Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin.

Autor: Rozanowska M; Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff CF10 3AX, UK.; School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK., Edge R; Dalton Cumbrian Facility, The University of Manchester, Westlakes Science Park, Moor Row, Cumbria CA24 3HA, UK., Land EJ; The Paterson Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK., Navaratnam S; Biomedical Sciences Research Institute, University of Salford, Manchester M5 4WT, UK., Sarna T; Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland., Truscott TG; School of Chemical and Physical Sciences, Lennard-Jones Building, Keele University, Staffordshire ST5 5BG, UK.
Jazyk: angličtina
Zdroj: International journal of molecular sciences [Int J Mol Sci] 2023 Dec 29; Vol. 25 (1). Date of Electronic Publication: 2023 Dec 29.
DOI: 10.3390/ijms25010506
Abstrakt: In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 10 7 M -1 s -1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4-1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.
Competing Interests: The authors declare no conflicts. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
Databáze: MEDLINE
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