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PubMed1999

Carotenoids in young and elderly healthy humans: dietary intakes, biochemical status and diet-plasma relationships.

OBJECTIVE: To determine dietary carotenoid concentrations using an established and newly developed food frequency questionnaire (FFQ) method, to determine plasma carotenoid concentrations and to determine the relationship between these dietary and plasma variables in 24-45 y and > or = 65 y groups. DESIGN: Descriptive assessment of (FFQ), 7-d estimated records, and plasma carotenoids and their relationships in 24-45 y and > or = 65 y groups. SETTING: Free living urban adults in Ireland. SUBJECTS: Sixty-four volunteers aged 24-45 y and 54 volunteers aged > or = 65 y. RESULTS: Beta-carotene was the predominant plasma carotenoid, but older groups had lower plasma concentrations of several carotenoids compared to younger groups (P < 0.005). Beta-carotene and lycopene were the major dietary carotenoids reported by estimated records and FFQ. Several estimated record and plasma carotenoid concentrations were positively associated in younger groups but not in older groups. FFQ overestimated dietary carotenoids relative to estimated records (P < or = 0.05), generally did not reflect estimated record carotenoid concentrations and showed positive associations with plasma carotenoids only in older men. Neither of the dietary methods revealed a positive association between plasma and dietary beta-carotene concentrations, whereas beta-cryptoxanthin was strongly associated. CONCLUSIONS: Dietary and plasma concentrations of individual carotenoids are documented in young and elderly groups of a European country. Estimated record data reveals positive associations between diet and plasma carotenoids in younger, but not elderly groups. Further work examining diet-plasma relationship in older groups and developing a common FFQ suitable for use in several European countries is required.

Adult↗
PubMed1999

Gender differences in food and nutrient intakes and status indices from the National Diet and Nutrition Survey of people aged 65 years and over.

OBJECTIVES: To determine the patterns and possible explanations for gender differences in food choices, nutrient intakes and status indices, especially for micronutrients, in a representative sample of older people living in Britain, who participated in the National Diet and Nutrition Survey of people aged 65 y and over during 1994-95. DESIGN: The Survey procedures included a health-and-lifestyle interview, a four-day weighed diet record, anthropometric measurements and a fasting blood sample for biochemical indices. SETTING: Eighty randomly-selected postcode sectors from mainland Britain. SUBJECTS: Of 1556 older people not living in institutions who were interviewed, 80% agreed to provide a complete four-day diet record and 63% agreed to give a blood sample for status index measurements. INTERVENTIONS: None. MAIN RESULT: The most highly significant gender differences in food choices were that women ate more butter, full-fat milk and certain beverages, cakes, apples, pears and bananas, whereas men ate more eggs, sugar, certain meat products and drank more alcoholic drinks, especially beer and lager. When adjusted for energy intakes, the younger women (65-79 y) had higher intakes than the younger men, of fat, retinol, vitamin C and calcium. The older women (80+ y) had higher intakes than older men, of fat and vitamin E, but lower intakes of protein, zinc and beta-carotene. The younger women had better status indices than the younger men: for alpha- and beta-carotenes, beta-cryptoxanthin and vitamin C. Women had higher plasma concentrations of cholesterol and HDL cholesterol, phosphate and copper, but lower indices of iron and vitamin D status, than men. These gender differences in status were not altered by inclusion of the corresponding nutrient intakes in the model. CONCLUSIONS: There are gender differences in food choices, in energy and nutrient intakes and in nutritional blood status indices in older British people, especially those aged 65-79 y. Some of the status differences are attenuated in the age group of 80 y and older, whereas others are enhanced. The relationships between the quantity and type of foods or nutrients consumed, and nutrient status, are complex. With respect to suspected risk and protective factors for vascular disease, women aged 65-79 y had significantly better status for plasma alpha- and beta-carotene, ascorbate, HDL-cholesterol and homocysteine; but, in contrast, they had lower blood haemoglobin concentrations and higher concentrations of total and non-HDL-cholesterol.

Age Factors↗
PubMed1999

Concentrations of tocopherols and carotenoids in maternal and cord blood plasma.

OBJECTIVES: To determine the levels of tocopherols, retinol and carotenoids in maternal and umbilical cord blood plasma and to investigate the relationships between them. DESIGN: Venous blood plasma concentrations of alpha, gamma and delta-tocopherol, retinol, lutein, lycopene, zeaxanthin, beta-cryptoxanthin, alpha and beta-carotene were determined by HPLC in healthy pregnant women and in pair-matched umbilical cords. Plasma levels of triglycerides and cholesterol were also measured. SUBJECTS: Sixty-six women, between 10 and 20 weeks gestation, were recruited randomly during their first antenatal appointment. From this group, 40 pair-matched umbilical cord blood samples were obtained. RESULTS: Tocopherols, retinol, carotenoids and lipids were present in significantly higher (P < 0.001) concentrations in maternal plasma than in cord plasma. There was a significant correlation (r = 0.45, P < 0.005) between maternal and cord levels of gamma-tocopherol, but not of alpha-tocopherol, retinol or carotenoids. Tocopherols and carotenoids were significantly correlated with each other (P < 0.05) in maternal and cord plasma. CONCLUSIONS: Plasma levels of tocopherols, carotenoids and lipids are substantially lower at birth than in adulthood. There is a clear relationship between gamma-tocopherol levels in maternal and cord plasma. The importance of gamma-tocopherol in human nutrition should be further investigated. There are no significant relationships between plasma alpha-tocopherol and carotenoids in pregnant mothers and cords. More research is needed to elucidate the maternal-foetal transfer of tocopherols and carotenoids, and to examine the impact of maternal antioxidant nutrient status on neonatal antioxidant capacity. It is important to determine if a low level of tocopherols and carotenoids at birth is a normal stage of human development or indicative of deficiency.

Adolescent↗
PubMed2000

Moderate consumption of beer, red wine and spirits has counteracting effects on plasma antioxidants in middle-aged men.

OBJECTIVE: To evaluate the in vivo effects of moderate consumption of red wine, beer and spirits on antioxidants, antioxidant enzymes and antioxidant capacity. DESIGN: Randomized, diet-controlled, cross-over study. SUBJECTS: Twelve apparently healthy, non-smoking middle-aged men were included; 11 of them completed the study. INTERVENTIONS: Each subject consumed four glasses of red wine, beer, spirits and water (negative control) with evening dinner during four successive periods of 3 weeks, daily at the Institute. The total diet was supplied to the subjects and had essential the same composition during these 12 weeks. RESULTS: Neither the enzyme activities of serum glutathion peroxidase, erythrocyte glutathion reductase and superoxide dismutase nor the plasma concentrations of alpha- and gamma-tocopherol, lutein, zeaxantin, beta-cryptoxanthin, lycopene and alpha-carotene were affected. Plasma beta-carotene concentrations were decreased after 3 weeks' consumption of red wine, beer and spirits (40 g alcohol/day) as compared to consumption of water, by 15% (P=0.0005), 11% (P=0.010) and 13% (P=0.003), respectively. Also, plasma ascorbic acid was decreased after beer (15%, P=0.004) and spirits (12%, P=0.030), but not after wine consumption. Serum uric acid concentrations were increased after consumption of beer (15%, P<0.0001), spirits (8%, P=0.008) and red wine (9%, P=0.003). The overall serum antioxidant capacity, assessed as Trolox equivalent antioxidant capacity (TEAC), was similar for all treatments. CONCLUSIONS: Moderate consumption of red wine, beer and spirits has counteracting effects on plasma antioxidant components, resulting in no significant effect on overall antioxidant status. The effects on antioxidant parameters are largely independent of the type of alcoholic beverage, and probably irrelevant to chronic disease risk. SPONSORSHIP: Dutch Foundation for Alcohol Research (SAR).

Adult↗
PubMed2003

C-reactive protein concentration and concentrations of blood vitamins, carotenoids, and selenium among United States adults.

OBJECTIVE: To examine the relationships between circulating concentrations of C-reactive protein and concentrations of retinol, retinyl esters, vitamin C, vitamin E, carotenoids, and selenium. DESIGN: Cross-sectional study using National Health and Nutrition Examination Survey III (1988-1994) data. SETTING: United States population. SUBJECTS: Up to 14 519 US noninstitutionalized civilian men and women aged > or=20 y. RESULTS: C-reactive protein concentration (dichotomized at the sex-specific 85th percentile) was inversely and significantly associated with concentrations of retinol, retinyl esters, vitamin C, alpha-carotene, beta-carotene, cryptoxanthin, lutein/zeaxanthin, lycopene, and selenium after adjustment for age, sex, race or ethnicity, education, cotinine concentration, body mass index, leisure-time physical activity, and aspirin use. CONCLUSIONS: These results suggest that the inflammatory process, through the production of reactive oxygen species, may deplete stores of antioxidants. Whether increased consumption of foods rich in antioxidants or supplementation with antioxidants can provide health benefits to people characterized by elevated C-reactive protein concentrations may be worthy of further study.

Adult↗
PubMed2003

Effects of enhanced consumption of fruit and vegetables on plasma antioxidant status and oxidative resistance of LDL in smokers supplemented with fish oil.

OBJECTIVE: To determine whether consumption of five portions of fruit and vegetables per day reduces the enhancement of oxidative stress induced by consumption of fish oil. SUBJECTS: A total of 18 free-living healthy smoking volunteers, aged 18-63 y, were recruited by posters and e-mail in The University of Reading, and by leaflets in local shops. DESIGN: A prospective study. SETTING: Hugh Sinclair Unit of Human Nutrition, School of Food Biosciences, The University of Reading, Whiteknights PO Box 226, Reading RG6 6AP, UK. INTERVENTION: All subjects consumed a daily supplement of 4 x 1 g fish oil capsules for 9 weeks. After 3 weeks, they consumed an additional five portions of fruits and vegetables per day, and then they returned to their normal diet for the last 3 weeks of the study. Fasting blood samples were taken at the ends of weeks 0, 3, 6 and 9. RESULTS: The plasma concentrations of ascorbic acid, lutein, beta-cryptoxanthin, alpha-carotene and beta-carotene all significantly increased when fruit and vegetable intake was enhanced (P<0.05). Plasma concentrations of alpha-tocopherol, retinol and uric acid did not change significantly during the period of increased fruit and vegetable consumption. Plasma oxidative stability, assessed by the oxygen radical absorbance capacity (ORAC) assay, also increased from weeks 3-6 (P<0.001) but not in association with increases in measured antioxidants. Lag phase before oxidation of low-density lipoprotein (LDL) significantly decreased in the first 3 weeks of the study, reflecting the incorporation of EPA and DHA into LDL (P<0.0001). Subsequent enhanced fruit and vegetable consumption significantly reduced the susceptibility of LDL to oxidation (P<0.005). CONCLUSION: Fish oil reduced the oxidative stability of plasma and LDL, but the effects were partially offset by the increased consumption of fruit and vegetables.

Adolescent↗
PubMed2004

Six carotenoids in plasma used to assess recommended intake of fruits and vegetables in a controlled feeding study.

BACKGROUND: There is a need for objective and universally applicable biomarkers for the intake of foods believed to affect human health. OBJECTIVE: The purpose of this feeding study was to test whether plasma concentrations of carotenoids could be used to distinguish recommended consumption of mixed fruits and vegetables (five a day) from the current national intake of fruits and vegetables (two a day). DESIGN: A strict crossover design was chosen to correct for observed interindividual variations in carotenoid response. A total of 40 healthy subjects were included in the study. After 1 week run-in period with no fruits and vegetables in the diet, one group was given two portions (300 g) of fruits and vegetables daily, while another group was given five portions (750 g) for 14 days. Following a 2 week wash-out period and 1 week run-in, the regimens were switched between the groups. Fruits and vegetables were combined to match a typical Norwegian diet. RESULTS: Enhanced intake from two to five portions of mixed fruits and vegetables increased plasma concentrations of alpha-carotene (P=0.033) and lutein (P=0.051) in a crossover analysis. Analysis of data in the parallel part of the study revealed differences between the high and low intake for plasma concentrations of alpha-carotene (P=0.013) and beta-carotene (P=0.016). A trend was also evident for plasma concentrations of lycopene (P=0.057) and lutein (P=0.076) in the parallel analysis. No effect of high vs low intake of fruits and vegetables was observed for plasma concentrations of beta-cryptoxanthin, zeaxanthin, cholesterol and triacylglycerols. CONCLUSION: The study indicates that plasma concentration of alpha-carotene, beta-carotene and lutein may be used to assess changes of fruit and vegetable intake corresponding to an increase from the present national intake in Norway to the recommended amount of five portions of fruits and vegetables daily. SPONSORSHIP: Norwegian Research Council, National Nutrition Council, Throne Holst Foundation for Nutrition Research and Freia Chokoladefabriks Medisinske Fond.

Adult↗
PubMed1966

Conversion of carotenoids into vitamins A(1) and A(2) in two species of freshwater fish.

1. Examination of two zooplankton species predominating in fish ponds, Daphnia magna and Chironomus larvae, revealed the presence of alpha- and beta-carotene, echinenone, canthaxanthin and 3-hydroxy-4-oxo-beta-carotene in Daphnia, and beta-carotene and cryptoxanthin ester in Chironomus. No specific provitamins A(2) (containing a 3,4-dehydro-beta-ionone ring) were detected. 2. Guppies (Lebistes reticulatus) and platies (Xiphophorus variatus) were found to form vitamin A from beta-carotene and from its oxygen-containing derivatives isozeaxanthin, canthaxanthin and astaxanthin. Slight conversion into vitamin A(2) seemed to occur simultaneously. 3,4-Dehydro-3'-hydroxy-beta-carotene formed little vitamin A, and the latter was mainly of the A(2) type. Lutein was devoid of provitamin A properties. 3. In addition to vitamin A, beta-carotene was detected in fish receiving the 4-oxo- and 4-hydroxy-carotenoids. A reaction scheme for the conversion of carotenoids into retinal and and 3,4-dehydroretinal is presented. 4. It is concluded that natural 4-oxo derivatives of beta-carotene may play a significant role as vitamin A precursors for fish.

Journal Article↗
PubMed1974

Alternative pathways of zeaxanthin biosynthesis in a Flavobacterium species.

In Flavobacterium R1519, nicotine blocks zeaxanthin biosynthesis by specifically inhibiting the cyclization reaction. Lycopene (at high nicotine concentrations, e.g. 7.5mm) and rubixanthin (at low nicotine concentration, e.g. 1mm) replace zeaxanthin as the main carotenoid. On removal of the nicotine lycopene is converted into beta-carotene under anaerobic conditions and into zeaxanthin in the presence of O(2). The conversion in vivo of beta-carotene into zeaxanthin was also demonstrated. Cyclization (an anaerobic process) thus precedes hydroxylation (O(2)-requiring) in the biosynthesis of zeaxanthin. The conversion in vivo of rubixanthin into beta-cryptoxanthin and into zeaxanthin was demonstrated, thus indicating the operation of alternative pathways of zeaxanthin biosynthesis. Several alternative biosynthetic pathways are considered and the results are also discussed in terms of reaction sequences of carotenoid ;half-molecules'.

Carotenoids↗
PubMed2000

Plasma antioxidant levels in chronic cholestatic liver diseases.

BACKGROUND: [corrected] A predictable consequence of cholestasis is malabsorption of fat-soluble factors, (vitamins A, D, E, K) and other free radical scavengers, such as carotenoids. It has been suggested that oxygen-derived free radicals may be involved in the pathogenesis of chronic liver damage. AIMS: (i) To evaluate retinol, alpha-tocopherol and carotenoid plasma levels in two groups of patients with chronic cholestatic liver disease (primary biliary cirrhosis and primary sclerosing cholangitis); (ii) to compare the respective plasma levels with those of the general population; (iii) to correlate the plasma levels with disease severity. METHODS: A total of 105 patients with chronic cholestasis were included in the study: 86 with primary biliary cirrhosis (81 female, five male, mean age 55.5 +/- 11 years), 19 with primary sclerosing cholangitis (seven female, 12 male, mean age 35 +/- 11 years; six patients had associated inflammatory bowel disease); 105 sex- and age-matched subjects from the general population in the same geographical area (88 female, 17 male, mean age 51.3.5 +/- 10 years) served as controls. Carotenoids (lutein zeaxanthin, lycopene, beta-carotene, alpha-carotene, beta-cryptoxanthin), retinol and alpha-tocopherol were assayed by high-pressure liquid chromatography. A food frequency questionnaire was administered to each subject to evaluate the quality and the quantity of dietary compounds. Data were processed by analysis of variance and linear regression analysis, as appropriate. RESULTS: Both primary biliary cirrhosis and primary sclerosing cholangitis patients had significantly lower levels of retinol, alpha-tocopherol, total carotenoids, lutein, zeaxanthin, lycopene, alpha- and beta-carotene than controls (P < 0.0001). Among the cholestatic patients, no significant difference in the concentration of antioxidants was observed between primary biliary cirrhosis and primary sclerosing cholangitis subjects. Anti-oxidant plasma levels were not affected by the severity of the histological stage in primary biliary cirrhosis, but a negative correlation was found between total carotenoids and both alkaline phosphatase (ALP) and gammaglutamyl transpeptidase (GGT) (P < 0.013 and P < 0.018, respectively). Within the primary sclerosing cholangitis group, no correlation was found between total carotenoids and cholestatic enzymes. Nutritional intake in cholestatic patients was comparable to controls, including fruit and vegetable intake. CONCLUSIONS: Although no clinical sign of deficiency is evident, plasma levels of antioxidants are low in cholestatic patients even in early stages of the disease. This is probably due to malabsorption of fat-soluble vitamins, as well as other mechanisms of hepatic release, suggesting the need for dietary supplementation.

Adult↗
PubMed2005

Microalbuminuria and concentrations of antioxidants among US adults.

BACKGROUND: Microalbuminuria may increase the risk for cardiovascular disease. Increased oxidative stress, which may be important in the pathophysiological process of cardiovascular disease, occurs frequently in people with microalbuminuria and could depress their antioxidant concentrations, which then could contribute to end-organ damage associated with microalbuminuria. METHODS: We examined associations between microalbuminuria and circulating concentrations of vitamins A, C, and E and carotenoids in 9,575 US adults aged 20 years or older who participated in the Third National Health and Nutrition Examination Survey (1988 to 1994). RESULTS: After adjustment for age, sex, race or ethnicity, education, smoking status, cotinine concentration, physical activity, alcohol use, fruit and vegetable intake, vitamin or mineral use during the past 24 hours, body mass index, systolic blood pressure, and total cholesterol, triglyceride, glucose, insulin, and C-reactive protein concentrations, concentrations of beta-cryptoxanthin (odds ratio for quartile of highest concentration compared with quartile of lowest concentration, 0.56; 95% confidence interval, 0.38 to 0.82), lutein/zeaxanthin (odds ratio, 0.59; 95% confidence interval, 0.37 to 0.94), lycopene (odds ratio, 0.64; 95% confidence interval, 0.46 to 0.89), and total carotenoids (odds ratio, 0.54; 95% confidence interval, 0.38 to 0.75) were associated inversely with microalbuminuria. Vitamin C, vitamin E, and selenium concentrations were not significantly associated with microalbuminuria. CONCLUSION: People with microalbuminuria may have reduced concentrations of selected antioxidants. Additional research is needed to examine the relationships between microalbuminuria and antioxidant status, mechanisms for depletion of antioxidants, and possible benefits from increased intake of antioxidants through dietary change or the use of supplements in people with microalbuminuria.

Adult↗
PubMed2002

Food intake characteristics of hemodialysis patients as obtained by food frequency questionnaire.

OBJECTIVES: Food frequency questionnaires (FFQ) are frequently used in epidemiologic studies of nutrition and food intake. However, the use of FFQs in patients receiving maintenance dialysis has not been extensively studied. We hypothesize that FFQ is a useful tool to assess the food intake differences between patients receiving dialysis and patients not receiving dialysis. DESIGN: Matched exposed-unexposed study with case-controlled design. SETTING: Outpatient dialysis unit affiliated with a tertiary-care community medical center. PATIENTS: From a pool of 102 maintenance hemodialysis (MHD) outpatients in a community dialysis unit, 30 adult MHD outpatients (15 men, 15 women, aged 55.8 +/- 14.6 years) were selected randomly as case subjects. They included 16 African Americans, 8 whites, 4 Hispanics, and 2 Asians. Eleven MHD patients took the multivitamin, Nephrovite (R&D Laboratories, Marina del Rey, CA), regularly. From an archive of 1,610 nondialytic individuals with known FFQ data, 30 control subjects were selected randomly to match the age, race, and sex of the case subjects. INTERVENTION: We used Block's FFQ (version 98), an 8-page self-administered questionnaire that has been widely used in epidemiologic studies. A group of trained research assistants supervised the FFQ administration and interviewed those patients who were not able to answer all of the questions without assistance. Student t test was used to compare group means in form of daily dietary intake, and conditional logistic regression was used to calculate odds ratios for predetermined dichotomizing cutoff levels. MAIN OUTCOME MEASURES: Food intake characteristics of MHD patients as compared with control patients not receiving dialysis. RESULTS: Statistically significant differences between MHD case subjects and nondialytic control subjects were observed between the amounts of daily intake for vitamin C (84 +/- 63 mg/d v 127 +/- 70 mg/d, P = .01), dietary fiber (12 +/- 6 g/d v 18 +/- 11 g/d, P = .02), potassium (2,024 +/- 1,088 mg/d v 2,701 +/- 1,429 mg/d, P = .04), cryptoxanthin (56 +/- 88 microg/d v 140 +/- 118 microg/d, P = .003), and lycopene (2,052 +/- 2,234 microg/d v 4,524 +/- 3,979 microg/d, P = .004). These data indicate that MHD patients had a significantly lower intake of vitamin C, dietary fibers, potassium, and 2 of the carotenoid compounds when compared with individuals not receiving dialysis. Moreover, the daily intake of vitamin B(6) was significantly higher in MHD patients probably because of the high pyridoxine content in Nephrovite. By using the conditional logistic regression analysis, the odds ratios for lower than predetermined cutoff levels in patients receiving dialysis were significant for vitamin C, potassium, and the 2 previously mentioned carotenoids (odds ratio between 3.50 and 7.50, P < .05). CONCLUSIONS: Patients receiving dialysis may consume significantly lower amounts of potassium, vitamin C, and dietary fibers as well as lower amounts of some carotenoids. The FFQ seems to be a useful tool to compare dietary intake of MHD patients with other groups, although it may underestimate the amount of daily protein and energy intake and, hence, may not be an accurate tool for individual assessment of food intake. More studies are required to evaluate the validity of the FFQ in dialysis patients. The lower vitamin C, fiber, and carotenoid intake of MHD patients may be atherogenic. Hence, the hypothesis is proposed that prescribed restrictions in potassium in MHD patients may lead to reduced fruit and vegetable intake, leaving meat and fats as the main source of calories. This may contribute to atherosclerosis and increased cardiovascular morbidity and mortality in these patients. This hypothesis needs to be evaluated in future studies.

Ascorbic Acid↗
PubMed2001

Effects of diets enriched with two different plant stanol ester mixtures on plasma ubiquinol-10 and fat-soluble antioxidant concentrations.

Plant stanols lower intestinal cholesterol absorption. This causes a decrease in serum low-density lipoprotein (LDL)-cholesterol, despite a compensatory increase in cholesterol synthesis. We therefore hypothesized that plant stanols also change LDL-cholesterol-standardized concentrations of ubiquinol-10 (a side product of the cholesterol synthesis cascade) and of those fat-soluble antioxidants that are mainly carried by LDL. To examine this, 112 nonhypercholesterolemic subjects consumed low erucic acid rapeseed oil (LEAR)-based margarine and shortening for 4 weeks. For the next 8 weeks, 42 subjects consumed the same products, while the other subjects received products with vegetable oil-based stanols (2.6 g sitostanol plus 1.2 g campestanol daily, n = 36) or wood-based stanols (3.7 g sitostanol plus 0.3 g campestanol daily, n = 34). Consumption of both plant stanol ester mixtures increased cholesterol synthesis and lowered cholesterol absorption, as indicated by increased serum cholesterol-standardized lathosterol and decreased plant sterol concentrations, respectively. Compared with the control group, absolute plasma ubiquinol-10 concentrations were lowered by 12.3% +/- 18.9% (-0.14 microg/mL v. the control group; P =.004; 95% confidence interval [CI] for the difference in changes, -0.05 to -0.22 microg/mL) in the vegetable oil-based group and by 15.4% +/- 13.0% (-0.17 microg/mL v. the control group; P <.001; 95% CI for the difference, -0.08 to -0.27 microg/mL) in the wood-based group. Changes in LDL-cholesterol-standardized ubiquinol-10 concentrations were not significantly changed. The most lipophylic antioxidants, the hydrocarbon carotenoids (beta-carotene, alpha-carotene, and lycopene), decreased most, followed by the less lipophylic oxygenated carotenoids (lutein/zeaxanthin and beta-cryptoxanthin) and the tocopherols. These reductions were related to the reduction in LDL, which carry most of these antioxidants. The decrease in the hydrocarbon carotenoids, however, was also significantly associated with a decrease in cholesterol absorption. LDL-cholesterol-standardized antioxidant concentrations were not changed, except for beta-carotene, which was still, although not significantly, lowered by about 10%. We conclude that the increase in endogenous cholesterol synthesis during plant stanol ester consumption does not result in increased LDL-cholesterol-standardized concentrations of ubiquinol-10, a side product of the cholesterol synthesis cascade. Furthermore, decreases in absolute fat-soluble antioxidant concentrations are related to decreases in LDL-cholesterol. However, for the most lipophylic carotenoids, some of the reduction was also related to the decrease in cholesterol absorption.

Absorption↗
PubMed1978

Photosynthetic unit size, carotenoids, and chlorophyll-protein composition of Prochloron sp., a prokaryotic green alga.

Six samples of the prokaryotic, unicellular algae Prochloron sp., which occur in association with didemnid ascidians, were collected from various localities in the tropical Pacific Ocean, and their pigments and chlorophyll-protein complexes were identified and characterized. No phycobilin pigments were detected in any of the species. Chlorophylls a and b were present in ratios of a/b = 4.4-6.9. The major carotenoids were beta-carotene (70%) and zeaxanthin (20%). Minor carotenoids of one isolate were identified as echinenone, cryptoxanthin, isocryptoxanthin, mutachrome, and trihydroxy-beta-carotene; no epsilon-ring carotenoids were found in any sample. Except for the absence of glycosidic carotenoids, the overall pigment composition is typical of cyanobacteria. A chlorophyll a/b-protein complex was present in Prochloron; it was electrophoretically and spectrally indistinguishable from the light-harvesting chlorophyll a/b-protein of higher plants and green algae. It accounted for 26% (compared to approximately 50% in green plants) of the total chlorophyll; 17% was associated with a P700-chlorophyll a-protein. The photosynthetic unit size of 240 +/- 10 chlorophylls per P700 in Prochloron was about half that of eukaryotic green plants. A model is proposed for the in vivo organization of chlorophyll in Prochloron.

Journal Article↗
PubMed1996

Cloning and functional analysis of the beta-carotene hydroxylase of Arabidopsis thaliana.

An Arabidopsis thaliana cDNA encoding the enzyme beta-carotene hydroxylase was identified by functional complementation in Escherichia coli. The product of this cDNA adds hydroxyl groups to both beta rings of the symmetrical beta-carotene (beta,beta-carotene) to form zeaxanthin (beta,beta-carotene-3,3'-diol) and converts the monocyclic beta-zeacarotene (7',8'-dihydro-beta,psi-carotene) to hydroxy-beta-zeacarotene (7',8'-dihydro-beta,psi-carotene-3-ol). The epsilon rings of delta-carotene (epsilon,psi-carotene) and alpha-zeacarotene (7',8'-dihydro-epsilon,psi-carotene) are poor substrates for the enzyme. The predicted amino acid sequence of the A. thaliana enzyme resembles the four known bacterial beta-carotene hydroxylase enzymes (31-37% identity) but is much longer, with an N-terminal extension of more than 130 amino acids. Truncation of the cDNA to produce a polypeptide lacking the first 69 amino acids does not impair enzyme activity in E. coli. Truncation to yield a polypeptide of a length comparable with the bacterial enzymes (lacking 129 N-terminal amino acids) resulted in the accumulation of the monohydroxy intermediate beta-cryptoxanthin (beta,beta-carotene-3-ol), predominantly, when beta-carotene was provided as the substrate. It is suggested that amino acid residues 70-129 of the A. thaliana enzyme may play a role in formation of a functional homodimer.

Amino Acid Sequence↗
PubMed1996

Xanthophyll biosynthesis. Cloning, expression, functional reconstitution, and regulation of beta-cyclohexenyl carotenoid epoxidase from pepper (Capsicum annuum).

Pepper (Capsicum annuum) beta-cyclohexenyl xanthophyll epoxidase cDNA was cloned and the corresponding enzyme overexpressed and purified from Escherichia coli, for investigation of its catalytic activity. The recombinant protein did not directly accept NADPH for epoxidation of cyclohexenyl carotenoids, nor did it operate according to a peroxygenase-based mechanism. Instead, the reducing power of NADPH was transferred to the epoxidase via reduced ferredoxin as shown by reconstitution of epoxidase activity in the presence of NADPH, ferredoxin oxidoreductase, and ferredoxin. Bacterial rubredoxin could be substituted for ferredoxin. The pepper epoxidase acted specifically on the beta-ring of xanthophylls such as beta-cryptoxanthin, zeaxanthin, and antheraxanthin. The proposed reaction mechanism for epoxidation involves the formation of a transient carbocation. This characteristic allows selective inhibition of the epoxidase activity by different nucleophilic diethylamine derivatives, p-dimethylaminobenzenediazonium fluoroborate and N,N-dimethyl-2-phenylaziridinium. It was also shown that the epoxidase gene was up-regulated during oxidative stress and when chloroplasts undergo differentiation into chromoplasts in pepper fruit.

Amines↗
PubMed1997

In vitro characterization of astaxanthin biosynthetic enzymes.

Escherichia coli strains expressing the marine bacteria (Agrobacterium aurantiacum and Alcaligenes sp. strain PC-1) astaxanthin biosynthetic genes (crtZ and W), Haematococcus pluvialis bkt, and Erwinia uredovora crtZ genes were used for in vitro characterization of the respective enzymes. Specific enzyme assays indicated that all of the enzymes are bifunctional, in that the CrtZ enzymes formed zeaxanthin from beta-carotene via beta-cryptoxanthin, as well as astaxanthin from canthaxanthin via phoenicoxanthin (adonirubin). The BKT/CrtW enzymes synthesized canthaxanthin via echinenone from beta-carotene and 4-ketozeaxanthin (adonixanthin) with trace amounts of astaxanthin from zeaxanthin. Comparison of maximum catalytic activities as well as selectivity experiments carried out in the presence of both utilizable substrates indicated that the CrtZ enzymes from marine bacteria converted canthaxanthin to astaxanthin preferentially, whereas the Erwinia CrtZ possessed a favorability to the formation of zeaxanthin from beta-carotene. The CrtW/BKT enzymes were not so defined in their substrate preference, responding readily to fluctuations in substrate levels. Other properties obtained indicated that the enzymes were strictly oxygen-requiring; and a cofactor mixture of 2-oxoglutarate, ascorbic acid, and Fe2+ was beneficial to activity. Based on enzymological data, a predicted pathway for astaxanthin biosynthesis is described, and it is proposed that CrtZ-like enzymes be termed carotenoid 3, (3')-beta-ionone ring hydroxylase and CrtW/BKT carotenoid 4, (4')-beta-ionone ring oxygenase.

Bacterial Proteins↗
PubMed1997

Purification and partial characterization of a cellular carotenoid-binding protein from ferret liver.

A cellular carotenoid-binding protein was purified to homogeneity from beta-carotene-fed ferret liver utilizing the following steps: ammonium sulfate precipitation, ion exchange, gel filtration, and affinity chromatography. The final purification was 607-fold. [14C]beta-Carotene co-purified with the binding protein throughout the purification procedures. SDS-PAGE of the purified protein showed a single band with an apparent molecular mass of 67 kDa. Scatchard analysis of the specific binding of the purified protein to beta-carotene showed two classes of binding sites, a high affinity site with an apparent Kd of 56 x 10(-9) M and a low affinity site with a Kd of 32 x 10(-6) M. The Bmax for beta-carotene binding to the high affinity site was 1 mol/mol, while that for the low affinity site was 145 mol/mol. The absorption spectrum of the complex showed a 32-nm bathochromic shift in lambdamax with minor peaks at 460 and 516 nm. Except for alpha-carotene and cryptoxanthin, none of the model carotenoids or retinol competed with beta-carotene binding to the protein. Thus, a specific carotenoid-binding protein of 67 kDa has been characterized in mammalian liver with a high degree of specificity for binding only carotenoids with at least one unsubstituted beta-ionone ring.

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