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Roberto Bassi - One of the best experts on this subject based on the ideXlab platform.
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a quadruple mutant of arabidopsis reveals a β carotene hydroxylation activity for lut1 cyp97c1 and a regulatory role of Xanthophylls on determination of the psi psii ratio
BMC Plant Biology, 2012Co-Authors: Alessia Fiore, Giovanni Giuliano, Stefano Cazzaniga, Roberto Bassi, Luca Dallosto, Gianfranco DirettoAbstract:Xanthophylls are oxygenated carotenoids playing an essential role as structural components of the photosynthetic apparatus. Xanthophylls contribute to the assembly and stability of light-harvesting complex, to light absorbance and to photoprotection. The first step in xanthophyll biosynthesis from α- and β-carotene is the hydroxylation of e- and β-rings, performed by both non-heme iron oxygenases (CHY1, CHY2) and P450 cytochromes (LUT1/CYP97C1, LUT5/CYP97A3). The Arabidopsis triple chy1chy2lut5 mutant is almost completely depleted in β-Xanthophylls. Here we report on the quadruple chy1chy2lut2lut5 mutant, additionally carrying the lut2 mutation (affecting lycopene e-cyclase). This genotype lacks lutein and yet it shows a compensatory increase in β-Xanthophylls with respect to chy1chy2lut5 mutant. Mutant plants show an even stronger photosensitivity than chy1chy2lut5, a complete lack of qE, the rapidly reversible component of non-photochemical quenching, and a peculiar organization of the pigment binding complexes into thylakoids. Biochemical analysis reveals that the chy1chy2lut2lut5 mutant is depleted in Lhcb subunits and is specifically affected in Photosystem I function, showing a deficiency in PSI-LHCI supercomplexes. Moreover, by analyzing a series of single, double, triple and quadruple Arabidopsis mutants in xanthophyll biosynthesis, we show a hitherto undescribed correlation between xanthophyll levels and the PSI-PSII ratio. The decrease in the xanthophyll/carotenoid ratio causes a proportional decrease in the LHCII and PSI core levels with respect to PSII. The physiological and biochemical phenotype of the chy1chy2lut2lut5 mutant shows that (i) LUT1/CYP97C1 protein reveals a major β-carotene hydroxylase activity in vivo when depleted in its preferred substrate α-carotene; (ii) Xanthophylls are needed for normal level of Photosystem I and LHCII accumulation.
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role of Xanthophylls in light harvesting in green plants a spectroscopic investigation of mutant lhcii and lhcb pigment protein complexes
Journal of Physical Chemistry B, 2012Co-Authors: Marcel Fuciman, Roberto Bassi, Tomáš Polívka, Luca Dallosto, Miriam M Enriquez, Harry A. FrankAbstract:The spectroscopic properties and energy transfer dynamics of the protein-bound chlorophylls and Xanthophylls in monomeric, major LHCII complexes, and minor Lhcb complexes from genetically altered Arabidopsis thaliana plants have been investigated using both steady-state and time-resolved absorption and fluorescence spectroscopic methods. The pigment–protein complexes that were studied contain Chl a, Chl b, and variable amounts of the Xanthophylls, zeaxanthin (Z), violaxanthin (V), neoxanthin (N), and lutein (L). The complexes were derived from mutants of plants denoted npq1 (NVL), npq2lut2 (Z), aba4npq1lut2 (V), aba4npq1 (VL), npq1lut2 (NV), and npq2 (LZ). The data reveal specific singlet energy transfer routes and excited state spectra and dynamics that depend on the xanthophyll present in the complex.
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different roles of α and β branch Xanthophylls in photosystem assembly and photoprotection
Journal of Biological Chemistry, 2007Co-Authors: Luca Dallosto, Giovanni Giuliano, Alessia Fiore, Stefano Cazzaniga, Roberto BassiAbstract:Xanthophylls (oxygenated carotenoids) are essential components of the plant photosynthetic apparatus, where they act in photosystem assembly, light harvesting, and photoprotection. Nevertheless, the specific function of individual xanthophyll species awaits complete elucidation. In this work, we analyze the photosynthetic phenotypes of two newly isolated Arabidopsis mutants in carotenoid biosynthesis containing exclusively alpha-branch (chy1chy2lut5) or beta-branch (chy1chy2lut2) Xanthophylls. Both mutants show complete lack of qE, the rapidly reversible component of nonphotochemical quenching, and high levels of photoinhibition and lipid peroxidation under photooxidative stress. Both mutants are much more photosensitive than npq1lut2, which contains high levels of viola- and neoxanthin and a higher stoichiometry of light-harvesting proteins with respect to photosystem II core complexes, suggesting that the content in light-harvesting complexes plays an important role in photoprotection. In addition, chy1chy2lut5, which has lutein as the only xanthophyll, shows unprecedented photosensitivity even in low light conditions, reduced electron transport rate, enhanced photobleaching of isolated LHCII complexes, and a selective loss of CP26 with respect to chy1chy2lut2, highlighting a specific role of beta-branch Xanthophylls in photoprotection and in qE mechanism. The stronger photosystem II photoinhibition of both mutants correlates with the higher rate of singlet oxygen production from thylakoids and isolated light-harvesting complexes, whereas carotenoid composition of photosystem II core complex was not influential. In depth analysis of the mutant phenotypes suggests that alpha-branch (lutein) and beta-branch (zeaxanthin, violaxanthin, and neoxanthin) Xanthophylls have distinct and complementary roles in antenna protein assembly and in the mechanisms of photoprotection.
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Different Roles of α- and β-Branch Xanthophylls in Photosystem Assembly and Photoprotection
Journal of Biological Chemistry, 2007Co-Authors: Luca Dall'osto, Giovanni Giuliano, Alessia Fiore, Stefano Cazzaniga, Roberto BassiAbstract:Abstract Xanthophylls (oxygenated carotenoids) are essential components of the plant photosynthetic apparatus, where they act in photosystem assembly, light harvesting, and photoprotection. Nevertheless, the specific function of individual xanthophyll species awaits complete elucidation. In this work, we analyze the photosynthetic phenotypes of two newly isolated Arabidopsis mutants in carotenoid biosynthesis containing exclusively α-branch (chy1chy2lut5) or β-branch (chy1chy2lut2) Xanthophylls. Both mutants show complete lack of qE, the rapidly reversible component of nonphotochemical quenching, and high levels of photoinhibition and lipid peroxidation under photooxidative stress. Both mutants are much more photosensitive than npq1lut2, which contains high levels of viola- and neoxanthin and a higher stoichiometry of light-harvesting proteins with respect to photosystem II core complexes, suggesting that the content in light-harvesting complexes plays an important role in photoprotection. In addition, chy1chy2lut5, which has lutein as the only xanthophyll, shows unprecedented photosensitivity even in low light conditions, reduced electron transport rate, enhanced photobleaching of isolated LHCII complexes, and a selective loss of CP26 with respect to chy1chy2lut2, highlighting a specific role of β-branch Xanthophylls in photoprotection and in qE mechanism. The stronger photosystem II photoinhibition of both mutants correlates with the higher rate of singlet oxygen production from thylakoids and isolated light-harvesting complexes, whereas carotenoid composition of photosystem II core complex was not influential. In depth analysis of the mutant phenotypes suggests that α-branch (lutein) and β-branch (zeaxanthin, violaxanthin, and neoxanthin) Xanthophylls have distinct and complementary roles in antenna protein assembly and in the mechanisms of photoprotection.
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Mechanistic aspects of the xanthophyll dynamics in higher plant thylakoids
Physiologia Plantarum, 2003Co-Authors: Tomas Morosinotto, Stefano Caffarri, Luca Dall'osto, Roberto BassiAbstract:Plant thylakoids have a highly conserved xanthophyll composition, consisting of β-carotene, lutein, neoxanthin and a pool of violaxanthin that can be converted to antheraxanthin and zeaxanthin in excess light conditions. Recent work has shown that Xanthophylls undergo dynamic changes, not only in their composition but also in their distribution among Lhc proteins. Xanthophylls are released from specific binding site in the major trimeric LHCII complex of photosystem II and are subsequently bound to different sites into monomeric Lhcb proteins and dimeric Lhca proteins. In this work we review available evidence from in vivo and in vitro studies on the structural determinants that control xanthophyll exchange in Lhc proteins. We conclude that the xanthophyll exchange rate is determined by the structure of individual Lhc gene products and it is specifically controlled by the lumenal pH independently from the activation state of the violaxanthin deepoxidase enzyme. The xanthophyll exchange induces important modifications in the organization of the antenna system of Photosystem II and, possibly of Photosystem I. Major changes consist into a modulation of the light harvesting efficiency and an increase of the protection from lipid peroxidation. The xanthophyll cycle thus appears to be a signal transduction system for co-ordinated regulation of the photoprotection mechanisms under persistent stress from excess light.
Elizabeth J Johnson - One of the best experts on this subject based on the ideXlab platform.
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xanthophyll lutein zeaxanthin content in fruits vegetables and corn and egg products
Journal of Food Composition and Analysis, 2009Co-Authors: Alisa Perry, Helen Rasmussen, Elizabeth J JohnsonAbstract:Lutein and zeaxanthin are carotenoids that are selectively taken up into the macula of the eye where they are thought to protect against the development of age-related macular degeneration. Current dietary databases make it difficult to ascertain their individual roles in eye health because their concentrations in foods are generally reported together. The objective of this work is to determine the concentrations of lutein and zeaxanthin, separately, within major food sources of dietary Xanthophylls as determined by NHANES 2001-2002 intakes. Corn and corn products were found to be major contributors of dietary zeaxanthin whereas green leafy vegetables were major contributors of dietary lutein. The predominant isomeric xanthophyll form was trans for all foods. Processed foods contained more cis xanthophyll isomers than fruits and vegetables. These data will provide added information to the current databases for lutein and zeaxanthin content of commonly consumed foods as well as enhance the validity of estimates of dietary intake of these Xanthophylls and their respective contributions to health.
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the selective retention of lutein meso zeaxanthin and zeaxanthin in the retina of chicks fed a xanthophyll free diet
Experimental Eye Research, 2007Co-Authors: Yingming Wang, Sonja L Connor, Elizabeth J Johnson, William E ConnorAbstract:Abstract Lutein and zeaxanthin are pigmented oxygenated carotenoids, or Xanthophylls, derived from plants and concentrated in the retina of primates and birds. We investigated the transport, distribution and depletion of lutein and zeaxanthin in the plasma and tissues of newly hatched chicks fed xanthophyll-free diets. One-day-old Leghorn chicks were randomly divided into two groups. A control group was fed a diet containing lutein and zeaxanthin (5.2 and 1.7 mg/kg diet, respectively) for 28 days. An experimental group was fed a diet containing no lutein and zeaxanthin for 28 days. Plasma and tissues were analyzed for lutein and zeaxanthin at 28 days (control) and on days 1, 14 and 28 (experimental). At hatching, lutein and zeaxanthin were the predominant carotenoids present in the blood and tissues. As indicated by their similar mass contents, there was complete transfer of these carotenoids from egg yolk to chick. Lutein and zeaxanthin concentrations in the plasma and tissues of chicks fed the xanthophyll-free diet decreased rapidly to almost zero (with a depletion time of seven days [ t 1/2 ]). In contrast, the retina retained its initial concentrations of lutein and zeaxanthin similar to the control group. meso -Zeaxanthin and cis -zeaxanthin were identified only in the retina. The retina concentrated zeaxanthin over lutein. Lutein and zeaxanthin were selectively retained in the retinas of chicks fed a xanthophyll-free diet. In contrast, the plasma and other tissues lost up to 90% of their original content of Xanthophylls. These data emphasize the relative stability of lutein and zeaxanthin in the cone-rich retina where they are present as esters in oil droplets. The tissue depletion suggests the need for a regular dietary intake of lutein and zeaxanthin because of rapid depletion in the body. It is clear that these Xanthophylls may have an essential role in the cone-rich retina of the chick as evidenced by their selective retention.
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nutritional manipulation of primate retinas iii effects of lutein or zeaxanthin supplementation on adipose tissue and retina of xanthophyll free monkeys
Investigative Ophthalmology & Visual Science, 2005Co-Authors: Elizabeth J Johnson, Martha Neuringer, Robert M Russell, Wolfgang Schalch, Max D SnodderlyAbstract:PURPOSE. Macular pigment (MP) is composed of the Xanthophylls lutein (L) and zeaxanthin (Z) and may help to prevent age-related macular degeneration or retard its progression. In this study the effects of L or Z supplementation on carotenoid levels was examined in serum, adipose tissue, and retina in rhesus monkeys with no previous intake of Xanthophylls. METHODS. From birth to 7 to 16 years of age, 18 rhesus monkeys were fed semipurified diets containing all essential nutrients but no Xanthophylls. Six were supplemented with pure L and 6 with pure Z at 3.9 mol/kg per day for 24 to 101 weeks. At baseline and at 4- to 12-week intervals, carotenoids in adipose tissue were measured by HPLC. At study completion, carotenoids in serum and retina (central 4 mm, 8-mm annulus, and the periphery) were determined. Results were compared with data from control monkeys fed a standard laboratory diet. RESULTS. Monkeys fed xanthophyll-free diets had no L or Z in serum or tissues. After L or Z supplementation, serum and adipose tissue concentrations significantly increased in the supplemented groups. Both L and 3R,3S-Z (RSZ or meso-Z, not present in the diet) were incorporated into retinas of monkeys supplemented with L, with RSZ present only in the macula (central 4 mm). All-trans Z, but no RSZ, accumulated in retinas of monkeys supplemented with Z. CONCLUSIONS. L is the precursor of RSZ, a major component of macular pigment. Xanthophyll-free monkeys can accumulate retinal Xanthophylls and provide a valuable model for examining their uptake and conversion. (Invest Ophthalmol Vis Sci. 2005;46:692‐702) DOI:10.1167/iovs.02-1192
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nutritional manipulation of primate retinas i effects of lutein or zeaxanthin supplements on serum and macular pigment in xanthophyll free rhesus monkeys
Investigative Ophthalmology & Visual Science, 2004Co-Authors: Martha Neuringer, Elizabeth J Johnson, Marita M Sandstrom, Max D SnodderlyAbstract:PURPOSE The Xanthophylls lutein (L) and zeaxanthin (Z) are the primary components of macular pigment (MP) and may protect the macula from age-related degeneration (AMD). In this study, L or Z was fed to rhesus monkeys reared on xanthophyll-free diets to follow the accumulation of serum carotenoids and MP over time. METHODS Eighteen rhesus monkeys were fed xanthophyll-free semipurified diets from birth until 7 to 16 years. The diets of six were then supplemented with pure L and six with pure Z at 3.9 micromol/kg per day (2.2 mg/kg per day) for 24 to 56 weeks. At baseline and 4- to 12-week intervals during supplementation, serum carotenoids were measured by HPLC, and MP density was estimated by two-wavelength reflectometry. Serum carotenoids and MP were also measured in monkeys fed a stock diet. RESULTS Monkeys fed xanthophyll-free diets had no L or Z in serum and no detectable MP. During supplementation, serum L or Z increased rapidly over the first 4 weeks and from 16 weeks onward maintained similar levels, both several times higher than in stock-diet-fed monkeys. The central peak of MP optical density increased to a relatively steady level by 24 to 32 weeks in both L- and Z-fed groups. Rhesus monkeys fed a stock diet had lower blood concentrations of L than those found in humans and other nonhuman primates. CONCLUSIONS Rhesus monkeys respond to either dietary L or Z supplementation with increases in serum Xanthophylls and MP, even after life-long xanthophyll deficiency. These animals provide a potential model to study mechanisms of protection from AMD.
Adam M Gilmore - One of the best experts on this subject based on the ideXlab platform.
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photosystem ii chlorophyll a fluorescence lifetimes and intensity are independent of the antenna size differences between barley wild type and chlorina mutants photochemical quenching and xanthophyll cycle dependent nonphotochemical quenching of fluo
Photosynthesis Research, 1996Co-Authors: Adam M Gilmore, Theodore L Hazlett, Peter G DebrunnerAbstract:Photosystem II (PS II) chlorophyll (Chl) a fluorescence lifetimes were measured in thylakoids and leaves of barley wild-type and chlorina f104 and f2 mutants to determine the effects of the PS II Chl a+b antenna size on the deexcitation of absorbed light energy. These barley chlorina mutants have drastically reduced levels of PS II light-harvesting Chls and pigment-proteins when compared to wild-type plants. However, the mutant and wild-type PS II Chl a fluorescence lifetimes and intensity parameters were remarkably similar and thus independent of the PS II light-harvesting antenna size for both maximal (at minimum Chl fluorescence level, Fo) and minimal rates of PS II photochemistry (at maximum Chl fluorescence level, Fm). Further, the fluorescence lifetimes and intensity parameters, as affected by the trans-thylakoid membrane pH gradient (ΔpH) and the carotenoid pigments of the xanthophyll cycle, were also similar and independent of the antenna size differences. In the presence of a ΔpH, the xanthophyll cycle-dependent processes increased the fractional intensity of a Chl a fluorescence lifetime distribution centered around 0.4–0.5 ns, at the expense of a 1.6 ns lifetime distribution (see Gilmore et al. (1995) Proc Natl Acad Sci USA 92: 2273–2277). When the zeaxanthin and antheraxanthin concentrations were measured relative to the number of PS II reaction center units, the ratios of fluorescence quenching to [xanthophyll] were similar between the wild-type and chlorina f104. However, the chlorina f104, compared to the wild-type, required around 2.5 times higher concentrations of these Xanthophylls relative to Chl a+b to obtain the same levels of xanthophyll cycle-dependent fluorescence quenching. We thus suggest that, at a constant ΔpH, the fraction of the short lifetime distribution is determined by the concentration and thus binding frequency of the Xanthophylls in the PS II inner antenna. The ΔpH also affected both the widths and centers of the lifetime distributions independent of the xanthophyll cycle. We suggest that the combined effects of the xanthophyll cycle and ΔpH cause major conformational changes in the pigment-protein complexes of the PS II inner or core antennae that switch a normal PS II unit to an increased rate constant of heat dissipation. We discuss a model of the PS II photochemical apparatus where PS II photochemistry and xanthophyll cycle-dependent energy dissipation are independent of the Peripheral antenna size.
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Carotenoids 3: in vivo function of carotenoids in higher plants.
The FASEB Journal, 1996Co-Authors: Barbara Demmig-adams, Adam M Gilmore, William W. AdamsAbstract:The function of the long-chain, highly unsaturated carotenoids of higher plants in photoprotection is becoming increasingly well understood, while at the same time their function in other processes, such as light collection, needs to be reexamined. Recent progress in this area has been fueled by more accurate determinations of the photophysical properties of these molecules, as well as extensive characterization of the physiology and ecology of a particular group of carotenoids, those of the xanthophyll cycle, that play a key role in the photoprotection of photosynthesis under environmental stress. The deepoxidized Xanthophylls zeaxanthin and antheraxanthin, together with a low pH within the photosynthetic membrane, facilitate the harmless dissipation of excess excitation energy directly within the light-collecting chlorophyll antennae. Evidence for this function as well as current contrasting hypotheses concerning its molecular mechanism are reviewed. In addition, the acclimation of the xanthophyll cycle...
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xanthophyll cycle dependent quenching of photosystem ii chlorophyll a fluorescence formation of a quenching complex with a short fluorescence lifetime
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Adam M Gilmore, Theodore L HazlettAbstract:Abstract Excess light triggers protective nonradiative dissipation of excitation energy in photosystem II through the formation of a trans-thylakoid pH gradient that in turn stimulates formation of zeaxanthin and antheraxanthin. These Xanthophylls when combined with protonation of antenna pigment-protein complexes may increase nonradiative dissipation and, thus, quench chlorophyll a fluorescence. Here we measured, in parallel, the chlorophyll a fluorescence lifetime and intensity to understand the mechanism of this process. Increasing the xanthophyll concentration in the presence of a pH gradient (quenched conditions) decreases the fractional intensity of a fluorescence lifetime component centered at approximately 2 ns and increases a component at approximately 0.4 ns. Uncoupling the pH gradient (unquenched conditions) eliminates the 0.4-ns component. Changes in the xanthophyll concentration do not significantly affect the fluorescence lifetimes in either the quenched or unquenched sample conditions. However, there are differences in fluorescence lifetimes between the quenched and unquenched states that are due to pH-related, but nonxanthophyll-related, processes. Quenching of the maximal fluorescence intensity correlates with both the xanthophyll concentration and the fractional intensity of the 0.4-ns component. The unchanged fluorescence lifetimes and the proportional quenching of the maximal and dark-level fluorescence intensities indicate that the Xanthophylls act on antenna, not reaction center processes. Further, the fluorescence quenching is interpreted as the combined effect of the pH gradient and xanthophyll concentration, resulting in the formation of a quenching complex with a short (approximately 0.4 ns) fluorescence lifetime.
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Epoxidation of zeaxanthin and antheraxanthin reverses non-photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans-thylakoid ΔpH
FEBS Letters, 1994Co-Authors: Adam M Gilmore, Narendranath Mohanty, Harry Y. YamamotoAbstract:Abstract The xanthophyll cycle apparently aids the photoprotection of photosystem II by regulating the nonradiative dissipation of excess absorbed light energy as heat. However, it is a controversial question whether the resulting nonphotochemical quenching is soley dependent on xanthophyll cycle activity or not. The xanthophyll cycle consists of two enzymic reactions, namely deepoxidation of the diepoxide violaxanthin to the epoxide-free zeaxanthin and the much slower, reverse process of epoxidation. While deepoxidation requires a transthylakoid pH gradient (ΔpH), epoxidation can proceed irrespective of a ΔpH. Herein, we compared the extent and kinetics of deepoxidation and epoxidation to the changes in fluorescence in the presence of a light-induced thylakoid ΔpH. We show that epoxidation reverses fluorescence quenching without affecting thylakoid ΔpH. These results suggest that epoxidase activity reverses quenching by removing deepoxidized xanthophyll cycle pigments from quenching complexes and converting them to a nonquenching form. The transmembrane organization of the xanthophyll cycle influences the localization and the availability of deepoxidized Xanthophylls is to support nonphotochemical quenching capacity. The results confirm the view that rapidly reversible nonphotochemical quenching is dependent on deepoxidized xanthophyll.
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linear models relating Xanthophylls and lumen acidity to non photochemical fluorescence quenching evidence that antheraxanthin explains zeaxanthin independent quenching
Photosynthesis Research, 1993Co-Authors: Adam M Gilmore, Harry Y. YamamotoAbstract:Zeaxanthin has been correlated with high-energy non-photochemical fluorescence quenching but whether antheraxanthin, the intermediate in the pathway from violaxanthin to zeaxanthin, also relates to quenching is unknown. The relationships of zeaxanthin, antheraxanthin and ΔpH to fluorescence quenching were examined in chloroplasts ofPisum sativum L. cv. Oregon andLactuca sativa L. cv. Romaine. Data matrices as five levels of violaxanthin de-epoxidation against five levels of light-induced lumen-proton concentrations were obtained for both species. The matrices included high levels of antheraxanthin as well as lumen-proton concentrations induced by subsaturating to saturation light levels. Analyses of the matrices by simple linear and multiple regression showed that quenching is predicted by models where the major independent variable is the product of lumen acidity and de-epoxidized Xanthophylls, the latter as the sum of zeaxanthin and antheraxanthin. The interactions of lumen acidity and xanthophyll concentration are shown in three-dimensional plots of the best-fit multiple regression models. Antheraxanthin apparently contributes to quenching as effectively as zeaxanthin and explains quenching previously not accounted for by zeaxanthin. Hence, we propose that all high-energy dependent quenching is xanthophyll dependent. Quenching requires a threshold lumen pH that varies with xanthophyll composition. After the threshold, quenching is linear with lumen acidity or xanthophyll composition.
Silvia Blazquezgarcia - One of the best experts on this subject based on the ideXlab platform.
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in vitro bioaccessibility of carotenoids and tocopherols from fruits and vegetables
Food Chemistry, 2007Co-Authors: F Granadolorencio, Begona Olmedillaalonso, Carmen Herrerobarbudo, I Blanconavarro, B Perezsacristan, Silvia BlazquezgarciaAbstract:Abstract Aim of the study To assess the in vitro bioaccessibility of carotenoids, including xanthophyll esters, and tocopherols from fruits and vegetables. Results Stability for carotenoids and tocopherols was over 70%. Xanthophyll esters were cleaved by cholesterol esterase but not by human pancreatic lipase. Less than 40% of the β-cryptoxanthin initially present was hydrolyzed and the amount of free Xanthophylls recovered was higher when liquid was used than when fresh homogenized matrix was employed. cis-Isomers of β-carotene and lutein did not significantly increase during the process. Xanthophylls were more efficiently transferred into supernatants than tocopherols and β-carotene. cis-Carotenoids, epoxy-Xanthophylls and ester forms were also transferred. Conclusion The results are consistent with observations in other in vitro digestion models and human studies and support the usefulness of in vitro assessment to study food-related determinants of the bioavailability of carotenoids and tocopherols from fruits and vegetables.
Max D Snodderly - One of the best experts on this subject based on the ideXlab platform.
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nutritional manipulation of primate retinas iii effects of lutein or zeaxanthin supplementation on adipose tissue and retina of xanthophyll free monkeys
Investigative Ophthalmology & Visual Science, 2005Co-Authors: Elizabeth J Johnson, Martha Neuringer, Robert M Russell, Wolfgang Schalch, Max D SnodderlyAbstract:PURPOSE. Macular pigment (MP) is composed of the Xanthophylls lutein (L) and zeaxanthin (Z) and may help to prevent age-related macular degeneration or retard its progression. In this study the effects of L or Z supplementation on carotenoid levels was examined in serum, adipose tissue, and retina in rhesus monkeys with no previous intake of Xanthophylls. METHODS. From birth to 7 to 16 years of age, 18 rhesus monkeys were fed semipurified diets containing all essential nutrients but no Xanthophylls. Six were supplemented with pure L and 6 with pure Z at 3.9 mol/kg per day for 24 to 101 weeks. At baseline and at 4- to 12-week intervals, carotenoids in adipose tissue were measured by HPLC. At study completion, carotenoids in serum and retina (central 4 mm, 8-mm annulus, and the periphery) were determined. Results were compared with data from control monkeys fed a standard laboratory diet. RESULTS. Monkeys fed xanthophyll-free diets had no L or Z in serum or tissues. After L or Z supplementation, serum and adipose tissue concentrations significantly increased in the supplemented groups. Both L and 3R,3S-Z (RSZ or meso-Z, not present in the diet) were incorporated into retinas of monkeys supplemented with L, with RSZ present only in the macula (central 4 mm). All-trans Z, but no RSZ, accumulated in retinas of monkeys supplemented with Z. CONCLUSIONS. L is the precursor of RSZ, a major component of macular pigment. Xanthophyll-free monkeys can accumulate retinal Xanthophylls and provide a valuable model for examining their uptake and conversion. (Invest Ophthalmol Vis Sci. 2005;46:692‐702) DOI:10.1167/iovs.02-1192
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nutritional manipulation of primate retinas i effects of lutein or zeaxanthin supplements on serum and macular pigment in xanthophyll free rhesus monkeys
Investigative Ophthalmology & Visual Science, 2004Co-Authors: Martha Neuringer, Elizabeth J Johnson, Marita M Sandstrom, Max D SnodderlyAbstract:PURPOSE The Xanthophylls lutein (L) and zeaxanthin (Z) are the primary components of macular pigment (MP) and may protect the macula from age-related degeneration (AMD). In this study, L or Z was fed to rhesus monkeys reared on xanthophyll-free diets to follow the accumulation of serum carotenoids and MP over time. METHODS Eighteen rhesus monkeys were fed xanthophyll-free semipurified diets from birth until 7 to 16 years. The diets of six were then supplemented with pure L and six with pure Z at 3.9 micromol/kg per day (2.2 mg/kg per day) for 24 to 56 weeks. At baseline and 4- to 12-week intervals during supplementation, serum carotenoids were measured by HPLC, and MP density was estimated by two-wavelength reflectometry. Serum carotenoids and MP were also measured in monkeys fed a stock diet. RESULTS Monkeys fed xanthophyll-free diets had no L or Z in serum and no detectable MP. During supplementation, serum L or Z increased rapidly over the first 4 weeks and from 16 weeks onward maintained similar levels, both several times higher than in stock-diet-fed monkeys. The central peak of MP optical density increased to a relatively steady level by 24 to 32 weeks in both L- and Z-fed groups. Rhesus monkeys fed a stock diet had lower blood concentrations of L than those found in humans and other nonhuman primates. CONCLUSIONS Rhesus monkeys respond to either dietary L or Z supplementation with increases in serum Xanthophylls and MP, even after life-long xanthophyll deficiency. These animals provide a potential model to study mechanisms of protection from AMD.
