Influence/impact of lutein complex (marigold flower and wolfberry) on visual function with early age-related macular degeneration subjects: A randomized clinical trial

Potential application of traditional Chinese medicine in age-related macular degeneration-focusing on mitophagy

Retinal pigment epithelial cell and neuroretinal damage in age-related macular degeneration (AMD) can lead to serious visual impairments and blindness. Studies have shown that mitophagy, a highly specialized cellular degradation system, is implicated in the pathogenesis of AMD. Mitophagy selectively eliminates impaired or non-functioning mitochondria via several pathways, such as the phosphatase and tensin homolog-induced kinase 1/Parkin, BCL2-interacting protein 3 and NIP3-like protein X, FUN14 domain-containing 1, and AMP-activated protein kinase pathways. This has a major impact on the maintenance of mitochondrial homeostasis. Therefore, the regulation of mitophagy could be a promising therapeutic strategy for AMD. Traditional Chinese medicine (TCM) uses natural products that could potentially prevent and treat various diseases, such as AMD. This review aims to summarize recent findings on mitophagy regulation pathways and the latest progress in AMD treatment targeting mitophagy, emphasizing methods involving TCM.

Lutein Production and Extraction from Microalgae: Recent Insights and Bioactive Potential

Microalgae have been reported to be excellent producers of bioactive molecules. Lutein is a pigment reported to have various beneficial effects for humans, and especially for eye well-being. In the current review, we summarize various methods that have been developed to optimize its extraction and bioactivities reported for human health. Several protective effects have been reported for lutein, including antioxidant, anticancer, anti-inflammatory, and cardioprotective activity. This review also reports attempts to increase lutein production by microalgae by changing culturing parameters or by using pilot-scale systems. Genetic engineering lutein production is also discussed. Considering the increasing aging of the worldwide population will create an increased need for lutein, a viable economic and eco-sustainable method to produce lutein is needed to face this market demand.

Effect of xanthophyll-rich food and supplement intake on visual outcomes in healthy adults and those with eye disease: a systematic review, meta-analysis, and meta-regression of randomized controlled trials

CONTEXT

Xanthophyll intake is known to improve eye health; however, its benefits on visual outcomes have not been systematically studied, particularly in a population with eye diseases.

OBJECTIVE

A systematic review, meta-analysis, and meta-regression were conducted to investigate the effect of xanthophyll intake on visual outcomes, and further subgroup analysis was performed on the basis of eye disease status.

DATA SOURCES

The PubMed, Scopus, Embase, CINAHL, Cochrane, and Web of Science databases were searched, and relevant randomized controlled trials were identified.

DATA EXTRACTION

For systematic review, meta-analysis, and meta-regression, 43, 25, and 21 articles were selected, respectively.

DATA ANALYSIS

Xanthophyll intake enhanced macular pigment optical density (MPOD) for both heterochromatic flicker photometry (weighted mean difference [WMD], 0.05; 95% confidence interval [CI], 0.03-0.07) and autofluorescence imaging (WMD, 0.08; 95%CI, 0.05-0.11) measurements and decreased photostress recovery time (WMD, -2.35; 95%CI, -4.49 to -0.20). While enhancement in visual acuity logarithm of the minimum angle of resolution was observed in response to the xanthophyll-rich food and supplement intake only for patients with eye disease (WMD, -0.04; 95%CI, -0.07 to -0.01). Meta-regression showed a positive correlation between change in MPOD (heterochromatic flicker photometry) and the corresponding change in serum lutein levels (regression coefficient = 0.068; P = 0.00).

CONCLUSION

Intake of xanthophyll-rich food or supplements can improve eye health. Additional improvement in visual acuity was observed in patients with eye disease. A positive association between MPOD and serum lutein level, while absent with dietary xanthophyll intake, suggests the importance of bioavailability when examining the effect of xanthophyll on eye health.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021295337.

Potential roles of dietary zeaxanthin and lutein in macular health and function

Lutein, zeaxanthin, and meso-zeaxanthin are three xanthophyll carotenoid pigments that selectively concentrate in the center of the retina. Humans cannot synthesize lutein and zeaxanthin, so these compounds must be obtained from the diet or supplements, with meso-zeaxanthin being converted from lutein in the macula. Xanthophylls are major components of macular pigments that protect the retina through the provision of oxidant defense and filtering of blue light. The accumulation of these three xanthophylls in the central macula can be quantified with non-invasive methods, such as macular pigment optical density (MPOD). MPOD serves as a useful tool for assessing risk for, and progression of, age-related macular degeneration, the third leading cause of blindness worldwide. Dietary surveys suggest that the dietary intakes of lutein and zeaxanthin are decreasing. In addition to low dietary intake, pregnancy and lactation may compromise the lutein and zeaxanthin status of both the mother and infant. Lutein is found in modest amounts in some orange- and yellow-colored vegetables, yellow corn products, and in egg yolks, but rich sources of zeaxanthin are not commonly consumed. Goji berries contain the highest known levels of zeaxanthin of any food, and regular intake of these bright red berries may help protect against the development of age-related macular degeneration through an increase in MPOD. The purpose of this review is to summarize the protective function of macular xanthophylls in the eye, speculate on the compounds' role in maternal and infant health, suggest the establishment of recommended dietary values for lutein and zeaxanthin, and introduce goji berries as a rich food source of zeaxanthin.

Therapeutic Approaches for Age-Related Macular Degeneration

Damage to the retinal pigment epithelium, Bruch's membrane and/or tissues underlying macula is known to increase the risk of age-related macular degeneration (AMD). AMD is commonly categorized in two distinct types, namely, the nonexudative (dry form) and the exudative (wet form). Currently, there is no ideal treatment available for AMD. Recommended standard treatments are based on the use of vascular endothelial growth factor (VEGF), with the disadvantage of requiring repeated intravitreal injections which hinder patient's compliance to the therapy. In recent years, several synthetic and natural active compounds have been proposed as innovative therapeutic strategies against this disease. There is a growing interest in the development of formulations based on nanotechnology because of its important role in the management of posterior eye segment disorders, without the use of intravitreal injections, and furthermore, with the potential to prolong drug release and thus reduce adverse effects. In the same way, 3D bioprinting constitutes an alternative to regeneration therapies for the human retina to restore its functions. The application of 3D bioprinting may change the current and future perspectives of the treatment of patients with AMD, especially those who do not respond to conventional treatment. To monitor the progress of AMD treatment and disease, retinal images are used. In this work, we revised the recent challenges encountered in the treatment of different forms of AMD, innovative nanoformulations, 3D bioprinting, and techniques to monitor the progress.

Nutraceuticals and Food-Grade Lipid Nanoparticles: From Natural Sources to a Circular Bioeconomy Approach

Nutraceuticals have gained increasing attention over the last years due to their potential value as therapeutic compounds formulated from natural sources. For instance, there is a wide range of literature about the cardioprotective properties of omega-3 lipids and the antioxidant value of some phenolic compounds, which are related to antitumoral activity. However, the value of nutraceuticals can be limited by their instability under gastric pH and intestinal fluids, their low solubility and absorption. That is why encapsulation is a crucial step in nutraceutical design. In fact, pharmaceutical nanotechnology improves nutraceutical stability and bioavailability through the design and production of efficient nanoparticles (NPs). Lipid nanoparticles protect the bioactive compounds from light and external damage, including the gastric and intestinal conditions, providing a retarded delivery in the target area and guaranteeing the expected therapeutic effect of the nutraceutical. This review will focus on the key aspects of the encapsulation of bioactive compounds into lipid nanoparticles, exploring the pharmaceutical production methods available for the synthesis of NPs containing nutraceuticals. Moreover, the most common nutraceuticals will be discussed, considering the bioactive compounds, their natural source and the described biological properties.

Lutein exerts its cardioprotective effect against the experimental model of isoprenaline-induced myocardial infarction via MIAT/miR-200a/Nrf2/TXINP pathway

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality worldwide. Lutein (LU) possesses numerous pharmacological activities, including anti-inflammatory, antioxidant, and antiapoptotic effects. This study aimed to investigate the cardioprotective potential of LU in isoprenaline (ISO)-induced MI and to explore its molecular mechanisms of action. AMI was induced by two consecutive subcutaneous doses of ISO (65 mg/kg; s.c.). The LU group was pretreated with LU (20 mg/kg; p.o.) for 30 days followed by ISO injections on Days 29 and 30. ISO group showed elevated serum creatine kinas-MB (CK-MB) and considerable electrocardiographic changes along with reduced ejection fraction compared to the normal group. LU pretreatment could decrease serum CK-MB activity, normalize QRS and QTc intervals and restore ejection fraction compared to the untreated group. The ISO group demonstrated infarcted-like lesions, which were ameliorated in the LU-pretreated group. Immunohistochemical investigation revealed upregulated cardiac troponin T (cTn T) and desmin expressions in the LU-pretreated group. LU pretreatment also enhanced cardiac thioredoxin (Trx) and glutathione (GSH) contents as well as reduced lipid peroxidation, compared to the untreated group. Importantly, LU pretreatment could downregulate long noncoding MI associated transcript (lncRNA MIAT) and thioredoxin-interacting protein (TXNIP) and augment micro RNA (miR)-200a and nuclear factor erythroid 2-related factor 2 (Nrf2) expressions compared to the ISO group. Moreover, a significant inverse correlation between MIAT and miR-200a was observed. In conclusion, this study revealed that LU could ameliorate ISO-induced MI in rats by modulating MIAT/miR-200a/Nrf2 pathway.

Genetic factors involved in modulating lutein bioavailability

Lutein exhibits effective antioxidant activity conferring protective action against oxidative stress in age-related macular degeneration and cognitive decline. The inability to synthesize these compounds by the human body and the necessity to combat day-to-day oxidative stress prioritizes daily consumption of lutein. However, the bioavailability of the orally consumed lutein largely depends on its gastrointestinal absorption and subsequent metabolism which is in turn governed by various intrinsic and extrinsic factors. One of the most important yet least studied factors is the genetic make-up of an individual. The proteins that partake in the absorption, transportation, metabolism and excretion of lutein are encoded by the genes that experience inter-individual variability. Reports suggest that the unanimous effect of phenotypes resulting from such inter-individual variability in the genes of interest causes modulation of lutein bioavailability which is discussed in detail in this review article. However, despite the available reports, a community-based approach to a larger population is required to obtain a stronger understanding of the relationship between inter-individual variability among these genes and lutein bioavailability. Such an understanding of nutrigenetics could not only pave a way to decipher mechanisms that modulate lutein bioavailability but also help in setting the dosage requirements of each patient.

Carotenoid metabolite and transcriptome dynamics underlying flower color in marigold (Tagetes erecta L.)

Marigold (Tagetes erecta L.) is an important ornamental plant with a wide variety of flower colors. Despite its economic value, few biochemical and molecular studies have explored the generation of flower color in this species. To study the mechanism underlying marigold petal color, we performed a metabolite analysis and de novo cDNA sequencing on the inbred line 'V-01' and its petal color mutant 'V-01M' at four flower developmental stages. A total of 49,217 unigenes were identified from 24 cDNA libraries. Based on our metabolites and transcriptomic analyses, we present an overview of carotenoid biosynthesis, degradation, and accumulation in marigold flowers. The carotenoid content of the yellow mutant 'V-01M' was higher than that of the orange inbred line 'V-01', and the abundances of the yellow compounds lutein, neoxanthin, violaxanthin, zeaxanthin, and antheraxanthin were significantly higher in the mutant. During flower development, the carotenoid biosynthesis genes were upregulated in both 'V-01' and 'V-01M', with no significant differences between the two lines. By contrast, the carotenoid degradation genes were dramatically downregulated in the yellow mutant 'V-01M'. We therefore speculate that the carotenoid degradation genes are the key factors regulating the carotenoid content of marigold flowers. Our research provides a large amount of transcriptomic data and insights into the marigold color metabolome.

Determination of carotenoids in flowers and food supplements by HPLC-DAD

Marigold flowers (Tagetes patula and Calendula officinalis) were chosen for analysis because they are the most often used source of lutein and its isomer zeaxanthin for the production of food supplements on the Czech market. Direct extraction and extraction with alkaline hydrolysis were compared to detect free or bound carotenoids. For carotenoid separation, C18 and C30 columns were used. A new method for determination of carotenoid content in food supplements in form of capsules has been developed and validated. All matrices were analysed by high-performance liquid chromatography with diode array detection (HPLC-DAD). It has been found that alkaline hydrolysis is required for both Marigold flowers and food supplements to release lutein from ester bonds to fatty acids. In Calendula officinalis lutein in the concentration of 807—1472 mg·kg−1 of dry matter was detected. Tagetes patula has been identified as a better lutein source with the content of 5906—8677 mg·kg−1 of dry matter. It has been found that the content of lutein and zeaxanthin in commercial food supplements (Lutein Complex Premium and Occutein Brillant) is consistent with the declared quantity. Linearity of the HPLC-DAD method ranged from 0.1—20 μg·mL−1 with the limit of quantification (LOQ) of 1.7 mg·kg−1 for lutein in Marigold flowers and 200 mg·kg−1 in food supplements. Repeatability was 2.3 % for lutein in all tested matrices.

Nutraceutical approach to enhance lutein bioavailability via nanodelivery systems

Lutein, a potent dietary carotenoid, has considerable biological activity and confers protection against age-related macular degeneration. Its bioavailability following consumption, however, depends on its rate of degradation. Nanodelivery systems with improved efficacy and stability are currently being developed to increase the bioavailability of lutein. This review examines nutraceutical approaches used in the development of such nanodelivery systems. It describes the methods of lutein preparation, the characteristics of various delivery systems, and the lutein delivery profile. In order to enhance lutein loading, provide electrostatic stabilization, and achieve the controlled release of lutein, adjuvants such as dextran moieties, whey proteins, medium-chain triglycerides, and chitosan polymers can be used to effectively reduce the particle size (< 70 nm) and improve encapsulation efficiency (to 99.5%). The improved bioavailability of lutein via nanocrystals incorporated into rapidly dissolving films for oral consumption is a new area of exploratory research. This review aims to provide clarity about current research aimed at enhancing the bioavailability of lutein through the development of nanodelivery systems.

The protective role of lutein on isoproterenol-induced cardiac failure rat model through improving cardiac morphology, antioxidant status via positively regulating Nrf2/HO-1 signalling pathway

Context: Lutein (LU) is a major carotenoid with various pharmacological activities including anti-inflammatory, antioxidant and anti-apoptosis. Objective: The cardioprotective efficacy of LU was determined by evaluating the biochemical and histopathological changes in isoproterenol (ISO) induced myocardial infarction (MI) rat model. Materials and methods: Healthy male albino rats (n = 40) were segregated into 4 equal groups. Group I (control) rats were administered with olive oil, Group II (LU) rats were orally pre-treated with only 40 mg of LU for 28 days, Group III (MI induced) rats were injected (subcutaneously; s.c) with 85 mg/kg of ISO for 2 consecutive days, whereas Group IV (LU + ISO) rats were pre-treated with 40 mg of LU for 28 days before ISO induction. Results: ISO-induced group showed increased infarct size and cardiac/inflammatory/apoptotic markers. However, pre-treatment with LU (28 days) considerably reduced (p < 0.01) the infarct size (14%), lipid peroxidation product (MDA;42%), cardiac markers [(lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB), cardiac troponin T (cTn T)], inflammatory markers [IL-1β, IL-6, tumour necrosis factor alpha (TNF-α), nuclear factor kappa B p65 subunit (NF-κB p65)] and apoptotic markers (caspase-3 and -9). Also, LU significantly improved (p < 0.01) the antioxidants [catalase (CAT), superoxide dismutase (SOD)] as well as markedly upregulated (p < 0.01) the protein expression of HO-1 and Nrf2. Moreover, LU considerably reversed all the histopathological changes and thus exhibits its cardioprotective activity. Conclusion: LU exhibits potent cardioprotective activity against ISO-induced cardiotoxicity and might be recommended with standard cardioprotective agents for treating various MI-related complications.

Nano based lutein extraction from marigold petals: optimization using different surfactants and co-surfactants

Nanotechnology has high potential in processing of industrial crops and by-products in order to extract valuable biological active compounds. The present study endeavored to take advantage of nanotech approach (i.e microemulsion, ME), as a novel green technique, for lutein extraction from marigold (Tagetes erecta) as an industrial crop. The pseudo-ternary phase diagrams confirmed the effect of surfactant type on the formation of mono-phasic lutein MEs. The combination of sucrose monopalmitate:1-poropanol (1:5) showed the highest efficiency in the presence of marigold petal powder (MPP, 18%) and water (42%). In addition, the efficiency of primitive MEs (without co-surfactants) was outstandingly increased as MPP was moistened by co-surfactants. Furthermore, different MEs resulted in various droplet size (14–250nm), PDI (0.05–0.32) and zeta potential (−1.96 to −38.50 mV). These findings revealed the outstanding importance of the surfactants and co-surfactants and their ratio on the extraction capability of MEs. These findings also proved the capability of microemulsion technique (MET) as a potential alternative to conventional solvent with possible applicability for extraction of lutein and other industrial plant based bio-compounds.

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.

Photoprotective effects of cranberry juice and its various fractions against blue light-induced impairment in human retinal pigment epithelial cells

CONTEXT

Cranberry has numerous biological activities, including antioxidation, anticancer, cardioprotection, as well as treatment of urinary tract infection (UTI), attributed to abundant phenolic contents.

OBJECTIVE

The current study focused on the effect of cranberry juice (CJ) on blue light exposed human retinal pigment epithelial (ARPE-19) cells which mimic age-related macular degeneration (AMD).

MATERIALS AND METHODS

Preliminary phytochemical and HPLC analysis, as well as total antioxidant capacity and scavenging activity of cranberry ethyl acetate extract and different CJ fractions (condensed tannins containing fraction), were evaluated. In cell line model, ARPE-19 were irradiated with blue light at 450 nm wavelength for 10 h (mimic AMD) and treated with different fractions of CJ extract at different doses (5-50 μg/mL) by assessing the cell viability or proliferation rate using MTT assay (repairing efficacy).

RESULTS

Phytochemical and HPLC analysis reveals the presence of several phenolic compounds (flavonoids, proanthocyanidin, quercetin) in ethyl acetate extract and different fractions of CJ. However, the condensed tannin containing fraction of ethyl acetate extract of CJ displayed the greater (p < 0.05) scavenging activity especially at the dose of 1 mg/mL. Similarly, the condensed tannin containing fraction at 50 μg/mL presented better (p < 0.05) repairing ability (increased cell viability). Furthermore, the oligomeric condensed tannin containing fraction display the best (p < 0.05) repairing efficiency at 50 μg/mL.

DISCUSSION AND CONCLUSION

In conclusion, this study distinctly proved that condensed tannin containing fraction of CJ probably exhibits better free radicals scavenging activity and thereby effectively protected the ARPE-19 cells and thus, hampers the progress of AMD.

Serum and macular response to carotenoid-enriched egg supplementation in human subjects: the Egg Xanthophyll Intervention clinical Trial (EXIT)

The macular carotenoids lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ) accumulate at the macula, where they are collectively referred to as macular pigment (MP). Augmentation of this pigment, typically achieved through diet and supplementation, enhances visual function and protects against progression of age-related macular degeneration. However, it is known that eggs are a rich dietary source of L and Z, in a highly bioavailable matrix. In this single-blind placebo-controlled study, L- and MZ-enriched eggs and control non-enriched eggs were fed to human subjects (mean age 41 and 35 years, respectively) over an 8-week period, and outcome measures included MP, visual function and serum concentrations of carotenoids and cholesterol. Serum carotenoid concentrations increased significantly in control and enriched egg groups, but to a significantly greater extent in the enriched egg group (P<0·001 for L, Z and MZ). There was no significant increase in MP in either study group post intervention, and we saw no significant improvement in visual performance in either group. Total cholesterol increased significantly in each group, but it did not exceed the upper limit of the normative range (6·5 mmol/l). Therefore, carotenoid-enriched eggs may represent an effective dietary source of L, Z and MZ, reflected in significantly raised serum concentrations of these carotenoids, and consequentially improved bioavailability for capture by target tissues. However, benefits in terms of MP augmentation and /or improved visual performance were not realised over the 8-week study period, and a study of greater duration will be required to address these questions.