Department of Biochemistry, 89 Beaumont Ave, Given Laboratory, Room B413, Burlington, VT, 05405, USA.
Curr Opin Chem Biol. 2023 Aug;75:102328. doi: 10.1016/j.cbpa.2023.102328. Epub 2023 May 24.
Selenium is connected to three small molecule antioxidant compounds, ascorbate, α-tocopherol, and ergothioneine. Ascorbate and α-tocopherol are true vitamins, while ergothioneine is a "vitamin-like" compound. Here we review how selenium is connected to all three. Selenium and vitamin E work together as a team to prevent lipid peroxidation. Vitamin E quenches lipid hydroperoxyl radicals and the resulting lipid hydroperoxide is then converted to the lipid alcohol by selenocysteine-containing glutathione peroxidase. Ascorbate reduces the resulting α-tocopheroxyl radical in this reaction back to α-tocopherol with concomitant production of the ascorbyl radical. The ascorbyl radical can be reduced back to ascorbate by selenocysteine-containing thioredoxin reductase. Ergothioneine and ascorbate are both water soluble, small molecule reductants that can reduce free radicals and redox-active metals. Thioredoxin reductase can reduce oxidized forms of ergothioneine. While the biological significance of this is not yet realized, this discovery underscores the centrality of selenium to all three antioxidants.
硒与三种小分子抗氧化化合物——抗坏血酸、α-生育酚和麦角硫因相连。抗坏血酸和α-生育酚是真正的维生素，而麦角硫因是一种“类维生素”化合物。在这里，我们回顾一下硒与这三种物质的联系。硒和维生素 E 协同作用，共同预防脂质过氧化。维生素 E 猝灭脂质过氧自由基，生成的脂质过氧化物随后被含硒半胱氨酸的谷胱甘肽过氧化物酶转化为脂质醇。在这个反应中，抗坏血酸将生成的α-生育酚氧自由基还原回α-生育酚，同时产生抗坏血酸自由基。含硒半胱氨酸的硫氧还蛋白还原酶可以将抗坏血酸自由基还原回抗坏血酸。麦角硫因和抗坏血酸都是水溶性的小分子还原剂，可以还原自由基和氧化还原活性金属。硫氧还蛋白还原酶可以还原麦角硫因的氧化形式。虽然目前还没有意识到这一生物学意义，但这一发现突显了硒在这三种抗氧化剂中的核心地位。
