Astaxanthin Protects against Oxidative Stress and Calcium-Induced Porcine Lens Protein Degradation

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• 作者：Tzu-Hua Wu ; Jiahn-Haur Liao ; Wen-Chi Hou ; Fu-Yung Huang ; Timothy J. Maher ; and Chao-Chien Hu
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2006
• 出版时间：March 22, 2006
• 年：2006
• 卷：54
• 期：6
• 页码：2418 - 2423
• 全文大小：277K
• 年卷期：v.54,no.6(March 22, 2006)
• ISSN：1520-5118

文摘

Astaxanthin (ASTX), a carotenoid with potent antioxidant properties, exists naturally in various plants,algae, and seafoods. In this study, we investigated the in vitro ability of ASTX to protect porcine lenscrystallins from oxidative damage by iron-mediated hydroxyl radicals or by calcium ion-activatedprotease (calpain), in addition to the possible underlying biochemical mechanisms. ASTX (1 mM)was capable of protecting lens crystallins from being oxidized, as measured by changes in tryptophanfluorescence, in the presence of a Fenton reaction solution containing 0.2 mM Fe²⁺ and 2 mM H₂O₂.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that _high-crystallinwas the most vulnerable protein under these conditions of free radical exposure. The proteolysis oflens crystallins induced by calcium ion-activated calpain was also inhibited by ASTX (0.03-1 mM)as determined by daily measurement of the light-scattering intensity at 405 nm for five consecutivedays. ASTX at 1 mM was as potent as a concentration of 0.1 mM calpain inhibitor E64 in protectingthe oxidative damage/hydrolysis of porcine crystallins. At a concentration of 1 mM, ASTX providedbetter protection than the endogenous antioxidant glutathione in terms of suppressing calcium-inducedturbidity of lens proteins. Thin-layer chromatography analysis indicated that ASTX interacted withcalcium ions to form complexes, which we believe interfere with the hydrolysis of lens crystallins bycalcium-activated calpain. This in vitro study shows that ASTX is capable of protecting porcine lensproteins from oxidative insults and degradation by calcium-induced calpain.Keywords: Astaxanthin; calcium-induced turbidity; calcium complex; lens proteins; oxidative stress