Quantification of carotenoids in chicken plasma after feeding free or esterified lutein and capsanthin using high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis.

The present study reports about the plasma carotenoid levels of chickens achieved after feeding diets containing free and esterified lutein (from marigold) and capsanthin (from red pepper) by applying HPLC analyses using a RP-C30 column. Forty chickens were divided at random into four groups and were fed 2 wk with different diets after receiving a basal diet with a low carotenoid content for carotenoid depletion (3 wk). One group was fed a diet containing free lutein (G1), another group received a diet with esterified lutein (G2), two other diets contained free (R1) and esterified capsanthin (R2), respectively. To unequivocally identify plasma carotenoids, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis was applied, which had never been used as an analytical tool to evaluate the carotenoids of chicken plasma; HPLC chromatograms of chicken plasma following capsanthin feeding have not been presented. The study showed that not only lutein but also capsanthin appeared in the blood stream after feeding free or esterified xanthophylls, demonstrating that capsanthin esters were bioavailable. Quantitative analysis showed comparable concentrations of plasma lutein and capsanthin, respectively, no matter if free or esterified carotenoids were fed.

Carotenoid esters in vegetables and fruits: a screening with emphasis on beta-cryptoxanthin esters.

Carotenoids are found in food plants in free form or as fatty acid esters. Most studies have been carried out after saponification procedures, so the resulting data do not represent the native carotenoid composition of plant tissues. Therefore, nonsaponified extracts of 64 fruits and vegetables have been screened to determine the amount of carotenoid esters in food plants. Because one of the major problems in the quantitation of carotenoids is the availability of pure standard material, the total carotenoid ester content was calculated as lutein dimyristate equivalents. Lutein dimyristate was independently synthesized from lutein and myristoyl chloride. The highest ester concentrations were found in red chili (17.1 mg/100 g) and orange pepper (9.2 mg/100 g); most of the investigated fruits and vegetables showed concentrations up to 1.5 mg/100 g. Special attention was dedicated to beta-cryptoxanthin esters. To enable an accurate detection of the beta-cryptoxanthin ester content, beta-cryptoxanthin was purified from papaya and used for synthesis of beta-cryptoxanthin laurate, myristate, and palmitate, representing the major beta-cryptoxanthin esters in food plants. The study proved tropical and subtropical fruits to be an additional source of beta-cryptoxanthin esters in the human diet. The contents ranged from 8 microg/100 g beta-cryptoxanthin laurate in Tunisian orange to 892 microg/100 g beta-cryptoxanthin laurate in papaya.

Identification and characterization of a mammalian enzyme catalyzing the asymmetric oxidative cleavage of provitamin A.

In vertebrates, symmetric versus asymmetric cleavage of beta-carotene in the biosynthesis of vitamin A and its derivatives has been controversially discussed. Recently we have been able to identify a cDNA encoding a metazoan beta,beta-carotene-15,15'-dioxygenase from the fruit fly Drosophila melanogaster. This enzyme catalyzes the key step in vitamin A biosynthesis, symmetrically cleaving beta-carotene to give two molecules of retinal. Mutations in the corresponding gene are known to lead to a blind, vitamin A-deficient phenotype. Orthologs of this enzyme have very recently been found also in vertebrates and molecularly characterized. Here we report the identification of a cDNA from mouse encoding a second type of carotene dioxygenase catalyzing exclusively the asymmetric oxidative cleavage of beta-carotene at the 9',10' double bond of beta-carotene and resulting in the formation of beta-apo-10'-carotenal and beta-ionone, a substance known as a floral scent from roses, for example. Besides beta-carotene, lycopene is also oxidatively cleaved by the enzyme. The deduced amino acid sequence shares significant sequence identity with the beta,beta-carotene-15,15'-dioxygenases, and the two enzyme types have several conserved motifs. To establish its occurrence in different vertebrates, we then attempted and succeeded in cloning cDNAs encoding this new type of carotene dioxygenase from human and zebrafish as well. As regards their possible role, the apocarotenals formed by this enzyme may be the precursors for the biosynthesis of retinoic acid or exert unknown physiological effects. Thus, in contrast to Drosophila, in vertebrates both symmetric and asymmetric cleavage pathways exist for carotenes, revealing a greater complexity of carotene metabolism.

Photoinduced addition of the fungicide anilazine to cyclohexene and methyl oleate as model compounds of plant cuticle constituents.

Photoreactions, initiated by sunlight irradiation, between organochlorine pesticides and olefinic compounds of plant cuticles have been postulated. Concerning the formation of bound residues, which so far have not been detectable by common analytical techniques, photoaddition reactions are of main interest. In order to study the photochemical behavior of chlorinated fungicides, anilazine was irradiated in cyclohexene and methyl oleate as model compounds for olefinic plant cuticle constituents. Anilazine extensively reacted with the cis-double bond of both model compounds via radical mechanisms. In addition to a dechlorinated photoproduct several addition products were formed showing plausible reaction pathways for the formation of bound residues in plant cuticles. Photoproducts were isolated by preparative HPLC and analyzed by HPLC, MS, 1H-, and 13C-NMR.

Enzymatic hydrolysis of carotenoid fatty acid esters of red pepper (Capsicum annuum L.) by a lipase from Candida rugosa.

Analyses of red pepper extracts which had been pretreated with lipase type VII (EC 3.1.1.3.) from Candida rugosa showed for the first time pepper carotenoid esters to be substrates of this enzyme. However, the extent of enzymatic hydrolysis depends on the respective carotenoid and was not quantitative compared to chemical saponification. After enzymatic cleavage, 67-89% of total capsanthin, 61-65% of total zeaxanthin, 70-81% of total beta-cryptoxanthin and 70-86% of total violaxanthin were detected in free form. Nevertheless, the method described here offers the possibility to cleave in part several carotenoid esters originating from red pepper quickly and under comparatively mild reaction conditions. Replacement of the generally performed alkaline hydrolysis by enzymatic cleavage allows the resulting product to be used in food industry as "natural" coloring agent e.g. to colour cheese and jellies.