Carotenoid Absorption Research Articles

The photocycle of orange carotenoid protein conceals distinct intermediates and asynchronous changes in the carotenoid and protein components

The 35-kDa Orange Carotenoid Protein (OCP) is responsible for photoprotection in cyanobacteria. It acts as a light intensity sensor and efficient quencher of phycobilisome excitation. Photoactivation triggers large-scale conformational rearrangements to convert OCP from the orange OCPO state to the red active signaling state, OCPR, as demonstrated by various structural methods. Such rearrangements imply a complete, yet reversible separation of structural domains and translocation of the carotenoid. Recently, dynamic crystallography of OCPO suggested the existence of photocycle intermediates with small-scale rearrangements that may trigger further transitions. In this study, we took advantage of single 7 ns laser pulses to study carotenoid absorption transients in OCP on the time-scale from 100 ns to 10 s, which allowed us to detect a red intermediate state preceding the red signaling state, OCPR. In addition, time-resolved fluorescence spectroscopy and the assignment of carotenoid-induced quenching of different tryptophan residues derived thereof revealed a novel orange intermediate state, which appears during the relaxation of photoactivated OCPR to OCPO. Our results show asynchronous changes between the carotenoid- and protein-associated kinetic components in a refined mechanistic model of the OCP photocycle, but also introduce new kinetic signatures for future studies of OCP photoactivity and photoprotection.

Spectrally selective fluorescence imaging of Chlorobaculum tepidum reaction centers conjugated to chelator-modified silver nanowires

A polyhistidine tag (His-tag) present on Chlorobaculum tepidum reaction centers (RCs) was used to immobilize photosynthetic complexes on a silver nanowire (AgNW) modified with nickel-chelating nitrilo-triacetic acid (Ni-NTA). The optical properties of conjugated nanostructures were studied using wide-field and confocal fluorescence microscopy. Plasmonic enhancement of RCs conjugated to AgNWs was observed as their fluorescence intensity dependence on the excitation wavelength does not follow the excitation spectrum of RC complexes in solution. The strongest effect of plasmonic interactions on the emission intensity of RCs coincides with the absorption spectrum of AgNWs and is observed for excitation into the carotenoid absorption. From the absence of fluorescence decay shortening, we attribute the emission enhancement to increase of absorption in RC complexes.

Molecular cloning and characterisation of scavenger receptor class B in pearl oyster Pinctada fuctada martensii

Abstract Background Molluscs can accumulate carotenoids in their body tissues by predominantly feeding on aquatic plant sources. Carotenoid transport and absorption are determined by the regulation of various proteins such as Scavenger receptor class B( SR-BI ). We report the identification and characterisation of pearl oyster Pinctada fuctada martensii SR-BI ( PmSR-BI ). The correlation between total carotenoid content (TCC) and gene expression was also estimated. Results The full-length cDNA of PmSR-BI was 1828 bp, including an open-reading frame encoding of 1518 bp with a pI value of 5.83. PmSR-BI protein contains a hydrophobic CD36 domain and four centrally clustered cysteine residues for the arrangement of disulphide bridges. The deduced amino acid sequence had an identity of 30% to 60% with the SR-B of other organisms. Reverse transcription polymerase chain reaction analysis showed that mRNA transcripts were expressed in multiple tissues of adult pearl oyster. A higher expression of PmSR-BI gene was observed in the hepatopancreas than in the adductor muscle, gill and mantle. The TCC and gene expression of PmSR-BI were significantly correlated ( P Conclusions The results suggested that PmSR-BI is involved in the absorption of carotenoids in the pearl oyster P. fuctada martensii .

Provitamin A carotenoids from an engineered high-carotenoid maize are bioavailable and zeaxanthin does not compromise β-carotene absorption in poultry.

High-carotenoid (HC) maize, a biofortified staple crop which accumulates β-carotene, β-cryptoxanthin, lutein and zeaxanthin, was used as a feed component in a chicken feeding trial to assess the bioavailability of provitamin A (PVA) carotenoids in the kernel matrix compared to the synthetic and natural color additives routinely used in the poultry industry. We found that the PVA carotenoids in HC maize were not metabolized in the same manner: β-carotene was preferentially converted into retinol in the intestine whereas β-cryptoxanthin accumulated in the liver. We also considered the effect of zeaxanthin on the absorption of PVA carotenoids because zeaxanthin is the major carotenoid component of HC maize. We found that chickens fed on diets with low levels of zeaxanthin accumulated higher levels of retinol in the liver, suggesting that zeaxanthin might interfere with the absorption of β-carotene, although this observation was not statistically significant. Our results show that HC maize provides bioavailable carotenoids, including PVA carotenoids, and is suitable for use as a feed component.

No influence of supplemental dietary calcium intake on the bioavailability of spinach carotenoids in humans.

Dietary carotenoid intake, especially from fruits and vegetables, has been associated with a reduced incidence of several chronic diseases. However, its bioavailability can vary, depending on the food matrix and host factors. Recently, it has been suggested that divalent minerals negatively impinge on carotenoid bioavailability by reducing bile-salt and non-esterified fatty-acid levels in the gut, which normally aid in emulsifying carotenoids. The aim of the present study was to investigate whether supplemental Ca would negatively influence carotenoid absorption in humans. A total of twenty-five healthy, non-obese men (age: 20-46 years, BMI<30 kg/m2) were recruited for this postprandial, randomised, crossover, double-blinded trial. Following a randomised block design, each participant received (after 2-week washout periods), on three occasions separated by 1 week, 270 g of spinach-based meals (8·61 (sd 1·08) mg carotenoids/100 g fresh weight), supplemented with 0, 500 or 1000 mg of Ca (as calcium carbonate), with each participant acting as his or her own control. Blood samples were collected at regular postprandial intervals for up to 10 h following test meal intake, and standardised lunches were served. TAG-rich lipoprotein fractions were separated and carotenoid concentrations determined. AUC for meals without supplemented Ca were 22·72 (sem 2·78) nmol×h/l (lutein), 0·19 (sem 3·90) nmol×h/l (β-carotene) and 2·80 (sem 1·75) nmol×h/l (β-cryptoxanthin). No significant influence of supplementation with either 500 or 1000 mg of supplemental Ca was found. In conclusion, Ca - the most abundant divalent mineral in the diet - given at high but physiological concentrations, does not appear to have repercussions on the bioavailability of carotenoids from a spinach-based meal.

Dependence of the hydration status of bacterial light-harvesting complex 2 on polyol cosolvents.

Low molecular weight (MW) polyols are organic osmolytes influencing protein structure and activity. We have intended to investigate the effects of low MW polyols on the optical and the excited-state properties of the light-harvesting complex 2 (LH2) isolated from the photosynthetic bacterium Thermochromatium (Tch.) tepidum, a thermophile growing at ∼50 °C. Steady state spectroscopy demonstrated that, on increasing glycerol or sorbitol fractions up to 60% (polyol/water, v/v), the visible absorption of carotenoids (Crts) remained unchanged, while the near infrared Qy absorption of bacteriochlorophyll a (BChl) at 800 nm (B800) and 850 nm (B850) varied slightly. Further increasing the fraction of glycerol (but not sorbitol) to 80% (v/v) induced distinct changes of the near infrared absorption and fluorescence spectra. Transient absorption spectroscopy revealed that, following the fast processes of BChl-to-Crt triplet energy transfer, rather weak Qy signals of B800 and B850 remained and evolved in phase with the kinetics of triplet excited state Crt (3Crt*), which are attributed to the Qy band shift as a result of 3Crt*-BChl interaction. The steady state and the transient spectral responses of the Qy bands are found to correlate intimately with the water activity varying against polyol MW and mixing ratio, which are rationalized by the change of the hydration status of the C- and N-termini of LH2. Our results suggest that, with reference to the mesophilic purple bacterium Rhodobacter sphaeroides 2.4.1, Tch. tepidum adopts substantially more robust LH2 hydration against the osmotic effects from the low MW polyols.

Bioavailability of Palm Oil Carotenoids Consumed from Different Foods

Crude palm oil (CPO), an ingredient with a high content in provitamins A, is usually consumed associated with foods that could affect carotenoids metabolism. This work aimed to evaluate the influence of foodstuffs prepared with the incorporation of CPO on carotenoids absorption. Thus, we studied carotenoids bioavailability in Cameroonian local meals based on CPO and three different foodstuffs: maize (Zea mais), cassava (Manihot esculente) or black eyed peas (Vigna unguiculata). Modified ‘yellow sauce’ prepared mainly with CPO was used as control meal. Eleven healthy volunteers with age range between 20-30 year and similar body mass index were submitted to the study. A total of four interventions (i.e., meal ingestion) were performed every six days. After meal ingestion blood samples were collected at 0, 2, 4 and 6 h, and carotenoids content were analyzed by HPLC. Results showed that control meal had the highest carotenoids absorption (0.479±0.063 µg.h/ml.), followed by maize (0.329±0.115 µg.h/ml) and cassava (0.141±0.075 µg.h/ml) cakes. Food based on black eyed peas incorporated with CPO showed the smallest increase in blood carotenoids (0.053±0.062 µg.h/ml). Notably, CPO consumption leads to a short term significant increase of blood carotenoids (p&lt;0.05) that declines over time. Our results suggest that the association of CPO with different foodstuffs significantly affects carotenoids bioavailability. This effect seems to be more important for leguminous, followed by tubers and cereals.

Modeling the dose effects of soybean oil in salad dressing on carotenoid and fat-soluble vitamin bioavailability in salad vegetables

Background: Previously, we showed that vegetable oil is necessary for carotenoid absorption from salad vegetables. Research is needed to better define the dose effect and its interindividual variation for carotenoids and fat-soluble vitamins.Objective: The objective was to model the dose-response relation between the amount of soybean oil in salad dressing and the absorption of 1) carotenoids, phylloquinone, and tocopherols in salad vegetables and 2) retinyl palmitate formed from the provitamin A carotenoids.Design: Women (n = 12) each consumed 5 vegetable salads with salad dressings containing 0, 2, 4, 8, or 32 g soybean oil. Blood was collected at selected time points. The outcome variables were the chylomicron carotenoid and fat-soluble vitamin area under the curve (AUC) and maximum content in the plasma chylomicron fraction (Cmax). The individual-specific and group-average dose-response relations were investigated by fitting linear mixed-effects random coefficient models.Results: Across the entire 0-32-g range, soybean oil was linearly related to the chylomicron AUC and Cmax values for α-carotene, lycopene, phylloquinone, and retinyl palmitate. Across 0-8 g of soybean oil, there was a linear increase in the chylomicron AUC and Cmax values for β-carotene. Across a more limited 0-4-g range of soybean oil, there were minor linear increases in the chylomicron AUC for lutein and α- and total tocopherol. Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002). For 32 g oil, the interindividual rank order of the chylomicron AUCs was consistent across the carotenoids and fat-soluble vitamins (P < 0.0001).Conclusions: Within the linear range, the average absorption of carotenoids and fat-soluble vitamins could be largely predicted by the soybean oil effect. However, the effect varied widely, and some individuals showed a negligible response. There was a global soybean oil effect such that those who absorbed more of one carotenoid and fat-soluble vitamin also tended to absorb more of the others. This trial was registered at clinicaltrials.gov as NCT02867488.

Influence of Cooking Conditions on Carotenoid Content and Stability in Porridges Prepared from High-Carotenoid Maize.

Maize is a staple food crop in many developing countries, hence becoming an attractive target for biofortification programs toward populations at risk of micronutrient deficiencies. A South African white endosperm maize inbred line was engineered with a carotenogenic mini-pathway to generate high-carotenoid maize, which accumulates β-carotene, lutein and zeaxanthin. As maize porridge is a traditional meal for poor populations in sub-Saharan African countries, high-carotenoid maize was used as raw material to prepare different maize meals. The objective of this work was to assess the impact of popular home-cooking techniques and different cooking parameters (temperature, time and pH) on the final carotenoid content in the cooked product, using a spectrophotometric technique based on the mean absorption of carotenoids at 450nm. Carotenoid levels were not only preserved, but also enhanced in high-carotenoid maize porridges. The carotenoid content was increased when temperatures ≤95°C were combined with short cooking times (10-60min). The most optimum thermal treatment was 75°C/10min. When treated under those conditions at pH5, high-carotenoid maize porridges doubled the initial carotenoid content up to 88μg/g dry weight. Regarding to cooking techniques, the highest carotenoid content was found when unfermented thin porridges were prepared (51μg/g dry weight of high-carotenoid maize porridge). We conclude that high-carotenoid maize may contribute to enhance the dietary status of rural populations who depend on maize as a staple food.

Retinal accumulation of zeaxanthin, lutein, and β-carotene in mice deficient in carotenoid cleavage enzymes

Carotenoid supplementation can prevent and reduce the risk of age-related macular degeneration (AMD) and other ocular disease, but until now, there has been no validated and well-characterized mouse model which can be employed to investigate the protective mechanism and relevant metabolism of retinal carotenoids. β-Carotene oxygenases 1 and 2 (BCO1 and BCO2) are the only two carotenoid cleavage enzymes found in animals. Mutations of the bco2 gene may cause accumulation of xanthophyll carotenoids in animal tissues, and BCO1 is involved in regulation of the intestinal absorption of carotenoids. To determine whether or not mice deficient in BCO1 and/or BCO2 can serve as a macular pigment mouse model, we investigated the retinal accumulation of carotenoids in these mice when fed with zeaxanthin, lutein, or β-carotene using an optimized carotenoid feeding method. HPLC analysis revealed that all three carotenoids were detected in sera, livers, retinal pigment epithelium (RPE)/choroids, and retinas of all of the mice, except that no carotenoid was detectable in the retinas of wild type (WT) mice. Significantly higher amounts of zeaxanthin and lutein accumulated in the retinas of BCO2 knockout (bco2-/-) mice and BCO1/BCO2 double knockout (bco1-/-/bco2-/-) mice relative to BCO1 knockout (bco1-/-) mice, while bco1-/- mice preferred to take up β-carotene. The levels of zeaxanthin and lutein were higher than β-carotene levels in the bco1-/-/bco2-/- retina, consistent with preferential uptake of xanthophyll carotenoids by retina. Oxidative metabolites were detected in mice fed with lutein or zeaxanthin but not in mice fed with β-carotene. These results indicate that bco2-/- and bco1-/-/bco2-/- mice could serve as reasonable non-primate models for macular pigment function in the vertebrate eye, while bco1-/- mice may be more useful for studies related to β-carotene.

Dietary fat composition, food matrix and relative polarity modulate the micellarization and intestinal uptake of carotenoids from vegetables and fruits.

Dietary fat increases carotenoid bioavailability by facilitating their transfer to the aqueous micellar fraction during digestion. However, the specific effect of both quantity and type of dietary fat required for optimal carotenoid absorption remained unexplored. In the present study, the effect of amount and type of vegetable oils on carotenoid micellarization from carrot, spinach, drumstick leaves and papaya using in vitro digestion/Caco-2 cell model have been assessed. Although, dietary fat (0.5-10%w/w) significantly increased the micellarization of carotenoids from all the test foods, the extent of increase was determined by the food matrix (papaya>drumstick=spinach>carrot) and polarity of carotenoids (lutein>β-carotene=α-carotene>lycopene). Among the dietary fats tested the carotenoid micellarization was twofold to threefold higher with dietary fat rich in unsaturated fatty acids (olive oil=soybean oil=sunflower oil) compared to saturated fatty acids (peanut oil=palm oil>coconut oil). Intestinal cell uptake of lutein exceeded that of β-carotene from micellar fraction of spinach leaves digested with various oils. However, cellular uptake of β-carotene is depended on the carotenoid content in micellar fraction rather than the type of fat used. Together these results suggest that food matrix, polarity of carotenoids and type of dietary fat determines the extent of carotenoid micellarization from vegetables and fruits.

Food matrix: Natural barrier or vehicle for effective delivery of carotenoids from processed foods?

Carotenoids are lipophilic compounds naturally occurring in plant species where they exert their main biological role as photosynthetic pigments. Due to their chemical structure, carotenoids have the ability to act as antioxidants primarily by scavenging reactive oxygen species. The antioxidant potential of carotenoids is of significant importance to human health and a carotenoidrich diet is recommended for the prevention of a number of chronic and age-related diseases. The bioaccessibily and bioavailabilty of carotenoids is not proportional to their relative abundance in the original food matrix. The structural integrity of the plant material in which they are embedded and their chemical interactions with other food components seem to be critical factors for their release from the food source and their subsequent uptake by cells at the intestinal epithelium. In addition to food microstructure, food processing is also important for carotenoid bioavailabilty. Heat treatment, acidification and exposure to light can induce isomerisation and oxidation of the phytochemical compounds. It is evident that the absorption of carotenoids in a biologically active form is a complex, multi-step process depending on many variables. In this context the aim of this review is to present and critically discuss evidence relating to the association between food processing and carotenoid bioavailability. Emphasis is given on the food matrix composition and the chemical properties of the individual phytochemicals for formulating conclusions on carotenoid availability from processed meals.

Dietary Encapsulated Butyric Acid (Butipearl™) and Microemulsified Carotenoids (Quantum GLO™ Y) on the Growth, Immune Parameters and their Synergistic Effect on Pigmentation of Hybrid Catfish (Clarias macrocephalus × Clarias gariepinus)

A 12-weeks feeding trial was conducted to evaluate the effects of encapsulated butyric acid (ButiPEARL™) and microemulsified yellow carotenoid (Quantum GLO™ Y) on growth, immune parameters and their synergistic effect on pigmentation of hybrid catfish. In the experiment, the catfish was randomly divided into 12 groups of 15 fishes and then fed with four experimental diets containing 0.5 kg/t ButiPEARL™, 0.7 kg/t Quantum GLO™ Y, 0.5 kg/t ButiPEARL™ + 0.7 kg/t Quantum GLO™ Y, or none of these supplements (control diet). The results showed that the ButiPEARL™ + Quantum GLO™ Y fed group gave the highest yellowness (b*) score of 18.43 in the back muscle and almost double the total carotenoid measured in the fish muscle (151.35 mg/kg) compared to the Quantum™ Y fed group. This suggests that butyric acid in the diet had a synergistic effect on carotenoid absorption and pigmentation performance of catfish. The body weight of all treatment groups was significantly different from the control group and the catfish fed ButiPEARL™ alone had the highest body weight gained followed by the ButiPEARL™ + Quantum GLO™ Y fed group with an FCR improvement of 25 points and 13 points respectively over the control. There was no adverse effect on the immune system after feeding both butyric acid and carotenoid to the catfish and the immune parameters (number of leucocytes, erythrocyte, percent of hematocrit, haemoglobin and total protein) of ButiPEARL™ + Quantum GLO™ Y fed group were improved compared with the other groups. In conclusion, ButiPEARL™, Quantum GLO™ Y and the combination have positive effects on performance and pigmentation in catfish aquaculture.

Gastrointestinal absorption, antiproliferative and anti-inflammatory effect of the major carotenoids of Gardenia jasminoides Ellis on cancer cells.

The gastrointestinal absorption of the main carotenoids present in Gardenia jasminoides Ellis, crocetin, crocin-1 and crocin-2, was assayed through transport studies on MKN-28 and Caco-2 cell lines. Overall, crocetin was the compound that presented the highest gastrointestinal transport efficiency. Additionally, and since after absorption crocins are metabolized into crocetin, the antiproliferative capacity of crocetin was assayed in MKN-28 (stomach), MCF-7 (breast) and Caco-2 (colon) cancer cell lines. The results point to an antiproliferative effect of crocetin on the three cell lines tested. Anti-inflammatory properties were also assayed. Overall, crocetin showed a potential involvement in the downregulation of IL-1β and TNF-α but not IL-6. Altogether, these results suggest that these compounds can have an important role against cancer proliferation, highlighting the importance of Gardenia jasminoides Ellis as a nutraceutical food source.

No detectable carotenoid concentrations in serum of llamas and alpacas.

Carotenoids are lipid-soluble pigments and important for a variety of physiological functions. They are major dietary vitamin A precursors and act as lipophilic antioxidants in a variety of tissues and are associated with important health benefits in humans and animals. All animals must acquire carotenoids from their diet, but to our knowledge, there are no studies investigating the intestinal carotenoid absorption and their blood concentrations in New World camelids. The present study aimed to assess the serum concentrations of selected carotenoids in llamas (n=13) and alpacas (n=27). Serum carotenoids as well as retinol (vitamin A) and α-tocopherol (vitamin E) were determined by high-performance liquid chromatography coupled with mass spectrometry and these were unable to detect any carotenoids (α- and β-carotene, α- and β-cryptoxanthin, lutein, zeaxanthin, lycopene) in the samples. The concentrations of retinol in alpacas (2.89±1.13μmol/l; mean±SD) were higher (p=0.024) than those found in llamas (2.05±0.87μmol/l); however, the concentrations of α-tocopherol were not significantly (p=0.166) different (llamas: 3.98±1.83μmol/l; alpacas: 4.95±2.14μmol/l). The results show that both llamas and alpacas are not able to absorb intact carotenoids, but efficiently convert provitamin A carotenoids to retinol.

Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria.

Carotenoids are a class of natural pigments present in all phototrophic organisms, mainly in their light-harvesting proteins in which they play roles of accessory light absorbers and photoprotectors. Extensive time-resolved spectroscopic studies of these pigments have revealed unexpectedly complex photophysical properties, particularly for carotenoids in light-harvesting LH2 complexes from purple bacteria. An ambiguous, optically forbidden electronic excited state designated as S* has been postulated to be involved in carotenoid excitation relaxation and in an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway, as well as being a precursor of the carotenoid triplet state. However, no definitive and satisfactory origin of the carotenoid S* state in these complexes has been established, despite a wide-ranging series of studies. Here, we resolve the ambiguous origin of the carotenoid S* state in LH2 complex from Rba. sphaeroides by showing that the S* feature can be seen as a combination of ground state absorption bleaching of the carotenoid pool converted to cations and the Stark spectrum of neighbor neutral carotenoids, induced by temporal electric field brought by the carotenoid cation–bacteriochlorophyll anion pair. These findings remove the need to assign an S* state, and thereby significantly simplify the photochemistry of carotenoids in these photosynthetic antenna complexes.

The effect of chopped, extruded and pelleted alfalfa silage on the egg quality of organic laying hens

The experiment was carried out to determine the effect of incorporating young alfalfa in the form of chopped, extruded or pelleted silage in the diet of laying hens on egg quality. Four hundred forty hens, divided into four groups, were used in the study. The control group (A) received a complete feed mixture (CFM), while the silage groups (B, C and D) received a supplementary feed mixture (SFM). The SFM recipe was formulated based on an assumed ingestion of 20% silage in the diet. To achieve the energy requirements of the silage groups, canola oil was incorporated in the SFM. Before ensiling, the alfalfa was chopped for group B and additionally extruded for group C. One half of the extruded silage was pelleted together with the SFM to conform the pelletized silage for group D.The study showed a mixed effect of silage and the feed mixtures on the parameters measured. For this reason, the daily intake of lipids was calculated to clarify the results. Eggs from hens fed with silage (B, C and D) contained 2.4 times more n-3 fatty acids (FA) than the control (A). Chopped, extruded and pelleted silage showed the same effect on the quality of eggs, but thermally treated silage (C and D) produced yolks with higher concentrations of SFA. The yolks from D exhibited the highest content of odd-numbered fatty acids (15:0, 17:0, 17:1), corresponding to the highest intake of silage. Groups B and C with high canola oil intake showed the highest 18:1 n-9, 22:5 n-3 and MUFA. Furthermore, in spite of the high fat intake, their cholesterol levels were similar to A (A: 12.4; B: 12.3; C: 12.6mg/g yolk; p>0.05) due to the anti-cholesterolemic effect of the alfalfa silage. Hens from group D consumed the lowest amount of fat but the highest amount of silage, which corresponding to the lowest level of cholesterol. The fat consumed in the diet was essential in the absorption of carotenoids from the consumed silage. Thus, yolks from the silage groups showed decreasing values for the intensity of red (B: 7.5; C: 6.9; D: 5.2) and yellow (B: 38.6; C: 36.8; D: 32.9) colour as the intake in terms of the amount of fat/silage decreased (B: 6.8; C: 5.0; D: 2.8 fat/10g silage).

PHOTOSTABILITY OF PURPLE BACTERIAL LIGHT–HARVESTING COMPLEXES TOWARDS EXPOSURE OF LIGHT ILLUMINATION TRACED BY PIGMENT RATIO

Purple photosynthetic light–harvesting (LH2) is an attractive complex module for assembling hybrid nanostructures that feature energy transfer. LH2 has a broad absorption spectrum range from ultraviolet (UV) to near-infra red (NIR) region. Bacteriochlorophyll a molecules absorb at 320 nm to 400 nm (Soret band), 585 nm (Qx) and at NIR region (B800 and B850 bands), while carotenoid absorption bands span from 400 nm to 550 nm. LH2 has to be extracted from its native lipid bilayer membrane and placed in suitable matrix that less mobile and better adherent than the native lipid environment to determine its function. Previous results on pigment ratio determination in different strains of purple photosynthetic bacteria suggested a variation during initial log phase and late log phase. In this experiment, the goal is to reveal the behavior of pigment ratio in LH2 of Rhodopseudomonas palustris during irradiation of certain intensity of light. Photostability assay of LH2 from Rhodopseudomonas palustris in n-dodecyl-β-D-maltoside or DDM was determined under continuous illumination (3 000 μmol·m–2·s–1) for 300 min at room temperature by recording the absorption spectra. Degradation was observed in B850 and B800 at about 67 % and 64 %, respectively, as well as blue shift in B850. Initial pigments isolated from LH2 suggested a mixture of carotenoids and bacteriochlorophylls which was determined further using a high-performance liquid chromatography (HPLC).

Dietary beta-carotene and lutein metabolism is modulated by the APOE genotype.

The human apolipoprotein E (APOE) genotype has been suggested to interact with nutrient metabolism particularly with lipid soluble vitamins. Plasma carotenoid levels are determined by numerous dietary and genetic factors with high inter-individual variation; however, the APOE genotype has not been systematically examined so far. Our aim was to investigate the effect of the APOE genotype on dietary carotenoid metabolism with special regard to transcriptional regulation of carotenoid absorption, cleavage and adipocyte fat storage. We supplemented targeted replacement mice expressing human APOE3 and APOE4 isoforms with dietary beta-carotene (BC) and lutein (LUT) for 8 weeks. Plasma BC and adipose tissue BC and LUT levels were in trend lower in APOE4 than APOE3 mice, while hepatic expression of the beta-carotene oxygenases BCO1 and BCO2 was significantly higher. In contrast to the liver, mRNA levels of proteins involved in carotenoid absorption and cleavage in the small intestinal mucosa as well as of adipogenic markers in the adipose tissue were not different between APOE3 and APOE4 mice. Our data suggest that the hepatic carotenoid cleavage activity is higher in APOE4 mice partially reducing the circulation and extra-hepatic accumulation of intact carotenoids as compared to APOE3. Therefore we suggest considering the APOE genotype as modulator of carotenoid status in the future. © 2016 BioFactors, 42(4):388-396, 2016.

SNPs in Lipid and Carotenoid Metabolism and Absorption Genes Impact Carotenoid Responses to a Tomato‐Soy Juice Intervention

Several single nucleotide polymorphisms (SNPs) in genes regulating lipid and carotenoid absorption and metabolism have been associated with individual differences in plasma concentrations and absorption kinetics of beta‐carotene (BC) and lycopene (LYC). However, whether these SNPs impact plasma and prostatic carotenoid concentrations in response to a dietary tomato product intervention is not known. The primary question addressed was whether any of seven common SNPs, previously found to be related to plasma carotenoid levels, are associated with the plasma LYC response in prostate cancer patients (n=47) consuming 0, 1, or 2 cans/d of a custom formulated tomato‐soy juice (20.6 mg LYC/can) for 23±1.7 d before scheduled therapeutic prostatectomy. Secondarily, the association of these SNPs with the plasma concentrations of other tomato carotenoids, phytoene (PE), phytofluene (PF), and BC, and prostate concentrations of LYC, PE, and PF were also explored. BCMO1 (rs12934922, rs7501331, and rs6564851), SCARB1 (rs11057841), ABCA1 (rs2230808), MTTP (rs2306985), and APOB48 (rs679899) genotypes were determined using TaqMan Genotyping Assays, and plasma and prostatic carotenoid levels were measured by HPLC. Significant relationships were defined using single SNP linear models with covariates for intervention duration, body mass, baseline plasma carotenoid concentrations, and extraneous carotenoid intake; plasma carotenoid concentrations were cholesterol‐adjusted. Significant SNPs and covariates were combined into a final, predictive linear model. The genotypes of BCMO1 rs12934922 and rs6564851 significantly interacted with treatment group (p=0.021 and p=0.046, respectively) to explain 5.6% of the variance in plasma LYC response to the dietary intervention, with baseline plasma LYC and treatment group being the major predictors of the plasma LYC response (15%, p&lt;0.001 and 55%, p&lt;0.001, respectively), body mass being a minor predictor (2%, p=0.021), and the remainder of the variation (23%) currently unexplained. The rs12934922 genotype interacted with group (p=0.085) to contribute 4% of the variability in prostate LYC concentrations, the rs12934922 genotype alone contributed 4% (p=0.018), and rs6564851 contributed 2% (p=0.053), while treatment group contributed 1% (p=0.035) and baseline plasma LYC contributed 16% (p=0.002), with the remaining variance being unexplained (72%). The rs12934922 genotype was significantly related to the plasma PF and BC responses, the rs7501331 genotype to the plasma PE response, and the rs2306985 and rs2230808 to the plasma and prostatic PF response, respectively. These findings indicate that common SNPs in genes related to lipid and carotenoid absorption and metabolism contribute to the variability in physiologic responses to dietary carotenoids in a controlled trial, and such SNPs may be important to consider when analyzing clinical data. Furthermore, these findings suggest novel relationships of these genes with PE and PF biodistribution. Future studies on the mechanistic effects of these SNPs on tomato carotenoid transport and metabolism are warranted. Clinicaltrials.gov #NCT01009736Support or Funding InformationNIH‐R01CA112632, NIH‐UL1TR001070, NIH‐P30CA01605, The Ohio State University's Food Innovation Center and The Center for Advancement of Functional Foods Research and Entrepreneurship