期刊
ANTIOXIDANTS
卷 11, 期 6, 页码 -出版社
MDPI
DOI: 10.3390/antiox11061132
关键词
carotenoid; xanthophyll; zeaxanthin; alpha-tocopherol; ascorbate; retina; retinal pigment epithelium; photosensitized oxidation; phototoxicity; age-related macular degeneration
资金
- Ministry of Science and Higher Education/State Committee for Scientific Research, Poland [PB 6PO4A 06217, 3P04A 044 23]
The study aimed to determine the optimal combinations of vitamins C, E, and zeaxanthin to prevent phototoxicity mediated by vitamin A aldehyde. Results showed that combining zeaxanthin with alpha-tocopherol provided substantial protection, enhancing cell viability significantly.
Vitamins C and E and zeaxanthin are components of a supplement tested in a large clinical trial-Age-Related Eye Disease Study 2 (AREDS2)-and it has been demonstrated that they can inhibit the progression of age-related macular degeneration. The aim of this study was to determine the optimal combinations of these antioxidants to prevent the phototoxicity mediated by vitamin A aldehyde (ATR), which can accumulate in photoreceptor outer segments (POS) upon exposure to light. We used cultured retinal pigment epithelial cells ARPE-19 and liposomes containing unsaturated lipids and ATR as a model of POS. Cells and/or liposomes were enriched with lipophilic antioxidants, whereas ascorbate was added just before the exposure to light. Supplementing the cells and/or liposomes with single lipophilic antioxidants had only a minor effect on phototoxicity, but the protection substantially increased in the presence of both ways of supplementation. Combinations of zeaxanthin with alpha-tocopherol in liposomes and cells provided substantial protection, enhancing cell viability from similar to 26% in the absence of antioxidants to similar to 63% in the presence of 4 mu M zeaxanthin and 80 mu M alpha-tocopherol, and this protective effect was further increased to similar to 69% in the presence of 0.5 mM ascorbate. The protective effect of ascorbate disappeared at a concentration of 1 mM, whereas 2 mM of ascorbate exacerbated the phototoxicity. Zeaxanthin or alpha-tocopherol partly ameliorated the cytotoxic effects. Altogether, our results suggest that the optimal combination includes upper levels of zeaxanthin and oc-tocopherol achievable by diet and/or supplementations, whereas ascorbate needs to be at a four-fold smaller concentration than that in the vitreous. The physiological relevance of the results is discussed.
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