TY - JOUR
T1 - Electrospray tandem mass spectrometric analysis of zeaxanthin and its oxidation products
AU - Prasain, Jeevan Kumar
AU - Moore, Ray
AU - Hurst, John S.
AU - Barnes, Stephen
AU - Van Kuijk, Frederik J.G.M.
PY - 2005/7
Y1 - 2005/7
N2 - 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 (CH2)and 26 (C2H 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 ra/z 252 and mlz 370 respectively, in a human eye sample.
AB - 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 (CH2)and 26 (C2H 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 ra/z 252 and mlz 370 respectively, in a human eye sample.
KW - Analysis
KW - Electrospray ionization
KW - Oxidized carotenoids
KW - Oxime
KW - Tandem mass spectrometry
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U2 - 10.1002/jms.868
DO - 10.1002/jms.868
M3 - Article
C2 - 15934038
AN - SCOPUS:23244460165
SN - 1076-5174
VL - 40
SP - 916
EP - 923
JO - Journal of Mass Spectrometry
JF - Journal of Mass Spectrometry
IS - 7
ER -