SEARCH · PubMed Health

Results for “Xanthophylls”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed2001

Cadmium inhibits epoxidation of diatoxanthin to diadinoxanthin in the xanthophyll cycle of the marine diatom Phaeodactylum tricornutum.

Cd has pleiotropic effects on plant physiology and in particular on photosynthesis. It has not been established yet if Cd alters the functioning of the xanthophyll cycle. To answer this question, an exponentially growing culture of the marine diatom Phaeodactylum tricornutum was incubated with Cd (20 mg/l) for 24 h and irradiated with a light activating the xanthophyll cycle, which in diatoms, consists of the reversible deepoxidation of diadinoxanthin to diatoxanthin. The measurements show that the deepoxidation step is not influenced by Cd. In contrast, the Cd concentration used sharply inhibits the epoxidation of diatoxanthin to diadinoxanthin.

Cadmium↗

PubMed2002

Metabolic engineering of xanthophyll content in tomato fruits.

Ripe tomato fruits accumulate significant amounts of the linear carotene lycopene, but only trace amounts of xanthophylls (oxygenated carotenoids). We overexpressed the lycopene beta-cyclase (b-Lcy) and beta-carotene hydroxylase (b-Chy) genes under the control of the fruit-specific Pds promoter. Transgene and protein expression was followed through semi-quantitative reverse transcription-PCR, Western blotting, and enzyme assays. Fruits of the transformants showed a significant increase of beta-carotene, beta-cryptoxanthin and zeaxanthin. The carotenoid composition of leaves remained unaltered. The transgenes and the phenotype are inherited in a dominant Mendelian fashion. This is the first example of successful metabolic engineering of xanthophyll content in tomato fruits.

Arabidopsis↗

PubMed2002

Degradation of non-esterified and esterified xanthophylls by free radicals.

beta-Carotene and other xanthophylls present in pepper fruit as both free and esterified forms were oxidized using a free radical initiator (2,2'-azo-bis-isobutyronitrile). Capsorubin was degraded most slowly, followed by zeaxanthin, capsanthin, and beta-carotene. The presence of keto groups at the ends of the polyene chain could be a structural factor contributing to this difference in reactivity. It was also shown that whereas capsanthin and its esters and capsorubin and its esters were degraded at the same rate, zeaxanthin esters responded differently to the oxidation process, and were degraded more quickly than free zeaxanthin. The presence of unsaturated fatty acids (mainly linoleic) that esterify zeaxanthin help to accelerate the degradation of this xanthophyll and decreasing its antioxidant action. The antioxidant capacity of capsorubin and capsanthin (both in free and esterified form) exclusive to the genus capsicum should be taken into account.

Antioxidants↗

PubMed2002

Xanthophyll pigments lutein and zeaxanthin in lipid multibilayers formed with dimyristoylphosphatidylcholine.

This paper reports the research on the effect of two main carotenoid pigments present in the membranes of macula lutea of the vision apparatus of primates, including humans, lutein and zeaxanthin, on the structure of model membranes formed with dimyristoylphosphatidylcholine (DMPC). The effects observed in DMPC are compared to the effects observed in the membranes formed with other phosphatidylcholines (PC): egg yolk PC (EYPC), and dipalmitoyl-PC (DPPC). The analysis has been focused, in particular, on the following aspects of the organization of lipid-carotenoid membranes: aggregation state of pigments, an effect on a thickness of the bilayer and pigment orientation within the membranes. These problems have been addressed with the application of UV-Vis absorption spectroscopy, linear dichroism measurements and the diffractometric technique. (1) Both lutein and zeaxanthin appear in a partially aggregated form in the oriented DMPC multibilayers, even at molar fractions as low as 2 mol.% with respect to lipid. (2) Orientation of the transition dipole of both xanthophylls with respect to the axis normal to the plane of DMPC membrane is different in the case of a monomeric form (34+/-3 degrees in the case of lutein and 26+/-3 degrees in the case of zeaxanthin) but essentially the same in the case of aggregated forms of both pigments (42+/-3 degrees in the case of lutein and 40+/-5 degrees in the case of zeaxanthin). It was found that only lutein has an effect on the increase in the thickness of the DMPC membranes (by about 3 A at 25 degrees C). A similar effect was observed also in the case of DPPC at the same temperatures despite the differences in the physical state of both membrane systems. The differences between the effects of lutein and zeaxanthin observed are interpreted in terms of differences of stereochemical structure of both xanthophylls leading to the different localization in the lipid phase. The results demonstrate significant differences in the behavior of lutein and zeaxanthin in model membranes, which may contribute to their different physiological functions and different efficacy as membrane antioxidants.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2002

Pigment compositions, spectral properties, and energy transfer efficiencies between the xanthophylls and chlorophylls in the major and minor pigment-protein complexes of photosystem II.

Absorption, fluorescence, and fluorescence excitation spectra have been measured from CP26, CP29, and monomeric and trimeric LHCIIb light-harvesting complexes isolated from Photosystem II subchloroplast particles from spinach. The complexes were purified using a combination of isoelectric focusing and sucrose gradient ultracentrifugation. The chlorophyll (Chl) and xanthophyll pigment compositions were measured using high-performance liquid chromatography (HPLC). Using the pigment compositions from the HPLC analysis as a starting point, the absorption spectral profiles of the complexes have been reconstructed from the individual absorption spectra obtained for each of the pigments. Also, the fluorescence excitation spectra of the complexes have been deconvoluted. The data reveal the energy transfer efficiencies between Chl b and Chl a and between specific xanthophylls and Chl a in the complexes. The spectral analyses reveal the underlying features of the highly congested spectral profiles associated with the complexes and are expected to be beneficial to researchers employing spectroscopic methods to investigate the mechanisms of energy transfer between the pigments bound in these complexes.

Chlorophyll↗

PubMed2004

Light-modulated exposure of the light-harvesting complex II (LHCII) to protein kinase(s) and state transition in Chlamydomonas reinhardtii xanthophyll mutants.

Reversible phosphorylation of chl a/b protein complex II (LHCII), the mobile light-harvesting antenna, regulates its association and energy transfer/dissipation to photosystem (PS) II or I (state transition). Excitation of LHCII induces conformational changes affecting the exposure of the phosphorylation site at the N-terminal domain to protein kinase(s) [Zer, H., et al. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 8277-8282; Zer, H., et al. (2003) Biochemistry 42, 728-738]. Thus, it was of interest to examine whether the pigment composition of LHCII affects the light-induced modulation of LHCII phosphorylation and state transition. To this end, we have used thylakoids of wild-type Chlamydomonas reinhardtii and xanthophyll deficient mutants npq1, lor1, npq2, npq1 lor1, and npq2 lor1. Phosphorylated protein bands P11, P13, and P17 are considered components of the mobile C. reinhardtii LHCII complex. The protein composition of these bands has been analyzed by mass spectrometry using Qtof-2 with a nanospray attachment. P11 and P13 contain C. reinhardtii light-harvesting chlorophyll a/b binding protein LhcII type I. P17 contains C. reinhardtii LhcII types III and IV. Illumination of isolated thylakoids inhibits the redox-controlled phosphorylation of polypeptide bands P13 and P17 and to a lower extent that of P11. The light-induced inhibition of LHCII phosphorylation and the state transition process are not influenced by extensive differences in the xanthophyll composition of the mutants. Thus, LHCII can be visualized as possessing two functionally distinct, independent domains: (i) the pigment binding transmembrane domain regulating the extent of energy transfer/dissipation and (ii) the surface-exposed phosphorylation site regulating the association of LHCII with PSII or PSI.

Animals↗

PubMed2004

Improving xanthophyll extraction from marigold flower using cellulolytic enzymes.

In this work is studied the effect of a noncommercial enzyme preparation on xanthophyll extraction from marigold flower (Tagetes erecta). The enzymatic extract was synthesized by endogenous microorganisms previously isolated and identified as Flavobacterium IIb, Acinetobacter anitratus, and Rhizopus nigricans. The results show that the extraction yield depends directly on the extent of the enzymatic hydrolysis of cell walls in the flower petals and that it is possible to reach yields in excess of those previously reported for treatments with commercially available enzymes (29.3 g/kg of dry weight). HPLC analysis of the product indicates that the original xanthophyll profile is not altered. The enhanced extraction system appears to be very competitive when compared to the traditional process and current alternatives.

Cell Wall↗

PubMed2002

Carotenoids, mostly the xanthophylls, exchange between plasma lipoproteins.

Carotenoids are exclusively transported by lipoproteins; in vitro studies suggest that they might protect these particles against oxidation. Little is known about the factors that govern the distribution of these micronutrients among lipoproteins. The objective of this study was to assess whether carotenoids are exchanged between lipoproteins and what factors, if any, were involved. In the first experiment, different groups of trout were fed for five days with either a carotenoid-free diet or with diets containing 80 mg pure carotenoid per kilogram of feed. Lipoproteins were separated by ultracentrifugation and carotenoid-rich, high-density lipoproteins (HDL) were incubated for two hours at 37 degrees C with carotenoid-free, very low-density lipoproteins (VLDL), and vice versa. After incubation, lipoproteins were re-separated and carotenoids were quantified to measure the transfer. The same experiments were done in the presence of cholesteryl ester transfer protein (CETP) and lecithin cholesterol acyltransferase (LCAT) inhibitors. In a second experiment, the exchange was measured between human VLDL and HDL. In trout, incubation of carotenoid-rich HDL with carotenoid-free VLDL resulted in the appearance of carotenoids in VLDL, and inversely. The higher the hydrophobicity of a carotenoid, the lower its proportion in HDL after incubation. CETP and LCAT inhibitors significantly increased the proportion of carotenoids in HDL after incubation. Results obtained with human lipoproteins showed that the xanthophyll lutein transferred between lipoproteins, but could not show any carotenes (alpha-carotene, beta-carotene, and lycopene) transfer. We conclude that carotenoids, chiefly the xanthophylls, exchange between lipoproteins. The transfer depends on plasma factor(s) sensitive to CETP and/or LCAT inhibitors.

Adolescent↗

PubMed2002

Molecular configuration of xanthophyll cycle carotenoids in photosystem II antenna complexes.

The molecular configuration of the xanthophyll cycle carotenoids, violaxanthin and zeaxanthin, was studied in various isolated photosystem II antenna components in comparison to intact photosystem II membranes using resonance Raman combined with low-temperature absorption spectroscopy. The molecular configurations of zeaxanthin and violaxanthin in thylakoids and isolated photosystem II membranes were found to be the same within an isolated oligomeric LHCII antenna, confirming our recent conclusion that these molecules are not freely located in photosynthetic membranes (Ruban, A. V., Pascal, A. A., Robert, B., and Horton, P. (2001) J. Biol. Chem. 276, 24862-24870). In contrast, xanthophyll cycle carotenoids bound to LHCII trimers had largely lost their in vivo configuration, suggesting their partial dissociation from the binding locus. Violaxanthin and zeaxanthin associated with the minor antenna complexes, CP26 and CP29, were also found to be in a relaxed configuration, similar to that of free pigment. The origin of the characteristic C-H vibrational bands of violaxanthin and zeaxanthin in vivo is discussed by comparison with those of neoxanthin and lutein in oligomeric and trimeric LHCII respectively.

Lutein↗

PubMed2003

Photo-oxidative stress in a xanthophyll-deficient mutant of Chlamydomonas.

When there is an imbalance between the light energy absorbed by a photosynthetic organism and that which can be utilized in photosynthesis, photo-oxidative stress can damage pigments, proteins, lipids, and nucleic acids. In this work we compared the wild type and a xanthophyll-deficient mutant of Chlamydomonas reinhardtii in their response to high amounts of light. Wild-type Chlamydomonas cells were able to acclimate to high amounts of light following transfer from low light conditions. In contrast, the npq1 lor1 double mutant, which lacks protective xanthophylls (zeaxanthin and lutein) in the chloroplast, progressively lost viability and photosynthetic capacity along with destruction of thylakoid membrane protein-pigment complexes and accumulation of reactive oxygen species and membrane lipid peroxides. Loss of viability was partially rescued by lowered oxygen tension, suggesting that the high sensitivity of the mutant to light stress is caused by the production of reactive oxygen species in the chloroplast. Cell death was not prevented by the addition of an organic carbon source to the growth medium, demonstrating that the photo-oxidative damage can target other essential chloroplast processes besides photosynthesis. From the differential sensitivity of the mutant to exogenously added pro-oxidants, we infer that the reactive oxygen species produced during light stress in npq1 lor1 may be singlet oxygen and/or superoxide but not hydrogen peroxide. The bleaching phenotype of npq1 lor1 was not due to enhanced photodamage to photosystem II but rather to a less localized phenomenon of accumulation of photo-oxidation products in chloroplast membranes.

Animals↗

PubMed2001

Xanthophyll epoxides, unlike beta-carotene monoepoxides, are not detectibly absorbed by humans.

Increased intake of fruits and vegetables is associated with reduced risk of cancer and other chronic diseases. Epoxycarotenoids are widely distributed in nature and constitute major dietary carotenoids in a number of fruits and vegetables. Previous studies have shown that beta-carotene 5,6-epoxide was absorbed well by humans, and was much more active than beta-carotene in inducing the differentiation of NB4 cells. Xanthophyll epoxides such as neoxanthin, violaxanthin and lutein 5,6-epoxide, are more abundant than epoxy-hydrocarbon carotenes in a number of vegetables and fruits that humans consume. To determine whether xanthophyll epoxides are also absorbed by humans, lutein 5,6-epoxide (taraxanthin) and zeaxanthin 5,6,5'6'-diepoxide (violaxanthin) were chemically prepared, dissolved in corn oil and orally administered to three human subjects. Analysis of plasma for carotenoids within 9 h after a single oral dose of either violaxanthin or taraxanthin failed to show any violaxanthin, taraxanthin or any of their metabolites.

Absorption↗

PubMed2006

Xanthophyll and hydrocarbon carotenoid patterns differ in plasma and breast milk of women supplemented with red palm oil during pregnancy and lactation.

Currently limited information exists on how maternal supplementation with provitamin A carotenoids might influence the carotenoid pattern in breast milk during lactation. This study was designed to investigate the effect of maternal red palm oil supplementation ( approximately 12 g/d) throughout the 3rd trimester of pregnancy and the first 3 mo postpartum on carotenoid pattern in both plasma and breast milk. Plasma and breast milk alpha- and beta-carotene concentrations increased in response to red palm oil supplementation and were different (P < 0.001) from the control group at both 1 and 3 mo postpartum. Plasma lutein and zeaxanthin concentrations were reduced (P < 0.001) from pregnancy to 1 mo postpartum and remained stable until 3 mo postpartum. However, breast milk lutein concentrations, expressed per gram of milk fat, increased (P < 0.05) in both groups from 1 to 3 mo postpartum. The results of this study show that there are proportionally more hydrocarbon carotenoids such as alpha- and beta-carotene in plasma than in breast milk, whereas xanthophylls, such as lutein and zeaxanthin, are proportionally more prevalent in breast milk. More importantly, red palm oil supplementation increases the milk concentrations of provitamin A carotenes without decreasing the milk concentrations of xanthophylls. In summary, this study demonstrates that a regulated uptake of polar carotenoids into breast milk exists and that supplementation with alpha- and beta-carotene does not negatively affect this transfer. The mechanisms behind this transport are not fully understood and merit further study.

Adult↗

PubMed2006

In diatoms, the transthylakoid proton gradient regulates the photoprotective non-photochemical fluorescence quenching beyond its control on the xanthophyll cycle.

In diatoms, the non-photochemical fluorescence quenching (NPQ) regulates photosynthesis during light fluctuations. NPQ is associated with an enzymatic xanthophyll cycle (XC) which is controlled by the light-driven transthylakoid proton gradient (delta pH). In this report, special illumination conditions and chemicals were used to perturb the kinetics of the delta pH build-up, of the XC and of NPQ. We found that the delta pH-related acidification of the lumen is also needed for NPQ to develop by switching the xanthophylls to an 'activated' state, probably via the protonation of light-harvesting antenna proteins. It confirms the NPQ model previously proposed for diatoms.

Diatoms↗

PubMed2004

Seasonal changes in the xanthophyll cycle and antioxidants in sun-exposed and shaded parts of the crown of Cryptomeria japonica in relation to rhodoxanthin accumulation during cold acclimation.

Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winter, may have a photoprotective role during long-term cold acclimation. To examine how cold acclimation processes vary within tree crowns and to examine putative correlations between xanthophyll cycle pigments (VAZ), rhodoxanthin and the water-water cycle in photoprotection, we monitored seasonal changes in the activities of two key antioxidant enzymes (ascorbate peroxidase (APX) and glutathione reductase (GR)), pigment composition and chlorophyll fluorescence parameters in sun and shade needles of crowns of the gymnosperm Cryptomeria japonica D. Don. Although APX and GR activities in both sun and shade needles were higher in winter than in summer when assayed at 20 degrees C, differences between seasons were less pronounced when enzymatic activities in summer and winter were assayed at 20 and 5 degrees C, respectively. These results suggest that increases in the potential activity of antioxidant enzymes in winter is an adaptation that helps counterbalance reductions in absolute enzyme activity caused by low temperature, and thus allows the photoprotective capacity of the water-water cycle in C. japonica to be maintained at a roughly constant value throughout the year. In shade needles, the concentration of VAZ increased in winter, but no rhodoxanthin accumulated. Photosynthetic activity was maintained in winter. In sun needles, however, the electron transport rate (ETR) and photochemical quenching (q(P)) decreased to their lowest values in December, just before the accumulation of rhodoxanthin, which coincided with the highest amount of VAZ. Changes in rhodoxanthin concentration mirrored changes in VAZ concentration from January to March. Winter values of ETR and q(P) were comparable with summer values after accumulation of rhodoxanthin, indicating that rhodoxanthin may play a more important role than the VAZ cycle in protecting the photosynthetic apparatus from photodamage in winter. Photosynthetic activity may be modulated, as a result of the interception of light by rhodoxanthin, to match the extent to which absorbed light energy can be utilized in winter when the VAZ cycle is unable to operate effectively because of low temperatures.

Acclimatization↗

PubMed2003

Zeaxanthin accumulation in the absence of a functional xanthophyll cycle protects Chlamydomonas reinhardtii from photooxidative stress.

Xanthophylls participate in light harvesting and are essential in protecting the chloroplast from photooxidative damage. To investigate the roles of xanthophylls in photoprotection, we isolated and characterized extragenic suppressors of the npq1 lor1 double mutant of Chlamydomonas reinhardtii, which lacks zeaxanthin and lutein and undergoes irreversible photooxidative bleaching and cell death at moderate to high light intensities. Here, we describe three suppressor strains that carry point mutations in the coding sequence of the zeaxanthin epoxidase gene, resulting in the constitutive accumulation of zeaxanthin in a range of concentrations. The presence of zeaxanthin in these strains was sufficient to prevent photooxidative damage in the npq1 lor1 background. The size of the light-harvesting antenna in the suppressors decreased in high light in a manner that was proportional to the relative content of zeaxanthin, with the strain having the most zeaxanthin showing a severe reduction in levels of the major light-harvesting complex II proteins in high light. We show that the effect of constitutive zeaxanthin on light harvesting is not the main cause of increased photoprotection, because in the absence of zeaxanthin, a strain with a smaller light-harvesting antenna showed only minor protection against photobleaching in high light. Furthermore, the zeaxanthin-accumulating suppressors were able to tolerate higher levels of exogenous reactive oxygen than their parental strain under conditions that did not affect light harvesting. Our results are consistent with an antioxidant role of zeaxanthin in the quenching of singlet oxygen and/or free radicals in the thylakoid membrane in vivo.

Amino Acid Sequence↗

PubMed2006

[Effects of salicylic acid on chlorophyll fluorescence and xanthophyll cycle in cucumber leaves under high temperature and strong light].

In this study, cucumber leaves were under high temperature and strong light stress after two days of spraying with 50 to approximately 400 micromol x L(-1) salicylic acid (SA) solution. The measurements showed that SA pretreatment could inhibit the decrease of intrinsic photochemical efficiency (Fv/ /Fm), quantum yield of PSII(phiPSII), maximum fluorescence value (Fm), and photochemical quenching (qP) by 16.1% to approximately 30.2%, 11.9% to approximately 33.0%, 7.2% to approximately 41.0% and 27.2% to approximately 160.8%, respectively, and promote the increase of non-photochemical quenching (NPQ) by 13.1% to approximately 62.9%, but had little effect on initial fluorescence value (Fo). SA pretreatment could also inhibit the decrease of xanthophyll cycle pool in cucumber leaves, and increase the de-epoxidation extent of xanthophyll cycle (A + Z)/(V + A + Z),which was 29.5% and 24.6% higher than control, respectively. It was suggested that SA could protect the photosynthetic apparatus of cucumber leaves under high temperature and strong light through promoting non-radiative energy dissipation.

Chlorophyll↗

PubMed1994

In vivo manipulation of the xanthophyll cycle and the role of zeaxanthin in the protection against photodamage in the green alga Chlorella pyrenoidosa.

Chlorella pyrenoidosa was grown in steady-state continuous cultures in either high or low light. Samples of these cultures were incubated in darkness (violaxanthin state) or in saturating light (zeaxanthin state). These samples were kept in the respective preadapted states throughout the entire photodamage treatment. Photodamage involved exposure to single-turnover flashes fired at a low (non-actinic) frequency. The damage caused by the light stress thus applied was monitored by changes in photosynthetic properties and pigment composition. Cells preadapted in the light resisted photodamage better than those kept in darkness. The low light grown cells were more vulnerable to photodamage than the high light grown cells. Our experimental approach permitted the equilibria between the components that participate in the xanthophyll cycle to be set without addition of inhibitors. Regardless of the total amount of violaxanthin being present, its conversion to anthera- and zeaxanthin is a prerequisite for protection. The protection is most effective for photosystem II. It appeared that antheraxanthin accumulates as a result of photodamaging flashes provided that these are fired in the presence of background light, i.e. with zeaxanthin present. From this, it is newly derived that the xanthophyll cycle operates in full in the light, including epoxidation of zeaxanthin. The latter conversion was also demonstrated in vitro, via nonenzymatic oxygen-dependent turnover of zeaxanthin into violaxanthin.

Carotenoids↗

PubMed1998

Xanthophyll esters in human skin.

Carotenol fatty acid esters in various fruits and vegetables are sources of carotenoids for humans and are cleaved during intestinal absorption to yield the parent xanthophyll. In the present study we demonstrate that low amounts of carotenol esters are present in human skin. Eighteen different carotenol fatty acid esters were separated in extracts from human skin by means of reversed-phase high-performance liquid chromatography. After saponification of tissue samples, lutein, zeaxanthin, 2',3'-anhydrolutein, alpha-cryptoxanthin and beta-cryptoxanthin were identified as the major parent carotenoids. Based on comparison with synthetic reference compounds, several carotenol mono- and di-fatty acid esters were tentatively assigned, ranging from linoleate to stearate; the levels are low, in the range of pmol/g human skin, i.e. , several orders of magnitude lower than that of beta-carotene. Carotenol esters in human skin may be formed by reesterification of xanthophylls following absorption. Also, very small amounts of esters may circulate in the blood and subsequently accumulate in tissues such as skin.

Adult↗