Thioprolines formed by reacting cysteine with reactive carbonyls have been demonstrated to possess antitumor, antioxidative, and hepatoprotective properties. Using our developed QuEChERS sample preparation in combination with a liquid chromatography–tandem mass spectrometry coupled with stable isotope-dilution method, we identified and quantitated 2-methylthioproline (1) and 2-methylthioprolinylglycine (2) in grape wines. In particular, 2 was identified for the first time in wines. We further tested the hypothesis that these adducts, despite originating from carcinogenic acetaldehyde condensing with aminothiols, could serve as antioxidants protecting cells from oxidative insults. Results showed that human liver cells pretreated with 1 or 2 were more tolerant to oxidative stress, as indicated by a concentration-dependent increase in cell viability under an H₂O₂-oxidative environment. It is believed that these compounds may contribute to the antioxidative properties of grape wines.

中文翻译：

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2-甲基硫代脯氨酸和2-甲基硫代脯氨酸在葡萄中的形成、稳定性和抗氧化特性

通过半胱氨酸与反应性羰基反应形成的硫代脯氨酸已被证明具有抗肿瘤、抗氧化和保肝的特性。使用我们开发的 QuEChERS 样品制备方法，结合液相色谱-串联质谱和稳定同位素稀释方法，我们鉴定并定量了葡萄酒中的2-甲基硫代脯氨酸 ( 1 ) 和 2-甲基硫代脯氨酰甘氨酸 ( 2 )。特别是，2首次在葡萄酒中被发现。我们进一步检验了这些加合物尽管源自与氨基硫醇缩合的致癌乙醛，但可以作为抗氧化剂保护细胞免受氧化损伤的假设。结果表明，用1或2对氧化应激的耐受性更强，如在 H ₂ O ₂氧化环境下细胞活力的浓度依赖性增加所表明的。据信，这些化合物可能有助于葡萄酒的抗氧化特性。