中性红吸收光毒性试验 (NRU PT) 和活性氧 (ROS) 试验，用于检测光反应性化学物质。然而，这两个测试很难应用于疏水性化学品。在本研究中，我们试图开发一种新的光安全测试方法，称为基于电子自旋共振的光安全测试（ESR-PT），基于使用 ESR 检测辐照后单线态氧的产生，该方法甚至适用于疏水性化学品以 4-羟基-2,2,6,6-四甲基-哌啶作为自旋陷阱试剂进行光谱分析。为了实现定量评估，单线态氧形成 (SOF) 值，可计算为测试混合物辐照后的相对强度增量，该增量通过赋形剂对照溶液辐照后的相对强度增量归一化，计算。ESR-PT 的性能是通过测试 ROS 测定的所有熟练化学品以及其他化学品来评估的，包括疏水性化学品和在 3T3-NRU PT 和 ROS 测定中测试为假阴性的化学品。成功计算了所有测试化学品的 SOF 值，包括疏水性化学品，ESR-PT 使用暂定截止值 2.8 与光安全信息相比的准确性为 100%。因此，SOF 值可能是光安全评估的有效参数，