Carotenoid Depletion Research Articles

Plasma responses in human subjects after ingestions of multiple doses of natural α-cryptoxanthin: a pilot study

Xanthophylls have attracted a lot of interest since their health benefits were documented. Unfortunately, studying their intestinal absorption is often affected by high baseline levels present in the fasting plasma. As alpha-cryptoxanthin is rarely found in the traditional European diet, its concentration in human plasma is extremely low. A pilot human intervention study was designed using alpha-cryptoxanthin for the first time as a marker xanthophyll in a minimally formulated cellulose-based supplement. Alpha-cryptoxanthin was administered in gelatin soft-gel capsules in multiple doses of 156 microg/d to three male volunteers (age 27.3 (SD 4.7) years; BMI 21.6 (SD 0.3) kg/m(2)) for 16 d after a 2-week carotenoid depletion period. Fasting blood samples were taken before the intervention and after 3, 6, 9, 13 and 16 d. Plasma HPLC analyses allowed for determination of the concentration; liquid chromatography-MS in the single ion monitoring mode was used to confirm peak assignment. The concentrations of alpha-cryptoxanthin increased significantly after only 3 d of supplementation. The concentration-time plots showed a characteristic shape with a first maximum after day 6, a decline until day 9 and a gradual second rise until the end of the study. Standardisation of plasma alpha-cryptoxanthin concentrations to triacylglycerol or total cholesterol did not influence the characteristics. The maximum concentrations reached at the end of the intervention period ranged from 0.077 to 0.160 micromol/l. These results suggest a high intestinal absorption and an enrichment of alpha-cryptoxanthin in the plasma even from a minimally formulated cellulose-based supplement.

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 α- and γ-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.

Trade-offs between immune investment and sexual signaling in male mallards.

Allocation trade-offs between the immune system and sexual traits are central to current sexual selection hypotheses but remain contentious. Such trade-offs could be brought about by the dual action of testosterone that stimulates sexual signals but also suppresses immune functions and/or by competition for carotenoids that can be deposited in ornaments or used as antioxidants in support of immune functions. We investigated the trade-off between investment in immunity and maintenance of testosterone, carotenoids, and sexually selected, carotenoid-based bill color in male mallards. Following a nonpathogenic immune challenge, facultative immune investment resulted in a syndrome of changes in allocation. Plasma carotenoids disappeared from circulation proportional to antibody production. In addition, the reflectance spectrum of the bill was affected; greater antibody production was associated with an increase in relative UV reflectance. Although changes in bill reflectance and plasma carotenoids were related, the relationship appeared more complex than direct competition with immunity. Finally, maintenance of testosterone was affected by immune investment: testosterone levels declined substantially when males produced more antibodies. Because males with high testosterone are preferred by females, the decline in testosterone, in addition to carotenoid depletion and effects on bill reflectance, could constitute a significant cost of immune investment.

In vivo and in vitro evidences that carotenoids could modulate the neutrophil respiratory burst during dietary manipulation.

The primary role of polymorphonuclear neutrophils (PMNs) is to destroy pathogenic microorganisms after phagocytosis by producing reactive oxygen species (ROS) and toxic molecules. However, PMNs produce sufficient amounts of ROS during an oxidative burst to be autotoxic and detrimental to their own functions and to possibly cause DNA damage, protein and lipid oxidation and cell membrane destructuration. The aim of this study was to investigate in vivo the role of the antioxidant capacities of carotenoids in modulating ROS content in PMNs during oxidative burst. Moreover to investigate the direct or indirect effect of carotenoids, the modification of PMN ROS content was explored after in vitro supplementation with beta-carotene or lycopene, chosen taking account of their vitamin A and no vitamin A precursor effect, respectively. In vivo study: Venous blood was collected from 10 healthy male volunteers and ROS production from phorbol myristate acetate (PMA)-stimulated PMNs was determined, by flow cytometry using the fluorescent dye dihydrorhodamine 123, at baseline, after 3 weeks of carotenoid depletion (carotenoid intake limited to 25% of usual intake) and after 5 weeks of carotenoid repletion (30 mg beta-carotene, 15 mg lycopene and 9 mg lutein per day). In vitro study: ROS content in PMA-stimulated PMNs isolated from carotenoid depleted subjects and controls was quantified after an in vitro enrichment with beta-carotene (1 micromol/L) or lycopene (0.3 micromol/L). In vivo carotenoid depletion increased PMN H2O2 content after PMA activation by 38% (p < 0.05 vs baseline),while supplementation for 5 weeks restored basal H2O2 generation (p < 0.05 vs depletion). Although H2O2 measurement in PMNs from non-depleted subjects was not affected by an in vitro supply with beta-carotene or lycopene, a significant decrease in H2O2 content by 78.9 % and 81.2%, respectively, was observed in PMNs from carotenoid depleted subjects (p < 0.01 vs depleted control subjects). The carotenoid ROS quenching capacities control both in vivo and in vitro the PMNs ROS generation and probably protect these cells against DNA, membrane lipid and protein damages during oxidative burst. Moreover, these effects appear independent from the metabolic conversion of carotenoids to vitamin A.

Effects of dietary carotenoid depletion and repletion on lymphocyte proliferation during aging

Effects of dietary carotenoid depletion and repletion on lymphocyte proliferation during aging

Quantification of carotenoids in chicken plasma after feeding free or esterified lutein and capsanthin using high-performance liquid chromatography and liquid chromatography-mass spectrometry analysis

The present study reports about the plasma carotenoid levels of chickens achieved after feeding diets containing free and esterified lutein (from marigold) and capsanthin (from red pepper) by applying HPLC analyses using a RP-C30 column. Forty chickens were divided at random into four groups and were fed 2 wk with different diets after receiving a basal diet with a low carotenoid content for carotenoid depletion (3 wk). One group was fed a diet containing free lutein (G1), another group received a diet with esterified lutein (G2), two other diets contained free (R1) and esterified capsanthin (R2), respectively. To unequivocally identify plasma carotenoids, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis was applied, which had never been used as an analytical tool to evaluate the carotenoids of chicken plasma; HPLC chromatograms of chicken plasma following capsanthin feeding have not been presented. The study showed that not only lutein but also capsanthin appeared in the blood stream after feeding free or esterified xanthophylls, demonstrating that capsanthin esters were bioavailable. Quantitative analysis showed comparable concentrations of plasma lutein and capsanthin, respectively, no matter if free or esterified carotenoids were fed.

Effect of Carotenoid Depletion on the Hatching Rhythm of the Silkworm, Bombyx mori

To investigate the functional involvement of carotenoid in the insect circadian rhythm, we observed the effect of carotenoid depletion on the hatching patterns of the silkworm under several light conditions. When eggs were transferred from continuous light (LL) to continuous darkness (DD), an overt hatching rhythm was initiated. The first hatching peak, which was observed at 13.2 h after the transfer in the carotenoid-depleted silkworm, was reduced remarkably in both control groups (carotenoid-rich and carotenoid-depleted but with lutein supplementation), though subsequent peaks occurred with similar timing. Under LD 4 : 20, LD 12 : 12 and LD 20 :4, hatching patterns depended on the dietary carotenoid and the light intensity of the photophase. At a low light intensity, carotenoid depletion suppressed hatching as a masking effect just after light-on. Under LD 4 : 20 at a low light illumination, hatchings in the carotenoid-depleted silkworm were observed during scotophase, but few larvae hatched during scotophase in the control groups. Our findings suggest that carotenoid is not indispensable for the photoreception, formation and entrainment of the circadian hatching rhythm, but that a carotenoid-dependent process that is induced by light-off and damps out in an hour-glass mode, suppresses the hatching during darkness without affecting the circadian oscillation. The possibility that this carotenoid-dependent process is involved in the photoperiodic induction in the silkworm was discussed.

Carotenoids are degraded by free radicals but do not affect lipid peroxidation in unilamellar liposomes under different oxygen tensions

It has been questioned whether carotenoids can act as antioxidants in biological membranes. Biological membranes can be modeled for studies of lipid peroxidation using unilamellar liposomes. Both carotenoid depletion and lipid peroxidation were increased with increasing oxygen tension in unilamellar liposomes. Carotenoids in such liposomes were found to be very sensitive to degradation by free radicals generated from iron and 2,2′-azobis(2-amidinopropane) dihydrochloride, but they were not protective against lipid peroxidation. Lycopene and β-carotene were more sensitive to free radical attack than lutein, zeaxanthin, and β-cryptoxanthin.

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.

Antioxidant liposoluble vitamins and carotenoids in chronic hepatitis

Background: It is known that antioxidant liposoluble vitamins and carotenoids are reduced in liver cirrhosis, but little is known about chronic viral hepatitis, where oxidative damage has to be taken into account. Methods: Fifty-five patients with chronic hepatitis, mainly C virus-related, were matched with 16 patients with biliary stones and 20 healthy controls. Plasma and liver analyses were carried out using a well-tried HPLC technique that affords an accurate quantification of retinol, tocopherol, alpha- and beta-carotene, cryptoxanthin, and lycopene. Results: Plasma concentration of retinol, tocopherol, beta-carotene, and lycopene was significantly decreased in both patient groups, particularly in those with chronic hepatitis. In contrast, liver concentration of both esterified and free retinol, tocopherol, and some carotenoids was better preserved in the hepatitis group than in the cholelithiasis group. A strict correspondence between aminotransferases and the amount of liver-stored retinol was documented. Conclusions: Plasma vitamin and carotenoid depletion co-existing with preserved liver storage may indicate a functional defect in liver pool mobilization or even a real depletion of the antioxidant defenses, which play a key role in averting cellular damage. The implications for nutrition and therapy need to be taken into account.

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

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. 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. 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. 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.

Hydrogen bonding and circular dichroism of bacteriochlorophylls in the Rhodobacter capsulatus light-harvesting 2 complex altered by combinatorial mutagenesis.

We have investigated the spectroscopic properties of two classes of light-harvesting 2 (LH2, B800-850) mutants of Rhodobacter capsulatus obtained by combinatorial mutagenesis to the C-terminal half of the beta-apoprotein: a pseudoLH2 (pLH2) class, in which the 800-nm absorption was normal but the 850-nm peak was blue-shifted by up to 14 nm, and the other a pseudoLH1 (pLH1) class, which lacked the 800-nm absorption band and showed 850-nm absorption red-shifts of up to 30 nm. In several of the pLH1 antennae, carotenoid depletion contributed to the phenotype, while in the pLH2 complexes there was some carotenoid enrichment. A number of mutants from each class have also been characterized by low-temperature absorption and fluorescence spectroscopy, resonance Raman spectroscopy, and circular dichroism. In all of the mutants investigated, the B850 bacteriochlorophyll a binding site remained intact, conserving both the hydrogen bonding environment of the chromophores and their conformation and liganding. In contrast, the intensity of the CD spectra of pLH1 complexes was considerably reduced, relative to that of wild-type or pLH2 complexes, consistent with alterations in the interactions between pigments and in their relative orientation. Elevated fluorescence polarization over the red wing of the B850 band in the pLH2 complexes indicated a reduction of exciton mobility within the ring of BChl molecules. Possible structural alterations governing the spectral properties of the different mutants are discussed.

The effects of dietary astaxanthin on the carotenoid pattern of the prawn Penaeus japonicus during postlarval development.

Penaeus japonicus postlarvae, reared under laboratory conditions, were fed an astaxanthin enriched diet to the investigate carotenoid metabolic capabilities during the postlarval development. Animals fed astaxanthin were found to absorb this carotenoid. The decrease of pigment concentration in the carotenoid starved group is related to the duration of the experimental feeding conditions; the carotenoid depletion depends upon the postlarval status at the starting point. As has been shown for adult prawns, the carotenoid pattern of postlarval stages, regardless of the diet, consists mainly of free and esterified astaxanthin; the relative amounts of these fractions undergo slight variations depending on the diet.

Serum thyroid hormone concentrations may increase during carotenoid depletion of healthy adult women

Vitamin A and thyroid hormone status are interrelated. Much of vitamin A is derived from dietary carotenoids, so we investigated whether carotenoid depletion might influence thyroid hormone status. Nine healthy adult women were fed a low carotenoid diet (58 μg/day) for 68 days then repleted with the same diet supplemented with 15,000 μg of carotenoid/day for 28 days. The women lived on a metabolic unit, where their dietary intakes, exercise, and activities were controlled. Serum thyroid stimulating hormone (TSH) increased significantly after 39 days of carotenoid depletion ( P < 0.02), followed by significant increases in serum thyroxine (total T4), then free thyroxine (FT4), and free triiodothyronine (FT3; all p < 0.02). TSH and total T4 concentrations stabilized during carotenoid repletion but remained significantly elevated over baseline. Serum triiodothyronine (total T3), transthyretin, and total protein concentrations were not influenced by carotenoid depletion. Thus, carotenoid depletion may induce increases in some serum thyroid hormone concentrations in healthy young adult women.

Photosensitivity in the circadian hatching rhythm of the carotenoid-depleted silkworm, Bombyx mori.

Silkworms (Bombyx mori) were reared on a carotenoid-deprived artificial diet, and the carotenoid-depleted eggs of the next generation were incubated so that we could observe the effect of the depletion on the circadian rhythm of hatching. The phototactic response curves of newly hatched larvae showed that the visual photosensitivity in ocelli of larvae from the carotenoid-depleted eggs was at least 4 log units lower than that of a carotenoid-rich control group. However, the phase-shift experiment revealed that carotenoid depletion did not reduce the photosensitivity in the hatching rhythm. When the hatching rhythm was generated by exposure to a single light pulse in constant darkness, the first peak in the rhythm of the carotenoid-depleted silkworms occurred significantly earlier than that of the carotenoid-rich group, but the following second peaks of both groups were found at the same time. These results suggest that for the silkworm, carotenoid is not involved in photoreception for the hatching rhythm, but is involved in the timing of hatching.

Consequences of herbicide-induced pigment deficiencies on thylakoid membrane proteins of Chlamydomonas reinhardtii

Chlamydomonas reinhardtii synthesizes chlorophyll and assembles a photosynthetically competent thylakoid membrane system when grown in darkness. This alga thus offers a system in which the effects of carotenoid depletion on thylakoid biogenesis can be analyzed in the absence of photooxidative damage. Growth in darkness in the presence of 10 μM norflurazon reduced chlorophyll to 18% and carotenoids to 7% of the levels present in cells grown in darkness in the absence of the herbicide. Fluorescence emission spectra at 77°C reveal herbicide-induced loss of the photosystem I-associated signal at 715 nm. Accumulation of light-harvesting complex (LHC)-II polypeptides was also reduced. Thus, in Chlamydomonas, norflurazon has effects on the thylakoid membrane system that are independent of the photochemical damage that results from the absence of photoprotective carotenoids.

Effects of starvation and feeding on canthaxanthin depletion in the muscle of rainbow trout ( Salmo gairdneri Rich.)

An experiment was conducted to examine carotenoid depletion in the muscle of rainbow trout. After 4 weeks of ingestion of canthaxanthin, fish were divided into two groups: the first was fed the same diet but without the canthaxanthin, the second was starved. Lipid and canthaxanthin levels in epaxial muscle were followed for 38 days. The lipid content increased (× 1.84) in fed fish and remained stable in those which were starved. Fed fish lost more canthaxanthin than starved fish. The ratio of the relative weight gain of canthaxanthin to that of the lipids was higher in starved than in fed fish (0.91 and 0.69 respectively). It is concluded that an internal redistribution of canthaxanthin takes place in the absence of an intake of the pigment. These results also show that the muscle of rainbow trout has a high storage capacity.