Insights from in vitro exploration of factors influencing iron,zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereals

Developments in genetics, agronomics and processing has positioned staple cereals as important sources of iron, zinc and provitamin A (pVA) carotenoids for nutritionally vulnerable populations. Significant effort has been placed on understanding the bioavailability of these micronutrients from cereal foods, including the exploration of underlying mechanisms by which their bioavailability can be modified. While micronutrient bioavailability is preferably assessed in clinical trials, relevant in vitro digestion and intestinal cell culture models have been applied to study effects of genetic, agronomic, post-harvest and food processing on micronutrient bioavailability. This review (1) critically assesses the application of in vitro models in the exploration of mechanisms associated with iron, zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereal foods, and (2) identifies remaining gaps in order to frame future strategies to improve the nutritional impact of cereal foods.     

Marine carotenoids: biological functions and commercial applications

Carotenoids are the most common pigments in nature and are synthesized by all photosynthetic organisms and fungi. Carotenoids are considered key molecules for life. Light capture, photosynthesis photoprotection, excess light dissipation and quenching of singlet oxygen are among key biological functions of carotenoids relevant for life on earth. Biological properties of carotenoids allow for a wide range of commercial applications. Indeed, recent interest in the carotenoids has been mainly for their nutraceutical properties. A large number of scientific studies have confirmed the benefits of carotenoids to health and their use for this purpose is growing rapidly. In addition, carotenoids have traditionally been used in food and animal feed for their color properties. Carotenoids are also known to improve consumer perception of quality; an example is the addition of carotenoids to fish feed to impart color to farmed salmon.     

Hypocholesterolemic effect of amaranth seeds (Amaranthus esculantus)

Food lectins are known to affect the absorption of nutrients in experimental animals and altered morphology of the intestinal mucosa due to prolonged feeding of lectins is suggested to be the cause. However, toxic symptoms appear in humans immediately after consumption of lectin rich foods and the mechanism of this immediate action is not known. This study reports the immediate effect of Concanavalin A (Con A) and Phaseolus vulgaris lectin (PHA-P) on the absorption of Ca²⁺ and sucrose in rat intestine and the possible role of lectin-membrane interactions in the process. Calcium absorption was lowered by Con A, and this was observed to be due to Con A interacting with the intestinal mucosal membrane. Similarly, sucrose absorption was also altered, probably due to Con A binding the intestinal mucosal membrane. On the other hand PHA-P did not have any effect on either sucrose or calcium absorption. Results indicate that the effect on intestinal nutrient absorption depends on the type of lectin used (and its concentration) as well as the type of nutrient, besides the duration of exposure of intestinal mucosa to the lectin.     

Enhancement of Xanthophyll Synthesis in Porphyra/Pyropia Species (Rhodophyta,Bangiales) by Controlled Abiotic Factors: A Systematic Review and Meta-Analysis

Red alga species belonging to the Porphyra and Pyropia genera (commonly known as Nori), which are widely consumed and commercialized due to their high nutritional value. These species have a carotenoid profile dominated by xanthophylls, mostly lutein and zeaxanthin, which have relevant benefits for human health. The effects of different abiotic factors on xanthophyll synthesis in these species have been scarcely studied, despite their health benefits. The objectives of this study were (i) to identify the abiotic factors that enhance the synthesis of xanthophylls in Porphyra/Pyropia species by conducting a systematic review and meta-analysis of the xanthophyll content found in the literature, and (ii) to recommend a culture method that would allow a significant accumulation of these compounds in the biomass of these species. The results show that salinity significantly affected the content of total carotenoids and led to higher values under hypersaline conditions (70,247.91 µg/g dm at 55 psu). For lutein and zeaxanthin, the wavelength treatment caused significant differences between the basal and maximum content (4.16–23.47 µg/g dm). Additionally, in Pyropia spp., the total carotenoids were considerably higher than in Porphyra spp.; however, the lutein and zeaxanthin contents were lower. We discuss the specific conditions for each treatment and the relation to the ecological distribution of these species.     

Carotenoid β-ring hydroxylase and ketolase from marine bacteria-promiscuous enzymes for synthesizing functional xanthophylls

Marine bacteria belonging to genera Paracoccus and Brevundimonas of the α-Proteobacteria class can produce C₄₀-type dicyclic carotenoids containing two β-end groups (β rings) that are modified with keto and hydroxyl groups. These bacteria produce astaxanthin, adonixanthin, and their derivatives, which are ketolated by carotenoid β-ring 4(4′)-ketolase (4(4′)-oxygenase; CrtW) and hydroxylated by carotenoid β-ring 3(3′)-hydroxylase (CrtZ). In addition, the genus Brevundimonas possesses a gene for carotenoid β-ring 2(2′)-hydroxylase (CrtG). This review focuses on these carotenoid β-ring-modifying enzymes that are promiscuous for carotenoid substrates, and pathway engineering for the production of xanthophylls (oxygen-containing carotenoids) in Escherichia coli, using these enzyme genes. Such pathway engineering researches are performed towards efficient production not only of commercially important xanthophylls such as astaxanthin, but also of xanthophylls minor in nature (e.g., β-ring(s)-2(2′)-hydroxylated carotenoids).     

Carotenoid evolution during postharvest storage of durum wheat (Triticum turgidum conv. durum) and tritordeum (×Tritordeum Ascherson et Graebner) grains

The process of in vivo esterification of xanthophylls has proven to be an important part of the post-carotenogenesis metabolism which mediates their accumulation in plants. The biochemical characterization of this process is therefore necessary for obtaining new and improved crop varieties with higher carotenoid contents. This study investigates the impact of postharvest storage conditions on carotenoid composition, with special attention to the esterified pigments (monoesters, diesters and their regioisomers), in durum wheat and tritordeum, a novel cereal with remarkable carotenoid content. For tritordeum grains, the total carotenoid content decreased during the storage period in a clear temperature-dependent manner. On the contrary, carotenoid metabolism in durum wheat was very much dependent on the physiological adaptation of the grains to the imposed conditions. Interestingly, when thermal conditions were more intense (37 °C), a higher carotenoid retention was observed for tritordeum, and was directly related to the de novo esterification of the lutein induced by temperature. The profile of lutein monoester regioisomers was constant during storage, indicating that the regioisomeric selectivity of the XAT enzymes was not altered by temperature. These data can be useful for optimizing the storage conditions of grains favoring a greater contribution of carotenoids from these staple foods.     

Carotenoids from Marine Microalgae: A Valuable Natural Source for the Prevention of Chronic Diseases

Epidemiological studies have shown a relation between antioxidants and the prevention of several chronic diseases. Microalgae are a potential novel source of bioactive molecules, including a wide range of different carotenoids that can be used as nutraceuticals, food supplements and novel food products. The objective of this review is (i) to update the research that has been carried out on the most known carotenoids produced by marine microalgae, including reporting on their high potentialities to produce other less known important compounds; (ii) to compile the work that has been done in order to establish some relationship between carotenoids and oxidative protection and treatment; (iii) to summarize the association of oxidative stress and the various reactive species including free radicals with several human diseases; and (iv) to provide evidence of the potential of carotenoids from marine microalgae to be used as therapeutics to treat or prevent these oxidative stress-related diseases.     

Geographical Location has Greater Impact on Carotenoid Content and Bioaccessibility from Tomatoes than Variety

The suggested health benefits of consuming tomatoes and tomato-based products have been attributed, in part, to the carotenoids present in these foods. Therefore, the objectives of the present study were to (i) analyse carotenoid content and bioaccessibility from different tomato (Lycopersicon esculentum L.) types namely cherry, plum, round, and certain tomatoes-on-the-vine; and (ii) determine if geographical location (Ireland vs Spain) influenced the content and bioaccessibility of carotenoids in tomatoes of the same variety. Carotenoid bioaccessibility is defined as the amount of ingested carotenoids that, after digestion, are available for absorption by intestinal cells. Differences were seen in carotenoid content and bioaccessibility between the different tomato types tested. For instance, Irish round high-lycopene tomatoes contained the greatest amounts of lycopene and lutein but lowest levels of β-carotene compared with the other Irish tomatoes. Furthermore, the content and bioaccessibility of carotenoids that were sourced from Ireland and Spain also varied greatly. Spanish tomatoes were generally superior in the content, bioaccessibility, and micelle content of carotenoids. To conclude, our findings suggest that geographical location, rather than the type of tomato, seems to have a more pronounced effect on carotenoid bioaccessibility from tomatoes.     

Inhibition of Intestinal Lipid Absorption by Cyanobacterial Strains in Zebrafish Larvae

Obesity is a complex metabolic disease, which is increasing worldwide. The reduction of dietary lipid intake is considered an interesting pathway to reduce fat absorption and to affect the chronic energy imbalance. In this study, zebrafish larvae were used to analyze effects of cyanobacteria on intestinal lipid absorption in vivo. In total, 263 fractions of a cyanobacterial library were screened for PED6 activity, a fluorescent reporter of intestinal lipases, and 11 fractions reduced PED6 activity > 30%. Toxicity was not observed for those fractions, considering mortality, malformations or digestive physiology (protease inhibition). Intestinal long-chain fatty acid uptake (C16) was reduced, but not short-chain fatty acid uptake (C5). Alteration of lipid classes by high-performance thin-layer chromatography (HPTLC) or lipid processing by fluorescent HPTLC was analyzed, and 2 fractions significantly reduced the whole-body triglyceride level. Bioactivity-guided feature-based molecular networking of LC-MS/MS data identified 14 significant bioactive mass peaks (p < 0.01, correlation > 0.95), which consisted of 3 known putative and 11 unknown compounds. All putatively identified compounds were known to be involved in lipid metabolism and obesity. Summarizing, some cyanobacterial strains repressed intestinal lipid absorption without any signs of toxicity and could be developed in the future as nutraceuticals to combat obesity.     

Carotenoids in marine invertebrates living along the Kuroshio current coast

Carotenoids of the corals Acropora japonica, A. secale, and A. hyacinthus, the tridacnid clam Tridacna squamosa, the crown-of-thorns starfish Acanthaster planci, and the small sea snail Drupella fragum were investigated. The corals and the tridacnid clam are filter feeders and are associated with symbiotic zooxanthellae. Peridinin and pyrrhoxanthin, which originated from symbiotic zooxanthellae, were found to be major carotenoids in corals and the tridacnid clam. The crown-of-thorns starfish and the sea snail D. fragum are carnivorous and mainly feed on corals. Peridinin-3-acyl esters were major carotenoids in the sea snail D. fragum. On the other hand, ketocarotenoids such as 7,8-didehydroastaxanthin and astaxanthin were major carotenoids in the crown-of-thorns starfish. Carotenoids found in these marine animals closely reflected not only their metabolism but also their food chains.     

Marine Microbial-Derived Resource Exploration: Uncovering the Hidden Potential of Marine Carotenoids

Microbes in marine ecosystems are known to produce secondary metabolites. One of which are carotenoids, which have numerous industrial applications, hence their demand will continue to grow. This review highlights the recent research on natural carotenoids produced by marine microorganisms. We discuss the most recent screening approaches for discovering carotenoids, using in vitro methods such as culture-dependent and culture-independent screening, as well as in silico methods, using secondary metabolite Biosynthetic Gene Clusters (smBGCs), which involves the use of various rule-based and machine-learning-based bioinformatics tools. Following that, various carotenoids are addressed, along with their biological activities and metabolic processes involved in carotenoids biosynthesis. Finally, we cover the application of carotenoids in health and pharmaceutical industries, current carotenoids production system, and potential use of synthetic biology in carotenoids production.     

Xanthophyll levels in foxtail millet grains according to variety and harvesting time

Foxtail millet grains usually contain carotenoids, which are yellow pigments that are important for human health. Yellow grains are preferred by distributors and consumers, and special cultivars and cultivation methods are desired for a stable supply of yellow millet. We investigated the level of pigment fluctuation in several foxtail millet accessions, including the yellow grain cultivar ‘Yuikogane’ from Iwate Prefecture, using high-performance liquid chromatography. Most yellow grains primarily contained xanthophylls, including approximately 1 mg/100 g lutein and 0.2 mg/100 g zeaxanthin. These pigments were rare in the bran and grain husks but were readily detected in polished grains, indicating that xanthophylls accumulate in the endosperm. We examined ‘Yuikogane’ to investigate the relationship between xanthophyll accumulation and grain ripening. During the ripening stage, xanthophyll levels gradually increased, but they rapidly decreased in response to over-ripening. Xanthophyll accumulation was estimated using a colorimetric assay of yellow pigmentation, which could be a useful method for determining the proper harvesting time for foxtail millet.     

Marine carotenoids and cardiovascular risk markers

Marine carotenoids are important bioactive compounds with physiological activities related to prevention of degenerative diseases found principally in plants, with potential antioxidant biological properties deriving from their chemical structure and interaction with biological membranes. They are substances with very special and remarkable properties that no other groups of substances possess and that form the basis of their many, varied functions and actions in all kinds of living organisms. The potential beneficial effects of marine carotenoids have been studied particularly in astaxanthin and fucoxanthin as they are the major marine carotenoids. Both these two carotenoids show strong antioxidant activity attributed to quenching singlet oxygen and scavenging free radicals. The potential role of these carotenoids as dietary anti-oxidants has been suggested to be one of the main mechanisms for their preventive effects against cancer and inflammatory diseases. The aim of this short review is to examine the published studies concerning the use of the two marine carotenoids, astaxanthin and fucoxanthin, in the prevention of cardiovascular diseases.     

Evaluation of Intestinal Absorption of Dietary Halocynthiaxanthin,a Carotenoid from the Sea Squirt Halocynthia roretzi

Halocynthiaxanthin is an acetylenic carotenoid mainly found in Halocynthia roretzi. To date, several bioactivities of halocynthiaxanthin have been reported, but its mechanism of digestion and absorption in mammals has not been studied yet. In this study, we evaluated the intestinal absorption of halocynthiaxanthin in mice. The halocynthiaxanthin-rich fraction was prepared from the tunicate Halocynthia roretzi. Mice were orally administered the fraction at a dose of 5 mg/kg body weight. The halocynthiaxanthin levels in the plasma, liver, and small intestine, were quantified using HPLC-PDA, 1, 3, 6, and 9 h after ingestion. The halocynthiaxanthin-rich fraction mainly consisted of the all-trans form and a small amount of cis forms. These three isomers were detected in the plasma of mice 3 h after ingestion. Time-course changes after the ingestion of this fraction were found, with cis isomers being more abundant than the all-trans isomer in the mouse plasma and liver. In the small intestine, however, the all-trans isomer was primarily detected. The possibility that cis isomers might be absorbed rapidly from the small intestine cannot be denied, but our results suggest that dietary all-trans-halocynthiaxanthin might be isomerized to the cis isomer after intestinal absorption.     

Antioxidants in potato

The content of compounds in potato that may act as antioxidants in the human diet is not widely appreciated. Carotenoids are present in the flesh of all potatoes. The contents mentioned in the literature range from 50 to 100 μg per 100 g fresh weight (FW) in white-fleshed varieties to 2000 μg per 100 g FW in deeply yellow to orange-fleshed cultivars. The carotenoids in potato are primarily lutein, zexanthin, and violaxanthin, all of which are xanthophylls. There is just a trace of either alpha or beta-carotene, meaning that potato is not a source of pro-vitamin A carotenes. In potatoes with total carotenoids ranging from 35 to 795 μg per 100 g FW, the lipophilic extract of potato flesh presented oxygen radical absorbance capacity (ORAC) values ranging from 4.6 to 15.3 nmoles α-tocopherol equivalents per 100 g FW. Potatoes contain phenolic compounds and the predominant one is chlorogenic acid, which constitutes about 80% of the total phenolic acids. Up to 30 μg per 100 g FW of flavonoids are present in the flesh of white-fleshed potatoes with roughly twice the amount present in red and purple-fleshed potatoes. The predominant flavonoids are catechin and epicatechin. Red and purple potatoes derive their color from anthocyanins. The skin alone may be pigmented, or the flesh may be partially or entirely pigmented. Whole unpeeled with complete pigmentation in the flesh may have up to 40 mg per 100 g FW of total anthocyanins. Red-fleshed potatoes have acylated glucosides of pelargonidin while purple potatoes have, in addition, acylated glucosides of malvidin, petunidin, peonidin, and delphinidin. The hydrophilic antioxidant activity of solidly pigmented red or purple potatoes is comparable to brussels sprouts or spinach. In red and purple potatoes with solidly pigmented flesh with levels of total anthocyanin ranging from 9 to 38 mg per 100 g FW, ORAC ranged from 7.6 and 14.2 umole per g FW of Trolox equivalents. Potato contains on average 20 mg per 100 g FW of vitamin C, which may account for up to 13 % of the total antioxidant capacity. Potatoes should be considered vegetables that may have high antioxidant capacity depending on the flesh composition.     

Carotenoids in algae: distributions, biosyntheses and functions

For photosynthesis, phototrophic organisms necessarily synthesize not only chlorophylls but also carotenoids. Many kinds of carotenoids are found in algae and, recently, taxonomic studies of algae have been developed. In this review, the relationship between the distribution of carotenoids and the phylogeny of oxygenic phototrophs in sea and fresh water, including cyanobacteria, red algae, brown algae and green algae, is summarized. These phototrophs contain division- or class-specific carotenoids, such as fucoxanthin, peridinin and siphonaxanthin. The distribution of α-carotene and its derivatives, such as lutein, loroxanthin and siphonaxanthin, are limited to divisions of Rhodophyta (macrophytic type), Cryptophyta, Euglenophyta, Chlorarachniophyta and Chlorophyta. In addition, carotenogenesis pathways are discussed based on the chemical structures of carotenoids and known characteristics of carotenogenesis enzymes in other organisms; genes and enzymes for carotenogenesis in algae are not yet known. Most carotenoids bind to membrane-bound pigment-protein complexes, such as reaction center, light-harvesting and cytochrome b(6)f complexes. Water-soluble peridinin-chlorophyll a-protein (PCP) and orange carotenoid protein (OCP) are also established. Some functions of carotenoids in photosynthesis are also briefly summarized.     

Properties of Carotenoids in Fish Fitness: A Review

Carotenoids, one of the most common types of natural pigments, can influence the colors of living organisms. More than 750 kinds of carotenoids have been identified. Generally, carotenoids occur in organisms at low levels. However, the total amount of carotenoids in nature has been estimated to be more than 100 million tons. There are two major types of carotenoids: carotene (solely hydrocarbons that contain no oxygen) and xanthophyll (contains oxygen). Carotenoids are lipid-soluble pigments with conjugated double bonds that exhibit robust antioxidant activity. Many carotenoids, particularly astaxanthin (ASX), are known to improve the antioxidative state and immune system, resulting in providing disease resistance, growth performance, survival, and improved egg quality in farmed fish without exhibiting any cytotoxicity or side effects. ASX cooperatively and synergistically interacts with other antioxidants such as α-tocopherol, ascorbic acid, and glutathione located in the lipophilic hydrophobic compartments of fish tissue. Moreover, ASX can modulate gene expression accompanying alterations in signal transduction by regulating reactive oxygen species (ROS) production. Hence, carotenoids could be used as chemotherapeutic supplements for farmed fish. Carotenoids are regarded as ecologically friendly functional feed additives in the aquaculture industry.     

What Do We Know about Antimicrobial Activity of Astaxanthin and Fucoxanthin?

Astaxanthin (AST) and fucoxanthin (FUC) are natural xanthophylls, having multidirectional activity, including antioxidant, anti-inflammatory, and anticancer. Both compounds also show antimicrobial activity, which is presented in this review article. There are few papers that have presented the antimicrobial activity of AST. Obtained antimicrobial concentrations of AST (200–4000 µg/mL) are much higher than recommended by the European Food Safety Authority for consumption (2 mg daily). Therefore, we suggest that AST is unlikely to be of use in the clinical treatment of infections. Our knowledge about the antimicrobial activity of FUC is better and this compound acts against many bacteria already in low concentrations 10–250 µg/mL. Toxicological studies on animals present the safety of FUC application in doses 200 mg/kg body weight and higher. Taking available research into consideration, a clinical application of FUC as the antimicrobial substance is real and can be successful. However, this aspect requires further investigation. In this review, we also present potential mechanisms of antibacterial activity of carotenoids, to which AST and FUC belong.     

Caco-2细胞模型在茶叶生物活性成分研究中的应用

Caco-2细胞单层的形态和功能特性都类似于人小肠上皮细胞,是研究营养素或药物吸收、转运和代谢的一个重要体外模型,近年来在茶叶生物活性成分的研究中也得到广泛应用.本文对Caco-2细胞中儿茶素、茶氨酸、没食子酸和咖啡碱的吸收和转运机制,儿茶素的代谢以及茶叶生物活性成分药效机理的研究进行了综述,并对采用Caco-2细胞模型快速评价茶叶生物活性成分的吸收特性以促进茶叶保健产品和制剂的开发进行了展望.     

Marine Carotenoids against Oxidative Stress: Effects on Human Health

Carotenoids are lipid-soluble pigments that are produced in some plants, algae, fungi, and bacterial species, which accounts for their orange and yellow hues. Carotenoids are powerful antioxidants thanks to their ability to quench singlet oxygen, to be oxidized, to be isomerized, and to scavenge free radicals, which plays a crucial role in the etiology of several diseases. Unusual marine environments are associated with a great chemical diversity, resulting in novel bioactive molecules. Thus, marine organisms may represent an important source of novel biologically active substances for the development of therapeutics. In this respect, various novel marine carotenoids have recently been isolated from marine organisms and displayed several utilizations as nutraceuticals and pharmaceuticals. Marine carotenoids (astaxanthin, fucoxanthin, β-carotene, lutein but also the rare siphonaxanthin, sioxanthin, and myxol) have recently shown antioxidant properties in reducing oxidative stress markers. This review aims to describe the role of marine carotenoids against oxidative stress and their potential applications in preventing and treating inflammatory diseases.