School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK.
Photochem Photobiol. 2012 Nov-Dec;88(6):1408-17. doi: 10.1111/j.1751-1097.2012.01228.x. Epub 2012 Oct 1.
The purpose of this study was to determine the effects of increasing concentration of ascorbate alone and in combinations with α-tocopherol and zeaxanthin on phototoxicity to the retinal pigment epithelium. ARPE-19 cells were exposed to rose bengal and visible light in the presence and absence of antioxidants. Toxicity was quantified by an assay of cell-reductive activity. A 20 min exposure to visible light and photosensitizer decreased cell viability to ca 42%. Lipophilic antioxidants increased viabilities to ca 70%, 61% and 75% for α-tocopherol, zeaxanthin and their combination, respectively. Cell viabilities were ca 70%, 56% and 5% after exposures in the presence of 0.35, 0.7 and 1.4 mm ascorbate, respectively. A 45 min exposure increased cell death to ca 74% and >95% in the absence and presence of ascorbate, respectively. In the presence of ascorbate, zeaxanthin did not significantly affect phototoxicity. α-Tocopherol and its combination with zeaxanthin enhanced protective effects of ascorbate, but did not prevent from ascorbate-mediated deleterious effects. In conclusion, there is a narrow range of concentrations and exposure times where ascorbate exerts photoprotective effects, exceeding which leads to ascorbate-mediated increase in photocytotoxicity. Vitamin E and its combination with zeaxanthin can enhance protective effects of ascorbate, but do not ameliorate its deleterious effects.
本研究旨在确定单独增加抗坏血酸浓度以及与 α-生育酚和玉米黄质联合使用对抗光毒性对视网膜色素上皮的影响。ARPE-19 细胞在抗氧化剂存在或不存在的情况下暴露于玫瑰红和可见光下。通过细胞还原活性测定来量化毒性。可见光和光敏剂暴露 20 分钟可将细胞活力降低至约 42%。亲脂性抗氧化剂分别将活力提高至约 70%、61%和 75%，对于 α-生育酚、玉米黄质及其组合。暴露于 0.35、0.7 和 1.4 mm 抗坏血酸时，细胞活力分别约为 70%、56%和 5%。在不存在和存在抗坏血酸的情况下，45 分钟的暴露会将细胞死亡增加至约 74%和>95%。在抗坏血酸存在的情况下，玉米黄质并未显著影响光毒性。α-生育酚及其与玉米黄质的组合增强了抗坏血酸的保护作用，但不能防止抗坏血酸介导的有害作用。总之，在一定的浓度范围和暴露时间内，抗坏血酸具有光保护作用，超过该范围会导致抗坏血酸介导的光细胞毒性增加。维生素 E 及其与玉米黄质的组合可以增强抗坏血酸的保护作用，但不能减轻其有害作用。
