Lutein, Zeaxanthin, and meso-Zeaxanthin in the Clinical Management of Eye Disease

Clinical management of eye diseases: carotenoids and their nanoformulations as choice of therapeutics

Eye diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR), impose a substantial health cost on a worldwide scale. Carotenoids have emerged as intriguing candidates for pharmacological treatment of various disorders. Their therapeutic effectiveness, however, is hindered by poor solubility and vulnerability to degradation. Nanocarriers, such as nanoparticles, liposomes, and micelles, provide a transformational way to overcome these limits. This review explores the pharmacological potential of carotenoids, namely lutein, zeaxanthin, and astaxanthin, to treat several ocular disorders. The main emphasis is on their anti-inflammatory and antioxidant actions, which help to counteract inflammation and oxidative stress, crucial factors in the development of AMD and DR. The review evaluates the significant benefits of nano-formulated carotenoids, such as improved bioavailability, higher cellular absorption, precise administration to particular ocular tissues, and greater biostability, which make them superior to conventional carotenoids. Some clinical studies on the beneficial properties of carotenoids in eye diseases are discussed. Furthermore, safety and regulatory concerns are also taken into account. Ultimately, carotenoids, especially when created in their nano form, have significant potential for safeguarding eyesight and enhancing the overall well-being of several individuals afflicted with vision-endangering eye diseases.

Longevity factor FOXO3a: A potential therapeutic target for age-related ocular diseases

The forkhead box protein O3 (FOXO3a) belongs to the subgroup O of the forkhead transcription factor family and plays an important role in regulating the aging process by participating in the regulation of various life processes, including cell cycle arrest, apoptosis, autophagy, oxidative stress, and DNA repair. The eye is an organ that is affected by aging earlier. However, the functional role and potential clinical applications of FOXO3a in age-related eye diseases have not received widespread attention and lacked comprehensive and clear clarification. In this review, we demonstrated the relationship between FOXO3a and visual system health, summarized the functional roles of FOXO3a in various eye diseases, and potential ocular-related therapies and drugs targeting FOXO3a in visual system diseases through a review and summary of relevant literature. This review indicates that FOXO3a is an important factor in maintaining the normal function of various tissues in the eye, and is closely related to the occurrence and development of ophthalmic-related diseases. Based on its vital role in the normal function of the visual system, FOXO3a has potential clinical application value in related ophthalmic diseases. At present, multiple molecules and drugs targeting FOXO3a have been reported to have the potential for the treatment of related ophthalmic diseases, but further clinical trials are needed. In conclusion, this review can facilitate us to grasp the role of FOXO3a in the visual system and provide new views and bases for the treatment strategy research of age-related eye diseases.

A mechanistic review on growing multiple therapeutic applications of lutein and its global market research

Lutein is a naturally occurring carotenoid synthesized by plants and algae that has a beneficial effect on several biological processes and associated ailments. Its immediate application is in ophthalmology, where it significantly lowers the incidences of age-related macular degeneration (AMD). It also has anti-inflammatory action, treatment of diabetic retinopathy, and cataracts, and enhancement of visual contrast. To critically assess lutein biosynthesis, therapeutic applicability, and market research literature. We have discussed its theoretical frameworks, experimental evidence, limitations, as well as clinical trial results, and future research prospects. The literature for this review article was mined and compiled by collecting and analyzing articles from several databases, including ScienceDirect, Google Scholar, PubMed, Wiley Online Library, Patentscope, and ClinicalTrials.gov published until March 30, 2022. Patent publications were identified using the search terms like IC:(C07C67/56) AND EN_AB:(lutein) OR EN_TI:(lutein) OR EN_AB:(extraction) OR EN_TI:(process). According to the literature, lutein is an essential nutrient given that it cannot be synthesized in the human body and acts as an antioxidant, affecting AMD, diabetic retinopathy, Rheumatic diseases, inflammation, and cancer. Due to inadequate production and laborious extraction, lutein is expensive despite its high demand and applicability. Market research predicts a 6.3% compound annual growth rate for lutein by 2032. Optimizing lutein extraction for high yield and purity is necessary. Lutein has proven applicability in various ailments as well as cosmetics that can be developed as a candidate drug for various diseases discussed in the review.

Macular Pigment Assessment in Indian Population Using Degree of Polarization Threshold: Impact of Diet on Macular Pigment Density

Purpose

To determine macular pigment (MP) density scores in healthy Indians and examine correlations with demographic and lifestyle variables.

Methods

We observed 484 Indians without an ocular pathology. Body mass index (BMI) and self-reported lifestyle factors (sunglasses usage, physical activity, and smoking) were noted. MP density was assessed as the threshold of perception of the shadow of their macular pigments on their retina using a new MP assessment tool (MP-eye). Lutein and zeaxanthin intake was assessed using a prevalidated questionnaire regionally designed for the Indian diet. Clusters of participants were created for statistical analysis based on MP-eye scores secondarily to detect any relevant effects in very low, low, medium, and high ranges of MPs.

Results

Data analyzed included 235 males and 249 females with mean age of 36.1 ± 12.9 years (range, 14-72). The median MP-eye score was 6 (range, 0-10, with 10 being high). Most were non-smokers (413, 85.3%) and did not use sunglasses (438, 90.5%), and 314 (64.9%) had low physical activity. Diabetes was present in 62 participants (12.8%) and hypertension in 53 (10.9%). Advancing age (r = -0.209; P < 0.000) and BMI (r = -0.094; P = 0.038) had weak negative correlation with MP-eye scores. Hypertension was less prevalent (7/88) in the cluster with the highest median MP-eye score (P = 0.033). Dietary intake of MPs and other lifestyle factors did not correlate significantly with MP-eye score overall or when analyzed in clusters.

Conclusions

MP-eye scores of an Indian population were normally distributed. Higher age, high BMI, and presence of hypertension were weakly associated with lower MP-eye scores. The impact of diet on MPs requires further evaluation.

Translational Relevance

This normative regional database enables risk stratification of macular degeneration.

Comparative Genomic Analysis of Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05 for Producing Macular Pigment

Sphingomonas morindae sp. NBD5, which we previously identified and tested, is a new bacterial strain for producing lutein. Here, based on the next-generation sequencing technology, we analyzed high throughput genomic sequences and compared related functional genes of Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05. The genome of Sphingomonas morindae sp. NBD5 has two sets of chromosomes, which is 4,239,716 bp and harbors 3882 protein coding genes. There are 59 protein-coding genes related to the macular pigment (MP) biosynthesis, of which four genes (ackA, pgm, gpmI and pckA) are unique. These genes, pckG, porB, meh, and fldA, are unique in Sphingopyxis sp. USTB-05. The analysis of Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05 genomes gives an insight into the new pathway for MP production. These genes for the transformation of glucose to MP were also found in Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05. This study expands the understanding of the pathway for complete biosynthesis of MP by Sphingomonas morindae sp. NBD5 and Sphingopyxis sp. USTB-05.

Proteins involved in fat-soluble vitamin and carotenoid transport across the intestinal cells: New insights from the past decade

It is now well established that vitamins D, E, and K and carotenoids are not absorbed solely through passive diffusion. Broad-specificity membrane transporters such as SR-BI (scavenger receptor class B type I), CD36 (CD36 molecule), NPC1L1 (Niemann Pick C1-like 1) or ABCA1 (ATP-binding cassette A1) are involved in the uptake of these micronutrients from the lumen to the enterocyte cytosol and in their secretion into the bloodstream. Recently, the existence of efflux pathways from the enterocyte back to the lumen or from the bloodstream to the lumen, involving ABCB1 (P-glycoprotein/MDR1) or the ABCG5/ABCG8 complex, has also been evidenced for vitamins D and K. Surprisingly, no membrane proteins have been involved in dietary vitamin A uptake so far. After an overview of the metabolism of fat-soluble vitamins and carotenoids along the gastrointestinal tract (from the mouth to the colon where interactions with microbiota may occur), a focus is placed on the identified and candidate proteins participating in the apical uptake, intracellular transport, basolateral secretion and efflux back to the lumen of fat-soluble vitamins and carotenoids in enterocytes. This review also highlights the mechanisms that remain to be identified to fully unravel the pathways involved in fat-soluble vitamin and carotenoid intestinal absorption.

Nature's palette: An emerging frontier for coloring dairy products

Consumers all across the world are looking for the most delectable and appealing foods, while also demanding products that are safer, more nutritious, and healthier. Substitution of synthetic colorants with natural colorants has piqued consumer and market interest in recent years. Due to increasing demand, extensive research has been conducted to find natural and safe food additives, such as natural pigments, that may have health benefits. Natural colorants are made up of a variety of pigments, many of which have significant biological potential. Because of the promising health advantages, natural colorants are gaining immense interest in the dairy industry. This review goes over the use of various natural colorants in dairy products which can provide desirable color as well as positive health impacts. The purpose of this review is to provide an in-depth look into the field of food (natural or synthetic) colorants applied in dairy products as well as their potential health benefits, safety, general trends, and future prospects  in food science and technology. In this paper, we listed a plethora of applications of natural colorants in various milk-based products.

Vitamin A, systemic T-cells, and the eye: Focus on degenerative retinal disease

The first discovered vitamin, vitamin A, exists in a range of forms, primarily retinoids and provitamin carotenoids. The bioactive forms of vitamin A, retinol and retinoic acid, have many critical functions in body systems including the eye and immune system. Vitamin A deficiency is associated with dysfunctional immunity, and presents clinically as a characteristic ocular syndrome, xerophthalmia. The immune functions of vitamin A extend to the gut, where microbiome interactions and nutritional retinoids and carotenoids contribute to the balance of T cell differentiation, thereby determining immune status and contributing to inflammatory disease around the whole body. In the eye, degenerative conditions affecting the retina and uvea are influenced by vitamin A. Stargardt's disease (STGD1; MIM 248200) is characterised by bisretinoid deposits such as lipofuscin, produced by retinal photoreceptors as they use and recycle a vitamin A-derived chromophore. Age-related macular degeneration features comparable retinal deposits, such as drusen featuring lipofuscin accumulation; and is characterised by parainflammatory processes. We hypothesise that local parainflammatory processes secondary to lipofuscin deposition in the retina are mediated by T cells interacting with dietary vitamin A derivatives and the gut microbiome, and outline the current evidence for this. No cures exist for Stargardt's or age-related macular degeneration, but many vitamin A-based therapeutic approaches have been or are being trialled. The relationship between vitamin A's functions in systemic immunology and the eye could be further exploited, and further research may seek to leverage the interactions of the gut-eye immunological axis.

Haidinger's brushes: Psychophysical analysis of an entoptic phenomenon

Entoptic phenomena are visual artifacts arising from the interaction of light with the specific anatomic structure of the human eye. While they are usually too subtle to actually enable additional visual abilities, their perception can provide indirect information on the physiological conditions of the visual system. Among the most famous ones, Haidinger's brushes consist in the appearance of a yellowish bow tie perceived in the presence of linearly polarized white light and originate from the particular spatial distribution of dichroic carotenoid molecules forming a sort of embedded radial polarizer in the foveal region. In this work, we develop a compact and versatile optical setup for the psychophysical analysis of the perceptual threshold of such entoptic effect. The tests performed on a group of 113 healthy individuals under conditions of maximum contrast (blue light) reveal the capability to perceive an average polarization degree around 16%. The developed prototype outlines a new optical platform to train the users in the perception of the phenomenon and infer information on the polarization-degree sensitivity of the human visual system.

Hyperglycaemia-induced human hepatocellular carcinoma (HepG2) cell proliferation through ROS-mediated P38 activation is effectively inhibited by a xanthophyll carotenoid, lutein

AIMS

Diabetic population have a twofold to threefold increased risk of developing liver cancer, and hyperglycaemia is a prime causative factor that propends the tumour cells to undergo aggressive metabolic growth. In this study, we aimed to examine the molecular mechanism by which lutein inhibits hyperglycaemia-induced human hepatocarcinoma (HepG2) cell proliferation.

METHODS

The effect of lutein on high glucose-induced proliferation was measured using the WST-1 reagent. Its effect on intracellular reactive oxygen species (ROS) levels was measured by DCF assay. The effect on the expression of antioxidant enzymes, cell cycle regulatory proteins and intracellular protein kinases was analysed by western blotting. The modulatory effect of lutein on different phases of the cell cycle was analysed by flow cytometry.

RESULTS

The data showed that lutein at 5 µM concentration significantly blocked glucose-promoted HepG2 cell proliferation. Suppression of high glucose-induced cell proliferation by lutein was not associated with apoptosis induction, but it was linked with inhibition of hyperglycaemia-mediated elevated ROS and upregulated expression of high glucose-mediated repressed heme oxygenase 1 (HO1). Furthermore, G2/M phase cell cycle arrest and associated phosphorylation of Cdk1 and P53 were found to be linked with suppressed hyperglycaemia-mediated cell proliferation by lutein. In addition, lutein inhibited hyperglycaemia-induced activation of P38 which relates to high glucose-induced ROS-mediated growth suppression and modulated the phosphorylation of Erk, JNK and Akt in hyperglycaemic HepG2 cells.

CONCLUSION

Our findings portray that sufficient intake of lutein may offer a negative impact on diabetes-associated tumour growth.

Zeaxanthin Attenuates the Vicious Circle Between Endoplasmic Reticulum Stress and Tau Phosphorylation: Involvement of GSK-3β Activation

BACKGROUND

Alzheimer's disease (AD) characterized by neurofibrillary tangles caused by hyperphosphorylated tau is the most common cause of dementia. Zeaxanthin (Zea), derived from fruits and vegetables, may reduce the risk of AD. Endoplasmic reticulum stress (ERS) might cause memory impairment in AD.

OBJECTIVE

Here, we studied protective role of Zea on the relationship among ERS, activity of glycogen synthase kinase 3β (GSK-3β, tau phosphorylated kinase), and p-Tau (Ser 396 and Thr 231).

METHODS

The results were obtained in non-RA and RA group by using different treatment, such as 9-cis-retinoic acid (RA), TM (ERS inducer), Zea, 4-PBA (ERS inhibitor), and SB216763 (GSK-3β inhibitor). The methods included flow cytometry and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] for the detections of cell cycle and cell viability and western blot as a third measure of proteins in relation to ERS and tau phosphorylation. We have collected and analyzed all the data that suggested application of drugs for the treatment in non-RA and RA group.

RESULTS

Zea displays its protection on TM-induced cell injury, upregulation of GRP78 expression, and change of GSK-3β activity and tau phosphorylation when 4-PBA and SB216763 interfere with the process.

CONCLUSION

These studies indicated that Zea is in vicious circle in ERS, GSK-3β, and tau phosphorylation, and further reflect its potential value in AD.

Lutein activates downstream signaling pathways of unfolded protein response in hyperglycemic ARPE-19 cells

We have earlier demonstrated that lutein effectively prevents hyperglycemia generated sustained oxidative stress in ARPE-19 cells by activating Nrf2 (nuclear factor erythroid 2-related factor 2) signaling. Since evidence portrays an intricate connection between ER (endoplasmic reticulum) stress and hyperglycemia-mediated oxidative stress, we aimed to explore the protective mechanism of lutein on hyperglycemia-induced ER stress in ARPE-19 cells. To determine the effect of lutein, we probed three major downstream branches of unfolded protein response (UPR) signaling pathways using western blot, immunofluorescent and RT-PCR techniques. The data showed a reduction (38%) in protein expression of an imperative ER chaperon, BiP (binding immunoglobulin protein), in glucose-treated ARPE-19 cells. At the same time, lutein pretreatment blocked this glucose-mediated effect, leading to a significant increase in BiP expression. Lutein promoted the phosphorylation of IRE1 (inositol requiring enzyme 1) and subsequent splicing of XBP1 (X-box binding protein 1), leading to enhanced nuclear translocation. Likewise, lutein activated the expression and translocation of transcription factors, ATF6 (activating transcription factor 6) and ATF4 (activating transcription factor 4) suppressed by hyperglycemia. Lutein also increased CHOP (C/EBP-homologous protein) levels in ARPE-19 cultured under high glucose conditions. The mRNA expression study showed that lutein pretreatment upregulates downstream UPR genes HRD1 (ERAD-associated E3 ubiquitin-protein ligase HRD1), p58^IPK (protein kinase inhibitor p58) compared to high glucose treatment alone. From our study, it is clear that lutein show protection against hyperglycemia-mediated ER stress in ARPE-19 cells by activating IRE1-XBP1, ATF6, and ATF4 pathways and their downstream activators. Thus, lutein may have the pharmacological potential for protection against widespread disease conditions of ER stress.

A Systematic Review of Carotenoids in the Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of modifiable vision loss in older adults. Chronic oxidative injury and compromised antioxidant defenses represent essential drivers in the development of retinal neurodegeneration. Overwhelming free radical species formation results in mitochondrial dysfunction, as well as cellular and metabolic imbalance, which becomes exacerbated with increasing age. Thus, the depletion of systemic antioxidant capacity further proliferates oxidative stress in AMD-affected eyes, resulting in loss of photoreceptors, neuroinflammation, and ultimately atrophy within the retinal tissue. The aim of this systematic review is to examine the neuroprotective potential of the xanthophyll carotenoids lutein, zeaxanthin, and meso-zeaxanthin on retinal neurodegeneration for the purpose of adjunctive nutraceutical strategy in the management of AMD. A comprehensive literature review was performed to retrieve 55 eligible publications, using four database searches from PubMed, Embase, Cochrane Library, and the Web of Science. Epidemiology studies indicated an enhanced risk reduction against late AMD with greater dietary consumption of carotenoids, meanwhile greater concentrations in macular pigment demonstrated significant improvements in visual function among AMD patients. Collectively, evidence strongly suggests that carotenoid vitamin therapies offer remarkable synergic protection in the neurosensory retina, with the potential to serve as adjunctive nutraceutical therapy in the management of established AMD, albeit these benefits may vary among different stages of disease.

A Systematic Review of Carotenoids in the Management of Diabetic Retinopathy

Diabetic retinopathy, which was primarily regarded as a microvascular disease, is the leading cause of irreversible blindness worldwide. With obesity at epidemic proportions, diabetes-related ocular problems are exponentially increasing in the developed world. Oxidative stress due to hyperglycemic states and its associated inflammation is one of the pathological mechanisms which leads to depletion of endogenous antioxidants in retina in a diabetic patient. This contributes to a cascade of events that finally leads to retinal neurodegeneration and irreversible vision loss. The xanthophylls lutein and zeaxanthin are known to promote retinal health, improve visual function in retinal diseases such as age-related macular degeneration that has oxidative damage central in its etiopathogenesis. Thus, it can be hypothesized that dietary supplements with xanthophylls that are potent antioxidants may regenerate the compromised antioxidant capacity as a consequence of the diabetic state, therefore ultimately promoting retinal health and visual improvement. We performed a comprehensive literature review of the National Library of Medicine and Web of Science databases, resulting in 341 publications meeting search criteria, of which, 18 were found eligible for inclusion in this review. Lutein and zeaxanthin demonstrated significant protection against capillary cell degeneration and hyperglycemia-induced changes in retinal vasculature. Observational studies indicate that depletion of xanthophyll carotenoids in the macula may represent a novel feature of DR, specifically in patients with type 2 or poorly managed type 1 diabetes. Meanwhile, early interventional trials with dietary carotenoid supplementation show promise in improving their levels in serum and macular pigments concomitant with benefits in visual performance. These findings provide a strong molecular basis and a line of evidence that suggests carotenoid vitamin therapy may offer enhanced neuroprotective effects with therapeutic potential to function as an adjunct nutraceutical strategy for management of diabetic retinopathy.

Carotenoids in the Management of Glaucoma: A Systematic Review of the Evidence

Primary open-angle glaucoma (POAG) remains a leading cause of irreversible blindness globally. Recent evidence further substantiates sustained oxidative stress, and compromised antioxidant defenses are key drivers in the onset of glaucomatous neurodegeneration. Overwhelming oxidative injury is likely attributed to compounding mitochondrial dysfunction that worsens with age-related processes, causing aberrant formation of free radical species. Thus, a compromised systemic antioxidant capacity exacerbates further oxidative insult in glaucoma, leading to apoptosis, neuroinflammation, and subsequent tissue injury. The purpose of this systematic review is to investigate the neuroprotective benefits of the macular carotenoids lutein, zeaxanthin, and meso-zeaxanthin on glaucomatous neurodegeneration for the purpose of adjunctive nutraceutical treatment in glaucoma. A comprehensive literature search was conducted in three databases (PubMed, Cochrane Library, and Web of Science) and 20 records were identified for screening. Lutein demonstrated enhanced neuroprotection on retinal ganglion cell survival and preserved synaptic activity. In clinical studies, a protective trend was seen with greater dietary consumption of carotenoids and risk of glaucoma, while greater carotenoid levels in macular pigment were largely associated with improved visual performance in glaucomatous eyes. The data suggest that carotenoid vitamin therapy exerts synergic neuroprotective benefits and has the capacity to serve adjunctive therapy in the management of glaucoma.

Extraction of capsanthin from Capsicum annum L fruits and its effect on carbomer-induced intraocular pressure in Albino Wistar rats

The present study was aimed to explore the antiglaucoma activity of capsanthin enriched fraction (CEF) of Capsicum annum L fruits against carbomer-induced experimental glaucoma in Albino Wistar rats. CEF was orally administered to carbomer-induced glaucomatous rats, and pilocarpine 2% eye drops were used as a standard drug. Intraocular pressure (IOP) levels were determined after oral administration of a low, medium, and a high dose of CEF (20, 40, and 80 mg/kg bwt) in glaucomatous rats. In rats with elevated IOP in both eyes, oral administration of CEF resulted in a significant reduction in IOP (p < .05) even at a low dose of 20 mg/Kg body weight. There were no treatment-related changes in histopathology, hematology, and clinical chemistry parameters. Thus, CEF when administered orally in IOP-bearing rats successfully reduced IOP without any adverse effects. PRACTICAL APPLICATIONS: Capsanthin enriched fraction can be used to prevent permanent vision loss due to age-related macular diseases and high intraocular pressure. The intraocular pressure reduction action of capsanthin can be useful in the treatment of glaucoma. The medication available to treat glaucoma are topical drugs, and for the first time, we proved the oral supplementation of capsanthin from a food source can reduce the intraocular pressure in rats.

Visual Function and Macular Carotenoid Changes in Eyes with Retinal Drusen-An Open Label Randomized Controlled Trial to Compare a Micronized Lipid-Based Carotenoid Liquid Supplementation and AREDS-2 Formula

Purpose: To compare the changes in visual and ocular parameters in individuals with retinal drusen who were treated with two commercially available nutritional supplements. Methods: An open-label, single-center, randomized, parallel-treatment with an observational control group design was utilized. The treatment groups included individuals with fine retinal drusen sub-clinical age-related macular degeneration (AMD), while the control group consisted of ocular normal individuals. The treatment groups were randomly assigned to the micronized lipid-based carotenoid supplement, Lumega-Z (LM), or the PreserVision Age-Related Eye Disease Study 2 (AREDS-2) soft gel (PV). Visual performance was evaluated using the techniques of visual acuity, dark adaptation recovery and contrast sensitivity, at baseline, three months, and six months. Additionally, the macular pigment optical density (MPOD) was measured. The control group was not assigned any carotenoid supplement. The right eye and left eye results were analyzed separately. Results: Seventy-nine participants were recruited for this study, of which 68 qualified and 56 participants had useable reliable data. Of the individuals who completed this study, 25 participants belonged to the LM group, 16 belonged to the PV group, and 15 to the control group. The LM group demonstrated statistically significant improvements in contrast sensitivity function (CSF) in both eyes at six months (p < 0.001). The LM group displayed a positive linear trend with treatment time in CSF (p < 0.001), with benefits visible after just three months of supplementation. Although there was a trend showing improvement in CSF in the PV group, the change was not significant after a Bonferroni-corrected p-value of p < 0.00625. Visual acuity, dark adaptation recovery and MPOD did not significantly improve in either treatment groups. Conclusion: The LM group demonstrated greater and faster benefits in visual performance as measured by CSF when compared to the PV group. This trial has been registered at clinicaltrials.gov (NCT03946085).

Benefits of micronutrient supplementation for reducing the risk of wet age-related macular disease and diabetic retinopathy

Age-related macular disease and diabetic retinopathy are chronic degenerative diseases characterised by progressive visual impairment. In Europe, age-related macular disease accounts for over 15% of blindness in adults over 50 years of age, and although the burden of diabetic retinopathy in terms of vision impairment is lower, vision loss associated with diabetic retinopathy is increasing with the rising prevalence of diabetes mellitus and the ageing of the population. Late-stage age-related macular disease can be subdivided into dry (non-neovascular) or wet (neovascular or exudative) forms. The large Age-Related Eye Disease Study 2 showed that supplementation with antioxidant nutrients reduces choroids neovascularisation and reduces the risk of progression of neovascular age-related macular disease. Antioxidant micronutrient supplements have also shown promising results in preventing the pathogenesis of retinopathy in animal models of diabetes. Age-related macular disease and diabetic retinopathy are understood to share some common pathophysiological characteristics, suggesting that micronutrients have an important role in ocular health in both conditions. This article will review the current evidence for the utility of micronutrients in preventing the development and progression of neovascular age-related macular disease and diabetic retinopathy.

Association between dietary carotenoid intakes and hypertension in adults: National Health and Nutrition Examination Survey 2007-2014

OBJECTIVE

Few epidemiological studies concentrated on dietary carotenoids and hypertension since new hypertension guideline released in 2017. Thus, this study was aimed to evaluate their association.

METHODS

Data from National Health and Nutrition Examination Survey (NHANES) 2007-2014 were used in this cross-sectional study. Dietary carotenoids data were obtained from 24-h dietary recall interviews. Hypertension was defined as SBP at least 130 mmHg or DBP at least 80 mmHg, taking antihypertensive medicine or self-report. Logistic regression models and restricted cubic spline models were applied to explore the associations between α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein with zeaxanthin, and total carotenoids from diet and supplements and hypertension. Total carotenoids showed significant reductive risk of hypertension at 100 μg/kg per day and over.

RESULTS

A total of 17 398 adults aged 20 years and over were identified. High dose of β-carotene, lycopene, lutein with zeaxanthin, and total carotenoids were significantly associated with decreased risk of hypertension in crude results. After multivariate-adjustment in model 2, the odds ratios (OR) with 95% confidence intervals (CI) of β-cryptoxanthin, lycopene, lutein with zeaxanthin and total carotenoids for hypertension were 0.79 (0.67-0.93), 0.85 (0.73-0.98), 0.69 (0.58-0.83), 0.73 (0.62-0.86) for the highest versus lowest quartile intakes, respectively. Dose-response analyses showed that all of the carotenoids were inversely associated with hypertension in a linear manner. Total carotenoids showed significant effect of lower risk of hypertension at 100 μg/kg per day.

CONCLUSION

Intakes of α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein with zeaxanthin, and total carotenoids were inversely associated with hypertension in US adults. The intake of total carotenoids was suggested at least 100 μg/kg per day for general adult population.

Lutein and zeaxanthin attenuates VEGF-induced neovascularisation in human retinal microvascular endothelial cells through a Nox4-dependent pathway

Age-related macular degeneration (AMD) and proliferative diabetic retinopathy (DR) are two of the most common and severe causes of vision loss in the population. Both conditions are associated with excessive levels of vascular endothelial growth factor (VEGF) in the eye which results in an increase in the formation of new blood vessels through a process called neovascularisation. As such, anti-VEGF therapies are currently utilised as a treatment for patients with AMD however they are associated with painful administration of injections and potential degeneration of healthy endothelium. There is therefore growing interest in alternate treatment options to reduce neovascularisation in the eye. The use of carotenoids, lutein (L) and zeaxanthin (Z), has been shown to improve vision loss parameters in patients with AMD, however the underlying mechanisms are not well-understood. We studied the impact of these compounds on neovascularisation processes using an in vitro cell model of the retinal microvascular endothelium. Our findings show that L and Z reduced VEGF-induced tube formation whilst, in combination (5:1 ratio), the compounds significantly blocked VEGF-induced neovascularisation. The carotenoids, individually and in combination, reduced VEGF-induced oxidative stress concomitant with increased activity of the NADPH oxidase, Nox4. We further demonstrated that the Nox4 inhibitor, GLX7013114, attenuated the protective effect of L and Z. Taken together, these findings indicate the protective effect of the carotenoids, L and Z, in reducing VEGF-mediated neovascularisation via a Nox4-dependent pathway. These studies implicate the potential for these compounds to be used as a therapeutic approach for patients suffering from AMD and proliferative DR.

Efficacy of Commercially Available Nutritional Supplements: Analysis of Serum Uptake, Macular Pigment Optical Density and Visual Functional Response

Purpose: To compare the change in serum carotenoids, macular pigment optical density (MPOD) and visual function with the intake of two commercially available nutritional supplements. Methods: Participants were given a 24-week supply of a lipid-based micronized liquid medical food, Lumega-Z™ (LM), containing 28 mg of the macular carotenoids lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ), or given PreserVision™ AREDS 2 Formula (gel-caps; PV) containing 12 mg of the macular carotenoids L and Z, but no reported MZ. Serum levels of L, Z and MZ were obtained at baseline and after 12 weeks. Macular pigment optical densities (MPOD) and visual function were assessed at baseline and after 24 weeks. Results: Average blood serum concentrations of L, Z and MZ in the two groups at baseline were similar. The increases in L, Z and MZ were 0.434, 0.063 and 0.086 µmol/L vs. 0.100, 0.043 and 0.001 µmol/L, respectively, in the LM vs. PV group. From baseline to week 24, average MPOD in the LM-group increased by 0.064 from 0.418 to 0.482, whereas in the PV-group, it was essentially unchanged (0.461 to 0.459;). Although log-contrast sensitivity was improved in all groups under three conditions (photopic, mesopic and mesopic with glare), the change in log-contrast sensitivity was not statistically significant. Conclusion: Despite only a 2.3-fold higher carotenoid concentration than PV, LM supplementation provides approximately 3–4-fold higher absorption, which leads to a significant elevation of MPOD levels.

Borage, camellia, centaurea and pansies: Nutritional, fatty acids, free sugars, vitamin E, carotenoids and organic acids characterization

The present study aimed to evaluate the nutritional and bioactive potential of four edible flowers (borage, centaurea, camellia, and pansies). Significant differences were observed among the four. Water was the main constituent (>76%, fresh weight - fw). Linoleic and palmitic acids were the major fatty acids found in borage and red and yellow pansies, while in camellia it was the arachidic acid. In white pansies, behenic and arachidic acids were predominant. Concerning vitamin E, α-tocopherol was the major vitamer. Carotenoids values varied between 5.8 and 181.4 mg β-carotene/100 g dry weight (dw) in centaurea and borage, respectively, being particularly rich in lutein. Malic acid was the major organic acid, except in centaurea, where succinic acid was predominant. Fructose, glucose and sucrose were detected in all flowers. These results can contribute to the knowledge of these edible flowers and consequently increase their popularity among consumers and in the food industry.

Mechanistic insights into the effect of lutein on atherosclerosis, vascular dysfunction, and related risk factors: A systematic review of in vivo, ex vivo and in vitro studies

Lutein is an essential carotenoid commonly consumed in the diet; however, its dietary intake does not usually reach the minimum recommended intake to decrease the incidence of chronic diseases. Experimental and epidemiological evidence suggests an anti-atherosclerotic effect for lutein-rich foods or lutein supplementation. This systematic review aimed to assess the mechanistic pathways of lutein in the prevention of atherosclerosis. Electronic databases, including PubMed, SCOPUS, ProQuest, Embase, and Google Scholar were searched to May 2019. Original studies published in English-language journals that investigated the effects of lutein on atherosclerosis and related risk factors, including lipid profile, hemodynamic, glycemic and inflammatory measurements, and endothelial function indices, were considered. Two reviewers independently extracted data on study characteristics, methods and outcomes. The review protocol has been registered at PROSPERO database of Systematic Reviews (registration number: CRD42019121381). A total of 5818 articles were found in the first phase of the search; from these, 19 met the inclusion criteria: 3 in vitro, 1 ex vivo, 11 animal, and 4 human studies. Nine of ten studies showed positive effects of lutein on endothelial function by reducing blood pressure, arterial thickness, monocyte migration, and vascular smooth muscle cell migration. Twelve studies examined the anti-inflammatory properties of lutein and found a significant decrease in proinflammatory cytokines. Although few studies investigated the anti-hyperlipidemic effects of lutein, three animal studies and one clinical trial found a beneficial effect of lutein on lipid profile. Evidence supports positive effects of lutein on atherosclerosis development and some common risk factors of atherosclerosis, including inflammation and endothelial dysfunction. Further studies focused on the effects of lutein on hyperglycemia, lipid profile, blood pressure and coagulation are required.

Mechanisms of Carotenoid Intestinal Absorption: Where Do We Stand?

A growing literature is dedicated to the understanding of carotenoid beneficial health effects. However, the absorption process of this broad family of molecules is still poorly understood. These highly lipophilic plant metabolites are usually weakly absorbed. It was long believed that β-carotene absorption (the principal provitamin A carotenoid in the human diet), and thus all other carotenoid absorption, was driven by passive diffusion through the brush border of the enterocytes. The identification of transporters able to facilitate carotenoid uptake by the enterocytes has challenged established statements. After a brief overview of carotenoid metabolism in the human upper gastrointestinal tract, a focus will be put on the identified proteins participating in the transport and the metabolism of carotenoids in intestinal cells and the regulation of these processes. Further progress in the understanding of the molecular mechanisms regulating carotenoid intestinal absorption is still required to optimize their bioavailability and, thus, their health effects.

Treatments for dry age-related macular degeneration and Stargardt disease: a systematic review

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of visual loss in older people. Advanced AMD takes two forms, neovascular (wet) and atrophic (dry). Stargardt disease (STGD) is the commonest form of inherited macular dystrophy.

OBJECTIVE

To carry out a systematic review of treatments for dry AMD and STGD, and to identify emerging treatments where future NIHR research might be commissioned.

DESIGN

Systematic review.

METHODS

We searched MEDLINE, EMBASE, Web of Science and The Cochrane Library from 2005 to 13 July 2017 for reviews, journal articles and meeting abstracts. We looked for studies of interventions that aim to preserve or restore vision in people with dry AMD or STGD. The most important outcomes are those that matter to patients: visual acuity (VA), contrast sensitivity, reading speed, ability to drive, adverse effects of treatment, quality of life, progression of disease and patient preference. However, visual loss is a late event and intermediate predictors of future decline were accepted if there was good evidence that they are strong predictors of subsequent visual outcomes. These include changes detectable by investigation, but not necessarily noticed by people with AMD or STGD. ClinicalTrials.gov, the World Health Organization search portal and the UK Clinical Trials gateway were searched for ongoing and recently completed clinical trials.

RESULTS

The titles and abstracts of 7948 articles were screened for inclusion. The full text of 398 articles were obtained for further screening and checking of references and 112 articles were included in the final report. Overall, there were disappointingly few good-quality studies (including of sufficient size and duration) reporting useful outcomes, particularly in STGD. However we did identify a number of promising research topics, including drug treatments, stem cells, new forms of laser treatment, and implantable intraocular lens telescopes. In many cases, research is already under way, funded by industry or governments.

LIMITATIONS

In AMD, the main limitation came from the poor quality of much of the evidence. Many studies used VA as their main outcome despite not having sufficient duration to observe changes. The evidence on treatments for STGD is sparse. Most studies tested interventions with no comparison group, were far too short term, and the quality of some studies was poor.

FUTURE WORK

We think that the topics on which the Health Technology Assessment (HTA) and Efficacy Mechanism and Evaluation (EME) programmes might consider commissioning primary research are in STGD, a HTA trial of fenretinide (ReVision Therapeutics, San Diego, CA, USA), a visual cycle inhibitor, and EME research into the value of lutein and zeaxanthin supplements, using short-term measures of retinal function. In AMD, we suggest trials of fenretinide and of a potent statin. There is epidemiological evidence from the USA that the drug, levodopa, used for treating Parkinson's disease, may reduce the incidence of AMD. We suggest that similar research should be carried out using the large general practice databases in the UK. Ideally, future research should be at earlier stages in both diseases, before vision is impaired, using sensitive measures of macular function. This may require early detection of AMD by screening.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016038708.

FUNDING

The National Institute for Health Research HTA programme.

Nutraceuticals for the Treatment of Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes mellitus and is characterized by degeneration of retinal neurons and neoangiogenesis, causing a severe threat to vision. Nowadays, the principal treatment options for DR are laser photocoagulation, vitreoretinal surgery, or intravitreal injection of drugs targeting vascular endothelial growth factor. However, these treatments only act at advanced stages of DR, have short term efficacy, and cause side effects. Treatment with nutraceuticals (foods providing medical or health benefits) at early stages of DR may represent a reasonable alternative to act upstream of the disease, preventing its progression. In particular, in vitro and in vivo studies have revealed that a variety of nutraceuticals have significant antioxidant and anti-inflammatory properties that may inhibit the early diabetes-driven molecular mechanisms that induce DR, reducing both the neural and vascular damage typical of DR. Although most studies are limited to animal models and there is the problem of low bioavailability for many nutraceuticals, the use of these compounds may represent a natural alternative method to standard DR treatments.

Haidinger's brushes elicited at varying degrees of polarization rapidly and easily assesses total macular pigmentation

Macular pigments (MPs), by absorbing potentially toxic short-wavelength (400-500 nm) visible light, provide protection against photo-chemical damage thought to be relevant in the pathogenesis of age-related macular degeneration (AMD). A method of screening for low levels of MPs could be part of a prevention strategy for helping people to delay the onset of AMD. We introduce a new method for assessing MP density that takes advantage of the polarization-dependent absorption of blue light by MPs, which results in the entoptic phenomenon called Haidinger's brushes (HB). Subjects were asked to identify the direction of rotation of HB when presented with a circular stimulus illuminated with an even intensity of polarized white light in which the electric field vector was rotating either clockwise or anti-clockwise. By reducing the degree of polarization of the stimulus light, a threshold for perceiving HB (degree of polarization threshold) was determined and correlated (r²=0.66) to macular pigment optical density assessed using dual-wavelength fundus autofluoresence. The speed and ease of measurement of degree of polarization threshold makes it well suited for large-scale screening of macular pigmentation.

Lutein and Zeaxanthin Isomers Reduce Photoreceptor Degeneration in the Pde6b rd10 Mouse Model of Retinitis Pigmentosa

PURPOSE

Lutein, RR-zeaxanthin, and RS-zeaxanthin (L-Z) are antioxidants which can reduce endoplasmic reticulum stress (ERS) and oxidative stress (OS), and ameliorate neurodegenerative diseases. However, their treatment effect in the Pde6b rd10 (rd10) mouse model of retinitis pigmentosa (RP) and the underlying cellular mechanisms have not been studied. ERS is an important factor which causes photoreceptor apoptosis. The aim of the current project is to test the treatment effect of L-Z in rd10 mice and to investigate the underlying molecular mechanisms of ERS.

METHODS

L-Z (Lutemax 2020, 10 mg/kg) diluted in sunflower oil (SFO, 1 mg/ml) or the same volume of SFO was administrated via gavage from postnatal day 6 (P6) to P20 daily in L-Z group (n=5) or SFO group (n=6) of rd10 mice. At P21, electroretinography (ERG) was performed to show the functional change of retinas. 78 kDa glucose-regulated protein (GRP78) and endoplasmic reticulum protein 29 (ERp29) were tested by western blot and immunostaining.

RESULTS

The ERG amplitudes were larger in the L-Z group than those of the SFO group in all flash luminances of dark-adapted and light-adapted ERG (all p < 0.01). Western blot revealed that GRP78 in the retinas of the L-Z group was significantly downregulated compared to that of the SFO group (p < 0.01). Meanwhile, the retinal ERp29 protein was significantly upregulated in the L-Z treatment group than that of the SFO group (p < 0.01).

CONCLUSIONS

L-Z provide protection to the photoreceptors of rd10 mouse model of RP, which is probably associated with the reduction of ERS.

Nutritional Composition and Bioactive Content of Legumes: Characterization of Pulses Frequently Consumed in France and Effect of the Cooking Method

Pulses display nutritional benefits and are recommended in sustainable diets. Indeed, they are rich in proteins and fibers, and can contain variable amounts of micronutrients. However, pulses also contain bioactive compounds such as phytates, saponins, or polyphenols/tannins that can exhibit ambivalent nutritional properties depending on their amount in the diet. We characterized the nutritional composition and bioactive compound content of five types of prepared pulses frequently consumed in France (kidney beans, white beans, chickpeas, brown and green lentils, flageolets), and specifically compared the effects of household cooking vs. canning on the composition of pulses that can be consumed one way or the other. The contents in macro-, micronutrients, and bioactive compounds highly varied from one pulse to another (i.e., 6.9 to 9.7 g/100 g of cooked product for proteins, 4.6 to 818.9 µg/100 g for lutein or 15.0 to 284.3 mg/100 g for polyphenols). The preparation method was a key factor governing pulse final nutritional composition in hydrophilic compounds, depending on pulse species. Canning led to a greater decrease in proteins, total dietary fibers, magnesium or phytate contents compared to household cooking (i.e., −30%, −44%, −33% and −38%, p < 0.05, respectively, in kidney beans). As canned pulses are easy to use for consumers, additional research is needed to improve their transformation process to further optimize their nutritional quality.

Complement System and Age-Related Macular Degeneration: Implications of Gene-Environment Interaction for Preventive and Personalized Medicine

Age-related macular degeneration (AMD) is the most common cause of visual loss in developed countries, with a significant economic and social burden on public health. Although genome-wide and gene-candidate studies have been enabled to identify genetic variants in the complement system associated with AMD pathogenesis, the effect of gene-environment interaction is still under debate. In this review we provide an overview of the role of complement system and its genetic variants in AMD, summarizing the consequences of the interaction between genetic and environmental risk factors on AMD onset, progression, and therapeutic response. Finally, we discuss the perspectives of current evidence in the field of genomics driven personalized medicine and public health.

Screening, Isolation, and Identification of Zeaxanthin-Producing Bacteria

Zeaxanthin is a yellow xanthophyll, dihydroxy-carotenoid, that is naturally found in some of the green, orange, and yellow vegetables and fruits and has a powerful antioxidant activity. Epidemiological evidences suggest that increasing the consumption of zeaxanthin in the diet is associated with a lower risk of age-related macular degeneration (ARMD) and cataracts, two of the leading causes of blindness in the world. Zeaxanthin is a promising nutraceutical/colorant with many applications in feed, food, and pharmaceutical industries. Currently, the commercial production of zeaxanthin is dependent on synthetic routes with limitation in production from biological sources. However, the biotechnological production of natural zeaxanthin is favored due to its safety, potential large-scale production and consumers' preference for natural additives. In this chapter, we describe a rapid screening method based on 16S rRNA gene sequencing and effective HPLC with diode array detector/MS methods for the isolation and identification of zeaxanthin-producing bacteria and their carotenoid analysis.

Effect of Long-Term Xanthophyll and Anthocyanin Supplementation on Lutein and Zeaxanthin Serum Concentrations and Macular Pigment Optical Density in Postmenopausal Women

Xanthophylls (lutein, L; zeaxanthin, Z) and anthocyanins are often included in food supplements to improve ocular health. There are no dietary reference intakes for them. The aim was to assess the effects of L, Z and anthocyanin supplementation on short and long-term lutein status markers (serum concentration and macular pigment optical density (MPOD)). Seventy-two postmenopausal women were randomized into a parallel study of 8 months: Group A-anthocyanines (60 mg/day); Group X-xanthophylls (6 mg L + 2 mg Z/day); Group X+A-anthocyanines (60 mg/day) + xanthophylls (6 mg L + 2 mg Z/day). At the beginning of the study, 4 and 8 month serum L and Z concentrations were determined (HPLC), as well as L, Z and anthocyanine dietary intake and MPOD (heterochromic flicker photometry). Baseline concentrations of L (0.35 ± 0.19 μmol/L), Z (0.11 ± 0.05 μmol/L), L+Z/cholesterol/triglycerides (0.07 ± 0.04 μmol/mmol) increased in Group X (2.8- and 1.6-fold in L and Z concentrations) and in group XA (2- and 1.4-fold in L and Z concentrations). MPOD (baseline: 0.32 ± 0.13 du) was not modified in any of the groups at the end of the study. There were no differences in the dietary intake of L+Z and anthocyanin at any point in time in any group. Supplementation of L and Z at a dietary level provoked an increase in their serum concentration that was not modified by simultaneous supplementation with anthocyanins.

Macular pigment and serum zeaxanthin levels with Goji berry supplement in early age-related macular degeneration

AIM

To evaluate the efficacy of Goji berry supplementation on improving macular pigment, serum zeaxanthin levels and visual acuity in patients with early age-related macular degeneration (AMD).

METHODS

A total of 114 patients (aged from 51 to 92y, mean age 69.53±8.41y) with early AMD were enrolled in our prospective, randomized controlled study. The included patients were assigned randomly to the Goji group (n=57) with 25 g of Goji berries supplementation per day for 90d and the control group (n=57) with their normal diet for 90d. Macular pigment optical density (MPOD) was measured using heterochromatic flicker photometry (HFP). The levels of serum lutein (L)/zeaxanthin (Z) were analyzed using high-performance liquid chromatography (HPLC). MPOD, serum L/Z levels and best corrected visual acuity (BCVA) were recorded at baseline and 90d.

RESULTS

In the Goji group, there were no statistically significant differences in the serum L levels between the baseline (0.199±0.149 µmol/mL) and 90d (0.203±0.181 µmol/mL) (t=-0.186, P=0.850); however the serum Z levels were increased at 90d (0.101±0.087 µmol/mL) compared with those at the baseline (0.029±0.032 µmol/mL) (t=6.412, P<0.001). Patients treated with Goji berry for 90d showed an elevated MPOD (0.877±0.202 DU) from the baseline (0.731±0.205 DU) (t=-4.741, P=0.000). In contrast to the control group, the serum Z levels and MPOD were higher in the Goji group at 90d (both P<0.05). At 90d, patients with Goji berry supplementation had a relative decrease in BCVA (0.21±0.18 logMAR) compared with the baseline (0.27±0.20) (t=2.397, P=0.020).

CONCLUSION

Overall, daily supplementation with Goji berry for 90d improves MPOD by increasing serum Z levels rather than serum L levels in early AMD patients. Goji berry may be an effective therapeutic intervention for preventing the progression of early AMD.

Lutein, zeaxanthin and mammalian development: Metabolism, functions and implications for health

It is now widely accepted that nutrition during critical periods in early development, both pre- and postnatal, may have lifetime consequences in determining health or onset of major diseases in the adult life. Dietary carotenoids have shown beneficial health effects throughout the life cycle due to their potential antioxidant properties, their ability to serves as precursors of vitamin A and to the emerging signaling functions of their metabolites. The non-provitamin A carotenoids lutein and zeaxanthin are emerging as important modulators of infant and child visual and cognitive development, as well as critical effectors in the prevention and treatment of morbidity associated with premature births. This review provides a general overview of lutein and zeaxanthin metabolism in mammalian tissues and highlights the major advancements and remaining gaps in knowledge in regards to their metabolism and health effects during pre- and early post-natal development. Furthering our knowledge in this area of research will impact dietary recommendation and supplementation strategies aimed at sustaining proper fetal and infant growth.

Modulatory Effect of Carotenoid Supplement Constituting Lutein and Zeaxanthin (10:1) on Anti-oxidant Enzymes and Macular Pigments Level in Rats

Background:

Human eye is constantly exposed to different wavelengths and intensities of light. Oxidative stress results in distinct changes to retinal organs and tissues. Macular pigments (lutein and zeaxanthin), present in the central macular region, provide protection from photodamages by absorption of high energy blue light and also by virtue of their anti-oxidant activity. Ocular phototoxicity is thus prevented by our efficient anti-oxidant system, in both young and old. One of the best commercial sources of pure lutein and zeaxanthin is Marigold flowers.

Objective:

In the present study, oil-soluble dietary carotenoid supplement constituting lutein and zeaxanthin in the ratio of 10:1 was evaluated for its modulatory effect on anti-oxidant enzymes and macular pigments in the serum and macula of the Swiss albino rats.

Materials and Methods:

Male Swiss albino rats were treated with carotenoid supplement constituting lutein and trans-Zeaxanthin (10:1) at two different doses daily, under standard experimental conditions for 42 days. End of the treatment, serum and macula were collected and used for measurement of lutein and zeaxanthin levels along with anti-oxidant parameters.

Statistical Analysis Used:

Statistical differences were assessed by analysis of variance (ANOVA) followed by Dunnet's test. P < 0.05 was considered statistically significant. All the results were expressed as mean ± standard deviation.

Results:

The supplement exhibited significant elevation of anti-oxidant enzyme levels in treated animals in dose-dependent manner. Concomitantly, the total anti-oxidant capacity has also been found to show similar increment at the end of the study period. This study revealed significant expression of the two macular pigments investigated.

Conclusions:

Our study, therefore, provides a strong claim for the anti-oxidant effect of the oil-soluble dietary carotenoid supplement, and thus substantiates its use in the prevention of phototoxic damage to the eye on long-term supplementation.

SUMMARY

Apart from its ornamental value, Marigold (Tagetes erecta L.) flowers are well known as an herbal remedy due to its antimicrobial, anti-inflammatory, and anti-oxidant activities. Epidemiological studies have implicated prolonged exposure to ultraviolet radiations & blue light and in turn oxidative stress in the pathogenesis of the majority of the eye diseases, since childhood. Studies have shown that with age a number of changes occur predisposing the retinal various organs and tissues to oxidative stress. These changes manifest in decreased levels in plasma of Vitamin C, Vitamin E, glutathione, Retinal Pigment Epithelium (RPE), Catalase (CAT), Super Oxide Dismutase (SOD), Thiobarbituric Acid Reactive Substance (TBARS), and total anti-oxidant capacity (TAC). Age- and diet-related loss of Lutein and Zeaxanthin enhance phototoxic damage to the eye, and thus supplementation of these carotenoids becomes vital for maintaining optimal eye health

In the present study, XanMax^® 2002 oil, a supplement constituting lutein and trans-Zeaxanthin, extracted from the flowers of T. erecta, was evaluated for its modulatory effect on anti-oxidant enzymes and macular pigments in the serum and macula of the Swiss albino rats. XanMax^® 2002 oil exhibited significant elevation of anti-oxidant enzyme levels in treated animals in dose-dependent manner. Concomitantly, the TAC has also been found to show similar increment at the end of the study period. This study revealed significant expression of the two macular pigments investigated.

Abbreviations used: AMD: Age related Macular Diseases; RPE: Retinal Pigment Epithelium; CAT: Catalase; SOD: Super Oxide Dismutase; TAC: Total Antioxidant Capacity; ROS: Reactive Oxygen Species; LC-MS: Liquid chromatography-mass spectrometry; p.o.: Per Orally; CMC Carboxymethyl cellulose.

Effects of the Macular Carotenoid Lutein in Human Retinal Pigment Epithelial Cells

Retinal pigment epithelial (RPE) cells are central to retinal health and homoeostasis. Oxidative stress-induced damage to the RPE occurs as part of the pathogenesis of age-related macular degeneration and neovascular retinopathies (e.g., retinopathy of prematurity, diabetic retinopathy). The xanthophyll carotenoids, lutein and zeaxanthin, are selectively taken up by the RPE, preferentially accumulated in the human macula, and transferred to photoreceptors. These macular xanthophylls protect the macula (and the broader retina) via their antioxidant and photo-protective activities. This study was designed to investigate effects of various carotenoids (β-carotene, lycopene, and lutein) on RPE cells subjected to either hypoxia or oxidative stress, in order to determine if there is effect specificity for macular pigment carotenoids. Using human RPE-derived ARPE-19 cells as an in vitro model, we exposed RPE cells to various concentrations of the specific carotenoids, followed by either graded hypoxia or oxidative stress using tert-butyl hydroperoxide (tBHP). The results indicate that lutein and lycopene, but not β-carotene, inhibit cell growth in undifferentiated ARPE-19 cells. Moreover, cell viability was decreased under hypoxic conditions. Pre-incubation of ARPE-19 cells with lutein or lycopene protected against tBHP-induced cell loss and cell co-exposure of lutein or lycopene with tBHP essentially neutralized tBHP-dependent cell death at tBHP concentrations up to 500 μM. Our findings indicate that lutein and lycopene inhibit the growth of human RPE cells and protect the RPE against oxidative stress-induced cell loss. These findings contribute to the understanding of the protective mechanisms attributable to retinal xanthophylls in eye health and retinopathies.

Protective Effects of Oral Astaxanthin Nanopowder against Ultraviolet-Induced Photokeratitis in Mice

Purpose

Astaxanthin (AST) has a strong antioxidant cellular membrane chaperone protective effect. Recently, a water-soluble nanosized AST (nano-AST) form was produced, which is expected to improve the efficacy of oral intake effects. The purpose of this study was to examine whether oral nano-AST has therapeutic effects on UV-induced photokeratitis in mice.

Methods

C57BL/6 mice were administered twice with either nano-AST, AST oil, lutein, or bilberry extracts 3 hours before and shortly before UV irradiation (dose: 400 mJ/cm²). The corneas were collected 24 hours after irradiation and stained with H&E and TUNEL. NF-κB, dihydroethidium (DHE), COX-2, p-IκB-α, TNFα, and CD45 expression were evaluated through immunohistochemistry, Western blot analysis, and qPCR.

Results

Corneal epithelium was significantly thicker in mice orally administered with nano-AST than in the others (p < 0.01), with significantly less NF-κB nucleus translocation (p < 0.001), and significantly fewer TUNEL cells (p < 0.01). Weaker DHE signals were detected in the nano-AST group (p < 0.05) relative to the others. Furthermore, reduced inflammation and decreased cell death in corneal tissue were observed in the nano-AST group, as indicated by a reduction in the expression of COX-2, p-IκB-α, TNFα, and CD45.

Conclusions

Oral administration of nano-AST demonstrated a protective effect on UV-induced photokeratitis via antioxidative, anti-inflammatory, and antiapoptotic activity.

Lutein and zeaxanthin isomers modulates lipid metabolism and the inflammatory state of retina in obesity-induced high-fat diet rodent model

Background

Several studies associated high-fat intakes with a high incidence of age-related macular degeneration (AMD). Lutein and Zeaxanthin isomers (L/Zi) may counteract reactive oxygen species produced by oxidative stress. The present study was conducted to determine the possible effects of L/Zi administration on lipid profile, protein genes associated with oxidative stress and inflammation pathways in the obesity induced by a high-fat diet (HFD) in rodents.

Methods

Twenty-eight male Wistar rats were allocated into four groups as follows: (i) Control, (ii) Control + L/Zi, (iii) High Fat Diet (HFD), and (iv) HFD+ L/Z. L/Zi was administrated for 8 weeks at a daily dose of 100 mg/kg BW.

Results

L/Zi administration significantly reduced insulin and free fatty acid (FFA) levels (P < 0.001) and ameliorated the oxidative damage by reducing malondialdehyde (MDA) concentration and increasing antioxidant enzymes activities of retina induced by HFD. In addition, supplementation decreased the levels of vascular endothelial growth factor (VEGF), inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-κB) and intercellular adhesion molecule-1 (ICAM) (P < 0.001, respectively) and improved nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) gene proteins in retinal tissues (P < 0.001).

Conclusion

Rats fed with HFD exhibited increased oxidative stress and upregulation of inflammatory indicators. However, L/Zi supplementation modulates genes involved oxidative stress and inflammation including NF-κB and Nrf2 signaling pathways in the retina which may contribute to ameliorating retinal damage induced by HFD.

The Pharmacological Effects of Lutein and Zeaxanthin on Visual Disorders and Cognition Diseases

Lutein (L) and zeaxanthin (Z) are dietary carotenoids derived from dark green leafy vegetables, orange and yellow fruits that form the macular pigment of the human eyes. It was hypothesized that they protect against visual disorders and cognition diseases, such as age-related macular degeneration (AMD), age-related cataract (ARC), cognition diseases, ischemic/hypoxia induced retinopathy, light damage of the retina, retinitis pigmentosa, retinal detachment, uveitis and diabetic retinopathy. The mechanism by which they are involved in the prevention of eye diseases may be due their physical blue light filtration properties and local antioxidant activity. In addition to their protective roles against light-induced oxidative damage, there are increasing evidences that L and Z may also improve normal ocular function by enhancing contrast sensitivity and by reducing glare disability. Surveys about L and Z supplementation have indicated that moderate intakes of L and Z are associated with decreased AMD risk and less visual impairment. Furthermore, this review discusses the appropriate consumption quantities, the consumption safety of L, side effects and future research directions.

Lutein and Zeaxanthin-Food Sources, Bioavailability and Dietary Variety in Age-Related Macular Degeneration Protection

Lutein and zeaxanthin (L/Z) are the predominant carotenoids which accumulate in the retina of  the eye. The impact of L/Z intake on the risk and progression of age-related macular degeneration (AMD),  a leading cause of blindness in the developed world, has been investigated in cohort studies and clinical  trials. The aims of this review were to critically examine the literature and evaluate the current evidence  relating to L/Z intake and AMD, and describe important food sources and factors that increase the  bioavailability of L/Z, to inform dietary models. Cohort studies generally assessed L/Z from dietary  sources, while clinical trials focused on providing L/Z as a supplement. Important considerations to take  into account in relation to dietary L/Z include: nutrient-rich sources of L/Z, cooking methods, diet variety  and the use of healthy fats. Dietary models include examples of how suggested effective levels of L/Z can  be achieved through diet alone, with values of 5 mg and 10 mg per day described. These diet models  depict a variety of food sources, not only from dark green leafy vegetables, but also include pistachio nuts  and other highly bioavailable sources of L/Z such as eggs. This review and the diet models outlined  provide information about the importance of diet variety among people at high risk of AMD or with early  signs and symptoms of AMD.

Optimized, Fast-Throughput UHPLC-DAD Based Method for Carotenoid Quantification in Spinach, Serum, Chylomicrons, and Feces

An improved UHPLC-DAD-based method was developed and validated for quantification of major carotenoids present in spinach, serum, chylomicrons, and feces. Separation was achieved with gradient elution within 12.5 min for six dietary carotenoids and the internal standard, echinenone. The proposed method provides, for all standard components, resolution > 1.1, linearity covering the target range (R > 0.99), LOQ < 0.035 mg/L, and intraday and interday RSDs < 2 and 10%, respectively. Suitability of the method was tested on biological matrices. Method precision (RSD%) for carotenoid quantification in serum, chylomicrons, and feces was below 10% for intra- and interday analysis, except for lycopene. Method accuracy was consistent with mean recoveries ranging from 78.8 to 96.9% and from 57.2 to 96.9% for all carotenoids, except for lycopene, in serum and feces, respectively. Additionally, an interlaboratory validation study on spinach at two institutions showed no significant differences in lutein or β-carotene content, when evaluated on four occasions.

Negative effects of divalent mineral cations on the bioaccessibility of carotenoids from plant food matrices and related physical properties of gastro-intestinal fluids

Proposed interaction of divalent cations, bile acids, and fatty acids in the intestine, resulting in precipitation and entrapment of carotenoids.