Litchi fruit has high commercial value and significant benefits for humans. However, pericarp browning, as the indicator of litchi fruit senescence, limits the shelf life of litchi fruit. Effect of α-lipoic acid (α-LA) that has great antioxidant potential, on litchi fruit senescence was investigated. Results showed that α-LA delayed pericarp browning and attenuated redox stress of litchi fruit, indicated by lower hydrogen peroxide (H₂O₂) and superoxide radical (O₂^−·) contents but higher hydroxy radical scavenging rate. Compared to control, α-LA treatment enhanced enzymatic: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as nonenzymatic antioxidants: glutathione (GSH) and ascorbate (AsA). Meanwhile, α-LA was protective against oxidative stress by inducing glutaredoxin (LcGrx), thioredoxin (LcTrx) and methionine sulfoxide reductase (LcMsr) expression levels. These α-LA-induced antioxidant systems directly increased the antioxidant capacity. Further research indicated that α-LA pretreatment maintained higher intracellular ATP level and activated extracellular ATP signaling through up-regulating LcDORN1s expression, indirectly increasing the antioxidant capacity. In conclusion, α-LA is effective to increase the antioxidant capacity and delay the pericarp browning of litchi fruit.

荔枝果实具有很高的商业价值和对人类的显着益处。然而，果皮褐变作为荔枝果实衰老的标志，限制了荔枝果实的保质期。研究了具有强大抗氧化潜力的α-硫辛酸（α-LA）对荔枝果实衰老的影响。结果表明，α-LA延迟了荔枝果实的果皮褐变并减弱了氧化还原应激，表现为较低的过氧化氢（H ₂ O ₂）和超氧自由基（O ₂ ^-·) 含量，但羟基自由基清除率较高。与对照相比，α-LA 处理增强了酶促：超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、抗坏血酸过氧化物酶 (APX) 和谷胱甘肽还原酶 (GR) 以及非酶促抗氧化剂：谷胱甘肽 (GSH) 和抗坏血酸 (AsA)。同时，α-LA 通过诱导谷氧还蛋白( LcGrx )、硫氧还蛋白( LcTrx ) 和甲硫氨酸亚砜还原酶( LcMsr) 表达水平。这些 α-LA 诱导的抗氧化系统直接增加了抗氧化能力。进一步研究表明，α-LA预处理通过上调LcDORN1s的表达，维持较高的细胞内ATP水平并激活细胞外ATP信号，间接提高抗氧化能力。综上所述，α-LA可有效提高荔枝的抗氧化能力，延缓荔枝果皮褐变。