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Elizabeth J Johnson - One of the best experts on this subject based on the ideXlab platform.
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Role of lutein and Zeaxanthin in visual and cognitive function throughout the lifespan.
Nutrition reviews, 2014Co-Authors: Elizabeth J JohnsonAbstract:The relationship between lutein and Zeaxanthin and visual and cognitive health throughout the lifespan is compelling. There is a variety of evidence to support a role for lutein and Zeaxanthin in vision. Lutein's role in cognition has only recently been considered. Lutein and its isomer, Zeaxanthin, are taken up selectively into eye tissue. Lutein is the predominant carotenoid in human brain tissue. Lutein and Zeaxanthin in neural tissue may have biological effects that include antioxidation, anti-inflammation, and structural actions. In addition, lutein and Zeaxanthin may be protective against eye disease because they absorb damaging blue light that enters the eye. In pediatric brains, the relative contribution of lutein to the total carotenoids is twice that found in adults, accounting for more than half the concentration of total carotenoids. The greater proportion of lutein in the pediatric brain suggests a need for lutein during neural development as well. In adults, higher lutein status is related to better cognitive performance, and lutein supplementation improves cognition. The evidence to date warrants further investigation into the role of lutein and Zeaxanthin in visual and cognitive health throughout the lifespan.
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Lutein and Zeaxanthin and Eye Disease
Carotenoids and Human Health, 2012Co-Authors: Rohini Vishwanathan, Elizabeth J JohnsonAbstract:The xanthophylls lutein and Zeaxanthin are oxygenated carotenoids that preferentially accumulate in the macular region of the retina. Lutein, Zeaxanthin, and meso-Zeaxanthin (a conversion product of lutein formed in the macula) are referred to as macular pigment. Lutein and Zeaxanthin are also present in all other ocular structures except the vitreous, cornea, and sclera; although, their concentrations are much lower than in the macular region. Lutein and Zeaxanthin protect the ocular tissues by their ability to filter damaging blue light and their antioxidant potential.
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lutein and Zeaxanthin supplementation reduces photooxidative damage and modulates the expression of inflammation related genes in retinal pigment epithelial cells
Free Radical Biology and Medicine, 2012Co-Authors: Qingning Bian, Elizabeth J Johnson, Guangwen Tang, Shasha Gao, Jilin Zhou, Jian Qin, Allen Taylor, Janet R Sparrow, Dennis GierhartAbstract:Oxidative damage and inflammation are related to the pathogenesis of age-related macular degeneration (AMD). Epidemiologic studies suggest that insufficient dietary lutein and Zeaxanthin intake or lower serum Zeaxanthin levels are associated with increased risk for AMD. The objective of this work is to test the protective effects of lutein and Zeaxanthin against photooxidative damage to retinal pigment epithelial cells (RPE) and oxidation-induced changes in expression of inflammation-related genes. To mimic lipofuscin-mediated photooxidation in vivo, we used ARPE-19 cells that accumulated A2E, a lipofuscin fluorophore and photosensitizer, as a model system to investigate the effects of lutein and Zeaxanthin supplementation. The data show that supplementation with lutein or Zeaxanthin in the medium resulted in accumulation of lutein or Zeaxanthin in the RPE cells. The concentrations of lutein and Zeaxanthin in the cells were 2- to 14-fold of that detected in the medium, indicating that ARPE-19 cells actively take up lutein or Zeaxanthin. As compared with untreated cells, exposure of A2E-containing RPE to blue light resulted in a 40-60% decrease in proteasome activity, a 50-80% decrease in expression of CFH and MCP-1, and an~20-fold increase in expression of IL-8. The photooxidation-induced changes in expression of MCP-1, IL-8, and CFH were similar to those caused by chemical inhibition of the proteasome, suggesting that inactivation of the proteasome is involved in the photooxidation-induced alteration in expression of these inflammation-related genes. Incubation of the A2E-containing RPE with lutein or Zeaxanthin prior to blue light exposure significantly attenuated the photooxidation-induced inactivation of the proteasome and photooxidation-induced changes in expression of MCP-1, IL-8, and CFH. Together, these data indicate that lutein or Zeaxanthin modulates inflammatory responses in cultured RPE in response to photooxidation. Protecting the proteasome from oxidative inactivation appears to be one of the mechanisms by which lutein and Zeaxanthin modulate the inflammatory response. Similar mechanisms may explain salutary effects of lutein and Zeaxanthin in reducing the risk for AMD.
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Intake of lutein and Zeaxanthin differ with age, sex, and ethnicity.
Journal of the American Dietetic Association, 2010Co-Authors: Elizabeth J Johnson, Janice E. Maras, Helen Rasmussen, Katherine L. TuckerAbstract:Abstract Lutein and Zeaxanthin are carotenoids that are selectively taken up into the macula of the eye, where they may protect against development of age-related macular degeneration. Accurate assessment of their intakes is important in the understanding of their individual roles in eye health. Current dietary databases lack the appropriate information to ascertain valid dietary intakes of these individual nutrients. The purpose of this research is to determine intakes of lutein and Zeaxanthin separately in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. The top major food sources for lutein and Zeaxanthin intake in NHANES 2003-2004 were analyzed for lutein and Zeaxanthin by high-performance liquid chromatography from June to August 2006. Results were applied to dietary data from 8,525 participants in NHANES 2003-2004. Lutein and Zeaxanthin food contents were separated into lutein and Zeaxanthin in the nutrient database. Mean intakes from two nonconsecutive 24-hour recalls were grouped into food groups based on nutrient composition; these were matched to the new database, and lutein and Zeaxanthin intakes were calculated separately. Among all age groups, both sexes, and all ethnicities, intakes of lutein were greater than of Zeaxanthin. Relative intake of Zeaxanthin to lutein decreased with age, with Zeaxanthin to lutein ratios lower in females. Zeaxanthin to lutein ratios in Mexican Americans was considerably greater than other ethnicities (other Hispanics, non-Hispanic white, non-Hispanic black, other races). Lower Zeaxanthin to lutein ratios were measured in groups at risk for age-related macular degeneration (eg, older participants, females). Our findings suggest that the relative intake of lutein and Zeaxanthin may be important to age-related macular degeneration risk. Future studies are needed to assess the individual associations of lutein and Zeaxanthin in eye 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.
Herminia Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Efficient Heterologous Transformation of Chlamydomonas reinhardtii npq2 Mutant with the Zeaxanthin Epoxidase Gene Isolated and Characterized from Chlorella zofingiensis
Marine drugs, 2012Co-Authors: Inmaculada Couso, Baldo F. Cordero, M.a. Vargas, Herminia RodríguezAbstract:In the violaxanthin cycle, the violaxanthin de-epoxidase and Zeaxanthin epoxidase catalyze the inter-conversion between violaxanthin and Zeaxanthin in both plants and green algae. The Zeaxanthin epoxidase gene from the green microalga Chlorella zofingiensis (Czzep) has been isolated. This gene encodes a polypeptide of 596 amino acids. A single copy of Czzep has been found in the C. zofingiensis genome by Southern blot analysis. qPCR analysis has shown that transcript levels of Czzep were increased after Zeaxanthin formation under high light conditions. The functionality of Czzep gene by heterologous genetic complementation in the Chlamydomonas mutant npq2, which lacks Zeaxanthin epoxidase (ZEP) activity and accumulates Zeaxanthin in all conditions, was analyzed. The Czzep gene was adequately inserted in the pSI105 vector and expressed in npq2. The positive transformants were able to efficiently convert Zeaxanthin into violaxanthin, as well as to restore their maximum quantum efficiency of the PSII (Fv/Fm). These results show that Chlamydomonas can be an efficient tool for heterologous expression and metabolic engineering for biotechnological applications.
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Efficient Heterologous Transformation of Chlamydomonas reinhardtii npq2 Mutant with the Zeaxanthin Epoxidase Gene Isolated and Characterized from Chlorella zofingiensis
Marine Drugs, 2012Co-Authors: Inmaculada Couso, Baldo F. Cordero, M.a. Vargas, Herminia RodríguezAbstract:In the violaxanthin cycle, the violaxanthin de-epoxidase and Zeaxanthin epoxidase catalyze the inter-conversion between violaxanthin and Zeaxanthin in both plants and green algae. The Zeaxanthin epoxidase gene from the green microalga <em>Chlorella zofingiensis</em> (<em>Czzep</em>) has been isolated<em>. </em>This gene encodes a polypeptide of 596 amino acids. A single copy of <em>Czzep</em> has been found in the <em>C. zofingiensis</em> genome by Southern blot analysis. qPCR analysis has shown that transcript levels of <em>Czzep</em> were increased after Zeaxanthin formation under high light conditions. The functionality of <em>Czzep</em> gene by heterologous genetic complementation in the <em>Chlamydomonas</em> mutant <em>npq2</em>, which lacks Zeaxanthin epoxidase<strong> (</strong>ZEP) activity and accumulates Zeaxanthin in all conditions, was analyzed. The <em>Czzep</em> gene was adequately inserted in the pSI105 vector and expressed in <em>npq2</em>. The positive transformants were able to efficiently convert Zeaxanthin into violaxanthin, as well as to restore their maximum quantum efficiency of the PSII (Fv/Fm). These results show that <em>Chlamydomonas</em> can be an efficient tool for heterologous expression and metabolic engineering for biotechnological applications
Frederick Khachik - One of the best experts on this subject based on the ideXlab platform.
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distribution of lutein Zeaxanthin and related geometrical isomers in fruit vegetables wheat and pasta products
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Julia M Humphries, Frederick KhachikAbstract:Quantitative data with regard to dietary (3R,3‘R,6‘R)-lutein, (3R,3‘R)-Zeaxanthin, and their (E/Z)-geometrical isomers are scarce, and in most cases, only the combined concentrations of these two carotenoids in foods are reported. Lutein and Zeaxanthin accumulate in the human macula and have been implicated in the prevention of age-related macular degeneration (AMD). The qualitative and quantitative distributions of lutein, Zeaxanthin, and their (E/Z)-isomers in the extracts from some of the most commonly consumed fruits, vegetables, and pasta products were determined by HPLC employing a silica-based nitrile-bonded column. Green vegetables had the highest concentration of lutein (L) and Zeaxanthin (Z), and the ratios of these carotenoids (L/Z) were in the range 12−63. The yellow-orange fruits and vegetables, with the exception of squash (butternut variety), had much lower levels of lutein in comparison to greens but contained a higher concentration of Zeaxanthin. The ratio of lutein to Zeaxanthin (L/Z) in...
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distribution of lutein Zeaxanthin and related geometrical isomers in fruit vegetables wheat and pasta products
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Julia M Humphries, Frederick KhachikAbstract:Quantitative data with regard to dietary (3R,3'R,6'R)-lutein, (3R,3'R)-Zeaxanthin, and their (E/Z)-geometrical isomers are scarce, and in most cases, only the combined concentrations of these two carotenoids in foods are reported. Lutein and Zeaxanthin accumulate in the human macula and have been implicated in the prevention of age-related macular degeneration (AMD). The qualitative and quantitative distributions of lutein, Zeaxanthin, and their (E/Z)-isomers in the extracts from some of the most commonly consumed fruits, vegetables, and pasta products were determined by HPLC employing a silica-based nitrile-bonded column. Green vegetables had the highest concentration of lutein (L) and Zeaxanthin (Z), and the ratios of these carotenoids (L/Z) were in the range 12-63. The yellow-orange fruits and vegetables, with the exception of squash (butternut variety), had much lower levels of lutein in comparison to greens but contained a higher concentration of Zeaxanthin. The ratio of lutein to Zeaxanthin (L/Z) in two North American bread varieties of wheat (Pioneer, Catoctin) was 11 and 7.6, respectively, while in a green-harvested wheat (Freekeh) imported from Australia, the ratio was 2.5. Between the two pasta products examined, lasagne and egg noodles, the latter had a much higher concentration of lutein and Zeaxanthin. The levels of the (E/Z)-geometrical isomers of lutein and Zeaxanthin in these foods were also determined.
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identification of lutein and Zeaxanthin oxidation products in human and monkey retinas
Investigative Ophthalmology & Visual Science, 1997Co-Authors: Frederick Khachik, Paul S. Bernstein, Donita GarlandAbstract:Purpose To characterize fully all the major and minor carotenoids and their metabolites in human retina and probe for the presence of the oxidative metabolites of lutein and Zeaxanthin. Methods Carotenoids of a composite of 58 pairs of human retinas and a monkey retina were elucidated by comparing their high-performance liquid chromatography (HPLC)-ultraviolet/visible absorption spectrophotometry (UV/Vis)-mass spectrometry (MS) profile with those of authentic standards prepared by organic synthesis. Results In addition to lutein and Zeaxanthin, several oxidation products of these compounds were present in the extracts from human retina. A major carotenoid resulting from direct oxidation of lutein was identified as 3-hydroxy-beta, epsilon-caroten-3'-one. Minor carotenoids were identified as: 3'-epilutein, epsilon,epsilon-carotene-3,3'-diol, epsilon,epsilon-carotene-3,3'-dione, 3'-hydroxy-epsilon,epsilon-caroten-3-one, and 2,6-cyclolycopene-1,5-diol. Several of the geometric isomers of lutein and Zeaxanthin were also detected at low concentrations. These were as follows: 9-cis-lutein, 9'-cislutein, 13-cis-lutein, 13'-cis-lutein, 9-cis-Zeaxanthin, and 13-cis-Zeaxanthin. Similar results were also obtained from HPLC analysis of a freshly dissected monkey retina. Conclusions Lutein, Zeaxanthin, 3'-epilutein, and 3-hydroxy-beta,epsilon-caroten-3'-one in human retina may be interconverted through a series of oxidation-reduction reactions similar to our earlier proposed metabolic transformation of these compounds in humans. The presence of the direct oxidation product of lutein and 3'-epilutein (metabolite of lutein and Zeaxanthin) in human retina suggests that lutein and Zeaxanthin may act as antioxidants to protect the macula against short-wavelength visible light. The proposed oxidative-reductive pathways for lutein and Zeaxanthin in human retina, may therefore play an important role in prevention of age-related macular degeneration and cataracts.
William E Connor - One of the best experts on this subject based on the ideXlab platform.
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Competitive inhibition of carotenoid transport and tissue concentrations by high dose supplements of lutein, Zeaxanthin and beta-carotene
European Journal of Nutrition, 2010Co-Authors: Yingming Wang, Sonja L Connor, D. Roger Illingworth, P. Barton Duell, William E ConnorAbstract:Background Carotenoids may interact differently in their absorption and transport in animals and humans. The simultaneous administration of large amounts of lutein, Zeaxanthin and beta carotene would affect not only plasma values but also their concentrations in the retina and other tissues. Objective In this study, we investigated the transport, distribution and interactions of lutein, Zeaxanthin and beta-carotene in the plasma, retina and other tissues of chicks fed supplements rich in lutein, Zeaxanthin or beta-carotene. Methods Newly hatched male Leghorn chicks were randomly assigned to ten groups. One group provided baseline data (1-day-old group). The other groups were fed one of the following six diets for 14 or 28 days: high lutein diet; high Zeaxanthin diet; three high beta-carotene supplemented diets and the control diet. Plasma and tissues including retina were analyzed for lutein and Zeaxanthin and beta-carotene at baseline and at 14 and 28 days. Results All tissues had increased concentrations of lutein after the high lutein diet and had increased concentrations of Zeaxanthin after the high Zeaxanthin diet. After 28 days, the retinal concentrations of lutein and Zeaxanthin in the chicks supplemented with lutein (27.2 mg/kg diet) and Zeaxanthin (15.3 mg/kg diet) increased 128 and 116%, respectively, compared to the retinas of chicks fed the control diet (lutein 5.2 mg/kg and Zeaxanthin 1.7 mg/kg). Lutein was decreased in plasma and other non-retinal tissues when the diet was supplemented with Zeaxanthin; likewise, Zeaxanthin was decreased in plasma and non-retinal tissues after the lutein supplement. Zeaxanthin increased in the retina after the high lutein supplement, and retinal lutein was maintained after the high Zeaxanthin supplement. The high beta-carotene supplement increased the beta-carotene content of plasma and liver very little, and beta-carotene was not found in any other tissue in the chick, including the retina. More importantly, beta-carotene decreased the concentrations of both lutein and Zeaxanthin in the plasma and most tissues, including the retina. Conclusion High dose dietary supplementation of a single carotenoid may alter the assimilation of other carotenoids. The retina appears to have the capacity to preserve accumulation of lutein and Zeaxanthin, but this capacity is diminished when intake of beta-carotene is high.
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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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effect of dietary lutein and Zeaxanthin on plasma carotenoids and their transport in lipoproteins in age related macular degeneration
The American Journal of Clinical Nutrition, 2007Co-Authors: Wei Wang, Sonja L Connor, Elizabeth J Johnson, Michael L Klein, Shannon Hughes, William E ConnorAbstract:Background:Lowdietaryintakesandlowplasmaconcentrationsof lutein and Zeaxanthin are associated with an increased risk of agerelated macular degeneration (AMD). No studies have challenged AMD patients with a diet high in lutein and Zeaxanthin. Objective: The objective was to examine the effect of diets low or high in lutein and Zeaxanthin on plasma carotenoids and their transport in AMD patients. Design: Seven AMD patients and 5 control subjects were fed a low-lutein, low-Zeaxanthin diet (1.1 mg/d) for 2 wk, which was followedbyahigh-lutein,high-Zeaxanthindiet(11mg/d)for4wk. Ten subjects continued the diet for 8 wk. Plasma and lipoprotein carotenoids were measured by HPLC. Results: The high-lutein, high-Zeaxanthin diet resulted in 2- to 3-fold increases in plasma concentrations of lutein and Zeaxanthin andothercarotenoids,exceptlycopene,intheAMDpatientsandthe control subjects. With this diet, 52% of the lutein and 44% of the Zeaxanthin were transported by HDL; 22% of lutein and Zeaxanthin was transported by LDL. Only 20–25% of -carotene, -carotene, and lycopene was transported by HDL; 50–57% was transported by LDL. Conclusions: The AMD patients and control subjects responded similarly to a diet high in lutein and Zeaxanthin; plasma carotenoid concentrationsincreasedgreatlyinbothgroups,andthetransportof carotenoids by lipoproteins was not significantly different between the groups. This finding suggests that abnormalities in the metabolism of lutein and Zeaxanthin in AMD may reside in the uptake of lutein and Zeaxanthin from the plasma and transport into the retina. Am J Clin Nutr 2007;85:762–9.
Richard A. Bone - One of the best experts on this subject based on the ideXlab platform.
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biologic mechanisms of the protective role of lutein and Zeaxanthin in the eye
Annual Review of Nutrition, 2003Co-Authors: Norman I Krinsky, John T. Landrum, Richard A. BoneAbstract:▪ Abstract The macular region of the primate retina is yellow in color due to the presence of the macular pigment, composed of two dietary xanthophylls, lutein and Zeaxanthin, and another xanthophyll, meso-Zeaxanthin. The latter is presumably formed from either lutein or Zeaxanthin in the retina. By absorbing blue-light, the macular pigment protects the underlying photoreceptor cell layer from light damage, possibly initiated by the formation of reactive oxygen species during a photosensitized reaction. There is ample epidemiological evidence that the amount of macular pigment is inversely associated with the incidence of age-related macular degeneration, an irreversible process that is the major cause of blindness in the elderly. The macular pigment can be increased in primates by either increasing the intake of foods that are rich in lutein and Zeaxanthin, such as dark-green leafy vegetables, or by supplementation with lutein or Zeaxanthin. Although increasing the intake of lutein or Zeaxanthin might pr...
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Biologic mechanisms of the protective role of lutein and Zeaxanthin in the eye.
Annual review of nutrition, 2003Co-Authors: Norman I Krinsky, John T. Landrum, Richard A. BoneAbstract:The macular region of the primate retina is yellow in color due to the presence of the macular pigment, composed of two dietary xanthophylls, lutein and Zeaxanthin, and another xanthophyll, meso-Zeaxanthin. The latter is presumably formed from either lutein or Zeaxanthin in the retina. By absorbing blue-light, the macular pigment protects the underlying photoreceptor cell layer from light damage, possibly initiated by the formation of reactive oxygen species during a photosensitized reaction. There is ample epidemiological evidence that the amount of macular pigment is inversely associated with the incidence of age-related macular degeneration, an irreversible process that is the major cause of blindness in the elderly. The macular pigment can be increased in primates by either increasing the intake of foods that are rich in lutein and Zeaxanthin, such as dark-green leafy vegetables, or by supplementation with lutein or Zeaxanthin. Although increasing the intake of lutein or Zeaxanthin might prove to be protective against the development of age-related macular degeneration, a causative relationship has yet to be experimentally demonstrated.
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Analysis of Zeaxanthin distribution within individual human retinas.
Methods in enzymology, 1999Co-Authors: John T. Landrum, Richard A. Bone, Linda L Moore, Christina M. GomezAbstract:Publisher Summary This chapter discusses the analysis of Zeaxanthin distribution within individual human retinas. In this analysis, sections of individual eyes are analyzed for the content of the three stereoisomers of Zeaxanthin, thereby determining their distribution across the retina. Retina contains two isomeric xanthophylls—lutein arid Zeaxanthin—with the greatest concentration at the center of the macula and diminishing with eccentricity. The elution order of the three authentic Zeaxanthin dicarbamate diastereomer in a racemic mixture is prepared from rhodoxanthin. An analysis of serum Zeaxanthin reveals that the serum contains dominantly RR-Zeaxanthin. The principal peak was collected and combined with a sample of the racemic mixture. The results and observations support the hypothesis that lutein and/or Zeaxanthin undergoes oxidation in the retina followed by nonstereospecific reduction to regenerate the observed suite of stereoisomers. The presence and distribution of these stereoisomers appear to be consistent with, and support, a hypothesis of antioxidant function for the macular carotenoids.
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Distribution of Lutein and Zeaxanthin Stereoisomers in the Human Retina
Experimental eye research, 1997Co-Authors: Richard A. Bone, John T. Landrum, Larry M. Friedes, Christina M. Gomez, Mark D. Kilburn, Eugenio Menendez, Ivonne Vidal, Weili WangAbstract:The distribution of macular pigment stereoisomers in the human retina has been mapped and a pathway to account for the presence of the non-dietary carotenoid,meso-Zeaxanthin, is proposed. Adult neural retinas were cut into three concentric areas centered on the fovea, and the extracted carotenoids were analysed and purified by high-performance liquid chromatography. The dicarbamate or dibenzoate derivatives of the collected Zeaxanthin fractions for each tissue sample were further analysed by HPLC to determine their stereoisomer composition. Whole retinas from infant eyes were similarly analysed. The results show that, relative to Zeaxanthin, the concentration of lutein in the adult neural retina increases with radial distance from the fovea while that ofmeso-Zeaxanthin decreases. Infant retinas were found to have more lutein and lessmeso-Zeaxanthin, relative to Zeaxanthin, than adult retinas. Small quantities of (3S, 3′S)-Zeaxanthin were also found in the adult retina, particularly in the macula. It is proposed that lutein and Zeaxanthin are transported into an individual's retina in the same proportions found in his or her blood serum. Some of the lutein is then converted intomeso-Zeaxanthin, primarily in the macula, by a mechanism which is less developed in infants than adults.
