SEARCH · PubMed Health

Results for “CAROTENOIDS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1993

The correlation between two dietary assessments of carotenoid intake and plasma carotenoid concentrations: application of a carotenoid food-composition database.

A newly available carotenoid food-composition database providing specific carotenoid values for > 2300 foods was linked to dietary data on 57 male nonsmokers to examine the association between dietary carotenoid intake and plasma carotenoid concentrations over 3 wk when free-living. Carotenoid intake was estimated from a food-frequency questionnaire (FFQ) and 7 d of food diaries with concurrent analysis of plasma carotenoid concentrations. After adjustment for energy intake, percentage of energy from alcohol, and plasma lipid concentrations, significant diet-plasma correlations for the FFQ and the food diaries (FD) included alpha-carotene (r = 0.29 and 0.43), beta-carotene (r = 0.36 FFQ only), beta-cryptoxanthin (r = 0.46 and 0.44), lutein (r = 0.44 FD only), and lycopene (r = 0.53 FD only). Dietary carotenoid intakes were associated with plasma carotenoid concentrations for all the carotenoids except for beta-carotene when food diaries were used whereas the diet-plasma correlation for the provitamin A carotenoids were consistently significant when the FFQ was used.

Adult↗

PubMed1998

Associations of plasma carotenoid concentrations and dietary intake of specific carotenoids in samples of two prospective cohort studies using a new carotenoid database.

Diet-plasma carotenoid associations were examined in samples of women and men from each cohort in the Nurses' Health Study and the Health Professionals Follow-Up Study. In each sample, participants completed two self-administered food frequency questionnaires with at least a 1-year interval and provided a blood specimen preceding the second food frequency questionnaire. Carotenoid intakes were estimated from values for the five major carotenoids found in human plasma, specifically, alpha- and beta-carotene, beta-cryptoxanthin, lutein, and lycopene, using the United States Department of Agriculture-National Cancer Institute Carotenoid Database, as well as updated values for tomato products. Pearson correlation coefficients were calculated to compare diet-plasma correlations over time by sex after adjustment for recognized covariates. Among nonsmoking women (n = 162), the adjusted diet-plasma carotenoid associations were 0.48 for alpha-carotene, 0.27 for beta-carotene and lutein, 0.32 for beta-cryptoxanthin, and 0.21 for lycopene. Among nonsmoking men (n = 110), diet-plasma correlations were 0.47 for alpha-carotene and lycopene, 0.35 for beta-carotene, 0.43 for beta-cryptoxanthin, and 0.40 for lutein. Correlations between total fruit or vegetable intake and each plasma carotenoid level were not as high as any of the calculated carotenoid intake using the new database values. The correlations observed in this study indicate that the new carotenoid database provides valuable information on specific carotenoid intake and may be useful in epidemiological studies that attempt to account for associations between fruit or vegetable intake and disease.

Aged↗

PubMed1992

Enhancement of carotenoid-to-chlorophyll singlet energy transfer by carotenoid-carotenoid interaction.

The apparent quantum yield of singlet-singlet spirilloxanthin-to-bacteriochlorophyll a energy transfer increases linearly with the residual spirilloxanthin content in Rhodospirillum rubrum membrane vesicles from which this carotenoid has been partially removed. Since it has been previously shown that carotenoid-carotenoid interaction is a linear function of the residual spirilloxanthin level in the major pigment-protein complex of those vesicles (Zurdo, J., R. M. Lozano, C. Fernandez-Cabrera, and J. M. Ramirez. 1991. Biochem. J. 274:881-884), it appears that such degenerate interaction enhances singlet energy transfer. Part of the enhancement may be explained if the energy donor is the spirilloxanthin 1Bu----1Ag (S2----S0) transition, because exciton coupling probably brings its energy closer to that of the Qx (S2----S0) transition of bacteriochlorophyll. In contrast, it seems that the possible stabilization of the spirilloxanthin 2Ag (S1) state would hardly improve energy transfer, because this hidden state probably lies below the S1 bacteriochlorophyll state. In any case, the stabilizing effects of carotenoid-carotenoid interactions seem insufficient to explain the enhancement of energy transfer. Direct or indirect effects of carotenoid dimerization on the three-dimensional structure of the pigment cluster appear to be required to account for such enhancement.

Bacteriochlorophylls↗

PubMed1975

Bacterial carotenoids, XLVI. C50-Carotenoids, 14. C50-Carotenoids from Arthrobacter glacialis.

From the psychrophilic bacterium Arthrobacter glacialis have been isolated three C50-carotenoids with molecular formulae C50H72O2: the bicyclic decaprenoxanthin (1a, 7% of total carotenoids), the aliphatic bisanhydrobacterioruberin (2a, 10%) and the monocyclic A.g. 470 (3a, 83%). Decaprenoxanthin (1) and bisanhydrobacterioruberin (2) were in all respects, including chiroptical properties, identical with known carotenoids. The constitution of the previously undescribed A.g. 470 (3a) followed from its spectral properties (electronic, 1H NMR including Eu-shift experiments and mass spectra) and derivatization to 3b and 3c. 3a suffered remarkable elimination to the tridecaene 4a (C47H64O) upon DMSO/KOMe/MeOH treatment. Judged by CD data A.g. 470 (3a) also in stereochemical respect 3a appears to be half decaprenoxanthin (1a)+half bisanhydrobacterioruberin (2a). The intensity ratios of the M-92/M-106 ions on electron impact of 3a,b,c and 4a,b are consistent with the general theory.

Arthrobacter↗

PubMed2003

Maternal carotenoid status modifies the incorporation of dietary carotenoids into immune tissues of growing chickens (Gallus gallus domesticus).

Carotenoids provide pigmentation to avian species, and also have immunomodulatory potential, although experimental results are often inconsistent. Therefore, dietary carotenoid deposition into immune tissue of growing chicks was examined in relation to their maternal carotenoid status (i.e., yolk carotenoid level). Single-comb white leghorn chicks were hatched from carotenoid-replete (C+) or carotenoid-deplete (C-) eggs. For 4 wk posthatch, chicks were fed diets whose carotenoid level ranged from 0 to 38 mg total carotenoid/kg. Carotenoid additions consisted of lutein + canthaxanthin at a ratio of 4:1. After 4 wk, the carotenoid concentration of thymus, bursa, liver, plasma and shank epithelium was measured by HPLC. Egg yolk-derived carotenoids were detectable in chicks fed 0 dietary carotenoids for 4 wk. Chicks hatched from C+ eggs had significantly greater tissue lutein, zeaxanthin and/or canthaxanthin for all tissues (P < 0.05), compared to chicks hatched from C- eggs. Only bursa carotenoids were not dependent on chick diet (P = 0.24); for all other tissues, C+ chicks incorporated dietary carotenoids in a dose-dependent manner (P < 0.01), whereas C- chicks never achieved the same level of carotenoid incorporation. This study demonstrated the importance of maternal carotenoid status on incorporation of yolk- and diet-derived tissue carotenoids in an avian model, and may explain some variability in carotenoid-based research, given that maternal carotenoid status is rarely controlled.

Animals↗

PubMed2003

Evidence for a lack of reactivity of carotenoid addition radicals towards oxygen: a laser flash photolysis study of the reactions of carotenoids with acylperoxyl radicals in polar and non-polar solvents.

In this paper, we report the results of a laser flash photolysis study of the reactions of a range of carotenoids with acylperoxyl radicals in polar and nonpolar solvents. The results show, for the first time, that carotenoid addition radicals do not react with oxygen to form carotenoid peroxyl radicals; an observation which is of significance in relation to antioxidant/pro-oxidant properties of carotenoids. Acylperoxyl radicals, generated by photolysis of ketone precursors in oxygenated solvents, display high reactivity toward carotenoids in both polar and nonpolar solvents, but the nature of the carotenoid radicals formed is dependent on solvent polarity. In hexane, acylperoxyl radicals react with carotenoids with rate constants in the region of 10(9) M(-1) s(-1) and give rise to transient absorption changes in the visible region that are attributed to the formation of addition radicals. All of the carotenoids show bleaching in the region of ground-state absorption and, with the exception of 7,7'-dihydro-beta-carotene (77DH), no distinct absorption features due to addition radicals are observed beyond the ground state absorption region. For 77DH, the addition radical displays an absorption band that is spectrally resolved from the parent carotenoid absorption. The rate of decay of the 77DH addition radical is unaffected by oxygen in the concentration range 10(-4)-10(-2) M, suggesting that these resonance-stabilized carbon-centered radicals are not scavenged by oxygen. At low incident laser intensities, the 77DH addition radical decay kinetics are 1st order with k(1) approximately 4 x 10(3) s(-1) at room temperature. The 1st order decay is attributed to an intramolecular cyclization process, which is supported by the substantial negative entropies of activation obtained from measurements of the decay rate constants for different 77DH addition radicals as a function of temperature. No transient absorption features are observed in the red or near-infrared regions in hexane for any of the carotenoids studied. In polar solvents such as methanol, acylperoxyl radicals also react with carotenoids with rate constants in the region of 10(9) M(-1) s(-1), but give rise to transient absorption changes in both the visible and the red/near-infrared regions, where it is evident that there are two distinct species. For 77DH, the addition radical absorption around 450 nm is still evident, although its kinetic behavior differs from its behavior in hexane. For 77DH and zeta-carotene (zeta-CAR) the spectral and kinetic resolution of the various absorption bands simplifies kinetic analysis. The kinetic evidence suggests that addition radical formation precedes formation of the two near-infrared absorbing species, and that the kinetics of the addition radical decay match the kinetics of formation of the first of these species (NIR1, absorbing at shorter wavelengths). The decay of NIR1 leads to NIR2, which is attributed to the carotenoid radical cation. The solvent dielectric constant dependence of the relative amounts of NIR1 and NIR2 formed leads us to speculate that NIR1 is an ion-pair. However, an alternative assignment for NIR1 is an isomer of the radical cation. The results, in terms of the pattern of reactivity the carotenoids display and of the properties of the carotenoid radicals formed, are discussed in relation to the antioxidant/pro-oxidant properties of carotenoids.

Antioxidants↗

PubMed2005

Embryonic development within carotenoid-enriched eggs influences the post-hatch carotenoid status of the chicken.

Carotenoids in the diet of the laying hen are incorporated into the egg yolk and subsequently into the liver and other tissues of the chicken embryo. Since these pigments are known to provide a range of health benefits to a variety of animals, it is of interest to know whether the effects of maternally derived carotenoids are strictly limited to the embryonic period or if they persist in the progeny after hatching. The aim of this study is to compare the effectiveness of pre-hatch (from the hen's diet) with that of post-hatch (from the progeny's diet) supplementation with carotenoids on the carotenoid status of the chick during the first 4 weeks of post-hatch life. Hens were fed a control diet or a diet supplemented with a carotenoid-rich extract of alfalfa. Eggs from the supplemented hens contained up to 22 times more carotenoids than the controls. The concentration of carotenoids in the livers of chicks hatching from the enriched eggs was initially 29 times greater than in the control chicks. Hepatic carotenoid concentrations in chicks from enriched eggs maintained post-hatch on the control diet were sustained at higher values compared with chicks from control eggs that were fed post-hatch on the carotenoid-supplemented diet, for at least the first 7 days. However, by 14 days, the latter group had overtaken the former in terms of liver carotenoid levels. Thus, under these conditions, maternal effects predominate for at least the first week after hatching, whereas from 2 weeks onwards, the progeny's diet becomes the main determinant of its carotenoid status. Since the antioxidant and immunostimulatory roles of carotenoids are likely to be especially important during the immediate post-hatch period, maternal dietary intake of carotenoids may have important ramifications for the viability of the offspring.

Age Factors↗

PubMed2006

Enteral feeding enriched with carotenoids normalizes the carotenoid status and reduces oxidative stress in long-term enterally fed patients.

BACKGROUND & AIMS: Circulating carotenoid levels decrease progressively in patients receiving long-term enteral tube feeding with carotenoid-free formulas. Low dietary intake and low blood levels of carotenoids are associated with a higher risk of morbidity and mortality from chronic diseases. The aim of this study was to examine the effects of a low dose carotenoid mixture (3-mg/1500kcal) for 3 months on serum carotenoid levels and oxidative stress in patients receiving long-term enteral nutrition as the sole source of nutrition. METHODS: This randomized, double blind, controlled study compared patients receiving enteral nutrition with carotenoids (N=26) and without carotenoids (control group; N=25). RESULTS: Patients on long-term enteral nutrition had low baseline serum carotenoid levels. Three months of enteral feeding enriched with carotenoids significantly (P<0.01) increased serum carotenoid levels compared with the control group. Oxidative stress as measured by NF-kappaB levels was decreased at 3 months compared with the control group (P<0.05). No significant changes in MDA levels were observed during the study period in either group. CONCLUSIONS: This study demonstrated that enteral nutrition containing small amounts of carotenoids (3-mg/1500kcal) in patients requiring long-term enteral feeding normalizes serum carotenoid levels to the lower end of the range found in age-matched controls. The NF-kappaB data indicate a reduction in oxidative stress in these patients. Therefore, the use of formulas containing a mixture of carotenoids should be recommended for long-term enteral nutrition.

Aged↗

PubMed2004

Carotenoid depletion in serum of young type-1 diabetics fed low-carotenoid diets.

BACKGROUND/AIMS: Type-1 diabetics have been considered to be at risk for increased oxidative stress which has been implicated in the development of long-term diabetes complications. Evidence suggests that antioxidant activity may be an important mechanism by which carotenoids could confer protection in human health. Our aim was to compare the serum carotenoid depletion rate in type-1 diabetics and control subjects consuming low-carotenoid diets. METHODS: Ten type-1 diabetics and 8 controls followed a very low-carotenoid diet for 21 days. Dietary intake was recorded daily and fasting blood samples collected at baseline and after 1, 2, 3, 6, 11, 15, 16, 17, and 21 days. Individual carotenoids in serum were analyzed by a validated HPLC method. RESULTS: In both groups, carotenoid intake was less than 5% of the season-adjusted carotenoid reference intake. These diets resulted in decreased serum carotenoid levels in both groups, although depletion curves, final mean concentrations and the estimated half-life of carotenoids in serum revealed no differences between type-1 diabetics and controls. Levels of other minor serum carotenoids, cis-isomers and keto-carotenoids, also decreased whereas serum retinol and alpha- and gamma-tocopherol did not change during the study. CONCLUSION: Upon a low-carotenoid intake, the depletion rate of carotenoids in serum in young type-1 diabetics does not differ from that observed in matched related controls.

Adult↗

PubMed2006

Patterns of serum carotenoid accumulation and skin colour variation in kestrel nestlings in relation to breeding conditions and different terms of carotenoid supplementation.

Carotenoids are pigments synthesised by autotrophic organisms. For nestlings of raptorial species, which obtain carotenoids from the consumption of other heterotrophic species, the access to these pigments can be crucial. Carotenoids, indeed, have fundamental health maintenance functions, especially important in developing individuals as nestling kestrels. The aim of this study was to investigate how body carotenoid levels and skin pigmentation vary in kestrel nestlings (Falco tinnunculus) in relation to nesting parameters. Furthermore, we experimentally altered carotenoid availability (short- medium- and long-term) for nestlings and investigated skin and serum variance. The skin colour variance of 151 nestlings was explained by nest of origin, age and by the body condition (body mass corrected by age), older nestlings with higher body condition being redder. No difference in skin colour was detected between sexes. Differences in hue (skin "redness") between treatments did not emerge during the first week, but did occur 15 days after administration between long-term supplemented and control chicks. In contrast, the serum carotenoid concentration showed a treatment-dependent increase after 5 days from the first carotenoid administration and at least after two supplemented feedings. In general, hue but not serum carotenoids, was correlated with the body condition of nestlings. Based on the increased skin pigmentation of nestling kestrels in the long-term experimental group, we suggest carotenoid availability to be limited for colour expression. The small increase of serum carotenoids due to supplementation is consistent with the hypothesis that there is a physiological constraint on these pigments, as well as an environmental limitation. The presented results are useful for the understanding of carotenoid uptake and accumulation by a wild raptorial species, located at the top of the food web, highlighting that carotenoids are a limited resource for kestrel nestlings.

Age Factors↗

PubMed1998

Changes in plasma carotenoid and vitamin E profile during supplementation with oil palm fruit carotenoids.

It has been hypothesized that supplementation with a single source of carotenoids causes perturbations in the plasma level of diet-derived carotenoids and that this may explain the lack of association between disease rates and the intake of carotenoid supplements. This article describes the effect of supplementation with an oil palm fruit extract, rich in beta-and alpha-carotene, on the plasma carotenoid profile of 15 healthy women volunteers. Volunteers were supplemented for 35 days with 15 mg/d of total carotenoids. Blood samples were taken at regular intervals during the supplementation period and analyzed for a range of carotenoids. Results indicate that the hydrocarbon carotenoid components of the supplement are absorbed and appear in the plasma disproportionately to the ratios in the supplement and that the plasma concentration of diet-derived lutein, a dihydroxy carotenoid ((3R,3S,6R)-beta,epsilon-carotene-3,3-diol), is depressed, whereas that of lycopene is unaffected. Plasma alpha-tocopherol concentrations were unaffected by supplementation. It is concluded that supplementation with carotenoids from a single source results in plasma carotenoid profile changes that are not predictable from a knowledge of supplement composition and that such changes should be monitored and considered when drawing conclusions as to the effect of carotenoid supplementation on health outcomes.

Adult↗

PubMed2002

Carotenoids and carotenoid esters in potatoes (Solanum tuberosum L.): new insights into an ancient vegetable.

The carotenoid pattern of four yellow- and four white-fleshed potato cultivars (Solanum tuberosum L.), common on the German market, was investigated using HPLC and LC(APCI)-MS for identification and quantification of carotenoids. In each case, the carotenoid pattern was dominated by violaxanthin, antheraxanthin, lutein, and zeaxanthin, which were present in different ratios, whereas neoxanthin, beta-cryptoxanthin, and beta,beta-carotene generally are only minor constituents. In contrast to literature data, antheraxanthin was found to be the only carotenoid epoxide present in native extracts. The total concentration of the four main carotenoids reached 175 microg/100 g, whereas the sum of carotenoid esters accounted for 41-131 microg/100 g. Therefore, carotenoid esters are regarded as quantitatively significant compounds in potatoes. For LC(APCI)-MS analyses of carotenoid esters, a two-stage cleanup procedure was developed, involving column chromatography on silica gel and enzymatic cleavage of residual triacylglycerides by lipases. This facilitated the direct identification of several potato carotenoid esters without previous isolation of the compounds. Although the unequivocal identification of all parent carotenoids was not possible, the cleanup procedure proved to be highly efficient for LC(APCI)-MS analyses of very low amounts of carotenoid esters.

Carotenoids↗

PubMed2001

Serum carotenoid depletion follows first-order kinetics in healthy adult women fed naturally low carotenoid diets.

Dietary intakes of carotenoids are highly variable in human populations as are serum carotenoid concentrations. However, there are few controlled data relating carotenoid intake to concentration. Most of the data that are available are from measurements of the absorption and decay of large pharmacologic doses of carotenoids, and are therefore of unknown physiologic relevance. Our objective was to determine the half-life (t(1/2)) of the most abundant carotenoids in blood serum from healthy adult women living under controlled conditions. As part of two carotenoid isotopic studies, we measured serum concentrations of beta-carotene, alpha-carotene, lutein, zeaxanthin, beta-cryptoxanthin and lycopene in 19 healthy young adult women that were fed controlled low carotenoid diets for approximately 10 wk. All other nutrients (vitamins A, E and C) were provided at 100-150% of the 1989 U.S. recommended dietary allowance levels. Exercise and activities were controlled throughout the studies to simulate usual activity patterns. Carotenoid concentrations were measured by reversed-phase HPLC. Serum carotenoid concentration decreases during depletion followed first-order kinetics. The half-lives determined in decreasing order were as follows: lutein (76 d) > alpha-carotene (45 d) = beta-cryptoxanthin (39 d) = zeaxanthin (38 d) = beta-carotene (37 d) > lycopene (26 d). Half-lives were unrelated to physical or demographic characteristics such as body mass, body fat, racial background or age in these relatively homogeneous groups. Carotenoids decreased by similar first-order mechanisms, although the rates differed for individual carotenoids.

Adolescent↗

PubMed2001

A European carotenoid database to assess carotenoid intakes and its use in a five-country comparative study.

A food frequency questionnaire (FFQ) and carotenoid database with information on alpha- and beta-carotene, lutein, lycopene and beta-cryptoxanthin was prepared and used to compare the carotenoid intakes in five European countries: UK, Republic of Ireland, Spain, France and The Netherlands. Eighty, age- (25-45 years) and sex-matched volunteers were recruited in each of the five countries. A FFQ and carotenoid database was prepared of the most commonly consumed carotenoid rich foods in the participating countries and the information was used to calculate frequency and intake of carotenoid-rich foods. The median total carotenoid intake based on the sum of the five carotenoids, was significantly higher (P < 0.05) in France (16.1 mg/day) and lower in Spain (9.5 mg/day,) than the other countries, where the average intake was approximately 14 mg/day. Comparison of dietary source of carotenoids showed that carrots were the major source of beta-carotene in all countries except Spain where spinach was most important. Likewise, carrots were also the main source of alpha-carotene. Tomato or tomato products, were the major source of lycopene. Lutein was mainly obtained from peas in Republic of Ireland and the UK, however, spinach was found to be the major source in other countries. In all countries, beta-cryptoxanthin was primarily obtained from citrus fruit. Comparing the data with that from specific European country studies suggests that the FFQ and carotenoid database described in the present paper can be used for comparative dietary intake studies within Europe. The results show that within Europe there are differences in the specific intake of some carotenoids which are related to different foods consumed by people in different countries.

Adult↗

PubMed2026

Nitric oxide enhances SlSPL10-mediated transcriptional repression of carotenoid synthesis genes to delay tomato fruit carotenoid accumulation.

Nitric oxide (NO) inhibits climacteric fruit ripening, but its mechanisms remain elusive. Here, S-nitrosoglutathione (GSNO, a NO donor) reduces carotenoid accumulation in tomato fruit, confirming NO's role as carotenoid biosynthesis suppressor. Transcriptome analysis identified SlSPL10 (SQUAMOSA promoter binding protein-like 10) as a key player during this process. Genetic evidence further revealed that SlSPL10 negatively regulates carotenoid synthesis. Moreover, GSNO fails to suppress carotenoid synthesis in slspl10 mutant fruit, in contrast to wild-type fruit, highlighting the involvement of SlSPL10 in NO-inhibited carotenoid synthesis. Transcriptomic profiling of slspl10 mutant fruit showed that both NO and SlSPL10 regulate key carotenoid synthesis genes (SlGPS, SlPDS, SlZDS, SlZISO, and SlCRTISO). SlSPL10 directly binds to the promoters of these genes to repress their transcription, and NO enhances the transcriptional inhibition of SlGPS, SlZISO, and SlCRTISO. These three genes are indispensable for SlSPL10's role in NO-mediated carotenoid suppression. Collectively, NO enhances SlSPL10-mediated repression of carotenoid biosynthesis gene expression, reducing carotenoid accumulation in tomato fruit.

Solanum lycopersicum↗

PubMed1999

Plasma concentrations of carotenoids in healthy volunteers after intervention with carotenoid-rich foods.

AIM OF THE STUDY: The present study was conducted to investigate changes in the plasma concentration of carotenoids and carotenoid oxidation products, vitamin A, alpha- and gamma-tocopherol, and ubiquinone-10 during a dietary intervention trial with 23 male healthy volunteers. METHOD: A two week carotenoid depletion period was followed by a daily consumption of 330 mL tomato juice (40 mg lycopene), then by 330 mL carrot juice (15.7 mg alpha-carotene and 22.3 mg beta-carotene), and then by a 10 g spinach powder preparation (11.3 mg lutein and 3.1 mg beta-carotene) served with main meals for two weeks, respectively. Blood samples were collected in the morning after an overnight fasting and carotenoids, vitamin A, tocopherols, and ubichinone were analyzed by reversed-phase HPLC. RESULTS: During the tomato juice intervention, plasma concentrations of trans- and cis-lycopene increased 3-fold compared to the depletion period. Lycopene oxidation products could be demonstrated in plasma and were significantly elevated compared to control (p < 0.001). After two weeks of carrot juice consumption, alpha-carotene and beta-carotene concentrations increased 8.6- and 3.2-fold, respectively. Finally, during the spinach consumption period the lutein concentration increased 2-fold, while the beta-carotene concentrations were still elevated 2-fold. CONCLUSIONS: The moderate change in dietary habits, e.g., the consumption of 330 mL of carotenoid-rich vegetable juices caused significant changes in the plasma carotenoid concentrations, indicating a high bioavailability of carotenoids from these processed vegetable products. The changes in plasma carotenoid concentrations reflected the carotenoid composition of the consumed foods. However, particularly during the tomato juice intervention period the occurrence of lycopene oxidation products and cis-lycopene isomers in plasma was eminent. The formation may be due to antioxidant reactions of lycopene in the organism.

Adult↗

PubMed1997

Carotenoids and protection of phospholipids in solution or in liposomes against oxidation by peroxyl radicals: relationship between carotenoid structure and protective ability.

The ability of carotenoids to protect egg-yolk phosphatidylcholine (EYPC) lipids against oxidation by peroxyl radicals generated from azo-initiators was studied. In homogeneous organic solution, all the carotenoids tested ameliorated lipid peroxidation by AMVN, but none was as effective as alpha-tocopherol. Beta-ring carotenoids showed a correlation between protective effect and rate of carotenoid destruction. Beta,beta-Carotene and zeaxanthin, which react with peroxyl radicals at similar rates, gave a similar degree of protection in organic solution. The reactivity and protective ability of the 4,4'-diketocarotenoids, astaxanthin and canthaxanthin was less. Carotenoids incorporated into ordered membrane systems (EYPC liposomes) displayed different protective efficacies. Zeaxanthin and beta-cryptoxanthin were more effective than beta,beta-carotene against oxidation initiated in the aqueous and lipid phases. Astaxanthin and canthaxanthin afforded less protection to the liposomal lipids. Lycopene was destroyed most rapidly but was least effective as an antioxidant. Located in the hydrophobic inner core of the bilayer, the hydrocarbons lycopene and beta,beta-carotene would not be in a position to readily intercept free-radicals entering the membrane from the aqueous phase. Carotenoids with polar end groups span the bilayer with their end groups located near the hydrophobic-hydrophillic interface where free-radical attack from AAPH first occurs. Hydrogen abstraction from C-4 may be one of the mechanisms of carotenoid antioxidant activity in this system. The chemical reactivity of a carotenoid is not the only factor that determines its ability to protect membranes against oxidation. The position and orientation of the carotenoid in the bilayer is also of importance.

Azo Compounds↗

PubMed1998

In vitro antimutagenic and in vivo anticlastogenic effects of carotenoids and solvent extracts from fruits and vegetables rich in carotenoids.

The water insoluble residues of some carotenoid-rich fruits and vegetables, such as apricots, oranges, brussels sprouts, carrots, yellow-red peppers, and tomatoes, were sequentially extracted with n-hexane, dichloromethane, acetone, and 2-propanol, and solvent extracted materials were tested for inhibition of mutagenicities induced by aflatoxin B1 (AFB1), benzo[a]pyrene (BaP), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and cyclophosphamide (CP) in histidine-deficient strains of Salmonella typhimurium. Antimutagenic activities were found in many extracts, but especially in the n-hexane extracts. For example, in the case of oranges, 100 microg of this extract reduced the bacterial mutagenicity of AFB1, BaP, CP and IQ by 72, 67, 53, and 27%, respectively. Separation by semi-preparative HPLC of the n-hexane extracts of carrots, tomatoes, and oranges indicated that the antimutagenicity was mainly associated with the fractions of the hydrocarbon carotenoids (alpha-, beta-carotene, lycopene), the xanthophylls (beta-cryptoxanthin, lutein), and also the carotenolesters (oranges). When 16 reference carotenoids were investigated as described above, the following results were obtained: In the case of BaP, antimutagenic activity, quantified by dose-response curves, was exhibited by 8'-apo-beta-carotenal, alpha- and beta-carotene, beta-cryptoxanthin, lutein, retinal, and retinol (ID50-values: 20-100 nmol ml-1 top agar, 50-70% maximum inhibition at 1 micromol ml-1 top agar), while the maximum inhibition by torularhodin did not exceed 40%. Astaxanthin, 10'- and 12'-apo-beta-carotenal, bixin, canthaxanthin, ethyl-8'-apo-beta-caro-ten-8'-oate, lycopene, and zeaxanthin were inactive or at best marginally active (<20% inhibition). Closely similar results were obtained with AFB1. The bacterial mutagenicity of CP was strongly reduced by alpha- and beta-carotene, canthaxanthin, and retinol (ID50-values: 67-112 nmol ml-1 top agar, 50-63% maximum inhibition at 1 micromol ml-1 top agar), moderately by beta-cryptoxanthin, and lutein (45% and 28%, respectively), and only marginally or, not at all, by all remaining carotenoids. In the case of IQ, the carotenoids exhibited the weakest antimutagenic potency (7-43%, ID50-values of retinal and retinol: 160 and 189 nmol ml-1 top agar, 60% and 55% inhibition, respectively). The mutagenic activity of the proximal mutagen of IQ, N-OH-IQ, in S. typhimurium TA 98NR was not significantly reduced by any carotenoid tested. These observations as well as the inhibition of various cytochrome P-450 linked 7-alkoxyresorufin-O-dealkylase activities (EROD, MROD, PROD) by four selected carotenoids (retinol>beta-cryptoxanthin>beta-carotene>lutein, IC50-values: 19-109 microM), indicate that the inhibition of the metabolic activation of the different promutagens could cause antimutagenicity. Finally, it could be demonstrated that the number of BaP or CP induced micronuclei in polychromatic erythrocytes in bone-marrow of mice was reduced significantly by the carotenoids lycopene, canthaxanthin, lutein and beta-cryptoxanthin (25-46%). These results clearly show that carotenoids possess biological activities in vitro and in vivo distinct from their function as precursors of vitamin A or antioxidants suggesting effects on activation of promutagens.

Animals↗