光漂白提高褐黑色素的光毒性潜能：有氧光解合成褐黑色素的理化研究

2019/03/07   下载量： 0 次

方案摘要

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应用领域 医疗/卫生
检测样本 其他
检测项目
参考标准 暂无

采用立陶宛Ekspla公司的半导体泵浦的全集成固体纳秒可调谐YAG激光器NT242–1k‐SH/SFG，做光源激发褐黑色素样品，分析研究该种物质的光学漂白，以及有氧光解合成褐黑色素的理化特性。

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       Although melanin is a photoprotective pigment, its elevated photochemical reactivity
could lead to various phototoxic processes. Photoreactivity of synthetic pheomelanin,
derived from 5‐S‐cysteinyldopa (5SCD‐M) and its photodegradation products obtained by subjecting the melanin to aerobic irradiation with UV‐visible light, was examined employing an array of advanced physicochemical methods. Extensive photolysis of 5SCD‐M was accompanied by partial bleaching of the melanin, modification of its paramagnetic properties, and significant increase in the ability to photogenerate singlet oxygen. The changes correlated with a substantial decrease in the melanin content of benzothiazine (BT) units and increase of modified benzothiazole (BZ) units. Synthetically prepared BZ exhibited higher efficiency to photogenerate singlet oxygen than the synthetic BT, and the free radical form of BZ, unlike that of BT, did not show measurable spin density on nitrogen atom, which was confirmed by quantum chemical calculations. Formation of modified BZ units in the photobleached 5SCD‐M is responsible for the paramagnetic and photochemical changes of the melanin and its elevated phototoxic potential. Given a relatively constant pheomelanin–
eumelanin ratio, such undesirable changes could occur in individual of all skin types.

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北京欧兰科技发展有限公司
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