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Electrospray tandem mass spectrometric analysis of zeaxanthin and its oxidation products
Author(s) -
Prasain Jeevan Kumar,
Moore Ray,
Hurst John S.,
Barnes Stephen,
van Kuijk Frederik J. G. M.
Publication year - 2005
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.868
Subject(s) - chemistry , carotenoid , tandem mass spectrometry , zeaxanthin , electrospray ionization , electrospray , mass spectrometry , chromatography , hydroxylamine , photochemistry , organic chemistry , lutein , biochemistry
Abstract Carotenoids have been implicated in protection of the eye from light‐mediated photo‐toxicity caused by free radicals. Under conditions of normal oxidative stress the carotenoids serve as protective antioxidants; however, when the oxidative stress exceeds the antioxidant capacity, carotenoids can be oxidized into numerous cleavage products. The determination and identification of oxidized carotenoids in biological samples remains a major challenge due to the small sample size and low stability of these compounds. We investigated the reaction of various zeaxanthin cleavage products with O ‐ethyl hydroxylamine to evaluate their levels in a biological sample. For this, a sensitive and specific electrospray tandem mass spectrometry (ESI‐MS/MS) was developed, avoiding the classical lower sensitive and specific HPLC‐UV and fluorescence absorption methods. Protonated molecules [M + H] + of carotenoids upon collision‐induced dissociation produced a number of structurally characteristic product ions. A series of complicated clusters of product ions differing in 14 (CH 2 )and 26 (C 2 H 2 )Da was characteristic of the polyene chain of intact carotenoids. All carotenoid ethyl oximes of zeaxanthin cleavage products were characterized by the losses of 60 and 61 Da in their MS/MS spectra. Through the application of the LC/MS/MS method, we identified two oxime derivatives of 3‐hydroxy‐β‐ionone and 3‐hydroxy‐14′‐apocarotenal with protonated molecules at m / z 252 and m / z 370 respectively, in a human eye sample. Copyright © 2005 John Wiley & Sons, Ltd.