1.The role of lutein in the acclimation of higher plant chloroplast membranes to suboptimal conditions.
Pérez-Bueno ML;Horton P Physiol Plant. 2008 Sep;134(1):227-36. doi: 10.1111/j.1399-3054.2008.01124.x. Epub 2008 May 5.
Two mutants of Arabidopsis thaliana deficient in lutein have been investigated with respect to their responses to growth under a range of suboptimal conditions. The first mutant, lut1, was enriched in violaxanthin, antheraxanthin, zeaxanthin and zeinoxanthin compared with the wild-type (WT). In the second mutant, lut2, the lack of lutein was compensated for only by an increase in xanthophyll cycle (XC) carotenoids. Upon transfer of plants grown under optimal conditions to high light (HL), drought or HL + drought, both mutants acclimated during several days to the new conditions to the same extent as the WT. In contrast, transfer to chilling conditions (6 degrees C) for 6 days induced responses that were different between WT and mutants and between the mutants themselves. In contrast to the WT, the lut2 mutant in particular exhibited a large increase in the Chl a/b ratio and the XC pool size, extensive de-epoxidation and an enhanced extent of non-photochemical quenching. It is suggested that although the role of lutein in the structure and organisation of the light-harvesting complexes can be fulfilled by other xanthophylls under excess light conditions at optimal temperatures, this is not the case at low temperature.
2.Bioavailability of β-cryptoxanthin is greater from pasteurized orange juice than from fresh oranges - a randomized cross-over study.
Aschoff JK;Rolke CL;Breusing N;Bosy-Westphal A;Högel J;Carle R;Schweiggert RM Mol Nutr Food Res. 2015 Oct;59(10):1896-904. doi: 10.1002/mnfr.201500327. Epub 2015 Jul 20.
SCOPE: ;Orange fruits and products thereof represent important dietary sources of carotenoids, particularly β-cryptoxanthin. Since previous studies reported a positive effect of vegetable processing on carotenoid absorption, our objective was to compare the bioavailability of β-cryptoxanthin from either fresh navel oranges (Citrus sinensis L. Osbeck) or pasteurized orange juice.;METHODS AND RESULTS: ;The study was designed as a randomized 2-way cross-over study. Twelve volunteers consumed two meals delivering 744 μg of β-cryptoxanthin from either fresh navel oranges or pasteurized orange juice. Eight blood samples were collected over 9.5 h after test meal consumption and analyzed using HPLC-DAD. Additionally, carotenoid bioaccessibility was assessed after in vitro digestion of the same test foods. β-cryptoxanthin bioavailability from pasteurized orange juice was 1.8-fold higher than from fresh oranges (P = 0.011). Similarly, mean absorption of the non-dose adjusted carotenoids lutein (P = 0.301), zeaxanthin (P = 0.216), and zeinoxanthin (P = 0.090) were slightly higher from orange juice, although not reaching statistical significance. The in vitro digestion revealed a 5.3-fold higher bioaccessibility of β-cryptoxanthin from orange juice.
3.Nonaqueous reverse phase liquid chromatographic system for separation and quantitation of provitamins A.
Quackenbush FW;Smallidge RL J Assoc Off Anal Chem. 1986 Sep-Oct;69(5):767-72.
A reverse phase liquid chromatographic (LC) system has been developed for separating the main naturally occurring carotenoids that have provitamin A activity. The system produces baseline separation of beta-carotene, alpha-carotene, and beta-cryptoxanthin (beta, beta-carotene-3-ol, 472-70-8) from biologically inactive zeinoxanthin (beta, epsilon-carotene-3-ol, 24480-38-4) and from a pigment believed to be alpha-cryptoxanthin (beta, epsilon-carotene-3'-ol). Some cis-isomers are also separated. These separations are obtained on a C-18 column, isocratically, with methanol-chloroform eluant. For quantitation, peak areas from detection at 475 nm are compared with that of an internal standard, 1-(phenylazo)-2-naphthalenol (842-07-9), which elutes prior to the provitamins. Provitamin amounts are calculated from absorbance ratios. Prior to LC, esters are saponified, and interfering pigments are removed from ester-free extracts by adsorption on magnesia.