Malgorzata Rozanowska
Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin
Rozanowska, Malgorzata; Edge, Ruth; Land, Edward J.; Navaratnam, Suppiah; Sarna, Tadeusz; Truscott, T. George
Authors
Ruth Edge
Edward J. Land
Suppiah Navaratnam
Tadeusz Sarna
T. George Truscott
Contributors
Fabio Altieri
Editor
Abstract
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 × 107 M−1s−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.
Citation
Rozanowska, M., Edge, R., Land, E. J., Navaratnam, S., Sarna, T., & Truscott, T. G. (in press). Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin. International Journal of Molecular Sciences, 25(1), Article 506. https://doi.org/10.3390/ijms25010506
Journal Article Type | Article |
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Acceptance Date | Dec 28, 2023 |
Online Publication Date | Dec 29, 2023 |
Deposit Date | Jan 15, 2024 |
Journal | International Journal of Molecular Sciences |
Print ISSN | 1661-6596 |
Publisher | MDPI |
Peer Reviewed | Peer Reviewed |
Volume | 25 |
Issue | 1 |
Article Number | 506 |
DOI | https://doi.org/10.3390/ijms25010506 |
Keywords | vitamin A, retina, xanthophylls, vitamin C, age-related macular degeneration, Stargardt’s disease, vitamin E, carotenoids, retinal, free radicals |
Publisher URL | https://www.mdpi.com/1422-0067/25/1/506 |
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