The solubilisation pattern of lutein, zeaxanthin, canthaxanthin and beta-carotene differ characteristically in liposomes, liver microsomes and retinal epithelial cells

The incorporation efficiencies of lutein, zeaxanthin, canthaxanthin and beta-carotene into Retinal Pigment Epithelial (RPE) cells (the human RPE cell line D 407), liver microsomes and EYPC liposomes are investigated. In RPE cells the efficiency ratio of lutein and zeaxanthin compared to canthaxanthin and beta-carotene is higher than in the other membranes. The preferential interactions of lutein and zeaxanthin with RPE cells are discussed considering special protein binding properties. Incorporation yields were obtained from the UV-Vis spectra of the carotenoids. Membrane modulating effects of the carotenoids were obtained from the fluorescence spectra of co-incorporated Laurdan (6-dodecanoyl-2-dimethylaminonaphtalene). The Laurdan fluorescence quenching efficiencies of the membrane bound carotenoids offer an access to direct determinations of membrane carotenoid concentrations. Fetal calf serum as carrier for carotenoid incorporation appears superior to tetrahydrofuran.     

Oxidation of carotenoids by heat and tobacco smoke

The stability to autoxidation of the polar carotenoids, lutein and zeaxanthin, was compared to that of the less polar carotenoids, beta-carotene and lycopene at physiologically or pathophysiologically relevant concentrations of 2 and 6 microM, after exposure to heat or cigarette smoke. Three methodological approaches were used: 1) Carotenoids dissolved in solvents with different polarities were incubated at 37 and 80 degrees C for different times. 2) Human plasma samples were subjected to the same temperature conditions. 3) Methanolic carotenoid solutions and plasma were also exposed to whole tobacco smoke from 1-5 unfiltered cigarettes. The concentrations of individual carotenoids in different solvents were determined spectrophotometrically. Carotenoids from plasma were extracted and analyzed using high performance liquid chromatography. Carotenoids were generally more stable at 37 than at 80 degrees C. In methanol and dichloromethane the thermal degradation of beta-carotene and lycopene was faster than that of lutein and zeaxanthin. However, in tetrahydrofuran beta-carotene and zeaxanthin degraded faster than lycopene and lutein. Plasma carotenoid levels at 37 degrees C did not change, but decreased at 80 degrees C. The decrease of beta-carotene and lycopene levels was higher than those for lutein and zeaxanthin. Also in the tobacco smoke experiments the highest autoxidation rates were found for beta-carotene and lycopene at 2 microM, but at 6 microM lutein and zeaxanthin depleted to the same extent as beta-carotene. These data support our previous studies suggesting that oxidative stress degrade beta-carotene and lycopene faster than lutein and zeaxanthin. The only exception was the thermal degradation of carotenoids solubilized in tetrahydrofuran, which favors faster breakdown of beta-carotene and zeaxanthin.     

Lycopene and beta-carotene decompose more rapidly than lutein and zeaxanthin upon exposure to various pro-oxidants in vitro

Major carotenoids of human plasma and tissues were exposed to radical-initiated autoxidation conditions. The consumption of lutein and zeaxanthin, the only carotenoids in the retina, and lycopene and beta-carotene, the most effective quenchers of singlet oxygen in plasma, were compared. Under all conditions of free radical-initiated autoxidation of carotenoids which were investigated, the breakdown of lycopene and beta-carotene was much faster than that of lutein and zeaxanthin. Under the influence of UV light in presence of Rose Bengal, by far the highest breakdown rate was found for beta-carotene, followed by lycopene. Bleaching of carotenoid mixtures mediated by NaOCl, addition of azo-bis-isobutyronitril (AIBN), and the photoirradiation of carotenoid mixtures by natural sunlight lead to the following sequence of breakdown rates: lycopene > beta-carotene > zeaxanthin > lutein. The slow degradation of the xanthophylls zeaxanthin and lutein may be suggested to explain the majority of zeaxanthin and lutein in the retina of man and other species. In correspondence to that, the rapid degradation of beta-carotene and lycopene under the influence of natural sunlight and UV light is postulated to be the reason for the almost lack of those two carotenoids in the human retina. Nevertheless, a final proof of that theory is lacking.     

Changes of serum carotenoids in patients with esophageal, gastric, hepatocellular, pancreatic and colorectal cancer

The serum levels of carotenoids (vitamin A, lutein, zeaxanthin, alfa- and beta cryptoxanthin, alfa- and beta-carotene) were measured in healthy persons (n=40) and in 98 patients with different malignant gastrointestinal diseases (44 patients with colon adenocarcinoma, 21 with gastric cancer, 15 with hepatocellular adenocarcinoma, 10 patients with pancreas adenocarcinoma and eight patients with esophagus cancer). The serum levels of carotenoids were measured with high-pressure liquid chromatography. The sera of the patients were taken at the time of the diagnosis. RESULTS: the measurements indicated that (1) the serum level of vitamin A and zeaxanthin were significantly lower in all of these groups (except of pancreas adenocarcinoma), but the extent of the A decrease was different in the patients with different types of gastrointestinal malignancy. The serum level of vitamin A was in the healthy subjects 2.072+/-0.332 mmol/l and in the case of gastrointestinal malignancies was 0.77+/-0.14 mmol/l (P<0.001) The serum level of zeaxanthin was in the healthy subjects 0.143+/-0.057 mmol/l and at the malignancies was 0.042+/-0.014 mmol/l (P<0.01). (2) There were no significant differences in the serum levels of other carotenoids in the checked groups. (3) The serum level of cholesterol, total protein, albumin and haemoglobin were in the normal range in these patients. These results indicate that the carotenoids may be responsible nutritional factors (as nutritional scavengers) in the development of different malignant diseases. This supposed role in the carcinogenesis does not depend fully on the vitamin A activity.     

Antioxidant activity of palm oil carotenes in peroxyl radical-mediated peroxidation of phosphatidyl choline liposomes

The antioxidant efficacy of alpha-carotene and comparison with beta-carotene in multilamellar liposomes prepared from egg yolk phosphatidyl choline (EYPC) exposed to the lipid soluble 2,2'-azobis (2,4-dimethyl valeronitrile) (AMVN) was investigated. Lipid peroxidation was measured as thiobarbituric acid reacting substances (TBARS) at 532 nm or as hydroperoxide formation at 234 nm after separation of phosphatidyl choline hydroperoxide (PCOOH) by high-pressure liquid chromatography (HPLC). Lutein and zeaxanthin, the hydroxyl derivatives of alpha- and beta-carotenes, and the chain breaking antioxidant alpha-tocopherol were also included in the study. AMVN being a lipid soluble, non polar azo initiator penetrates into the hydrophobic interior of the phospholipid bilayer, forming peroxyl radicals which peroxidate the phospholipid leading to PCOOH accumulation. All the carotenoids tested at 1 mol% relative to EYPC significantly suppressed the formation of PCOOH compared to control samples. In this system, alpha-carotene retarded PCOOH formation better than beta-carotene. Similarly, lutein was a better antioxidant than is zeaxanthin. But lutein and zeaxanthin were more effective antioxidants than alpha- and beta-carotenes, respectively. After 1 h of incubation of the carotenoid with AMVN, alpha-, beta-carotene, lutein and zeaxanthin limited PCOOH formation by 77%, 68%, 85% and 82%, respectively, while alpha-tocopherol elicited 90% reduction. AMVN incubated with EYPC for 2 h induced the formation of TBARS compared to control (P < 0.001). alpha-Carotene significantly suppressed the TBARS formation by 78% whilst beta-carotene, lutein, zeaxanthin and alpha-tocopherol elicited 60%, 91% and 80% reductions, respectively. Increasing the concentration of the carotenoid > 1 mol% to EYPC did not significantly increase protection of the membrane against free radical attack. Our findings suggest that alpha-carotene is a better antioxidant than is beta-carotene in phosphatidyl choline vesicles. It may, therefore, be useful in limiting free radical mediated peroxidative damage against membrane phospholipids in vivo.     

Validation of overweight children's fruit and vegetable intake using plasma carotenoids

Assessing dietary intake in children is difficult and limited validated tools exist. Plasma carotenoids are nutritional biomarkers of fruit and vegetable intake and therefore suitable to validate reported dietary intakes. The aim of this study was to examine the comparative validity of a food frequency questionnaire (FFQ), completed by parents reporting child fruit and vegetable intake compared to plasma carotenoid concentrations. A sample of children aged 5-12 years (n = 93) from a range of weight categories were assessed. Dietary intake was measured using a 137-item semi-quantitative FFQ. Plasma carotenoids were measured using reverse phase high-performance liquid chromatography. Pearson correlation coefficients between reported dietary intake of carotenoids and plasma carotenoid concentrations were strongest after adjustment for BMI (beta-carotene (r = 0.56, P < 0.05), alpha-carotene (r = 0.51, P < 0.001), cryptoxanthin (r = 0.32, P < 0.001)). Significantly lower levels (P < 0.05) of all plasma carotenoids, except lutein, were found among overweight and obese children when compared to healthy weight children. Parental report of children's carotenoid intakes, using a FFQ can be used to provide a relative validation of fruit and vegetable intake. The lower plasma carotenoid concentrations found in overweight and obese children requires further investigation.     

Enhancing the carotenoid content of <Emphasis Type="Italic">Brassica napus</Emphasis> seeds by downregulating lycopene epsilon cyclase

The accumulation of carotenoids in higher plants is regulated by the environment, tissue type and developmental stage. In Brassica napus leaves, beta-carotene and lutein were the main carotenoids present while petals primarily accumulated lutein and violaxanthin. Carotenoid accumulation in seeds was developmentally regulated with the highest levels detected at 35-40 days post anthesis. The carotenoid biosynthesis pathway branches after the formation of lycopene. One branch forms carotenoids with two beta rings such as beta-carotene, zeaxanthin and violaxanthin, while the other introduces both beta- and epsilon-rings in lycopene to form alpha-carotene and lutein. By reducing the expression of lycopene epsilon-cyclase (epsilon-CYC) using RNAi, we investigated altering carotenoid accumulation in seeds of B. napus. Transgenic seeds expressing this construct had increased levels of beta-carotene, zeaxanthin, violaxanthin and, unexpectedly, lutein. The higher total carotenoid content resulting from reduction of epsilon-CYC expression in seeds suggests that this gene is a rate-limiting step in the carotenoid biosynthesis pathway. epsilon-CYC activity and carotenoid production may also be related to fatty acid biosynthesis in seeds as transgenic seeds showed an overall decrease in total fatty acid content and minor changes in the proportions of various fatty acids.     

Quantitative trait loci governing carotenoid concentration and weight in seeds of chickpea (Cicer arietinum L.)

Chickpea is a staple protein source in many Asian and Middle Eastern countries. The seeds contain carotenoids such as beta-carotene, cryptoxanthin, lutein and zeaxanthin in amounts above the engineered beta-carotene-containing golden rice level. Thus, breeding for high carotenoid concentration in seeds is of nutritional, socio-economic, and economic importance. To study the genetics governing seed carotenoids in chickpea, we studied the relationship between seed weight and concentrations of beta-carotene and lutein by means of high-performance liquid chromatography in segregating progeny from a cross between an Israeli cultivar and wild Cicer reticulatum Ladiz. Seeds of the cross progeny varied with respect to their carotenoid concentration (heritability estimates ranged from 0.5 to 0.9), and a negative genetic correlation was found between mean seed weight and carotenoid concentration in the F₃. To determine the loci responsible for the genetic variation observed, the population was genotyped using 91 sequence tagged microsatellite site markers and two CytP450 markers to generate a genetic map consisting of nine linkage groups and a total length of 344.6 cM. Using quantitative data collected for beta-carotene and lutein concentration and seed weight of the seeds of the F₂ population, we were able to identify quantitative trait loci (QTLs) by interval mapping. At a LOD score of 2, four QTLs for beta-carotene concentration, a single QTL for lutein concentration and three QTLs for seed weight were detected. The results of this investigation may assist in improving the nutritional quality of chickpea.     

Competitive carotenoid and cholesterol incorporation into liposomes: effects on membrane phase transition, fluidity, polarity and anisotropy

Pure 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) or mixed DPPC:1,2-dipalmitoyl phosphatidyletanolamine (DPPE):1,2-dipalmitoyl diphosphatidylserine (DPPS) (17:5:3) liposomes were incorporated with 5 mol% dietary carotenoids (beta-carotene, lutein and zeaxanthin) or with cholesterol (16 and 48 mol%) in the absence or presence of 15 mol% carotenoids, respectively. The carotenoid incorporation yields ranged from 0.42 in pure to 0.72 in mixed phospholipid liposomes. They decreased significantly, from 3 to 14%, in the corresponding cholesterol-doped liposomes, respectively. Highest incorporation yields were achieved by zeaxanthin and lutein in phospholipid liposomes while in cholesterol-containing liposomes, lutein was highest incorporated. The effects on membrane structure and dynamics were determined by differential scanning calorimetry, steady-state fluorescence and anisotropy measurements. Polar carotenoids and cholesterol cause similar, dose-dependent effects: ordering and rigidification revealed by broadening of the transition peak, and increase of anisotropy. Membrane hydrophobicity is determined by cholesterol content and carotenoid polarity. In cholesterol-doped liposomes, beta-carotene is less incorporated than in cholesterol-free liposomes. Our observations suggest effects of carotenoids, even at much lower effective concentrations than cholesterol (8 to 80-fold), on membrane structure and dynamics. Although they are minor constituents of animal membranes, carotenoids may act as modulators of membrane phase transition, fluidity, polarity and permeability, and therefore, can influence the membrane physiology and pathology.     

Relationships of body mass index with serum carotenoids, tocopherols and retinol at steady-state and in response to a carotenoid-rich vegetable diet intervention in Filipino schoolchildren

In marginally nourished children, information is scarce regarding the circulating concentrations of carotenoids and tocopherols, and physiological factors influencing their circulating levels. We determined the serum concentrations of carotenoids, tocopherols and retinol at steady state and in response to a 9-week vegetable diet intervention in 9-12-year-old girls (n=54) and boys (n=65) in rural Philippines. We determined cross-sectional relationships of BMI (body mass index) with serum micronutrient levels, and whether BMI is a determinant of serum carotenoid responses to the ingestion of carotenoid-rich vegetables. We measured dietary nutrient intakes and assessed inflammation by measurement of serum C-reactive protein levels. The children had low serum concentrations of carotenoids, tocopherols and retinol as compared with published values for similar-aged children in the U.S.A. The low serum retinol levels can be ascribed to inadequate diets and were not the result of confounding due to inflammation. Significant inverse correlations of BMI and serum all-trans-beta-carotene, 13-cis-beta-carotene, alpha-carotene, lutein, zeaxanthin and alpha-tocopherol (but not beta-cryptoxanthin, lycopene and retinol) were observed among girls at baseline. The dietary intervention markedly enhanced the serum concentrations of all carotenoids. Changes in serum all-trans-beta-carotene and alpha-carotene (but not changes in lutein, zeaxanthin and beta-cryptoxanthin) in response to the dietary intervention were inversely associated with BMI in girls and boys. Thus, in Filipino school-aged children, BMI is inversely related to the steady-state serum concentrations of certain carotenoids and vitamin E, but not vitamin A, and is a determinant of serum beta- and alpha-carotene responses, but not xanthophyll responses, to the ingestion of carotenoid-rich vegetable meals.     

The effect of an acute phase response on tissue carotenoid levels of growing chickens (Gallus gallus domesticus)

Plasma, liver and skin carotenoids decrease following infectious disease challenges. Since these challenges often involve substantial host pathology and chronic immune responses, the mechanism underlying altered carotenoid deposition is unclear. Therefore, changes in tissue carotenoid levels were examined during an acute phase response induced by lipopolysaccharide (LPS) or interleukin-1 (IL-1). In two experiments, chicks were hatched from carotenoid-deplete eggs (n=28, n=64, respectively) and fed 0, 8 or 38 mg carotenoids (lutein+canthaxanthin)/kg diet. For chicks fed 38 mg carotenoids, but not those fed 0 or 8 mg, LPS generally reduced plasma lutein, canthaxanthin and total carotenoids (P<0.05), and liver lutein, zeaxanthin, canthaxanthin and total carotenoids (P<0.05). Additionally, LPS reduced thymic total carotenoids (P=0.05) and increased thymocyte lutein (P=0.07), zeaxanthin (P=0.07) and total carotenoids (P=0.07). Finally, LPS increased bursal canthaxanthin (P<0.01), but had no effect on shank carotenoids (P>0.5). In chicks hatched from carotenoid-replete eggs (n=36) and fed dietary lutein (38 mg/kg diet), LPS reduced plasma and liver zeaxanthin and liver total carotenoids (P<0.05); IL-1 reduced plasma and liver lutein, zeaxanthin and total carotenoids (P<0.05). Therefore, an acute phase response plays a role in reduced tissue carotenoids during infectious disease.     

Selective absorption of carotenoids in the common green iguana (Iguana iguana)

In the animal kingdom, species-specific differences with regard to the absorption of intact carotenoids are observed. The causes of these differences are not entirely understood. To investigate the absorption of selected carotenoids, 20 juvenile green iguanas (Iguana iguana) were fed a carotenoid deficient basal diet for 56 days. Thereafter, the iguanas were assigned to receive a basal diet supplemented with different carotenoids (80 mg/kg diet) such as beta-carotene, canthaxanthin and apo-8'-carotenoic acid ethyl ester for 28 days. Changes in plasma carotinoid concentrations associated with the individual diets were used as indicators of carotenoid absorption. In both the experimental and control groups, only the oxygenated carotenoids (xanthophylls), lutein, zeaxanthin and canthaxanthin, were found in the plasma. Canthaxanthin and apo-8'-carotenoic acid ethyl ester were readily absorbed and recovered from the plasma. However, the supplementation of beta-carotene caused no increase in plasma beta-carotene concentration. Additionally, beta-carotene, canthaxanthin or apo-8'-carotenoic acid ethyl ester did not affect the concentrations of retinol and alpha-tocopherol in plasma. In conclusion, the study demonstrates that iguanas appear to be selective accumulators of polar xanthophylls. The iguana might, therefore, be a valuable model to investigate the selectiveness of carotenoid absorption as well as the function of xanthophylls in animals.     

Serum alpha- and gamma-tocopherols, retinol, retinyl palmitate, and carotenoid concentrations in captive and free-ranging bottlenose dolphins (Tursiops truncatus)

Concentrations of retinol, retinyl palmitate, beta-carotene, alpha-carotene, cryptoxanthin, lutein, lycopene, alpha-tocopherol, and gamma-tocopherol were measured in blood samples collected from 15 captive and 55 free-ranging bottlenose dolphins (Tursiops truncatus). From June 1991 to June 1994, blood samples were collected from captive animals residing at two locations; at Seven Seas (Brookfield Zoo, Brookfield, IL) and Hawk's Cay (Marathon Key, FL). Blood samples were collected from free-ranging animals from June 1991 to June 1996. Retinol levels were not significantly different between captive dolphin groups. However, Seven Seas animals had higher (P < 0.01) serum retinol concentrations compared to free-ranging animals (0.061 vs 0.041 microgram/ml). Retinyl palmitate was not detected in the serum of captive or free-ranging dolphins. Alpha-tocopherol levels were significantly (P < 0.05) higher for Seven Seas dolphins (16.4 micrograms/ml) than for Hawk's Cay (13.0 micrograms/ml) and free-ranging dolphins (12.5 micrograms/ml). Gamma-tocopherol concentrations were similar among captive and free-ranging dolphins. Free-ranging dolphins showed levels of circulating carotenoids (lutein and beta-carotene) while the captive animals did not. Additional carotenoids (lycopene, alpha-carotene and cryptoxanthin) were analyzed but not detected in any samples. Serum vitamin differences between captive and free-ranging dolphins may reflect the natural diet or indicate some potential biological or nutritional status significance.     

Carotenoids,vitamin A,and vitamin E concentrations during egg development in panther chameleons (Furcifer pardalis)

Insects are known to be poor sources of preformed vitamin A, leading to the speculation that insectivorous species, including reptiles, may be able to convert carotenoid precursors to meet dietary requirements for this nutrient. This study was conducted to indirectly evaluate carotenoid and vitamin A metabolism in the panther chameleon (Furcifer pardalis). Eggs were obtained from females in Madagascar that were yolked either early or later in the breeding season, and carotenoid (α‐ and β‐carotene, cryptoxanthin, lutein/zeaxanthin, and lycopene), vitamin A, and vitamin E concentrations were measured in egg contents in early, middle, or late embryonic development. An overall trend of decreased nutrient concentration as eggs matured (from egg period 1 (yolks) to egg period 3 (embryos)) was seen within both clutch groups. The season of clutch deposition was a significant influence on egg weight, α‐carotene, and lutein/zeaxanthin concentrations, but on no other nutrients. Chameleon yolks contained considerably higher levels of carotenoids than levels previously reported from two viviparous lizard species, and β‐carotene concentrations were of the same magnitude as reported in grazing tortoises. β‐Carotene and β‐cryptoxanthin were the predominant carotenoids in yolk and embryos, comprising about 95% of total carotenoids detected. Measurable concentrations of retinol at all stages of egg development in the chameleons suggests effective conversion from carotenoid precursors, with concentrations similar to those measured in other lizard eggs. Information from eggs obtained in native habitats may provide baseline data on nutrient interactions to improve and optimize captive dietary management; preliminary data suggest that micronutrient environments may vary over the protracted breeding season, with possible implications for embryo health and survival. Zoo Biol 21:295–303, 2002. © 2002 Wiley‐Liss, Inc.     

Dietary intake of carotenoids and retinol and the risk of acute myocardial infarction in Italy

BACKGROUND: Carotenoids may reduce the risk of coronary heart disease through their antioxidant properties, but the results of epidemiological studies are controversial. We analysed the relation between the intake of selected carotenoids and retinol and risk of acute myocardial infarction (AMI). METHODS: A case-control study was conducted in Milan, Italy, in 1995-2003. Cases were 760 patients with nonfatal AMI, and controls 682 patients admitted to hospital. RESULTS: The risk of AMI decreased with increasing intake of alpha-carotene (odds ratios, OR = 0.71, 95% confidence intervals, CI 0.51-0.98, for the highest vs the lowest quartile of intake), beta-carotene (OR = 0.71, 95% CI 0.50-1.01) and beta-criptoxanthin (OR = 0.64, 95% CI 0.46-0.88). No associations emerged for total carotenoids, lycopene, lutein plus zeaxanthin and retinol. CONCLUSIONS: Our study suggests a weak protective effect of alpha-carotene, beta-carotene and beta-criptoxanthin on the risk of AMI. It also indicates that total carotenoids, lycopene, lutein plus zeaxanthin and retinol were not related to the risk of the disease.     

A multicarotenoid beadlet for human nutrition - proof of concept of in vitro timed release

Since the 1980's when the predominate focus of study and use of carotenoids in human nutritional formulations was solely on beta-carotene, there has been a steady increase in research aimed to understand the role of a wide variety of carotenoids in human health. This work has increasingly demonstrated the benefits of a number of carotenoids, and there has been a corresponding increase in the number of carotenoids provided in nutritional supplements (multicarotenoids). Numerous published observations in both human and animal studies suggest significant interaction and competition between various carotenoids during absorption and metabolism, resulting in the inhibition of uptake of one over the other. This competition has the end result of reducing the beneficial effects of the inhibited carotenoid. To limit such competition and maximize carotenoid uptakes, a layered beadlet was designed to release a defined ratio of carotenoids sequentially. Preliminary dissolution testing is presented showing the release profile in simulated digestive conditions of a combination of beta-carotene, alpha carotene, lutein, zeaxanthin, lycopene and astaxanthin derived from natural sources. Comparison is made to an immediate release beadlet formulation using the same combination of carotenoids. These results will be used to guide proof of concept clinical testing for effectiveness in humans.     

Significant correlations of dermal total carotenoids and dermal lycopene with their respective plasma levels in healthy adults

Carotenoids in skin have been known to play a role in photoprotection against UV radiation. We performed dermal biopsies of healthy humans (N = 27) and collected blood samples for pair-wise correlation analyses of total and individual carotenoid content by high performance liquid chromatography (HPLC). The hydrocarbon carotenoids (lycopene and beta-carotene) made up the majority of carotenoids in both skin and plasma, and skin was somewhat enriched in these carotenoids relative to plasma. Beta-cryptoxanthin, a monohydroxycarotenoid, was found in similar proportions in skin as in plasma. In contrast, the dihydroxycarotenoids, lutein and zeaxanthin, were relatively lacking in human skin in absolute and relative levels as compared to plasma. Total carotenoids were significantly correlated in skin and plasma (r = 0.53, p < 0.01). Our findings suggest that human skin is relatively enriched in lycopene and beta-carotene, compared to lutein and zeaxanthin, possibly reflecting a specific function of hydrocarbon carotenoids in human skin photoprotection.     

Carotenoid content in Anguilla anguilla (L.) individuals undertaking spawning migration

The authors investigated the carotenoid content in different parts of Anguilla anguilla (L.) undertaking spawning migration, in spring, summer and autumn. By means of column and thin-layer chromatography, the following carotenoids were found to be present: beta-carotene, epsilon-carotene, beta-cryptoxanthin, neothxanthin, lutein, tunaxanthin, zeaxanthin, lutein epoxide, 3'-hydroxyechincnone, canthaxanthin, idoxanthin, phoenicoxanthin, alpha-doradexanthin, beta-doradexanthin and astaxanthin. In the eel examined individuals a different carotenoid content was found in October. In winter when eels do not feed and therefore do not absorb carotenoids, carotenoid content decreases in the liver, the intestines, and particularly in the muscles. In spring when eels undertake active life carotenoid concentration increases rapidly in these organs within a month. In summer during intensive predation, carotenoid concentration in the muscles reaches a maximum.     

Carotenoids inhibit DNA synthesis in human aortic smooth muscle cells

Quiescent, serum-starved human aortic smooth muscle cells were restimulated with 20% foetal calf serum in Dulbecco's modified Eagle medium, in the presence and absence of beta-carotene, canthaxanthin, zeaxanthin, lycopene, lutein or beta-cryptoxanthin, at final concentrations up to 23 microM. Concentration-dependent inhibition of DNA synthesis, measured by [methyl-3H]thymidine incorporation, was observed for the carotenoids, except for canthaxanthin and lutein which had no effect. Lycopene was the most potent of the carotenoids tested. The results suggest that antiproliferative effects of dietary carotenoids might be of significance in vivo.     

Plasma carotenoid and malondialdehyde levels in ischemic stroke patients: relationship to early outcome

An association between ischemic stroke and increased oxidative stress has been suggested from animal studies. However, there is a lack of evidence with respect to this association in humans. Here, the time course of plasma levels of six carotenoids, which are lipophilic micronutrients with antioxidant properties, as well as of malondialdehyde (MDA), a marker of lipid peroxidation, was followed in ischemic stroke patients. Plasma levels of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha- and beta-carotene, as well as MDA were measured by high-performance liquid chromatography in 28 subjects (19 men and nine women aged 76.9+/-8.7 years) with an acute ischemic stroke of recent onset (<24h) on admission, after 6 and 24 h, and on days 3, 5, and 7. Carotenoid and MDA levels in patients on admission were compared with those of age- and sex-matched controls. Plasma levels of lutein, lycopene, alpha- and beta-carotene were significantly lower and levels of MDA were significantly higher in patients in comparison with controls. Significantly higher levels of MDA and lower levels of lutein were found in patients with a poor early-outcome (functional decline) after ischemic stroke as compared to patients who remained functionally stable. These findings suggest that the majority of plasma carotenoids are lowered immediately after an ischemic stroke, perhaps as a result of increased oxidative stress, as indicated by a concomitant rise in MDA concentrations. Among the carotenoids, only lutein plasma changes are associated with a poor early-outcome.