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J.S. Hurst, F.J. G. M. van Kuijk; Synthesis and Identification of Aldehydes and Ketones Derived From Oxidation of Macular Pigments . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1773.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Carotenoids are antioxidants that are present in many biological systems. The eye is unique in that only two carotenoids, lutein and zeaxanthin, accumulate and constitute the macular pigment (MP). Previously we established the toxicity to RPE cells of aldehydes derived from the oxidative breakdown of ß–carotene. It is to be expected that carotenoid derived aldehydes (CDA) from the MP are present in the eye but they remain to be identified. The purpose of this study is to synthesize and characterize MP–derived CDA and to study their occurrence and toxicity in the eye Methods:Zeaxanthin was completely oxidized after incubation with NaOCl for different time periods. The samples were extracted and analyzed by high performance liquid chromatography (HPLC) with diode array detection. UV–spectra were acquired from each of the chromatographic peaks obtained from the CDA mixtures. Furthermore, ethyl oxime derivatives of the CDA derived from zeaxanthin were prepared and also characterized by HPLC with diode array detection Results: A series products could be identified from the HPLC profiles. Longer incubation of zeaxanthin with NaOCl produced products with shorter chain lengths When UV spectra were obtained they could be identified as 3–hydroxy–apo–carotenals of different carbon chain lengths and 3–hydroxy–ionone. Complex clusters of chromatographic peaks differing in C2H2 could be isolated because the shifts in maximum wavelength absorbance correlated with the number of conjugated double bonds in the molecules. All CDA–ethyl oximes of zeaxanthin oxidation could also be similarly characterized and a number of these products were recognized in human eye samples by their HPLC retention times. Conclusions: Oxidation products of macular pigment can be synthesized and characterized by HPLC using diode array detection. Analysis in human eyes is limited due to lack of sensitivity.
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