Giordano Maria Elena, Caricato Roberto, Lionetto Maria Giulia
Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via prov.le Lecce-Monteroni, 73100 Lecce, Italy.
Antioxidants (Basel). 2020 Oct 29;9(11):1058. doi: 10.3390/antiox9111058.
Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a hydrophilic analog of vitamin E, is known for its strong antioxidant activity, being a high radical scavenger of peroxyl and alkoxyl radicals. Under particular conditions, Trolox may also exhibit prooxidant properties. The present work aimed at studying the dual antioxidant/prooxidant behavior of Trolox over a wide range of concentrations (from 2.5 to 160 µM) in HeLa cells. In particular, the study addressed the dose-dependent effects of Trolox on the oxidative cell status and vitality of HeLa cells, focusing on the potential role of the vitamin E analog in the induction of one of the first steps of the apoptotic process, Apoptotic Volume Decrease (AVD). In HeLa cells, Trolox showed significant antioxidant activity, expressed as the ability to reduce the endogenous ROS production detected by the ROS-sensitive probe 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-HDCFDA), at low concentrations (range: 2.5-15 µM), but exerted a dose-dependent prooxidant effect at higher concentrations after 24 h exposure. The prooxidant effect was paralleled by the reduction in cell viability due to the induction of the apoptotic process. The dual behavior, antioxidant at lower concentrations and prooxidant at higher concentrations, was evident also earlier after 2 h incubation, and it was paralleled by the isotonic shrinkage of the cells, ascribed to AVD. The use of SITS, known Cl channel blocker, was able to completely inhibit the Trolox-induced isotonic cell shrinkage, demonstrating the involvement of the vitamin E analog in the alteration of cell volume homeostasis and, in turn, in the AVD induction. In conclusion, the study shed light on the concentration dependence of the Trolox antioxidant/prooxidant activity in HeLa cells and revealed its role in the induction of one of the first events of apoptosis, AVD, at high concentrations.
生育三烯酚（6-羟基-2,5,7,8-四甲基苯并二氢吡喃-2-羧酸）是维生素E的亲水性类似物，以其强大的抗氧化活性而闻名，是过氧自由基和烷氧自由基的高效清除剂。在特定条件下，生育三烯酚也可能表现出促氧化特性。本研究旨在探讨生育三烯酚在广泛浓度范围（2.5至160 μM）下对HeLa细胞的抗氧化/促氧化双重行为。具体而言，该研究关注生育三烯酚对HeLa细胞氧化状态和活力的剂量依赖性影响，重点研究维生素E类似物在诱导凋亡过程的第一步——凋亡体积减小（AVD）中的潜在作用。在HeLa细胞中，生育三烯酚在低浓度（范围：2.5至15 μM）时表现出显著的抗氧化活性，表现为能够降低由ROS敏感探针5-(和-6)-氯甲基-2',7'-二氯二氢荧光素二乙酸酯（CM-HDCFDA）检测到的内源性ROS产生，但在暴露24小时后，在较高浓度下表现出剂量依赖性促氧化作用。促氧化作用伴随着由于凋亡过程诱导导致的细胞活力降低。在孵育2小时后，较低浓度下抗氧化、较高浓度下促氧化的双重行为也很明显，并且与细胞的等渗收缩平行，这归因于AVD。使用已知的Cl通道阻滞剂SITS能够完全抑制生育三烯酚诱导的等渗细胞收缩，证明维生素E类似物参与了细胞体积稳态的改变，进而参与了AVD的诱导。总之，该研究揭示了生育三烯酚在HeLa细胞中抗氧化/促氧化活性的浓度依赖性，并揭示了其在高浓度下诱导凋亡的早期事件之一——AVD中的作用。
