Purchase this article with an account.
M. Santocono, M. Zurria, G. Paladino; Antioxidant Activity of the Xanthophylles Astaxanthin, Lutein and Zeaxanthin: In vitro Assays . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1699.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Oxidative stress plays a key role in the pathogenesis of Age-Related Macular Degeneration. In this study we tested the antioxidant activity of astaxanthin (A), zeaxanthin (Z), lutein (L), as well as ascorbic acid (AA) and tocopherol acetate (TA) by using different methods that include spectrophotometric, fluorimetric and chemiluminescence techniques. Methods: For spectrophotometric determinations, we used 2,2-diphenyl-1-picrylhydrazyl (DPPH) as a free radical compound, testing the free radical scavenging ability of A, Z, L, AA and TA recording the absorbance at 517nm. For fluorimetric determinations we used dichloro-fluorescein diacetate (H2-DCFA): upon oxidation with H2O2 this probe is first hydrolyzed to carboxy-H2-DCF and then transformed into highly fluorescent DCF. In this assay the carboxy-DCF fluorescence is directly proportional to the amount of H2O2. Measurements were performed with excitation at λ=488nm and emission at λ=530nm. Finally, chemiluminescence measurements were carried out using lucigenin as a chemiluminogenic probe, and the xanthin/xanthin oxidase system as a source of superoxide anion (O2-). Results: The results obtained provide direct evidence that the antioxidants tested act scavenging free radicals. In particular, in the spectrophotometric assay, A, L and Z showed a dose-ranging, almost equal antioxidant effect. In the same assay TA did not show any antioxidant activity, probably because of acetylation. However, conflicting data have been obtained using the different techniques. Differences could be due to the interference in the assay of impurities present in the natural extracts containing the antioxidants tested. Conclusions:Previous studies showed that xanthophylles (astaxanthin, lutein and zeaxanthin) cross the retina-blood barrier and bind to photoreceptor membranes, thus protecting them from light-induced damage. The present study confirms that xanthophylles have a high antioxidant effect and therefore, thanks to their properties, they can be antioxidants of first choice in order to prevent the oxidative stress at the retina level, which is in turn one of the primum movens of Age-Related Macular Degeneration.
This PDF is available to Subscribers Only