Intestinal absorption and metabolism of carotenoids: insights from cell culture

The potential of Chlorella spp. as antiviral source against African swine fever virus through a virtual screening pipeline

African swine fever (ASF) causes high mortality in pigs and threatens global swine production. There is still a lack of therapeutics available, with two vaccines under scrutiny and no approved small-molecule drugs. Eleven (11) viral proteins were used to identify potential antivirals in in silico screening of secondary metabolites (127) from Chlorella spp. The metabolites were screened for affinity and binding selectivity. High-scoring compounds were assessed through in silico ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity) predictions, compared to structurally similar drugs, and checked for off-target docking with prepared swine receptors. Molecular dynamics (MD) simulations determined binding stability while binding energy was measured in Molecular Mechanics - Generalized Born Surface Area (MMGBSA) or Poisson-Boltzmann Surface Area (MMPBSA). Only six (6) compounds passed until MD analyses, of which five (5) were stable after 100 ns of MD runs. Of these five compounds, only three had binding affinities that were comparable to or stronger than controls. Specifically, phytosterols 24,25-dihydrolanosterol and CID 4206521 that interact with the RNA capping enzyme (pNP868R), and ergosterol which bound to the Erv-like thioreductase (pB119L). The compounds identified in this study can be used as a theoretical basis for in vitro screening to develop potent antiviral drugs against ASFV.

Cluster of Differentiation 36 (CD36) Preferentially Mediates Intestinal Absorption of Dietary Z-Astaxanthin and Especially 9-Z-Isomer via Higher Binding Affinity

Variances in the biological functions of astaxanthin geometric isomers (i.e., all-E, Z) are related to their intestinal absorption, but the mechanism of isomer absorption mediated by transporters remains unclear. Here, models of in vitro cell overexpression, in situ intestinal perfusion, and in vivo mouse inhibition were employed to investigate the impact of cluster of differentiation 36 (CD36) on the absorption of astaxanthin isomers. Cells overexpressing CD36 notably enhanced the uptake of Z-astaxanthin, particularly the 9-Z-isomer (47.76%). The absorption rate and permeability of Z-astaxanthin surpassed that of the all-E-isomer by the in situ model. Furthermore, the addition of the CD36-specific inhibitor sulfo-N-succinimidyl oleate significantly reduced the absorption of Z-astaxanthin in the mouse duodenum and jejunum, especially the 9-Z-isomer (57.66%). Molecular docking and surface plasmon resonance techniques further validated that 9-Z-astaxanthin binds to more amino acids of CD36 with higher affinity and in a fast-binding, fast-dissociating mode, thus favoring transport. Our findings elucidate, for the first time, the mechanism of the CD36-mediated transmembrane transport of astaxanthin geometric isomers.

Vitamin A - discovery, metabolism, receptor signaling and effects on bone mass and fracture susceptibility

The first evidence of the existence of vitamin A was the observation 1881 that a substance present in small amounts in milk was necessary for normal development and life. It was not until more than 100 years later that it was understood that vitamin A acts as a hormone through nuclear receptors. Unlike classical hormones, vitamin A cannot be synthesized by the body but needs to be supplied by the food as retinyl esters in animal products and ß-carotene in vegetables and fruits. Globally, vitamin A deficiency is a huge health problem, but in the industrialized world excess of vitamin A has been suggested to be a risk factor for secondary osteoporosis and enhanced susceptibility to fractures. Preclinical studies unequivocally have shown that increased amounts of vitamin A cause decreased cortical bone mass and weaker bones due to enhanced periosteal bone resorption. Initial clinical studies demonstrated a negative association between intake of vitamin A, as well as serum levels of vitamin A, and bone mass and fracture susceptibility. In some studies, these observations have been confirmed, but in other studies no such associations have been observed. One meta-analysis found that both low and high serum levels of vitamin A were associated with increased relative risk of hip fractures. Another meta-analysis also found that low levels of serum vitamin A increased the risk for hip fracture but could not find any association with high serum levels of vitamin A and hip fracture. It is apparent that more clinical studies, including large numbers of incident fractures, are needed to determine which levels of vitamin A that are harmful or beneficial for bone mass and fracture. It is the aim of the present review to describe how vitamin A was discovered and how vitamin A is absorbed, metabolized and is acting as a ligand for nuclear receptors. The effects by vitamin A in preclinical studies are summarized and the clinical investigations studying the effect by vitamin A on bone mass and fracture susceptibility are discussed in detail.

An ex vivo intestinal absorption model is more effective than an in vitro cell model to characterise absorption of dietary carotenoids following simulated gastrointestinal digestion

To get the most accurate food digestion-related data, and how this affects nutrient absorption, it is critical to carefully simulate human digestion systems using model settings. In this study, the uptake and transepithelial transportation of dietary carotenoids was compared using two different models that have previously been used to assess nutrient availability. The permeability of differentiated Caco-2 cells and murine intestinal tissue were tested using all-trans-β-carotene and lutein prepared in artificial mixed micelles and micellar fraction from orange-fleshed sweet potato (OFSP) gastrointestinal digestion. Transepithelial transport and absorption efficiency were then determined using liquid chromatography tandem-mass spectrometry (LCMS-MS). Results showed that the mean uptake for all-trans-β-carotene in the mouse mucosal tissue was 60.2 ± 3.2% compared to 36.7 ± 2.6% in the Caco-2 cells with the mixed micelles as the test sample. Similarly, the mean uptake was higher in OFSP with 49.4 ± 4.1% following mouse tissue uptake compared to 28.9 ± 4.3% using Caco-2 cells for the same concentration. In relation to the uptake efficiency, the mean percentage uptake for all-trans-β-carotene from artificial mixed micelles was 1.8-fold greater in mouse tissue compared to Caco-2 cells (35.4 ± 1.8% against 19.9 ± 2.6%). Carotenoid uptake reached saturation at 5 µM when assessed with the mouse intestinal cells. These results demonstrate the practicality of employing physiologically relevant models simulating human intestinal absorption processes that compares well with published human in vivo data. When used in combination with the Infogest digestion model, the Ussing chamber model, using murine intestinal tissue, may thus be an efficient predictor of carotenoid bioavailability in simulating human postprandial absorption ex vivo.

Concurrent Production of α- and β-Carotenes with Different Stoichiometries Displaying Diverse Antioxidative Activities via Lycopene Cyclases-Based Rational System

α- and β-carotenes belong to the most essential carotenoids in the human body and display remarkable pharmacological value for health due to their beneficial antioxidant activities. Distinct high α-/β-carotene stoichiometries have gained increasing attention for their effective preventions of Alzheimer’s disease, cardiovascular disease, and cancer. However, it is extremely difficult to obtain α-carotene in nature, impeding the accumulations of high α-/β-carotene stoichiometries and excavation of their antioxidant activities. Herein, we developed a dynamically operable strategy based on lycopene cyclases (LCYB and LCYE) for concurrently enriching α- and β-carotenes along with high stoichiometries in E. coli. Membrane-targeted and promoter-centered approaches were firstly implemented to spatially enhance catalytic efficiency and temporally boost expression of TeLCYE to address its low competitivity at the starting stage. Dynamically temperature-dependent regulation of TeLCYE and TeLCYB was then performed to finally achieve α-/β-carotene stoichiometries of 4.71 at 37 °C, 1.65 at 30 °C, and 1.06 at 25 °C, respectively. In the meantime, these α-/β-carotene ratios were confirmed to result in diverse antioxidative activities. According to our knowledge, this is the first time that both the widest range and antioxidant activities of high α/β-carotene stoichiometries were reported in any organism. Our work provides attractive potentials for obtaining natural products with competitivity and a new insight on the protective potentials of α-/β-carotenes with high ratios for health supply.

Study on the Interaction between Four Typical Carotenoids and Human Gut Microflora Using an in Vitro Fermentation Model

Recent studies indicated a strong relationship between carotenoids and gut microflora. However, their structure-activity relationship remains unclear. This study evaluated the interaction between four typical carotenoids (β-carotene, lutein, lycopene, and astaxanthin) and gut microflora using an in vitro fermentation model. After 24 h of fermentation, the retention rates of the four carotenoids were 1.40, 1.38, 1.46, and 5.63 times lower than those of their without gut microflora control groups, respectively. All four carotenoid treated groups significantly increased total short-chain fatty acids (SCFAs) production. All carotenoid supplements significantly promoted the abundance of Roseburia and Parasutterella and inhibited the abundance of Collinsella, while β-carotene, lutein, lycopene, and astaxanthin significantly promoted the abundance of Ruminococcus, Sutterella, Subdoligranulum, and Megamonas, respectively. Furthermore, xanthophylls have a more significant impact on gut microflora than carotenes. This study provides a new way to understand how carotenoids work in the human body with the existing gut microflora.

Fucoxanthin: A Promising Phytochemical on Diverse Pharmacological Targets

Fucoxanthin (FX) is a special carotenoid having an allenic bond in its structure. FX is extracted from a variety of algae and edible seaweeds. It has been proved to contain numerous health benefits and preventive effects against diseases like diabetes, obesity, liver cirrhosis, malignant cancer, etc. Thus, FX can be used as a potent source of both pharmacological and nutritional ingredient to prevent infectious diseases. In this review, we gathered the information regarding the current findings on antimicrobial, antioxidant, anti-inflammatory, skin protective, anti-obesity, antidiabetic, hepatoprotective, and other properties of FX including its bioavailability and stability characteristics. This review aims to assist further biochemical studies in order to develop further pharmaceutical assets and nutritional products in combination with FX and its various metabolites.

Cardiovascular Disease and Possible Ways in Which Lycopene Acts as an Efficient Cardio-Protectant against Different Cardiovascular Risk Factors

Foods rich in antioxidants such as lycopene have a major role in maintaining cardiac health. Lycopene, 80% of which can be obtained by consuming a common vegetable such as tomato, can prevent the disturbances that contribute to cardiovascular disease (CVD). The present work begins with a brief introduction to CVD and lycopene and its various properties such as bioavailability, pharmacokinetics, etc. In this review, the potential cardio-protective effects of lycopene that reduce the progression of CVD and thrombotic complications are detailed. Further, the protective effects of lycopene including in vitro, in vivo and clinical trials conducted on lycopene for CVD protective effects are explained. Finally, the controversial aspect of lycopene as a protective agent against CVD and toxicity are also mentioned.

Lycopene: A Natural Arsenal in the War against Oxidative Stress and Cardiovascular Diseases

Lycopene is a bioactive red pigment found in plants, especially in red fruits and vegetables, including tomato, pink guava, papaya, pink grapefruit, and watermelon. Several research reports have advocated its positive impact on human health and physiology. For humans, lycopene is an essential substance obtained from dietary sources to fulfil the body requirements. The production of reactive oxygen species (ROS) causing oxidative stress and downstream complications include one of the major health concerns worldwide. In recent years, oxidative stress and its counter strategies have attracted biomedical research in order to manage the emerging health issues. Lycopene has been reported to directly interact with ROS, which can help to prevent chronic diseases, including diabetes and neurodegenerative and cardiovascular diseases. In this context, the present review article was written to provide an accumulative account of protective and ameliorative effects of lycopene on coronary artery disease (CAD) and hypertension, which are the leading causes of death worldwide. Lycopene is a potent antioxidant that fights ROS and, subsequently, complications. It reduces blood pressure via inhibiting the angiotensin-converting enzyme and regulating nitrous oxide bioavailability. It plays an important role in lowering of LDL (low-density lipoproteins) and improving HDL (high-density lipoproteins) levels to minimize atherosclerosis, which protects the onset of coronary artery disease and hypertension. Various studies have advocated that lycopene exhibited a combating competence in the treatment of these diseases. Owing to all the antioxidant, anti-diabetic, and anti-hypertensive properties, lycopene provides a potential nutraceutical with a protective and curing ability against coronary artery disease and hypertension.

Characterization of a Novel Lutein Cleavage Dioxygenase, EhLCD, from Enterobacter hormaechei YT-3 for the Enzymatic Synthesis of 3-Hydroxy-β-ionone from Lutein

3-Hydroxy-β-ionone, a flavor and fragrance compound with fruity violet-like characteristics, is widely applied in foodstuff and beverages, and is currently produced using synthetic chemistry. In this study, a novel lutein cleavage enzyme (EhLCD) was purified and characterized from Enterobacter hormaechei YT-3 to convert lutein to 3-hydroxy-β-ionone. Enzyme EhLCD was purified to homogeneity by ammonium sulfate precipitation, Q-Sepharose, phenyl-Sepharose, and Superdex 200 chromatography. The molecular mass of purified EhLCD, obtained by SDS-PAGE, was approximately 50 kDa. The enzyme exhibited the highest activity toward lutein, followed by zeaxanthin, β-cryptoxanthin, and β-carotene, suggesting that EhLCD exhibited higher catalytic efficiency for carotenoid substrates bearing 3-hydroxy-ionone rings. Isotope-labeling experiments showed that EhLCD incorporated oxygen from O2 into 3-hydroxy-β-ionone and followed a dioxygenase reaction mechanism for different carotenoid substrates. These results indicated that EhLCD is the first characterized bacterial lutein cleavage dioxygenase. Active EhLCD was also confirmed to be a Fe2+-dependent protein with 1 molar equivalent of non-haem Fe2+. The purified enzyme displayed optimal activity at 45 °C and pH 8.0. The optimum concentrations of the substrate, enzyme, and Tween 40 for 3-hydroxy-β-ionone production were 60 μM lutein/L, 1.5 U/mL, and 2% (w/v), respectively. Under optimum conditions, EhLCD produced 3-hydroxy-β-ionone (637.2 mg/L) in 60 min with a conversion of 87.0% (w/w), indicating that this enzyme is a potential candidate for the enzymatic synthesis of 3-hydroxy-β-ionone in biotechnological applications.

Eat yourself sexy: how selective macronutrient intake influences the expression of a visual signal in common mynas

Producing colored signals often requires consuming dietary carotenoid pigments. Evidence that food deprivation can reduce coloration, however, raises the question of whether other dietary nutrients contribute to signal coloration, and furthermore, whether individuals can voluntarily select food combinations to achieve optimal coloration. We created a two-way factorial design to manipulate macronutrient and carotenoid access in common mynas (Acridotheres tristis) and measured eye patch coloration as a function of the food combinations individuals selected. Mynas had access to either water or carotenoid-supplemented water and could either eat a standard captive diet or choose freely between three nutritionally defined pellets (protein, lipid or carbohydrate). Mynas supplemented with both carotenoids and macronutrient pellets had higher color scores than control birds. Male coloration tended to respond more to nutritional manipulation than females, with color scores improving in macronutrient- and carotenoid-supplemented individuals compared with controls. All mynas consuming carotenoids had higher levels of plasma carotenoids, but only males showed a significant increase by the end of the experiment. Dietary carotenoids and macronutrient intake consumed in combination tended to increase plasma carotenoid concentrations the most. These results demonstrate for the first time that consuming specific combinations of macronutrients along with carotenoids contributes to optimizing a colorful signal, and point to sex-specific nutritional strategies. Our findings improve our knowledge of how diet choices affect signal expression and, by extension, how nutritionally impoverished diets, such as those consumed by birds in cities, might affect sexual selection processes and, ultimately, population dynamics.

Hesperetin and Hesperidin Improved β-Carotene Incorporation Efficiency, Intestinal Cell Uptake, and Retinoid Concentrations in Tissues

Dietary constituents can influence the bioavailability of carotenoids. This study investigated the effect of citrus flavanones on β-carotene (Bc) bioavailability using four experimental models: in vitro digestion procedure, synthetic mixed micelles, Caco-2 cell monolayers, and gavage experiments in mice. The addition of hesperetin (Hes, 25 μM) and hesperidin (Hes-G, 25 μM) standards significantly increased the incorporation efficiency of the Bc standard to 68.7 ± 3.6 and 75.2 ± 7.5% ( p < 0.05), respectively. However, the addition of naringenin (Nar, 25 μM) and naringin (Nar-G, 25 μM) standards significantly reduced the incorporation efficiency of Bc by 23.8 and 26.4%, respectively ( p < 0.05). The increases in scavenger receptor class B type I (SR-BI) expression promoted by citrus flavanones played an important role in Bc cellular absorption in the Caco-2 cell model. Furthermore, after 3 days of gavage, four citrus flavanones (7.5 mg kg^-1 day^-1) increased the retinoid concentrations in tissues; in contrast, after 7 days of gavage, Nar and Nar-G significantly decreased hepatic retinoid concentrations ( p < 0.05). This finding suggested that the incorporation efficiency into micelles was the main step governing carotenoid bioavailability.

Uptake and metabolism of β-apo-8'-carotenal, β-apo-10'-carotenal, and β-apo-13-carotenone in Caco-2 cells

β-Apocarotenoids are eccentric cleavage products of carotenoids formed by chemical and enzymatic oxidations. They occur in foods containing carotenoids and thus might be directly absorbed from the diet. However, there is limited information about their intestinal absorption. The present research examined the kinetics of uptake and metabolism of β-apocarotenoids. Caco-2 cells were grown on 6-well plastic plates until a differentiated cell monolayer was achieved. β-Apocarotenoids were prepared in Tween 40 micelles, delivered to differentiated cells in serum-free medium, and incubated at 37°C for up to 8 h. There was rapid uptake of β-apo-8'-carotenal into cells, and β-apo-8'-carotenal was largely converted to β-apo-8'-carotenoic acid and a minor metabolite that we identified as 5,6-epoxy-β-apo-8'-carotenol. There was also rapid uptake of β-apo-10'-carotenal into cells, and β-apo-10'-carotenal was converted into a major metabolite identified as 5,6-epoxy-β-apo-10'-carotenol and a minor metabolite that is likely a dihydro-β-apo-10'-carotenol. Finally, there was rapid cellular uptake of β-apo-13-carotenone, and this compound was extensively degraded. These results suggest that dietary β-apocarotenals are extensively metabolized in intestinal cells via pathways similar to the metabolism of retinal. Thus, they are likely not absorbed directly from the diet.

Identification of Enzymatic Cleavage Products of -Carotene-Rich Extracts of Kale and Biofortified Maize

Provitamin A carotenoids in plant foods provide more than 80% of vitamin A intake for people in developing countries. Therefore, the conversion efficiency of β-carotene to vitamin A is important, as it determines the effectiveness of plant foods as sources of vitamin A in humans. The objective of this study was to determine the effect of plant food antioxidants such as α-tocopherol, γ-tocopherol, α-tocotrienol, γ-tocotrienol and total γ-oryzanol on the cleavage of β-carotene in vitro. Rat intestinal mucosa post mitochondrial fractions were incubated with β-carotene-rich extracts of kale and biofortified maize for an hour at 37°C. Rat intestinal mucosa post mitochondrial fractions were also incubated with β-carotene in the presence of either α-tocopherol, γ-tocopherol, α-tocotrienol, γ-tocotrienol or γ-oryzanol for 60 min at 37°C. The β-carotene cleavage products were extracted and analyzed by an HPLC equipped with a C18 column at 340nm and 450nm. When β-carotene alone was incubated without intestinal mucosa homogenate (control), no cleavage products were detected. When β-carotene alone was incubated with intestinal mucosa homogenate, β-apo-13-carotenone, β-apo-14-carotenal, retinal, retinol and retinoic acid were formed. However, incubation of β-carotene with either α-tocopherol, γ-tocopherol or α-tocotrienol resulted in a 10 fold inhibition of β-apo-14-carotenal and β-apo-13-carotenone formation. Antioxidant rich biofortified maize extract incubated with postmitochondrial fraction produced less β-apo-13-carotenone compared to the kale extract. These results suggest that antioxidants inhibit the cleavage of β-carotene and the formation of excentric cleavage products (β-apo-13-carotenone, β-apo-14-carotenal).

Improved absorption of β-carotene by encapsulation in an oil-in-water nanoemulsion containing tea polyphenols in the aqueous phase

β-Carotene (BC) serves as an important source of provitamin A and natural edible pigment, but the application is limited because of its instability and low oral-bioavailability. A tea polyphenols-β-carotene (TP-BC) oil-in-water (O/W) nanoemulsion was prepared with the core oil phase containing BC and the water phase containing TP. During storage at three different temperatures (4, 25 and 35 °C), the TP-BC nanoemulsion had a better stability and higher retention rate of BC than BC nanoemulsion. An in vitro simulated digestion assay indicated that the BC recovery rates of TP-BC nanoemulsion at digestion phases I and II were significantly increased compared to the BC nanoemulsion. An in vivo absorption study showed that TP-BC nanoemulsion had higher conversion efficiency on vitamin A compared to the BC nanoemulsion. These results suggested that tea polyphenols are effective ingredients for improving the oral-bioavailability of BC.

Anti-inflammatory, antiproliferative and cytoprotective potential of the Attalea phalerata Mart. ex Spreng. pulp oil

The anti-inflammatory, antiproliferative and cytoprotective activity of the Attalea phalerata Mart. ex Spreng pulp oil was evaluated by in vitro and in vivo methods. As for the chemical profile, the antioxidant activity was performed by spectrophotometry, and the profile of carotenoids and amino acids by chromatography. Our data demonstrated that A. phalerata oil has high carotenoid content, antioxidant activity and the presence of 5 essential amino acids. In the in vitro models of inflammation, the oil demonstrated the capacity to inhibit COX1 and COX2 enzymes, the production of nitric oxide and also induces macrophages to spreading. In the in vivo models of inflammation, the oil inhibited edema and leukocyte migration in the Wistar rats. In the in vitro model of antiproliferative and cytoprotective activity, the oil was shown inactive against the kidney carcinoma and prostate carcinoma lineage cells and with cytoprotective capacity in murine fibroblast cells, inhibiting the cytotoxic action of doxorubicin. Therefore, it is concluded that A. phalerata pulp oil has anti-inflammatory effects with nutraceutical properties potential due to the rich composition. Moreover, the oil also has cytoprotective activity probably because of its ability to inhibit the action of free radicals.

Relative contribution of α-carotene to postprandial vitamin A concentrations in healthy humans after carrot consumption

Background: Asymmetric α-carotene, a provitamin A carotenoid, is cleaved to produce retinol (vitamin A) and α-retinol (with negligible vitamin A activity). The vitamin A activity of α-carotene-containing foods is likely overestimated because traditional analytic methods do not separate α-retinol derivatives from active retinol.Objective: This study aimed to accurately characterize intestinal α-carotene cleavage and its relative contribution to postprandial vitamin A in humans after consumption of raw carrots.Design: Healthy adults (n = 12) consumed a meal containing 300 g raw carrot (providing 27.3 mg β-carotene and 18.7 mg α-carotene). Triglyceride-rich lipoprotein fractions of plasma were isolated and extracted, and α-retinyl palmitate (αRP) and retinyl palmitate were measured over 12 h postprandially via high-performance liquid chromatography-tandem mass spectrometry. The complete profile of all α-retinyl esters and retinyl esters was measured at 6 h, and total absorption of α- and β-carotene was calculated.Results: αRP was identified and quantified in every subject. No difference in preference for absorption of β- over α-carotene was observed (adjusting for dose, 28% higher, P = 0.103). After absorption, β-carotene trended toward preferential cleavage compared with α-carotene (22% higher, P = 0.084). A large range of provitamin A carotenoid conversion efficiencies was observed, with α-carotene contributing 12-35% of newly converted vitamin A (predicted contribution = 25.5%). In all subjects, a majority of α-retinol was esterified to palmitic acid (as compared with other fatty acids).Conclusions: α-Retinol is esterified in the enterocyte and transported in the blood analogous to retinol. The percentage of absorption of α-carotene from raw carrots was not significantly different from β-carotene when adjusting for dose, although a trend toward higher cleavage of β-carotene was observed. The results demonstrate large interindividual variability in α-carotene conversion. The contribution of newly absorbed α-carotene to postprandial vitamin A should not be estimated but should be measured directly to accurately assess the vitamin A capacity of α-carotene-containing foods. This trial was registered at clinicaltrials.gov as NCT01432210.

Green ultrasound-assisted extraction of carotenoids from pomegranate wastes using vegetable oils

The objective of this work was to develop a new process for pomegranate peels application in food industries based on ultrasound-assisted extraction of carotenoids using different vegetable oils as solvents. In this way, an oil enriched with antioxidants is produced. Sunflower oil and soy oil were used as alternative solvents and the effects of various parameters on extraction yield were studied. Extraction temperature, solid/oil ratio, amplitude level, and extraction time were the factors investigated with respect to extraction yield. Comparative studies between ultrasound-assisted and conventional solvent extraction were carried out in terms of processing procedure and total carotenoids content. The efficient extraction period for achieving maximum yield of pomegranate peel carotenoids was about 30min. The optimum operating conditions were found to be: extraction temperature, 51.5°C; peels/solvent ratio, 0.10; amplitude level, 58.8%; solvent, sunflower oil. A second-order kinetic model was successfully developed for describing the mechanism of ultrasound extraction under different processing parameters.

Anti-arthritic actions of β-cryptoxanthin against the degradation of articular cartilage in vivo and in vitro

An inverse correlation between the morbidity of rheumatoid arthritis and daily intake of β-cryptoxanthin has been epidemiologically shown. In this study, we investigated the effects of β-cryptoxanthin on the metabolism of cartilage extracellular matrix in vivo and in vitro. Oral administration of β-cryptoxanthin (0.1-1 mg/kg) to antigen-induced arthritic rats suppressed the loss of glycosaminoglycans in articular cartilage, which is accompanied by the interference of aggrecanase-mediated degradation of aggrecan. Inhibition of the interleukin 1α (IL-1α)-induced aggrecan degradation by β-cryptoxanthin was also observed with porcine articular cartilage explants in culture. β-Cryptoxanthin (1-10 μM) dose-dependently down-regulated the IL-1α-induced gene expression of aggrecanase 1 (ADAMTS-4) and aggrecanase 2 (ADAMTS-5) in cultured human chondrocytes. Moreover, β-cryptoxanthin was found to augment the gene expression of aggrecan core protein in chondrocytes. These results provide novel evidence that β-cryptoxanthin exerts anti-arthritic actions and suggest that β-cryptoxanthin may be useful in blocking the progression of rheumatoid arthritis and osteoarthritis.

Utilization of Dioxygen by Carotenoid Cleavage Oxygenases

Carotenoid cleavage oxygenases (CCOs) are non-heme, Fe(II)-dependent enzymes that participate in biologically important metabolic pathways involving carotenoids and apocarotenoids, including retinoids, stilbenes, and related compounds. CCOs typically catalyze the cleavage of non-aromatic double bonds by dioxygen (O2) to form aldehyde or ketone products. Expressed only in vertebrates, the RPE65 sub-group of CCOs catalyzes a non-canonical reaction consisting of concerted ester cleavage and trans-cis isomerization of all-trans-retinyl esters. It remains unclear whether the former group of CCOs functions as mono- or di-oxygenases. Additionally, a potential role for O2 in catalysis by the RPE65 group of CCOs has not been evaluated to date. Here, we investigated the pattern of oxygen incorporation into apocarotenoid products of Synechocystis apocarotenoid oxygenase. Reactions performed in the presence of (18)O-labeled water and (18)O2 revealed an unambiguous dioxygenase pattern of O2 incorporation into the reaction products. Substitution of Ala for Thr at position 136 of apocarotenoid oxygenase, a site predicted to govern the mono- versus dioxygenase tendency of CCOs, greatly reduced enzymatic activity without altering the dioxygenase labeling pattern. Reevaluation of the oxygen-labeling pattern of the resveratrol-cleaving CCO, NOV2, previously reported to be a monooxygenase, using a purified enzyme sample revealed that it too is a dioxygenase. We also demonstrated that bovine RPE65 is not dependent on O2 for its cleavage/isomerase activity. In conjunction with prior research, the results of this study resolve key issues regarding the utilization of O2 by CCOs and indicate that dioxygenase activity is a feature common among double bond-cleaving CCOs.

Purification and characterization of a novel β-carotene-9',10'-oxygenase from Saccharomyces cerevisiae ULI3

OBJECTIVES

A novel β-carotene-9,10'-oxygenase (ScBCO2) has been characterized from Saccharomyces cerevisiae ULI3 to convert β-carotene to β-apo-10'-carotenal, which is a precursor of the plant hormone strigolactone.

RESULTS

The ScBCO2 enzyme was purified to homogeneity by ammonium sulfate precipitation, Q sepharose and Superdex-200 chromatography. The molecular mass of the enzyme was ~50 kDa by SDS-PAGE. The purified ScBCO2 enzyme displayed optimal activity at 45 °C and pH 8. Tween 20 (1%, w/v), Trition X-100 (1%, w/v), Mg(2+) (5 mM), Zn(2+) (5 mM), Cu(2+) (5 mM), Ca(2+) (5 mM) or DTT (5 mM) increased in the activity by 3, 7, 14, 17, 23, 26 and 27%, respectively. ScBCO2 only exhibited cleavage activity towards carotenoid substrates containing two β-ionone rings and its catalytic efficiency (kcat/Km) followed the order β-carotene > α-carotene > lutein.

CONCLUSION

ScBCO2 could be used as a potential candidate for the enzymatic biotransformation of β-carotene to β-apo-10'-carotenal in biotechnological applications.

Multiple Mechanisms of Anti-Cancer Effects Exerted by Astaxanthin

Astaxanthin (ATX) is a xanthophyll carotenoid which has been approved by the United States Food and Drug Administration (USFDA) as food colorant in animal and fish feed. It is widely found in algae and aquatic animals and has powerful anti-oxidative activity. Previous studies have revealed that ATX, with its anti-oxidative property, is beneficial as a therapeutic agent for various diseases without any side effects or toxicity. In addition, ATX also shows preclinical anti-tumor efficacy both in vivo and in vitro in various cancer models. Several researches have deciphered that ATX exerts its anti-proliferative, anti-apoptosis and anti-invasion influence via different molecules and pathways including signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and peroxisome proliferator-activated receptor gamma (PPARγ). Hence, ATX shows great promise as chemotherapeutic agents in cancer. Here, we review the rapidly advancing field of ATX in cancer therapy as well as some molecular targets of ATX.

Longitudinal Survey of Carotenoids in Human Milk from Urban Cohorts in China, Mexico, and the USA

Emerging evidence indicates that carotenoids may have particular roles in infant nutrition and development, yet data on the profile and bioavailability of carotenoids from human milk remain sparse. Milk was longitudinally collected at 2, 4, 13, and 26 weeks postpartum from twenty mothers each in China, Mexico, and the USA in the Global Exploration of Human Milk Study (n = 60 donors, n = 240 samples). Maternal and neonatal plasma was analyzed for carotenoids from the USA cohort at 4 weeks postpartum. Carotenoids were analyzed by HPLC and total lipids by Creamatocrit. Across all countries and lactation stages, the top four carotenoids were lutein (median 114.4 nmol/L), β-carotene (49.4 nmol/L), β-cryptoxanthin (33.8 nmol/L), and lycopene (33.7 nmol/L). Non-provitamin A carotenoids (nmol/L) and total lipids (g/L) decreased (p<0.05) with increasing lactation stage, except the provitamin A carotenoids α- and β-cryptoxanthin and β-carotene did not significantly change (p>0.05) with lactation stage. Total carotenoid content and lutein content were greatest from China, yet lycopene was lowest from China (p<0.0001). Lutein, β-cryptoxanthin, and β-carotene, and lycopene concentrations in milk were significantly correlated to maternal plasma and neonatal plasma concentrations (p<0.05), with the exception that lycopene was not significantly associated between human milk and neonatal plasma (p>0.3). This enhanced understanding of neonatal exposure to carotenoids during development may help guide dietary recommendations and design of human milk mimetics.

Cellular localization of β-carotene 15,15' oxygenase-1 (BCO1) and β-carotene 9',10' oxygenase-2 (BCO2) in rat liver and intestine

The intestine and liver are crucial organs for vitamin A uptake and storage. Liver accounts for 70% of total body retinoid stores. Vitamin A deficiency (VAD) is a major micronutrient deficiency around the world. The provitamin A carotenoid, β-carotene, is a significant source of vitamin A in the diet. β-Carotene 15,15' oxygenase-1 (BCO1) and β-carotene 9',10' oxygenase-2 (BCO2) are the two known carotenoid cleavage enzymes in humans. BCO1 and BCO2 are highly expressed in liver and intestine. Hepatocytes and hepatic stellate cells are two main cell types involved in the hepatic metabolism of retinoids. Stellate-like cells in the intestine also show ability to store vitamin A. Liver is also known to accumulate carotenoids, however, their uptake, retention and metabolism in specific liver and intestinal cell types is still unknown. Hence, we studied the cellular and subcellular expression and localization of BCO1 and BCO2 proteins in rat liver and intestine. We demonstrate that both BCO1 and BCO2 proteins are localized in hepatocytes and mucosal epithelium. We also show that BCO1 is also highly expressed in hepatic stellate cells (HSC) and portal endothelial cells in liver. At the subcellular level in liver, BCO1 is found in cytosol, while BCO2 is found in mitochondria. In intestine, immunohistochemistry showed strong BCO1 immunoreactivity in the duodenum, particularly in Brunner's glands. Both BCO1 and BCO2 showed diffuse presence along epithelia with strong immunoreactivity in endothelial cells and in certain epithelial cells which warrant further investigation as possible intestinal retinoid storage cells.

Is there a place for nutrition-sensitive agriculture?

The focus of the review paper is to discuss how biotechnological innovations are opening new frontiers to mitigate nutrition in key agricultural crops with potential for large-scale health impact to people in Africa. The general objective of the Africa Biofortified Sorghum (ABS) project is to develop and deploy sorghum with enhanced pro-vitamin A to farmers and end-users in Africa to alleviate vitamin A-related micronutrient deficiency diseases. To achieve this objective the project technology development team has developed several promising high pro-vitamin A sorghum events. ABS 203 events are so far the most advanced and well-characterised lead events with about 12 μg β-carotene/g tissue which would supply about 40-50 % of the daily recommended vitamin A at harvest. Through gene expression optimisation other events with higher amounts of pro-vitamin A, including ABS 214, ABS 235, ABS 239 with 25, 30-40, 40-50 μg β-carotene/g tissue, respectively, have been developed. ABS 239 would provide twice recommended pro-vitamin A at harvest, 50-90 % after 3 months storage and 13-45 % after 6 months storage for children. Preliminary results of introgression of ABS pro-vitamin A traits into local sorghum varieties in target countries Nigeria and Kenya show stable introgression of ABS vitamin A into local farmer-preferred sorghums varieties. ABS gene Intellectual Property Rights and Freedom to Operate have been donated for use royalty free for Africa. Prior to the focus on the current target countries, the project was implemented by fourteen institutions in Africa and the USA. For the next 5 years, the project will complete ABS product development, complete regulatory science data package and apply for product deregulation in target African countries.

The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase

β-Carotene 15-15'-oxygenase (BCO1) catalyzes the oxidative cleavage of dietary provitamin A carotenoids to retinal (vitamin A aldehyde). Aldehydes readily exchange their carbonyl oxygen with water, making oxygen labeling experiments challenging. BCO1 has been thought to be a monooxygenase, incorporating oxygen from O2 and H2O into its cleavage products. This was based on a study that used conditions that favored oxygen exchange with water. We incubated purified recombinant human BCO1 and β-carotene in either (16)O2-H2(18)O or (18)O2-H2(16)O medium for 15 min at 37 °C, and the relative amounts of (18)O-retinal and (16)O-retinal were measured by liquid chromatography-tandem mass spectrometry. At least 79% of the retinal produced by the reaction has the same oxygen isotope as the O2 gas used. Together with the data from (18)O-retinal-H2(16)O and (16)O-retinal-H2(18)O incubations to account for nonenzymatic oxygen exchange, our results show that BCO1 incorporates only oxygen from O2 into retinal. Thus, BCO1 is a dioxygenase.

Retinol and retinyl esters: biochemistry and physiology

By definition, a vitamin is a substance that must be obtained regularly from the diet. Vitamin A must be acquired from the diet, but unlike most vitamins, it can also be stored within the body in relatively high levels. For humans living in developed nations or animals living in present-day vivariums, stored vitamin A concentrations can become relatively high, reaching levels that can protect against the adverse effects of insufficient vitamin A dietary intake for six months, or even much longer. The ability to accumulate vitamin A stores lessens the need for routinely consuming vitamin A in the diet, and this provides a selective advantage to the organism. The molecular processes that underlie this selective advantage include efficient mechanisms to acquire vitamin A from the diet, efficient and overlapping mechanisms for the transport of vitamin A in the circulation, a specific mechanism allowing for vitamin A storage, and a mechanism for mobilizing vitamin A from these stores in response to tissue needs. These processes are considered in this review.

Detection of key factors affecting lycopene in vitro accessibility

On the basis of a Plackett-Burman experimental design for a resolution IV level obtained via a foldover strategy, the effect of 11 factors on lycopene in vitro accessibility was investigated. The selected factors were thermal treatment (X1), olive oil addition (X2), gastric pH (X3), gastric digestion time (X4), pepsin concentration (X5), intestinal pH (X6), pancreatin concentration (X7), bile salts concentration (X8), colipase addition (X9), intestinal digestion time (X10), and intestinal digestion speed (X11). Tomato passata was used as a natural source of lycopene. Samples were collected after gastric and intestinal digestion, and from the micellar phase, to quantify the (all-E)-lycopene and its (Z)-isomers by HPLC. Except for X3, X6, X7, and X11, the other factors studied explained lycopene in vitro accessibility, mainly regarding intestinal digestion, with R(2) values ≥ 0.60. Our results showed that the accessibility of lycopene is influenced by the conditions applied during in vitro intestinal digestion.

Strong and weak plasma response to dietary carotenoids identified by cluster analysis and linked to beta-carotene 15,15'-monooxygenase 1 single nucleotide polymorphisms

The mechanisms as well the genetics underlying the bioavailability and metabolism of carotenoids in humans remain unclear. To begin to address these questions, we used cluster analysis to examine individual temporal responses of plasma carotenoids from a controlled-diet study of subjects who consumed carotenoid-rich beverages. Treatments, given daily for 3 weeks, were watermelon juice at two levels (20-mg lycopene, 2.5-mg β-carotene, n=23 and 40-mg lycopene, 5-mg β-carotene, n=12) and tomato juice (18-mg lycopene, 0.6-mg β-carotene, n=10). Cluster analysis revealed distinct groups of subjects differing in the temporal response of plasma carotenoids and provided the basis for classifying subjects as strong responders or weak responders for β-carotene, lycopene, phytoene and phytofluene. Individuals who were strong or weak responders for one carotenoid were not necessarily strong or weak responders for another carotenoid. Furthermore, individual responsiveness was associated with genetic variants of the carotenoid metabolizing enzyme β-carotene 15,15'-monooxygenase 1. These results support the concept that individuals absorb or metabolize carotenoids differently across time and suggest that bioavailability of carotenoids may involve specific genetic variants of β-carotene 15,15'-monooxygenase 1.

Carotenoid intake and risk of colorectal adenomas in a cohort of male health professionals

PURPOSE

Carotenoids have been hypothesized to prevent carcinogenesis through their antioxidant and pro-vitamin A properties. We examined associations between intakes of specific carotenoids and risk of colorectal adenomas.

METHODS

Among 29,363 men who reported having a lower bowel endoscopy between 1986 and 2006, 3,997 cases of colorectal adenoma were identified in the Health Professionals Follow-up Study. Participants completed food frequency questionnaires every 4 years; dietary information was cumulatively updated. The associations between carotenoid intakes and risk of colorectal adenomas overall and by anatomic site, stage, smoking status and alcohol consumption were investigated using multivariate logistic regression models.

RESULTS

Total β-carotene and dietary β-carotene, lycopene and lutein/zeaxanthin intakes and the total carotenoid score were inversely associated with colorectal adenoma risk. The odds ratios (95 % confidence intervals) comparing the highest versus lowest quintile of intake were 0.78 (0.69-0.88) for total β-carotene, 0.72 (0.64-0.81) for dietary β-carotene, 0.83 (0.74-0.93) for lycopene, 0.86 (0.76-0.96) for lutein/zeaxanthin, and 0.87 (0.77-0.97) for the total carotenoid score. Associations for α-carotene and β-cryptoxanthin intakes were null. We did not find significant differences in the associations between intakes of each carotenoid and risk of colorectal adenoma by anatomic site or stage (all p values, test for common effects >0.10). The inverse associations we observed for total β-carotene and dietary β-carotene, lycopene, and lutein/zeaxanthin intakes and the total carotenoid score with adenoma risk also did not vary by smoking status and alcohol consumption.

CONCLUSION

This study found that a diet high in carotenoids was associated with a reduced risk of colorectal adenomas.

Lycopene metabolism and its biological significance

The beneficial effects of a high intake of tomatoes and tomato products on the risk of certain chronic diseases have been presented in many epidemiologic studies, with the suggestion that lycopene (a major carotenoid in tomatoes) is a micronutrient with important health benefits. Within the past few years, we have gained greater knowledge of the metabolism of lycopene and the biological effects of lycopene derivatives. In particular, the characterization and study of β-carotene 9',10'-oxygenase has shown that this enzyme can catalyze the excentric cleavage of both provitamin and non-provitamin A carotenoids to form apo-10'-carotenoids, including apo-10'-lycopenoids from lycopene. This raised an important question of whether the effect of lycopene on various cellular functions and signaling pathways is a result of the direct actions of intact lycopene or its derivatives. Several reports, including our own, support the notion that the biological activities of lycopene can be mediated by apo-10'-lycopenoids. More research is clearly needed to identify and characterize additional lycopene metabolites and their biological activities, which will potentially provide invaluable insights into the mechanisms underlying the effects of lycopene in humans.

Alkene cleavage catalysed by heme and nonheme enzymes: reaction mechanisms and biocatalytic applications

The oxidative cleavage of alkenes is classically performed by chemical methods, although they display several drawbacks. Ozonolysis requires harsh conditions (−78°C, for a safe process) and reducing reagents in a molar amount, whereas the use of poisonous heavy metals such as Cr, Os, or Ru as catalysts is additionally plagued by low yield and selectivity. Conversely, heme and nonheme enzymes can catalyse the oxidative alkene cleavage at ambient temperature and atmospheric pressure in an aqueous buffer, showing excellent chemo- and regioselectivities in certain cases. This paper focuses on the alkene cleavage catalysed by iron cofactor-dependent enzymes encompassing the reaction mechanisms (in case where it is known) and the application of these enzymes in biocatalysis.

Grapefruit juices impair the bioaccessibility of β-carotene from orange-fleshed sweet potato but not its intestinal uptake by Caco-2 cells

Among various factors influencing β-carotene (Bc) bioavailability, information on interactions between carotenoids or other micronutrients such as flavonoids during a meal that contains different plant-derived foods is quite limited. Because orange-fleshed sweet potato (OFSP) is an important Bc-rich staple food, a source of vitamin A in developing countries, this study focused on the effect of citrus fruit juice carotenoids and flavonoids on Bc bioaccessibility from OFSP. In vitro digestion coupled with the Caco-2 cell culture model was used to evaluate the bioaccessibility and cellular uptake of Bc from OFSP in the presence of pink grapefruit (pGF) or white grapefruit (wGF) juices. The addition of grapefruit juices significantly decreased the bioaccessibility, by up to 30%, but not the cellular uptake of Bc from boiled OFSP. Lycopene, but more probably naringin, present in grapefruit juices was suspected to be responsible for the inhibitory effect of the citrus juices on Bc bioaccessibility. This inhibition was apparently due in part to competition for incorporation between Bc and naringin into mixed micelles during in vitro digestion. In contrast, Bc uptake from dietary micelles was not impaired by naringin.

β-Cryptoxanthin- and α-carotene-rich foods have greater apparent bioavailability than β-carotene-rich foods in Western diets

β-Carotene (BC), β-cryptoxanthin (CX) and α-carotene (AC) are common carotenoids that form retinol. The amount of retinol (vitamin A) formed from carotenoid-rich foods should depend chiefly on the bioavailability (absorption and circulation time in the body) of carotenoids from their major food sources and the selectivity and reactivity of carotene cleavage enzymes towards them. The objective of the present study was to estimate the apparent bioavailability of the major sources of provitamin A (AC, BC and CX) from the diet by comparing the concentrations of these carotenoids in blood to their dietary intakes. Dietary intakes were estimated by FFQ (three studies in this laboratory, n 86; apparent bioavailability calculated for six other studies, n 5738) or by food record (two studies in our laboratory, n 59; apparent bioavailability calculated for two other studies, n 54). Carotenoid concentrations were measured by reversed-phase HPLC. Apparent bioavailability was calculated as the ratio of concentration in the blood to carotenoid intake. Then apparent bioavailabilities for AC and CX were compared to BC. Eating comparable amounts of AC-, CX- and BC-rich foods resulted in 53 % greater AC (99 % CI 23, 83) and 725 % greater CX (99 % CI 535, 915) concentrations in the blood. This suggests that the apparent bioavailability of CX from typical diets is greater than that of BC. Thus, CX-rich foods might be better sources of vitamin A than expected.

Vitamin D intestinal absorption is not a simple passive diffusion: evidences for involvement of cholesterol transporters

SCOPE

It is assumed that vitamin D is absorbed by passive diffusion. However, since cholecalciferol (vitamin D(3) ) and cholesterol display similar structures, we hypothesized that common absorption pathways may exist.

METHODS AND RESULTS

Cholecalciferol apical transport was first examined in human Caco-2 and transfected Human embryonic kidney (HEK) cells. Cholecalciferol uptake was then valuated ex vivo and in vivo, using either wild-type mice, mice overexpressing Scavenger Receptor class B type I (SR-BI) at the intestinal level or mice treated or not with ezetimibe. Cholecalciferol uptake was concentration-, temperature- and direction-dependent, and was significantly impaired by a co-incubation with cholesterol or tocopherol in Caco-2 cells. Moreover Block Lipid Transport-1 (SR-BI inhibitor) and ezetimibe glucuronide (Niemann-Pick C1 Like 1 inhibitor) significantly decreased cholecalciferol transport. Transfection of HEK cells with SR-BI, Cluster Determinant 36 and Niemann-Pick C1 Like 1 significantly enhanced vitamin D uptake, which was significantly decreased by the addition of Block Lipid Transport-1, sulfo-N-succinimidyl oleate (Cluster Determinant 36 inhibitor) or ezetimibe glucuronide, respectively. Similar results were obtained in mouse intestinal explants. In vivo, cholecalciferol uptake in proximal intestinal fragments was 60% higher in mice overexpressing SR-BI than in wild-type mice (p<0.05), while ezetimibe effect remained non-significant.

CONCLUSION

These data show for the first time that vitamin D intestinal absorption is not passive only but involves, at least partly, some cholesterol transporters.

Clinical validation of a noninvasive, Raman spectroscopic method to assess carotenoid nutritional status in humans

BACKGROUND

Carotenoids are an important group of phytonutrients that are abundant in fruits and vegetables. Epidemiological and clinical intervention studies have implied the presence of protective qualities of these nutrients against the development of a variety of chronic diseases. Previously, human carotenoid status has been assessed in serum and tissue using high-performance liquid chromatography (HPLC) methodology. Recently, a Raman spectroscopy (RS)-based photonic method has been developed to accurately and noninvasively measure the carotenoid concentration in human skin.

OBJECTIVES

(1) To validate skin RS methodology against standard serum carotenoid measurements by HPLC and (2) to establish and compare the reliability of the 2 methods.

DESIGN

This study included 372 healthy adults who provided 3 blood samples and 3 RS skin carotenoid measurements within an 8-day period; each day-matched blood sample and RS determination was spaced by >or=48 hours.

RESULTS

Consistent positive correlations were observed for each of 3 separate same-day correlation plots of total serum versus RS skin carotenoids. Overall estimate of the line of best fit from analysis of covariance, using all 3 samples (n = 1116), yielded a Pearson correlation of R = 0.81 (r(2) = 0.66; p < 0.001). Based on analysis of variance, RS skin carotenoid methodology exhibited 0.9% less variance over the 3 tests than serum carotenoids by the HPLC method (p < 0.03).

CONCLUSIONS

RS accurately measures total carotenoids in human skin with less intra-individual variability than measurement of serum carotenoids by HPLC analysis. RS technology is a valid and reliable noninvasive method to rapidly assess carotenoid nutritional status in humans.

Biotransformation of carotenoids to retinal by carotenoid 15,15'-oxygenase

Retinal, a precursor of vitamin A, has been used in foods, cosmetics, pharmaceuticals, nutraceuticals, and animal feed additives. Carotenoid 15,15'-oxygenases, including β-carotene 15,15'-oxygenases from mammalians, chickens, fruit flies, zebrafishes, the uncultured marine bacterium, and the fungus Fusarium fujikuroi, and apo-carotenoid 15,15'-oxygenases from cyanobacteria produce retinal from carotenoids. In this article, the biochemical properties, reaction mechanism, and substrate specificity of carotenoid oxygenases are reviewed, along with a description of the enzymatic biotransformation of carotenoids to retinal. Retinal producing methods using metabolically engineered cells and uncharacterized proteins are suggested.

beta-Carotene deficiency in cholestatic liver disease of childhood is caused by beta-carotene malabsorption

BACKGROUND

: Depletion of beta-carotene (b-c) has not been extensively studied in children with chronic cholestatic liver disease.

PATIENTS AND METHODS

: We assessed b-c serum concentration in 53 children with cholestatic liver disease: 19 patients operated on for biliary atresia, 12 with Alagille syndrome, and 22 with progressive familial intrahepatic cholestasis. To test b-c absorption, 6 children with chronic cholestasis received a load of 10 mg b-c/kg body weight.

RESULTS

: We found decreased b-c concentrations in 45 patients. The absorption of b-c was not detectable in 5 of 6 children studied.

CONCLUSIONS

: b-c depletion is a common problem of chronic cholestatic liver disease in childhood that can be attributed to disturbed intestinal absorption.