Ovothiol A (OSH) is one of the strongest natural antioxidants. So far, its presence was found in tissues of marine invertebrates, algae and fish. Due to very low pKa value of the SH group, under physiological conditions, this compound is almost entirely present in chemically active thiolate form and reacts with ROS and radicals significantly faster than other natural thiols. In biological systems, OSH acts in tandem with glutathione GSH, with OSH neutralizing oxidants and GSH maintaining ovothiol in the reduced state. In the present work, we report the rate constants of OSH oxidation by H₂O₂ and of reduction of oxidized ovothiol OSSO by GSH and we estimate the Arrhenius parameters for these rate constants. The absorption spectra of reaction intermediates, adduct OSSG and sulfenic acid OSOH, were obtained. We also found that OSH effectively quenches the triplet state of kynurenic acid with an almost diffusion-controlled rate constant. This finding indicates that OSH may serve as a good photoprotector to inhibit the deleterious effect of solar UV irradiation; this assumption explains the high concentrations of OSH in the fish lens. The unique antioxidant and photoprotecting properties of OSH open promising perspectives for its use in the treatment of human diseases.

中文翻译：

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Ovothiol A 抗氧化性能的动力学研究

Ovothiol A (OSH) 是最强的天然抗氧化剂之一。迄今为止，在海洋无脊椎动物、藻类和鱼类的组织中发现了它的存在。由于 SH 基团的 pKa 值非常低，在生理条件下，该化合物几乎完全以化学活性硫醇盐的形式存在，并且与 ROS 和自由基的反应速度明显快于其他天然硫醇。在生物系统中，OSH 与谷胱甘肽 GSH 协同作用，OSH 中和氧化剂，GSH 将卵硫醇维持在还原状态。在目前的工作中，我们报告了 H ₂ O ₂氧化 OSH 的速率常数和通过 GSH 还原氧化的卵硫醇 OSSO，我们估计了这些速率常数的 Arrhenius 参数。获得了反应中间体、加合物OSSG和次磺酸OSOH的吸收光谱。我们还发现 OSH 以几乎受扩散控制的速率常数有效地淬灭犬尿酸的三重态。这一发现表明，OSH 可以作为一种良好的光保护剂来抑制太阳紫外线照射的有害影响；这一假设解释了鱼体中职业安全与卫生的高浓度。OSH 独特的抗氧化和光保护特性为其用于治疗人类疾病开辟了前景。