Lutein-5,6-epoxide

Absorption and Raman analysis of LHCII complexes from xanthophyll biosynthesis mutants and plants containing unusual carotenoids (e.g., lactucoxanthin and lutein-epoxide) should also be interesting, since the role of these pigments and their binding properties are unknown. Understanding the specificity of binding can help to understand the reasons for xanthophyll variety in photosynthetic antennae and aid in the discovery of yet unknown functions for these molecules. 

Acids also induce chemical modifications of carotenoids. For instance, juice preparation requires acidic conditions, which trigger the spontaneous conversion of 5,6- and 5,6 -epoxide groups of violaxanthin, lutein epoxide, and antheraxanthin to 5,8- and 5, 8/-furanoid epoxides (Coultate, 1996 Gross, 1991). This conversion has a dramatic effect on the color because furanoids are essentially colorless. To be convinced about this fact, it is enough to compare the flesh color of fresh (solid line) and canned (dashed line) pineapples (Coultate, 1996) (Figure 5). 

Nuclear Overhauser effects 142) of appropriate model compounds were studied for assignment of the all-trans configuration of the polyene chain of eschscholtzxanthin (27) 8) and for identification of the H-7 and H-8 signals of the furanoxides flavoxanthin and crysanthemaxanthin 46 a) derived from lutein epoxide (46). 

Natural lutein epoxide (46) gave (-)-loliolide (47) after conversion to the diastereomeric furanoxides and oxidative degradation with nickel peroxide, thus proving the 3 R,6 R-configuration for (46) (46). Similar degradation of 3,8-caroten-3-ol (48) provided (6R)-a-ionone (49) (38). 

Lutein (14), as diacetate, upon epoxidation with w-chlorperbenzoic acid gave a minor epoxide identical with lutein epoxide (46) diacetate besides the major 3,5-cis epoxide (46). In a similar way zeaxanthin (26) diacetate had previously been converted to violaxanthin (32) diacetate (20), the 3,5- and 3, 5 -Irons compounds being obtained as minor products in addition to the major 3,5- and 3, 5 -cis derivatives, consistent with results for simple model compounds (20) and subsequent NMR data (78). 

The importance of choosing the appropriate conditions for analyzing substances of interest is well demonstrated in the analysis of xanthoxin. The violaxanthin and lutein epoxide in plant extracts are cleaved by light, oxygen and water to give a mixture of the cis and trans isomers of xanthoxin. If care is taken to keep... 

First, among these results, the content of lutein (all trans-lutein, 6)in total xanthophylls was most abundant, followed by violaxanthin (8), 9"-cis-violaxanthin (64) and 9 -c/s-neoxanthin (67, lutein-5,6-epoxide (lutein epoxide, 61), and others. Interestingly, on their percentage on the enzymatic conversion of lutein (all trans-lutein, 6)to lutein-5,6-epoxide (lutein epoxide, 61), Abbot 9.3% was more efficient, followed by Monty, Heyward and Bruno, respectively. 

Figure 16a. Lutein (6), neolutein B (63), lutein epoxide (lutein-5,6-epoxide) (61), violaxanthin (8) and auroxanthin (65).

Fig. 114. Layer cellulose, impregnated with triglyceride solvent methanol-acetone-water (74 + 20 + 6), saturated with triglyceride. Applied in non-impregnated part 1 extract of Fucus serratus (brown seaweed) 2 extract of Chara fragilis (stonewort). Substances a jS-carotene b isomer of chlorophyll a c chlorophyll a d chlorophyll b e lutein / and g (in 1) unknown xanthophylls / (in 2) lutein epoxide g (in 2) viol-axanthin h fucoxanthin i neoxanthin [3d, 37]...

Epoxy-5,6-dihydro-p,e-carotene-3,3 -diol, 9CI. Xanthophyll epoxide. Lutein epoxide [28368-08-3]... 

By a combination of column and thin-layer chromatography and of spectrophotometry as many as 37 carotenoids in extracts of butterflies have been characterized. In most species lutein epoxide was found to be the predominant carotenoid. Specimens of the same species of butterfly collected in different months quite frequently contained different carotenoids (273). Saponified acetone extracts of the Japanese stick insect Neophirasea japonica were analyzed by a combination of TLC and HPLC on Hitachi gel columns with CHCI3/CH3CN as the mobile phase (274). Carotenoids in poplar hawkmoth caterpillars were analyzed by TLC... 

Oxidation of these compounds subsequently gives rise to 5,6-epoxides, such as antheraxanthin (9-183) derived from P-carotene or taraxanthin (lutein epoxide) derived from a-carotene. Oxidation... 

Cano and Marin (1992) studied differences in pigment profiles between fresh (uiuipe and ripe), frozen and canned kiwi fruit shces, using thin-layer chromatography (TLC), HPLC, UV-visible spectroscopy, and chemical tests. Pigments present in fresh and frozen kiwi fruit shces were xanthophyUs (9 -cis-neoxanthin, trans-violaxanthin, cw-violaxanthin, auroxanthin, lutein epoxide, and lutein), chlorophylls and their derivatives, and one hydrocarbon carotenoid... 

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