Abstract

The processes of the autooxidation and photooxidation of tetrahydrobiopterin (Н₄Bip) (a coenzyme present in a three- to fivefold excess in vitiligo) were studied in the context of vitiligo pathology and treatment. The study of the kinetics of Н₄Bip autooxidation and analysis of the reaction products via high-performance liquid chromatography (HPLC) demonstrated that autooxidation was intensive at a rate constant of 1 × 10^–3 s^–1 with the formation of dihydrobiopterin, dihydropterin, and their oxidized derivatives. Analysis of the autooxidation data led to a new conclusion that the oxidation of the excess of Н₄Bip in melanocytes obviously triggers an autocatalytic cycle of the synthesis of the excess of hydrogen peroxide (Н₂О₂). This, in turn, activates interferon-inducible GTP cyclohydrolase, which synthesizes an excess of Н₄Bip. The autocatalytic cycle of excess Н₂О₂ synthesis apparently underlies the pathology of vitiligo. The excess Н₂О₂ is also partly spent to activate the immune system. The autocatalytic cycle can be broken via the conversion of Н₄Bip into dihydropterin dimers during its UV photooxidation. The kinetics of Н₄Bip was studied, the reaction products were identified, and the quantum yields of the formation of dihydropterin dimers were calculated. The action spectrum of UV radiation was constructed based on the quantum yield data. It shows that the range of 300–325 nm is efficient for vitiligo phototherapy.

中文翻译：

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四氢生物蝶呤光氧化：白癜风光疗的关键过程

摘要

在白斑病病理和治疗的背景下，研究了四氢生物蝶呤 (Н ₄ Bip )（一种存在于白斑病中三到五倍过量的辅酶）的自氧化和光氧化过程。Н ₄ Bip 自动氧化动力学的研究和通过高效液相色谱 (HPLC) 对反应产物的分析表明，自动氧化在 1 × 10 ^–3 s ^–1的速率常数下是强烈的，形成二氢生物蝶呤，二氢蝶呤，以及它们的氧化衍生物。对自氧化数据的分析得出了一个新的结论，即过量的 Н ₄黑素细胞中的 Bip 显然会触发合成过量过氧化氢 (Н ₂ О ₂ )的自催化循环。这反过来又会激活干扰素诱导型 GTP 环化水解酶，从而合成过量的 Н ₄ Bip。过量Н ₂ О ₂合成的自催化循环显然是白癜风病理学的基础。多余的 Н ₂ О ₂也部分用于激活免疫系统。可以通过在紫外光氧化过程中将Н ₄ Bip 转化为二氢蝶呤二聚体来打破自催化循环。Н ₄的动力学研究了Bip，鉴定了反应产物，并计算了形成二氢蝶呤二聚体的量子产率。紫外辐射的作用光谱是基于量子产率数据构建的。它表明 300-325 nm 的范围对白斑光疗是有效的。