Xanthophylls Lutein Research Articles

Pistachio Consumption Increases Macular Pigment Optical Density in Healthy Adults: A Randomized Controlled Trial

BackgroundPistachios are a bioavailable source of the xanthophyll lutein. Along with zeaxanthin, these plant pigments are major components of macular pigment (MP) in the human retina. MP can be non-invasively measured and is referred to as MP optical density (MPOD). MPOD is modifiable with dietary interventions that include lutein and zeaxanthin (L/Z). Higher MPOD protects the eye from light damage and is positively associated with eye health. ObjectivesThis dietary intervention study aimed to evaluate the effect of pistachio consumption on MPOD. MethodsThis single-blinded, randomized controlled trial compared a 12-week pistachio intervention (2 oz/d) with usual diet (UD) on MPOD and serum L/Z in middle-aged to older healthy adults (n = 36) in a 1:1 randomization scheme. Participants were selected for habitually low L/Z intake and low baseline MPOD. MPOD was measured using heterochromatic flicker photometry at 4 retinal eccentricities during baseline, week 6, and week 12 study visits. Serum L/Z was analyzed using high-performance liquid chromatography. Primary statistical analysis was conducted on an intent-to-treat basis using repeated-measure analysis of variance. ResultsCompared with UD, MPOD of the participants in the pistachio intervention group (PIS) had significantly increased (P < 0.001) at all eccentricities over the initial 6-wk period. This increase was maintained at week 12. MPOD in the UD participants did not change during the 12-week period. Serum lutein concentration followed a similar pattern to MPOD; serum cis-lutein and zeaxanthin did not change in either group over the 12-wk intervention. ConclusionsThe results of our study demonstrate that a dietary intervention with pistachios is efficacious in increasing MPOD in healthy adults selected for habitually low intake of L/Z and low baseline MPOD. This suggests that pistachio consumption could be an effective dietary strategy for preserving eye health. Future studies need to evaluate the generalizability of our findings to other populations.This trial was registered at clinicaltrials.gov as NCT05283941.

A Scoping Review on Carotenoid Profiling in Passiflora spp.: A Vast Avenue for Expanding the Knowledge on the Species.

The Passiflora genus is recognised for its ethnopharmacological, sensorial, and nutritional significance. Yet, the screening of its dietary and bioactive molecules has mainly targeted hydrophilic metabolites. Following the PRISMA-P protocol, this review assessed the current knowledge on carotenoid composition and analysis within Passiflora, examining 968 records from seven databases and including 17 studies focusing on carotenoid separation and identification in plant parts. Those publications originated in America and Asia. P. edulis was the most frequently examined species of a total of ten, while pulp was the most studied plant part (16 studies). Carotenoid analysis involved primarily high-performance liquid chromatography separation on C18 columns and detection using diode array detectors (64.71%). Most studies identified the provitamin A β-carotene and xanthophylls lutein and zeaxanthin, with their geometric configuration often neglected. Only one study described carotenoid esters. Besides the methodology's insufficient description, the lack of use of more accurate techniques and practices led to a high risk of bias in the carotenoid assignment in 17.65% of the articles. This review highlights the opportunity to broaden carotenoid studies to other species and parts within the diverse Passiflora genus, especially to wild, locally available fruits, which may have a strategic role in enhancing food diversity and security amidst climatic changes. Additionally, it urges the use of more accurate and efficient analytical methods based on green chemistry to better identify Passiflora carotenoids.

Generation and physiological characterization of genome-edited Nicotiana benthamiana plants containing zeaxanthin as the only leaf xanthophyll

Main conclusionSimultaneous genome editing of the two homeologousLCYeandZEPgenes ofNicotiana benthamianaresults in plants in which all xanthophylls are replaced by zeaxanthin.Plant carotenoids act both as photoreceptors and photoprotectants in photosynthesis and as precursors of apocarotenoids, which include signaling molecules such as abscisic acid (ABA). As dietary components, the xanthophylls lutein and zeaxanthin have photoprotective functions in the human macula. We developed transient and stable combinatorial genome editing methods, followed by direct LC–MS screening for zeaxanthin accumulation, for the simultaneous genome editing of the two homeologous Lycopene Epsilon Cyclase (LCYe) and the two Zeaxanthin Epoxidase (ZEP) genes present in the allopolyploid Nicotiana benthamiana genome. Editing of the four genes resulted in plants in which all leaf xanthophylls were substituted by zeaxanthin, but with different ABA levels and growth habits, depending on the severity of the ZEP1 mutation. In high-zeaxanthin lines, the abundance of the major photosystem II antenna LHCII was reduced with respect to wild-type plants and the LHCII trimeric state became unstable upon thylakoid solubilization. Consistent with the depletion in LHCII, edited plants underwent a compensatory increase in PSII/PSI ratios and a loss of the large-size PSII supercomplexes, while the level of PSI-LHCI supercomplex was unaffected. Reduced activity of the photoprotective mechanism NPQ was shown in high-zeaxanthin plants, while PSII photoinhibition was similar for all genotypes upon exposure to excess light, consistent with the antioxidant and photoprotective role of zeaxanthin in vivo.

Understanding the Excited-State Relaxation Mechanisms of Xanthophyll Lutein by Multi-configurational Electronic Structure Calculations.

The contradictory behaviors in light harvesting and non-photochemical quenching make xanthophyll lutein the most attractive functional molecule in photosynthesis. Despite several theoretical simulations on the spectral properties and excited-state dynamics, the atomic-level photophysical mechanisms need to be further studied and established, especially for an accurate description of geometric and electronic structures of conical intersections for the lowest several electronic states of lutein. In the present work, semiempirical OM2/MRCI and multi-configurational restricted active space self-consistent field methods were performed to optimize the minima and conical intersections in and between the 1Ag-, 2Ag-, 1Bu+, and 1Bu- states. Meanwhile, the relative energies were refined by MS-CASPT2(10,8)/6-31G*, which can reproduce correct electronic state properties as those in the spectroscopic experiments. Based on the above calculation results, we proposed a possible excited-state relaxation mechanism for lutein from its initially populated 1Bu+ state. Once excited to the optically bright 1Bu+ state, the system will propagate along the key reaction coordinate, i.e., the stretching vibration of the conjugated carbon chain. During this period of time, the 1Bu- state will participate in and forms a resonance state between the 1Bu- and 1Bu+ states. Later, the system will rapidly hop to the 2Ag- state via the 1Bu+/2Ag- conical intersection. Finally, the lutein molecule will survive in the 2Ag- state for a relatively long time before it internally converts to the ground state directly or via a twisted S1/S0 conical intersection. Notably, though the photophysical picture may be very different in solvents and proteins, the current theoretical study proposed a promising calculation protocol and also provided many valuable mechanistic insights for lutein and similar carotenoids.

Improved Bioavailability and Bioaccessibility of Lutein and Isoflavones in Cultured Cells In Vitro through Interaction with Ginger, Curcuma and Black Pepper Extracts.

Intestinal absorption is intrinsically low for lipophilic micronutrients and phytochemicals. Plant extracts acting as bioavailability enhancers can complement for this deficiency by modulation of both, physicochemical and biochemical parameters, in the absorption process. However, these interactions often are limited to specific conditions and the mechanisms and potential synergisms are poorly understood. In this work, we used a human intestinal cell line to characterize the impact of extracts from C. longa (curcuma), Z. officinale (ginger) and P.nigrum (black pepper) on uptake and transport rates of the xanthophylls lutein and zeaxanthin as well as soy isoflavones measured by HPLC-DAD. We found a significant increase in the uptake of lutein in the presence of curcuma extract and enhanced isoflavone transport rates mediated by curcuma and ginger extracts. Combinations of the plant extracts did not lead to any additional increase in uptake or transport rates. By investigation of mixed micelle incorporation efficiency, we could dismiss changes in bioaccessibility as a potential enhancing mechanism in our experimental setup. We further conducted a rhodamine 123 efflux assay and discovered inhibition of P-glycoproteins by the ginger and black pepper extracts, highlighting a plausible route of action leading to increased isoflavone bioavailability.

The Loroxanthin Cycle: A New Type of Xanthophyll Cycle in Green Algae (Chlorophyta).

Xanthophyll cycles (XC) have proven to be major contributors to photoacclimation for many organisms. This work describes a light-driven XC operating in the chlorophyte Chlamydomonas reinhardtii and involving the xanthophylls Lutein (L) and Loroxanthin (Lo). Pigments were quantified during a switch from high to low light (LL) and at different time points from cells grown in Day/Night cycle. Trimeric LHCII was purified from cells acclimated to high or LL and their pigment content and spectroscopic properties were characterized. The Lo/(L + Lo) ratio in the cells varies by a factor of 10 between cells grown in low or high light (HL) leading to a change in the Lo/(L + Lo) ratio in trimeric LHCII from .5 in low light to .07 in HL. Trimeric LhcbMs binding Loroxanthin have 5 ± 1% higher excitation energy (EE) transfer (EET) from carotenoid to Chlorophyll as well as higher thermo- and photostability than trimeric LhcbMs that only bind Lutein. The Loroxanthin cycle operates on long time scales (hours to days) and likely evolved as a shade adaptation. It has many similarities with the Lutein-epoxide – Lutein cycle (LLx) of plants.

The effects of lutein and zeaxanthin (Lute-genandreg;) supplementation, with and without natural mixed carotenoids on macular pigment optical density in healthy adult subjects: A randomized, double-blind, placebo-controlled study

Levels of the macular xanthophylls lutein, zeaxanthin and other carotenoids have been associated with slower progression of age-related macular degeneration potentially through their action by quenching reactive oxygen species, scavenging blue light and thereby protecting the eye from photo-oxidative damage. The objective of this clinical study was to assess the effect of Lutein and Zeaxanthin (Lute-gen&reg;) supplementation, with and without natural mixed carotenoids on macular pigment optical density (MPOD) in healthy adult subjects. A total of 93 subjects were randomized in a double blind, placebo controlled, parallel, three arm study which was followed up for 180 days. Subjects who met the inclusion criteria underwent general physical and ophthalmic examinations. Further, study specific macular pigment optical density (MPOD) was assessed through macular assessment Profile (MAP) test. Data obtained post study period were subjected to advanced statistical analysis to determine efficacy of Lutein and Zeaxanthin (Lute-gen&reg;) with and without natural mixed carotenoids on macular pigment optical density (MPOD). Lutein and Zeaxanthin (Lute-gen&reg;) supplementation, with natural carotenoids (P=0.0009) and without natural mixed carotenoids (P=0.0001) showed statistically significant improvements in the MPOD levels when compared to baseline from the last visit. On the other hand, the placebo arm (P=0.6179) did not show any significant change in MPOD levels. It can be concluded that higher levels of MPOD may reduce the risk of age-related macular degeneration (AMD) and provide necessary protection against oxidative damage and blue-light.

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.

Factors Differentiating the Antioxidant Activity of Macular Xanthophylls in the Human Eye Retina.

Macular xanthophylls, which are absorbed from the human diet, accumulate in high concentrations in the human retina, where they efficiently protect against oxidative stress that may lead to retinal damage. In addition, macular xanthophylls are uniquely spatially distributed in the retina. The zeaxanthin concentration (including the lutein metabolite meso-zeaxanthin) is ~9-fold greater than lutein concentration in the central fovea. These numbers do not correlate at all with the dietary intake of xanthophylls, for which there is a dietary zeaxanthin-to-lutein molar ratio of 1:12 to 1:5. The unique spatial distributions of macular xanthophylls—lutein, zeaxanthin, and meso-zeaxanthin—in the retina, which developed during evolution, maximize the protection of the retina provided by these xanthophylls. We will correlate the differences in the spatial distributions of macular xanthophylls with their different antioxidant activities in the retina. Can the major protective function of macular xanthophylls in the retina, namely antioxidant actions, explain their evolutionarily determined, unique spatial distributions? In this review, we will address this question.

Isolation and Characterization of Novel Chlorella Vulgaris Mutants With Low Chlorophyll and Improved Protein Contents for Food Applications.

Microalgae are widely used as food supplements due to their high protein content, essential fatty acids and amino acids as well as carotenoids. The addition of microalgal biomass to food products (e.g., baked confectioneries) is a common strategy to attract novel consumers. However, organoleptic factors such as color, taste and smell can be decisive for the acceptability of foods supplemented with microalgae. The aim of this work was to develop chlorophyll-deficient mutants of Chlorella vulgaris by chemically induced random mutagenesis to obtain biomass with different pigmentations for nutritional applications. Using this strategy, two C. vulgaris mutants with yellow (MT01) and white (MT02) color were successfully isolated, scaled up and characterized. The changes in color of MT01 and MT02 mutant strains were due to an 80 and 99% decrease in their chlorophyll contents, respectively, as compared to the original wild type (WT) strain. Under heterotrophic growth, MT01 showed a growth performance similar to that of the WT, reaching a concentration of 5.84 and 6.06 g L−1, respectively, whereas MT02 displayed slightly lower growth (4.59 g L−1). When grown under a light intensity of 100 μmol m−2 s−1, the pigment content in MT01 increased without compromising growth, while MT02 was not able to grow under this light intensity, a strong indication that it became light-sensitive. The yellow color of MT01 in the dark was mainly due to the presence of the xanthophyll lutein. On the other hand, phytoene was the only carotenoid detected in MT02, which is known to be colorless. Concomitantly, MT02 contained the highest protein content, reaching 48.7% of DW, a 60% increase as compared to the WT. MT01 exhibited a 30% increase when compared to that of the WT, reaching a protein content of 39.5% of DW. Taken together, the results strongly suggest that the partial abrogation of pigment biosynthesis is a factor that might promote higher protein contents in this species. Moreover, because of their higher protein and lower chlorophyll contents, the MT01 and MT02 strains are likely candidates to be feedstocks for the development of novel, innovative food supplements and foods.

Development of zeaxanthin‐rich tomato fruit through genetic manipulations of carotenoid biosynthesis

SummaryThe oxygenated carotenoid zeaxanthin provides numerous benefits to human health due to its antioxidant properties. Especially it is linked to protecting, together with the xanthophyll lutein, the retina in the human eye by filtering harmful blue light thus delaying the progression of age‐related macular degeneration (AMD), the most prevalent cause of blindness in developed countries. Despite its high nutritional value, zeaxanthin is less available than other substantial carotenoids in our diet. To solve this shortage, we chose to develop a new food source that would contain a high concentration of natural zeaxanthin. Tomato (Solanum lycopersicum L.) was selected as the target plant since it is the second largest vegetable crop grown worldwide and its fruit characteristically synthesizes and accumulates a high concentration of carotenoids. We employed two genetic approaches in order to enhance zeaxanthin biosynthesis in tomato fruit: a transgenic metabolic engineering and classical genetic breeding. A nontransgenic tomato line, named ‘Xantomato’, was generated whose fruit accumulated zeaxanthin at a concentration of 39 μg/g fresh weight (or 577 μg/g dry weight), which comprised ca. 50% of total fruit carotenoids compared to zero in the wild type. This is the highest concentration of zeaxanthin reached in a primary crop. Xantomato can potentially increase zeaxanthin availability in the human diet and serve as raw material for industrial applications.

Chemoprotective effect of carotenoids from Lycium barbarum L. on SH-SY5Y neuroblastoma cells treated with beauvericin

Goji berry has recently been introduced in Mediterranean diet and its consumption is increasing. This study aims to determine cytoprotection of lutein (LUT), zeaxanthin (ZEAX) and goji berry extract (GBE) rich in carotenoids against Beauvericin (BEA)-induced cytotoxicity on SH-SY5Y neuroblastoma cells. Both carotenoids and GBE showed cytoprotective effects. Cytoprotection was evaluated by simultaneous combination of the two xanthophylls LUT and ZEAX with BEA, as well as using pre-treatment assays. The highest protective effect occurred in 16%, 24% and 12% respectively for LUT, ZEAX and LUT + ZEAX incubating simultaneously with BEA, while by pre-treatment assay LUT showed a cytoprotection effect over 30% and ZEAX alone or LUT + ZEAX promoted only a slight cytoprotection (<10%). Pre-treatment assays with GBE, showed a cytoprotection, between 3 and 20%, for BEA concentrations ranging from 0.1 to 6.25 μM, whereas no protective effect was observed when the cells were simultaneously incubated with GBE and BEA. Finally, by means of CI-isobologram method, the interaction between LUT, ZEAX and BEA were evaluated, and the results showed an synergism effect for almost all combinations tested. The data presented shows a option of using goji berries to potentially mitigate the toxicity of beauvericin eventually present in foods.

Effects of 12-week avocado consumption on cognitive function among adults with overweight and obesity

ObjectivesExcess adiposity increases risk for cognitive impairment. Consumption of avocado, a highly bioavailable source of the xanthophyll lutein, has been shown to improve retinal lutein accumulation and cognitive function. Thus, we evaluated the influence of avocado consumption on cognitive function and lutein status among adults with overweight and obesity using a randomized-controlled trial with matching design for pertinent study outcomes. MethodsA cohort of 84 adults (25–45 years, 31 males) were randomized to a treatment group (N = 47) that received a 12-week daily meal with fresh Hass avocado or a control group (N = 37) that received an isocaloric meal (clinicaltrials.gov, NCT02740439). Serum lutein and macular pigment optical density (MPOD) were used to assess xanthophyll status. Attention and inhibition were assessed using the Flanker, Oddball and Nogo tasks with accompanying electroencephalographic (EEG) recording. ResultsParticipants in the treatment group exhibited improvements in serum lutein and accuracy in the Flanker task. However, there were no relationships between performance and changes in lutein status, nor neuroelectric variables. No significant changes in MPOD were observed. ConclusionDaily avocado intake over 12 weeks, after controlling for covariates, improved attentional inhibition and increased serum lutein concentrations among adults with overweight and obesity. However, the cognitive benefits were independent of changes in lutein concentrations. Additional work is necessary to determine non-carotenoid, or carotenoid interactive, mechanisms by which avocados may influence cognitive function.

Carrot leaves improve color and xanthophyll content of egg yolk in laying hens but are not as effective as commercially available marigold fortificant

Yellow and orange egg yolks are good sources of xanthophyll carotenoids, consumption of which is associated with health benefits, such as cancer prevention, eye health, and bone health. Industrial feed fortificants used to improve egg yolk color and carotenoid concentration typically are derived from marigold flowers. Green leafy vegetables are also concentrated sources of the xanthophylls lutein and zeaxanthin (L+Z), but they have not been rigorously evaluated in laying hen feeds as a yolk colorant. The addition of food manufacturing byproducts, including carrot leaves, to animal feed is a promoted method of improving animal nutrition. The ability of dehydrated carrot leaves to improve egg yolk color and L+Z concentration was evaluated by feeding laying hens (n = 40) white maize-based feeds fortified with 2 different dehydrated carrot leaves, marigold as a positive control, or no fortificant as a negative control for 28 D. After a 7-D washout period, the hens were separated into 4 groups, and eggs were collected every other day. Yolks were analyzed by using a portable colorimeter to define the color space and by ultra-performance liquid chromatography to determine the carotenoid profile. Carotenoid concentration rapidly declined from day 0 to 8, confirming adequate washout conditions. The white maize negative control (WM) day 28 lutein concentration (3.59 ± 0.51nmol/g) was significantly less than orange-carrot leaf-treated (OCL) (5.34 ± 0.36nmol/g) and red-carrot leaf-treated hens (RCL) (5.92 ± 1.00nmol/g) in addition to the marigold-treated hens (MG). However, MG was significantly higher than both leaf-treated groups. From day 8 (3.93 ± 0.74nmol/g) to 28 (9.32 ± 1.66nmol/g), MG had the largest increase in lutein and was the only treatment to surpass day 0 initial concentrations (8.50 ± 1.64nmol/g). A similar trend was observed for zeaxanthin and was reflected in the color space.

Nutrients for Prevention of Macular Degeneration and Eye-Related Diseases.

The risk of macular degeneration can be reduced through the consumption of antioxidant-rich foods, supplements, and nutraceutical formulas. This review focuses on the antioxidants, vitamins, and minerals that have been reported for reducing the risk of macular degeneration and other eye-related diseases. Antioxidants including anthocyanins, carotenoids, flavonoids, and vitamins have been shown to reduce the risk of eye-related diseases. Anthocyanins extracted from berries are powerful antioxidants. Cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin are anthocyanin aglycones detected in berries, currants, and other colored fruits and vegetables. β-Carotene, as well as xanthophyll lutein and zeaxanthin, have been reported to reduce the risk of macular degeneration. Flavonoids from plants help in the prevention of eye-related diseases through anti-inflammatory mechanisms. A combination of these antioxidants, vitamins, and minerals possess a synergistic effect on the prevention or risk reduction of macular degeneration. Formulas have been developed as dietary supplements to cater to the high demand from consumers and patients with eye problems. Many of the formulated dietary supplements that are sold in the market have been clinically proven for their efficacy to treat eye diseases. Although the bioactivities in the supplement capsules or tablets have been scientifically established for reducing risks of several diseases, which include macular degeneration and other eye-related diseases, knowledge on the right dosage, efficacy, and bioavailability of antioxidants, vitamins, and minerals is important for consumers. The information may help them make the best decision in choosing the right dietary supplements and nutraceuticals following the evidence-based recommended dosages and reference intakes for improving general health and preventing eye-related diseases. This review covers the potential causal factors involved in eye diseases, clinically proven treatments, and controversial findings on the antioxidants in the prevention of macular degeneration. Future studies should consider multiethnic and multicenter trials for eliminating potential bias in research.

Antioxidant capacity and phytochemical content of 16 sources of corn distillers dried grains with solubles (DDGS).

Corn distillers dried grains with solubles (DDGS) is a co-product of the fuel ethanol industry that is an excellent source of energy, digestible amino acids, and digestible phosphorus. However, the antioxidant capacity and phytochemical content of DDGS and how it is influenced by production parameters is unknown. Therefore, 16 DDGS samples obtained from different ethanol production plants in the U.S. were characterized for antioxidant capacity, vitamin E, xanthophylls, and ferulic acid content and compared with corn. The antioxidant capacity of DDGS samples, measured using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay, varied almost 2 folds among samples, but in all cases was more than 3 times that of corn. All DDGS samples had a considerably greater concentration of tocopherols and tocotrienols (lipid-soluble antioxidants) than corn. However, the relative concentrations among the tocopherols and tocotrienols tended to be similar to corn. The xanthophyll lutein was present in all DDGS samples and in all cases exceeded the content in corn. Zeaxanthin was detected in most samples. The total ferulic acid content of the DDGS samples was almost 3-fold greater than corn, but, as in corn, almost all was present in a bound form. However, the concentration of unbound (free) ferulic acid was more than 3 times the concentration found in the corn sample. Thus, DDGS is a rich source of phytochemical compounds and may provide antioxidant and health benefits beyond its macronutrient composition. However, differences in processing can greatly influence the phytochemical content and quality of DDGS. In particular, thermal abuse due to excessive heat used in drying may lead to lipid oxidation products that may have deleterious effects when incorporated into feeds.

Technical note: Simultaneous carotenoid and vitamin analysis of milk from total mixed ration-fed cows optimized for xanthophyll detection

Concentrations of retinol, α-tocopherol, and major carotenoids in dairy products are often determined simultaneously by liquid chromatography. These compounds have different polarity and solubility; thus, extracting them simultaneously can be difficult and inefficient. In milks with low carotenoid concentrations, the xanthophylls lutein and zeaxanthin may not be completely resolved using common extraction techniques. A simplified method was developed to optimize extraction efficiency and the limit of detection and limit of quantification (LoQ) of lutein and zeaxanthin in bovine milk without decreasing sensitivity to other vitamins or carotenoids. The developed method evaluates lutein, zeaxanthin, β-carotene, retinol, and α-tocopherol simultaneously by ultra-high performance liquid chromatography-photodiode array detection. Common saponification temperatures (40-60°C) and concentrations of KOH in water (10-50% KOH wt/vol) were evaluated. Multiple solvents were evaluated for optimal xanthophyll extraction (diethyl ether, dichloromethane, hexane, and tetrahydrofuran) following saponification. The limit of detection and LoQ were defined as 3:1 and 10:1 signal-to-noise ratio, respectively. All experiments were performed in triplicate. The optimal saponification procedure was a concentration of 25% KOH at either 40 or 50°C. Saponified extracts solubilized in solutions containing diethyl ether had greater concentrations of lutein- than hexane- or tetrahydrofuran-based solutions, with peak areas above LoQ values. The solution containing diethyl ether solubilized similar concentrations of retinol, α-tocopherol, and β-carotene when compared with other solutions. The proposed optimized method allows for the simultaneous determination of carotenoids from milk with increased lutein and zeaxanthin sensitivity without sacrificing recovery of retinol, α-tocopherol, and β-carotene.

Anthocyanidins regenerating xanthophylls: a quantum mechanical approach to eye health

The xanthophylls lutein and zeaxanthin accumulate in human retina and protect vision functions against blue light, singlet oxygen and triplet photosensitizers, but are easily degraded by free radicals involved in lipid oxidation in eye tissue. Polyphenols may regenerate xanthophylls from their initial oxidation products, the carotenoid radical cations, by electron transfer protecting the ‘yellow spot.’ The reorganization energy of the donor/acceptor transition state should equal reaction free energy for optimal diffusion-controlled regeneration of the xanthophylls by polyphenols according to Marcus theory for electron transfer. Anthocyanidins match the reduction potential of xanthophyll radicals in contrast to the more reducing catechins and tocopherols, which overshoot energetically. Quantum mechanics may provide the explanation for the protective effect of blueberry on vision.

Provitamin A-biofortified maize consumption increases serum xanthophylls and 13C-natural abundance of retinol in Zambian children.

Plants that undergo C4 photosynthesis, such as maize, are enriched in the stable isotope of carbon (13C) compared with other dietary plants and foods. Consumption of maize that has been biofortified to contain elevated levels of provitamin A carotenoids (orange maize) increased the abundance of 13C in serum retinol of Mongolian gerbils. We evaluated this method in humans to determine if it has potential for further use in intervention effectiveness studies. A random subset of samples from a two-month randomized controlled feeding trial of rural three- to five-year old Zambian children were used to determine the impact of orange maize intake on serum carotenoid concentrations ( n = 88) and 13C-natural abundance in serum retinol ( n = 77). Concentrations of β-cryptoxanthin (a xanthophyll provitamin A carotenoid) and the dihydroxy xanthophylls lutein and zeaxanthin, which do not have vitamin A activity, were elevated in children consuming orange maize compared with those consuming a white maize control ( P < 0.001), while β-carotene was not different ( P > 0.3). Furthermore, 13C natural abundance was higher after two months' intervention in the orange maize group compared with the white maize group ( P = 0.049). Predictions made from equations developed in the aforementioned gerbil study estimated that maize provided 11% (2-21%, 95% confidence interval) of the recent dietary vitamin A to these children. These results demonstrate that orange maize is efficacious at providing retinol to the vitamin A pool in children through provitamin A carotenoids, as monitored by the change in 13C enrichment, which was not reflected in serum β-carotene concentrations. Further effectiveness studies in countries who have adopted orange maize should consider determining differences in retinol 13C-enrichment among target groups in addition to profiling serum xanthophyll carotenoids with specific emphasis on zeaxanthin. Impact statement Maize biofortified with provitamin A carotenoids (orange) has been released in some African markets. Responsive and sensitive methods to evaluate dissemination effectiveness are needed. This study investigated methods to evaluate effectiveness of orange maize consumption using serum from Zambian children fed orange maize for two months. Many varieties of orange maize contain higher amounts of the xanthophyll carotenoids in addition to β-carotene compared with typical varieties. This study uniquely showed higher concentrations of the maize xanthophylls lutein, zeaxanthin, and β-cryptoxanthin in children who consumed orange maize compared with white. Furthermore, maize is a C4 plant and is therefore naturally enriched with 13C. Higher 13C was detected in the serum retinol of the orange maize consumers with no change in serum β-carotene concentration suggesting preferential bioconversion to retinol. The combined analyses of serum zeaxanthin specifically and 13C-natural abundance of retinol could prove useful in effectiveness studies between orange maize adopters and non-adopters.

Compositional variability of nutrients and phytochemicals in corn after processing.

The result of various process strategies on the nutrient and phytochemical composition of corn samples were studied. Fresh and cooked baby corn, sweet corn, dent corn and industrially processed and cooked popcorn, corn grits, corn flour and corn flakes were analysed for the determination of proximate, minerals, xanthophylls and phenolic acids content. This study revealed that the proximate composition of popcorn is high compared to the other corn products analyzed while the mineral composition of these maize products showed higher concentration of magnesium, phosphorus, potassium and low concentration of calcium, manganese, zinc, iron, copper, and sodium. Popcorn was high in iron, zinc, copper, manganese, sodium, magnesium and phosphorus. The xanthophylls lutein and zeaxanthin were predominant in the dent corn and the total polyphenolic content was highest in dent corn while the phenolic acids distribution was variable in different corn products. This study showed preparation and processing brought significant reduction of xanthophylls and polyphenols.