Canthaxanthin Mitigates Cardiovascular Senescence in Vitro and in Vivo

BACKGROUND

The number of older people in the world is increasing year by year; studies have shown that more than 90% of cardiovascular disease occurs in the older people population, indicating that aging is one of the major risks involved in the development of cardiovascular disease. Therefore, retarding the development of cardiac aging is an important strategy to prevent aging-related cardiovascular diseases.

METHODS

In the current study, we examined the anti-cardiovascular aging potential of canthaxanthin in vitro and in vivo experiments. For this, a model of cardiomyocyte senescence induced by D-galactose was established, which was used to investigate the canthaxanthin's effect on cardiac premature aging.

RESULTS

We found that canthaxanthin obviously mitigated the cardiomyocyte senescence in vitro. Further mechanistic studies revealed that canthaxanthin seems to alleviate cardiomyocyte senescence by regulating the autophagy process. Furthermore, the effects of canthaxanthin on cardiovascular senescence were further evaluated. We also observed that canthaxanthin mitigated cardiac aging and fibrosis in the aged mice model.

CONCLUSIONS

To sum up, the current work showed that canthaxanthin could obviously alleviate cardiac premature aging, indicating that canthaxanthin could be used as a biologically active molecule for the treatment of cardiac aging and fibrosis.

Canthaxanthin Attenuates the Vascular Aging or Endothelial Cell Senescence by Inhibiting Inflammation and Oxidative Stress in Mice

BACKGROUND

Vascular endothelial dysfunction is an early phenotype of aging-related vascular dysfunction. Delaying vascular aging and preventing cardiovascular disease are major public health problems that urgently need to be solved. Scientists have studied various drugs to prevent the occurrence and progress of cardiovascular disease, but progress has been slow. Here, the antisenescence and anti-endothelial damage of canthaxanthin (CX, which is an active molecule from food) has been studied.

METHODS

This study was performed by adding CX to a model of cell senescence and oxidative damage induced by hydrogen peroxide. Cellular senescence markers (e.g., p16, p21, and p53) and oxidative damage markers (e.g., reactive oxygen species, nitric oxide, malondialdehyde, superoxide dismutase) were evaluated by the enzyme-linked immunosorbent assay, laser scanning confocal microscopy, and Western blotting.

RESULTS

We found that CX downregulated the expression level of senescence-associated molecules, and significantly reduced the oxidative damage of vascular endothelial cells. These observations showed that CX effectively alleviated the senescence of vascular endothelial cells. Furthermore, CX treatment reduced the expression levels of interleukin-6 (IL-6), tumor necrosis factor alpha, and IL-1β. Finally, in vivo, CX significantly alleviated vascular senescence.

CONCLUSIONS

The current study shows that CX has potential application value for treating vascular aging or endothelial cell senescence.

The effects of canthaxanthin microencapsulation on yolk color and canthaxanthin deposition in egg yolk of laying hens

Canthaxanthin is widely used as a feed additive to improve skin and yolk color in poultry. It is insoluble in water and sensitive to oxidation, so commercial canthaxanthin is often microencapsulated with wall materials to improve its solubility and stability. The objective of this study was to evaluate the effects of canthaxanthin microencapsulation on yolk color and canthaxanthin deposition in egg yolk of laying hens. A total of 288 Hyline Brown laying hens (48 wk of age) were allocated to 4 groups with 6 replicates of 12 hens each, and fed a basal diet or the basal diet supplemented with 5 mg/kg canthaxanthin microencapsulated with modified starch (CMMS), gelatin (CMG), and sodium lignosulfonate (CMSL), respectively. Canthaxanthin supplementation did not affect laying performance of hens, but improved (P < 0.05) yolk color of fresh, fried, boiled, and stored (4 and 25°C) eggs. The improvement of yolk color of fresh eggs was greatest in the CMSL group and least in the CMG group (P < 0.05). Both CMMS and CMSL resulted in higher (P < 0.05) yolk canthaxanthin concentration than CMG. The CMSL resulted in higher (P < 0.05) yolk color score of fried eggs than CMMS and CMG and higher (P < 0.05) yolk color score of boiled eggs than CMG, but no difference was observed in stored eggs among three canthaxanthin groups. In conclusion, CMMS and CMSL were more effective in yolk pigmentation than CMG, and CMSL was slightly better than CMMS.

Dietary supplementation with canthaxanthin and 25-hydroxycholecalciferol on the incubation performance and fertility of European quail breeders

This study assessed the effects of combined supplementation with canthaxanthin (Cx) and 25-hydroxycholecalciferol (25-OH-D₃) on incubation performance, fertility, and chick quality in European quail breeders. A total of 240 birds were distributed in a completely randomized design with 5 diets and 8 replicates. The animals were fed a basal diet containing 50 µg of vitamin D₃ or the basal diet supplemented with 3 ppm Cx and 34.5 µg 25-OH-D₃, 6 ppm Cx, and 69 µg 25-OH-D₃, 9 ppm Cx and 103.5 µg 25-OH-D₃, or 12 ppm Cx and 138 µg 25-OH-D₃. Incubation performance was analyzed in 2 periods (32 and 38 wk). Breeders aged 32 wk produced eggs with higher hatchability (P = 0.024), hatchability of fertile eggs (P = 0.026) and lower initial plus mid embryonic mortality (P = 0.021), whereas 38-week-old breeders generated chicks with a higher length at hatching (P < 0.001) and lower final plus pipped embryonic mortality (P = 0.021). In both age groups, Cx + 25-OH-D₃ levels had a quadratic effect on egg fertility (P < 0.001), hatchability of total (P < 0.001), and fertile eggs (P < 0.001). The fertility and the number of sperm cells in the perivitelline membrane was analyzed in two periods (26 and 40 wk). A quadratic effect of diet and days after mating on both parameters (P < 0.05) was observed. Eggs from supplementing breeders showed a high fertility (P < 0.001) and sperm cell counts (P < 0.001) for up to 7 and 3 d after mating, respectively, then the control group. Moreover, the supplementation of quail breeder diets with 6 ppm Cx + 69 µg 25-OH-D₃ enhances sperm cell longevity in sperm storage tubules, hatchability of total and fertile eggs, fertility, and chick quality, especially in older quail's breeders and reduces embryonic mortality.

Effects of astaxanthin and canthaxanthin on oxidative stress biomarkers in rainbow trout

Farmed trout are commonly fed carotenoid-enriched diets during the finishing period to acquire typical red-to-pink flesh color in salmonid muscle. The aim of this study was to examine the effects of two xanthophylls, astaxanthin (Ax) or canthaxanthin (Cx), administered individually or in combination, on oxidative stress biomarkers in kidney and liver of rainbow trout. Specimens were fed Ax (75 mg/kg) or Cx (25 mg/kg) individually or in combination in the diets for 8 weeks. Changes in concentration of oxidative stress biomarkers, including total glutathione, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase, were recorded in Ax- and Cx-dosed trout. These two carotenoids, predominantly Cx, initiated enzymatic responses in rainbow trout. It is noteworthy that lipid peroxidation processes were not apparent in all Ax or Cx-dosed trout. Further, both combined xanthophylls did not exert significant synergistic effects in liver and kidney. Biomarker responses were generally altered in both tissues through the 4 and 8 weeks suggesting that different time-dependent mechanisms led to enhanced antioxidant defense in Ax and/or Cx-fed trout. Data demonstrated that these two xanthophylls did not exert detrimental effects on rainbow trout.

Effect of broiler breeders fed with corn or sorghum diet and canthaxanthin supplementation on production and reproductive performance

This study was designed to evaluate the effect of corn or sorghum diet and canthaxanthin (CX) supplementation on performance in broiler breeders. A total of 440 females with similar body weight (BW) (3.71 ± 0.14 kg) and 60 roosters were placed in an open-sided house with 20 pens, randomly distributed in a factorial arrangement (2 × 2). There were 4 diets of 2 ingredients; corn (CO) or sorghum (SO) and 2 levels of CX; 6 mg/kg (CX) and 0 mg/kg (NCX) totaling 5 replicate pens of 22 females and 3 males each, from 42 to 65 wk, divided in 2 periods (from wk 42 to 53 and wk 54 to 65). Birds' BW was measured every 28 d and mortality rate was calculated at the end of trial. Egg production (%), egg specific gravity (g/cm3), egg weight (g), yolk weight (%), albumen weight (%), eggshell weight (%) and yolk colorimetric score were measured weekly. Incubation parameters were recorded in 12 incubations to evaluate hatching eggs, hatching (%), hatchability (%), fertility (%), weight of the chicks born and their quality. The BW, mortality, percentage of yolk and albumen weight, fertility and some incubation parameters were not affected (P > 0.05) by diets used. An increase in the egg production, hatching eggs, chicks born and first quality chick by hen at the second period were observed in CX breeder's diets (P = 0.0066; P = 0.0060; P = 0.0368; P = 0.0326). Egg specific gravity and eggshell weight were improved at the first period by SO+CX diet (P = 0.0138; P = 0.0209) and the same effect to egg weight, but at the second period (P = 0.0251). The CX was well absorbed from the diet and effectively transferred to the egg yolk, thereby increasing egg yolk pigmentation in the both periods (P < 0.0001). The CX supplementation in broiler breeder diets improved the productive and reproductive performance (laying% and hatchable eggs) at the second period, also to the both periods improved the egg yolk pigmentation.

Carotenoids reverse multidrug resistance in cancer cells by interfering with ABC-transporters

Proteins of the ATP-binding cassette superfamily, mainly P-glycoprotein (P-gp; MDR1), play an important role in the development of multidrug resistance (MDR) in cancer cells and thus in the potential failure of chemotherapy. A selection of carotenoids (β-carotene, crocin, retinoic acid, canthaxanthin, and fucoxanthin) was investigated whether they are substrates of P-gp, and if they can reverse MDR in resistant Caco-2 and CEM/ADR5000 cells as compared to the sensitive parent cell line CCRF-CEM. The activity of ABC transporter was determined in resistant and sensitive cells by spectrofluorometry and flow cytometry using the substrates doxorubicin, rhodamine 123, and calcein as fluorescent probes. The carotenoids increased accumulation of these P-gp substrates in a dose-dependent manner indicating that they themselves also function as substrates. Fucoxanthin and canthaxanthin (50-100 μM) produced a 3-5-fold higher retention of the fluorescent probes than the known competitive inhibitor verapamil. Carotenoids showed a low cytotoxicity in cells with MDR with IC(50) values between 100 and 200 μM. The combination of carotenoids with eight structurally different cytotoxic agents synergistically enhanced their cytotoxicity in Caco-2 cells, probably by inhibiting the function of the ABC transporters. For example, fucoxanthin synergistically enhanced the cytotoxicity of 5-FU 53.37-fold, of vinblastine 51.01-fold, and of etoposide 12.47-fold. RT-PCR was applied to evaluate the mRNA levels of P-gp in Caco-2 cells after treatment with carotenoids. Fucoxanthin and canthaxanthin significantly decreased P-gp levels to 12% and 24%, respectively as compared to untreated control levels (p<0.001). This study implies that carotenoids may be utilised as chemosensitisers, especially as adjuvants in chemotherapy.

[Influence of canthaxanthin on D-galactose induced osseous changes of rat]

OBJECTIVE

To study the influence of canthaxanthin on D-galactose induced osseous changes of rat.

METHODS

Forty-five six-week-old Wistar male rats were randomly divided into model group, canthaxanthin group and young control group. In addition, 15 sixteen-month-old Wistar male rats were used as old control group. Model group and canthaxanthin group were given injections of D-galactose for 5 months (20 mg/kg/once per-day) to cause aging of rat. Then routine osseous parameters were tested and compared among the 4 groups.

RESULTS

Compared with young control group, the BMD, parameters of structural mechanics and biomechanics, bone calcium, manganese, magnesium and the content of hydroxyproline in the model group decreased significantly (P < 0.01), however, the content of bone phosphorus, the activity of bone and serum ALP increased significantly (P < 0.01). Those changes of the model group were the same as the old control group,but the changes in the canthaxanthin group significantly differed with the model group (P < 0.01).

CONCLUSION

The high does of D-galactose intake can cause aging and osteoporosis at the same time in rat, but canthaxanthin can prevent and inhibit D-galactose induced osseous changes.

Bayesian semiparametric dynamic frailty models for multiple event time data

Many biomedical studies collect data on times of occurrence for a health event that can occur repeatedly, such as infection, hospitalization, recurrence of disease, or tumor onset. To analyze such data, it is necessary to account for within-subject dependency in the multiple event times. Motivated by data from studies of palpable tumors, this article proposes a dynamic frailty model and Bayesian semiparametric approach to inference. The widely used shared frailty proportional hazards model is generalized to allow subject-specific frailties to change dynamically with age while also accommodating nonproportional hazards. Parametric assumptions on the frailty distribution are avoided by using Dirichlet process priors for a shared frailty and for multiplicative innovations on this frailty. By centering the semiparametric model on a conditionally conjugate dynamic gamma model, we facilitate posterior computation and lack-of-fit assessments of the parametric model. Our proposed method is demonstrated using data from a cancer chemoprevention study.

Dietary carotenoid pigment supplementation influences hepatic lipid and mucopolysaccharide levels in rainbow trout (Oncorhynchus mykiss)

We assessed the effects of dietary carotenoid pigment supplementation on liver histochemistry in the rainbow trout. One hundred and eight rainbow trout (mean mass 266+/-10 g) were assigned to each of three replicate tanks for each of three dietary treatments; astaxanthin, canthaxanthin, or control at a target dietary inclusion of 100 mg/kg, by top-coating a pigment-free commercially extruded basal diet (Trouw Aquaculture, U.K.). Fish were fed for 3 weeks at a ration of 1.2% body mass/day, in a recirculating freshwater system maintained at 16 degrees C. Frozen liver sections were stained for total lipids, unsaturated lipids, glycogen, mucopolysaccharides, glycogen phosphorylase and aspartate aminotransferase. Relative amounts were measured quantitatively by image analysis. Carotenoid treatment significantly (P<0.05) altered the total lipid profile and hepatic mucopolysaccharide contents of livers of rainbow trout. Results are discussed in relation to the catabolic potential of the liver in carotenoid pigment metabolism.

Effect of canthaxanthin content of the maternal diet on the antioxidant system of the developing chick

1. Effects of canthaxanthin supplementation of the maternal diet on the antioxidant system of the developing chick were investigated. 2. Three hundred and twenty female broiler breeder birds were housed in one of 4 controlled environment rooms with 3 replicates for all treatments, with the exception of the control treatment of which there were 4 replicates. All birds received one of 5 diets: control low xanthophyll diet, or the same diet supplemented with 3, 6, 12 or 24 mg/kg canthaxanthin in the form of Carophyll Red. At 30 weeks of age 60 eggs from each of the 5 groups were incubated. At d 16 of the embryo development, at d 1 and d 7 posthatch tissue samples were collected and analysed by HPLC-based methods. 3. Canthaxanthin accumulation in the egg yolk was proportional to dietary content. Furthermore, at 12 to 24 mg/kg canthaxanthin was associated with an increase in gamma-tocopherol concentration in the egg yolk. Canthaxanthin was transferred from the egg yolk to the developing embryo and, as a result, its concentration in the liver of the embryo at 16 and in 1-d-old chicks was increased. Even at d 7 posthatch canthaxanthin concentration in the chicken liver was elevated. 4. Canthaxanthin supplementation of the maternal diet at 12 mg/kg was associated with an increased alpha-tocopherol concentration in the liver of 1-d-old chicks and resulted in decreased tissue susceptibility to lipid peroxidation. 5. Canthaxanthin supplementation at 6 to 24 mg/kg was also associated with a delay in alpha-tocopherol depletion from the liver for 7-d posthatch. As a result of the increased canthaxanthin and vitamin E concentrations in the liver of 7-d-old chicks, tissue susceptibility to lipid peroxidation decreased. 6. The results support an idea that dietary carotenoids can modulate antioxidant systems of the developing chicken.

Astaxanthin and canthaxanthin do not induce liver or kidney xenobiotic-metabolizing enzymes in rainbow trout (Oncorhynchus mykiss Walbaum)

This study was designed to assess the effects of dietary carotenoid supplementation on liver and kidney xenobiotic-metabolizing enzymes in the rainbow trout. Twelve rainbow trout (mean weight 266+/-10 g) were assigned to each of three replicate tanks for each of four dietary treatments; astaxanthin, canthaxanthin, negative control and positive control using beta-naphthoflavone, at a target dietary inclusion of 100 mg kg(-1) for each additive. Fish were fed for 3 weeks at a level of 1.2% body wt. day(-1). Serum carotenoid levels were used as indicators of exposure and were not significantly different (P>0.05) between carotenoid-fed trout. Livers and kidney were frozen separately in liquid N(2) by immersion and microsomal fractions from pooled samples (n=3) assayed for xenobiotic-metabolizing enzyme (cytochrome P450 monoxygenase) activities including ethoxyresorufin O-deethylase; methoxyresorufin O-demethylase; pentoxyresorufin O-dealkylase; benzoxyresorufin O-dearylase; and the conjugating enzymes glucuronosyl transferase; and glutathione-s-transferase. Results revealed that carotenoid treatment did not significantly (P>0.05) induce any enzyme system examined. Results are discussed in the context of metabolism of absorbed carotenoids.

Carotenoids induce apoptosis in the T-lymphoblast cell line Jurkat E6.1

Epidemiologically, a high-carotenoid intake via a fruit- and vegetable-rich diet is associated with a decreased risk of various forms of cancer. The mechanisms by which carotenoids exert this protective effect are controversial. In this study, we examined the potency of a range of carotenoids commonly found in human plasma to induce apoptosis in Jurkat E6.1 malignant T-lymphoblast cells. At a concentration of 20 microM, the order of potency to induce apoptosis after 24 h was: beta-carotene > lycopene > lutein > beta-cryptoxanthin = zeaxanthin. Canthaxanthin failed to induce apoptosis under these conditions. beta-Carotene induced apoptosis in a time- and concentration-dependent manner with a lowest effective concentration of about 3 microM. Pre-conditioning of beta-carotene for 72 h destroyed its pro-apoptotic activity almost completely, whereas degradation for 6 h or less did not, indicating that either beta-carotene itself and/or an early degradation product of beta-carotene are the death-inducing compounds. Apoptosis induced by beta-carotene was characterized by chromatin condensation and nuclear fragmentation, DNA degradation, PARP cleavage and caspase-3 activation. The antioxidant BO-653 inhibited the degradation of beta-carotene in vitro and significantly increased its cytotoxicity, indicating that a pro-oxidant effect of beta-carotene is unlikely to cause its pro-apoptotic activity. The induction of apoptosis in transformed cells by carotenoids may explain their protective effect against cancer formation in humans. Possible pathways for induction of apoptosis by carotenoids are discussed.

[The effects of carotenoids on the proliferation of human breast cancer cell and gene expression of bcl-2]

OBJECTIVE

To investigate the effects of various carotenoids on the proliferation, cell cycle, apoptosis and expression of bcl-2 gene in breast cancer cell MCF-7.

METHODS

Time and dose effects of individual carotenoids were detected using the MTT assay. The effects of individual carotenoids on cell cycle and the apoptosis were observed by flow cytometry. The expression of bcl-2 mRNA gene was detected using the RT-PCR method.

RESULTS

All 4 carotenoids tested inhibited the proliferation of MCF-7 cell line, but with different potencies. beta-carotene and lycopene were the most active inhibitors (inhibition rate 88.2% and 87.8%, respectively) followed by zeaxanthin and astaxanthin. All 4 carotenoids did not induce cell apoptosis. Cell cycle progression was blocked at G(2)/M phase with 60 micromol/L lycopene and at G(0)/G(1) phase with 60 micromol/L zeaxanthin dipalmitate. Carotenoids down regulated bcl-2 gene expression.

CONCLUSION

Carotenoids could inhibit the proliferation of human beast cancer MCF-7 cell line in vitro and the action of carotenoids may be worked through different pathways.

The effect of dietary carotenoid access on sexual dichromatism and plumage pigment composition in the American goldfinch

We investigated potential dietary and biochemical bases for carotenoid-based sexual dichromatism in American goldfinches (Carduelis tristis). Captive male and female finches were given access to the same type and amount of carotenoid pigments in the diet during their nuptial molt to assess differences in the degree to which the two sexes incorporated ingested pigments into their plumage. When birds were fed a uniform, plain-seed diet, or one that was supplemented with the red carotenoid canthaxanthin, we found that males grew more colorful plumage than females. HPLC analyses of feather pigments revealed that male finches incorporated a higher concentration of carotenoids into their pigmented feathers than females. Compared to females, males also deposited significantly more canary xanthophyll B into feathers when fed a plain-seed diet and a greater concentration and proportion of canthaxanthin when fed a carotenoid-supplemented diet. These results indicate that sex-specific expression of carotenoid pigmentation in American goldfinches may be affected by the means by which males and females physiologically utilize (e.g. absorb, transport, metabolize, deposit) carotenoid pigments available to them in the diet.

Influence of source and ratio of xanthophyll pigments on broiler chicken pigmentation and performance

One experiment was conducted using 960 1-d-old, sexed broilers of Ross 308 strain from 1 to 43 d to evaluate if one type of chemically isomerized marigold with 25% of xanthophylls as zeaxanthin (SME-25) could produce pigmentation equivalent to the current addition of conventional marigold with 10% of xanthophylls as zeaxanthin (SME-10) plus canthaxanthin (CTX) in practical broiler diets (maize-wheat-soybean). Birds were allocated in 32 pens, in a randomized complete block design (four blocks x four treatments). The treatments consisted of a nonpigmented control (T1), a combination of 35 ppm of yellow xanthophylls (YX) from SME-10 + 5 ppm of CTX (T2), a combination of 32 ppm of YX from SME-10 + 2 ppm of CTX (T4), and one treatment with 40 ppm of YX from a new SME-25 (T3). There were no significant treatment effects on chicken performance. All color parameters (Minolta coordinates, Roche color fan scores, Rank test) presented significant differences (P < 0.0001) because of dietary pigments on shanks and breast skin. Birds fed the SME-25 diet had less pigmentation than those fed equivalent quantities of a combination of SME-10 + CTX. The Minolta coordinate "b" measured in breast skin was a good indicator of YX content in feed, whereas the "a" coordinate measured on the shank showed a linear relationship with the dietary CTX level (r = 0.61, P < 0.0001). The same visual color classification of chickens was achieved irrespective of the rank test performed (by shank or carcass color). Lutein and zeaxanthin from the SME-25 product had lower deposition rates in skin and fat tissues than those from the SME-10 product. This finding seems to be related to the ratio of zeaxanthin stereoisomer RR (optically active) vs. RS that was found in tissues from the SME-10 product (97.8%:2.2%), whereas with SME-25 this ratio was 16.0:84.0%. These results suggest that inclusion of only the SME-25 product could not replace the current addition of SME-10 and CTX combinations.

Canthaxanthin supplementation alters antioxidant enzymes and iron concentration in liver of Balb/c mice

The 4,4'-diketo-beta-carotene, canthaxanthin, alters tocopherol status when fed to Balb/c mice, suggesting an involvement of carotenoids in the modulation of oxidative stress in vivo. We investigated further the modifications induced by an oral administration of canthaxanthin on lipid peroxidation, antioxidant enzymes and iron status in liver of Balb/c mice. Female 6-wk-old Balb/c mice were randomly divided into two groups (n = 10/group). The control group (C) received olive oil alone (vehicle) and the canthaxanthin-treated group (Cx) received canthaxanthin at a dose of 14 microg/(g body wt.d). The 15-d canthaxanthin treatment resulted in carotenoid incorporation but did not modify lipid peroxidation as measured by endogenous production of malondialdehyde (MDA). However, glutathione peroxidase activity was 35% lower (P<0.01) and catalase (59%, P<0.005) and manganese superoxide dismutase (MnSOD) (28%, P<0.05) activities were higher in canthaxanthin-treated mice than in controls. Moreover, carotenoid feeding caused a significant (P<0.05) overexpression of the MnSOD gene; mRNA levels of the enzyme were greater in treated mice than in controls. Concomitantly, a 27% (P<0.05) greater iron concentration was found in liver from canthaxanthin-treated mice compared with controls. These findings support the hypothesis that canthaxanthin alters the protective ability of tissues against oxidative stress in vivo.

Inhibitory effects of carotenoids on the invasion of rat ascites hepatoma cells in culture

The effects of carotenoids--alpha-carotene, beta-carotene, lycopene, beta-cryptoxanthin, zeaxanthin, lutein, canthaxanthin, astaxanthin--on the invasion of rat ascites hepatoma AH109A cells were investigated by co-culturing the hepatoma cells with rat mesentery-derived mesothelial cells (M-cells). All the carotenoids examined inhibited AH109A invasion in a dose-dependent manner up to 5 microM. Cancer cells previously cultured with hypoxanthine (HX) and xanthine oxidase (XO) showed a highly invasive activity. Carotenoids, 5 microM of beta-carotene and astaxanthin, suppressed this reactive oxygen species-potentiated invasive capacity by simultaneously treating AH109A cells with the carotenoids, HX and XO. These results suggest that the antioxidative property of these carotenoids may be involved in their anti-invasive action.

Exogenously incorporated ketocarotenoids in large unilamellar vesicles. Protective activity against peroxidation

The ability of astaxanthin and canthaxanthin as chain-breaking antioxidants was studied in Cu(2+)-initiated peroxidation of phosphatidylcholine large unilamellar vesicles (LUVs). Both carotenoids increased the lag period that precedes the maximum rate of lipid peroxidation, though astaxanthin showed stronger activity. For these experiments, different amounts of xanthophylls were exogenously added to previously made LUVs, non-incorporated pigment being afterwards removed. Differential scanning calorimetry assays with L-beta,gamma-dimyristoyl-alpha-phosphatidylcholine LUVs demonstrated that xanthophylls incorporated as described interact with the lipid matrix becoming interspersed among the phospholipid molecules.

Effect of dried tomato pulp on the performance and egg traits of laying hens

1. Grouped laying hens were fed on experimental diets containing dried tomato pulp (DTP) at inclusion rates up to 120 g/kg and two control diets (A and A+Carophyll). 2. The addition of DTP did not significantly affect egg production, food consumption and efficiency, egg weight and shell thickness. 3. There was a significant improvement in the egg yolk colour in treatments containing DTP. However, this improvement was significantly lower in comparison to the diet which contained carophyll.

Dietary beta-carotene and astaxanthin but not canthaxanthin stimulate splenocyte function in mice

The in vivo modulatory effect of beta-carotene, astaxanthin and canthaxanthin on lymphocyte function was investigated. Female BALB/c mice (8 wk old) were fed a basal diet containing 0, 0.1% or 0.4% beta-carotene, astaxanthin or canthaxanthin for 0, 2 or 4 wk (n = 8/diet/period). Splenic lymphocytes were isolated and mitogen-stimulated proliferation, IL-2 production and lymphocyte cytotoxicity were assessed. Body weight and feed intake were not different among dietary treatments. Plasma carotenoids were undetectable in unsupplemented mice but concentrations of the respective carotenoids were elevated in mice fed 0.1 or 0.4% beta-carotene (0.22 and 0.39 mumol/L), astaxanthin (16.4 and 50.2 mumol/L) and canthaxanthin (5.00 and 7.02 mumol/L) respectively. Mice fed both dietary levels of beta-carotene and astaxanthin had enhanced phytohemagglutinin-induced lymphoblastogenesis compared to unsupplemented mice (P < 0.03). No treatment difference was detected with concanavalin A- or lipopolysaccharide-induced lympho-proliferation nor with IL-2 production (P < 0.05). Astaxanthin (0.1%) also enhanced lymphocyte cytotoxic activity (P < 0.08). In contrast, canthaxanthin did not significantly influence any of the lymphocyte functions measured. Results indicate that beta-carotene and astaxanthin but not canthaxanthin exert enhanced splenic lymphocyte function in mice.

Suppressive effect of carotenoids on the luminol dependent chemiluminescence of the stimulated rat macrophages

Rat macrophages stimulated by phorbol 12-myristate 13-acetate (PMA) produced significant chemiluminescence in luminol. Carotenoids suppressed the luminol-dependent chemiluminescence at the beginning and after two minutes of the stimulation. Canthaxanthin and bixin had higher suppressive activity that beta-carotene and lutein. The measurement of the absorption spectra of carotenoids showed that the absorption by carotenoids was diminished during the stimulation of macrophages. The results suggest that the suppressive effect of carotenoids may be due to their scavenging the reactive oxygen metabolites released by macrophages.

In vitro growth changes of oral human keratinocytes after treatment with carotenoids, retinoid, and/or DMBA

In vitro changes of normal human keratinocytes (NHKs) derived from the oral mucosa after treatment with the chemical carcinogen 7,12 dimethylbenz[a]anthracene (DMBA; 5, 50, 200 ng/10 ml) were evaluated. NHKs were also treated with chemopreventive nutrient agents that previously had enhanced growth of epidermal and oral keratinocytes or suppressed growth of oral squamous cell carcinoma. These agents included the carotenoids beta-carotene and canthaxanthin and the retinoid retinyl palmitate (60 microM). Plating efficiency, growth in agarose (independent growth), viability [tetrazolium salt (MTT) assay], and proliferation ([3H]thymidine labeling) defined the growth of NHKs. The number of cornified cells and keratin expression (high-molecular-weight keratin) defined differentiation. gamma-Glutamyl transpeptidase, p53 expression, and tumorigenesis in mice defined oxidation and malignant transformation. Treatment with DMBA (50 ng/10 ml) was detected by autofluorescence; it produced an increase in pleomorphism and multinucleation and enhanced plating efficiency and the number of colonies grown in agarose. Chemopreventive treatment enhanced the number of colonies grown in agarose, but the MTT levels and [3H]thymidine incorporation-proliferation (24 h) were reduced. Chemopreventives also increased differentiation defined by the number of cornified cells and the expression of high-molecular-weight keratin-positive cells. Malignant transformation potential was depressed by reducing gamma-glutamyl transpeptidase and mutant p53 expression, whereas tumor suppressor p53 was enhanced. NHKs treated with DMBA and injected into nude mice (nu/nu: 1 x 10(6) cells/0.25 ml) produced tumor masses (3 of 3 animals), whereas the nutrient and DMBA groups produced smaller tumor masses, some with central ulcers (2 of 3 animals). Mock injection of untreated or nutrient-treated NHKs without DMBA treatment did not produce a tumor mass (0 of 3 animals). beta-Carotene, retinyl palmitate, and canthaxanthin increased differentiation and reduced transformation induced by DMBA in oral NHKs.

Biological activities of Apo-canthaxanthinoic acids related to gap junctional communication

Apo-carotenoids with different numbers of conjugated double bonds are formed upon eccentric cleavage of carotenoids. These compounds may exhibit biological activities similar to those of the parent carotenoids or their central cleavage products, the retinoids. 11-Apo-canthaxanthin-11-oic acid, 13-apo-canthaxanthin-13-oic acid, and 14'-apo-canthaxanthin-14'-oic acid, carrying 2, 3, or 5 conjugated double bonds in the polyene chain, respectively, were tested for their effects on gap junctional communication (GJC), on stabilization of connexin43 mRNA, and on the activation of the retinoic acid-beta2 receptor (RAR-beta2 receptor); the effects were compared to those of retinoic acid and 4-oxo-retinoic acid, known to stimulate GJC and to activate the RAR-beta2 receptor. The effects of 4-oxo-retinoic acid were comparable to those of retinoic acid. 4-Oxo-retinoic acid, like retinoic acid, influences the stability of connexin 43 mRNA via elements located in the 3'-UTR. No effects were observed with the short-chain apo-canthaxanthinoic acids. A small but statistically significant induction of GJC and transactivation activity towards the RARbeta2 was found with 14'-apo-canthaxanthin-14'-oic acid. This might be due to biological effects of the compound itself or to biologically active breakdown products. The data suggest that the major biological effects of canthaxanthin on retinoid signaling pathways are related to activities mediated by the products of the central cleavage.

Supplementation with canthaxanthin affects plasma and tissue distribution of alpha- and gamma-tocopherols in mice

The effects of oral doses of canthaxanthin on tissue distribution of alpha- and gamma-tocopherols were investigated in three experiments in male and female Balb/c mice. Mice were assigned to receive canthaxanthin [7 or 14 microg/(g body weight.d)] or placebo (olive oil) by gavage for different periods of time (0, 1, 2, 4 and 6 wk). A 2 wk-treatment with canthaxanthin resulted in incorporation of the carotenoid in all tissues analyzed, including liver, spleen, kidney, lung and heart. In liver, the maximum accumulation of the carotenoid was reached after 2 wk of dosing in female mice and after 6 wk in male mice. Canthaxanthin incorporation was accompanied by changes in alpha- and gamma-tocopherol concentrations in plasma and tissues. These included the following: 1) a significant increase (P < 0.001) in alpha-tocopherol concentration in spleen (21 and 27% in male and female mice, respectively) after 2 wk and in liver ( approximately 50% in both male and female mice) after 6 wk; 2) a significant decrease in gamma-tocopherol concentration in plasma (P < 0.05) and tissues (P < 0.001) after 2 wk of treatment. In female mice, this decrease was 55% in plasma, 43% in liver, 44% in kidney, 71% in lung and 70% in heart. In male mice, the decrease was observed only in plasma (30%), kidney (54%) and heart (46%). In liver, the decrease in gamma-tocopherol concentration was both dose- and time-dependent and significantly (P < 0.001) greater in female than in male mice. We conclude that dietary administration of canthaxanthin modifies tocopherol status in murine tissues.

Canthaxanthin induces apoptosis in human cancer cell lines

To investigate the possibility that canthaxanthin inhibits cancer cell growth by inducing apoptosis, human WiDr colon adenocarcinoma and SK-MEL-2 melanoma cells were treated with two different doses of the carotenoid for 48 h. Canthaxanthin was incorporated and/or associated to cells. The treatment with the carotenoid caused growth inhibition in both cell types. Concomitantly, apoptosis was induced. Increasing time of exposure and carotenoid concentration, this effect was more pronounced. At 48 h, the percentages of apoptotic cells were 13 and 15, using 1 microM canthaxanthin, and 18 and 20, using 10 microM canthaxanthin in WiDr and SK-MEL-2 cells, respectively. This study represents the first demonstration that canthaxanthin is able to induce apoptosis in tumour cells.

In vitro and in vivo inhibition of beta-carotene dioxygenase activity by canthaxanthin in rat intestine

beta-Carotene dioxygenase catalyzes the conversion of provitamin A carotenoids to vitamin A in mammalian tissues. Whether the enzyme can also cleave non-provitamin A carotenoids to retinoid analogs with biological activities is still unclear. We investigated (i) substrate specificities of beta-carotene dioxygenase toward provitamin A and non-provitamin A carotenoids and (ii) potential antagonistic effects of non-provitamin A carotenoids on beta-carotene conversion to vitamin A. Provitamin A substrates were 8 to 23% as active as beta-carotene. No polar metabolites were detected with canthaxanthin or zeaxanthin as substrates; these compounds efficiently inhibited the beta-carotene cleavage reaction by 71 and 40%, respectively. Kinetic studies indicated mixed inhibition for canthaxanthin (Ki = 1.6 microM) and non-competitive for zeaxanthin (Ki = 7.8 microM), suggesting that both compounds do not interact significantly with the active site of the enzyme. In vivo, dietary combinations of canthaxanthin and beta-carotene resulted in lower liver levels of both carotenoids and vitamin A and in a higher beta-carotene/vitamin A ratio as compared to groups supplemented with the compounds separately. This supports the view that canthaxanthin at high doses competes with beta-carotene for intestinal absorption and inhibits the conversion of beta-carotene to vitamin A. Thus, we suggest that although canthaxanthin is not a substrate for beta-carotene dioxygenase, it is likely to affect the activity of provitamin A carotenoids by direct interaction with the enzyme.

Effects of beta-carotene and canthaxanthin on aflatoxicosis in broilers

In 2 x 3 factorial experiments, 240 broiler chicks were fed diets containing 0, 0.01, and 0.02% beta-carotene or canthaxanthin with or without 5 ppm aflatoxin to determine the effects of these two carotenoids on the health and well-being of broilers subjected to aflatoxin poisoning. Neither beta-carotene nor canthaxanthin was effective at overcoming the growth-depressing effects of aflatoxin. Relative liver weights were significantly higher in broilers receiving dietary aflatoxin in the presence of beta-carotene but not canthaxanthin. beta-Carotene and canthaxanthin had no effect on antibody production against infectious bursal disease (IBD). Interestingly, secondary antibody production against IBD was enhanced by the presence of aflatoxin in the diet. Canthaxanthin significantly increased the concentrations of cholesterol, total protein, uric acid, and triglyceride, all of which were significantly depressed by aflatoxin. beta-Carotene did not effect any of the measured blood analytes. There was a significant interaction between canthaxanthin and aflatoxin with respect to creatine kinase activity. Creatine kinase activity decreased as dietary canthaxanthin increased in the presence of aflatoxin. The data suggest that beta-carotene is not effective at ameliorating aflatoxicosis in broiler chickens but that canthaxanthin may be somewhat effective with respect to certain clinical blood chemistry indicators.

Ah receptor-dependent CYP1A induction by two carotenoids, canthaxanthin and beta-apo-8'-carotenal, with no affinity for the TCDD binding site

The assays of several phase I and phase II xenobiotic-metabolizing enzyme activities, as well as CYP1A immunoblot analysis, were performed in liver microsomes and cytosol of male C57BL/6 mice (Ah receptor-responsive), of male DBA/2 mice (Ah receptor-low responsive) and of female Ah receptor gene knockout mice that were fed diets containing 300 mg/kg of a nonprovitamin A carotenoid, canthaxanthin, or a provitamin A carotenoid, beta-apo-8'-carotenal for 14 days, or which were injected i.p. with 3-methylcholanthrene. Previous studies have shown that some carotenoids, such as canthaxanthin and beta-apo-8'-carotenal, are strong inducers of liver CYP1A1 and 1A2 when given to rats. In this work, only canthaxanthin induced both CYP1A1 and 1A2 in C57BL/6 mice, whereas beta-apo-8'-carotenal induced only CYP1A2 in this strain. Neither of the two carotenoids modified CYP1A1/2 protein contents or enzyme activities in Ah receptor-low responsive DBA/2 or in Ah receptor gene knockout mice. Cytosol prepared from C57BL/6 mice liver tissue was incubated with [3H] 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the presence of canthaxanthin or beta-apo-8'-carotenal and analyzed by sucrose density gradient sedimentation: neither of the carotenoids, even when present in large excess, competed with TCDD for the TCDD binding site of the cytosolic Ah receptor of C57BL/6 mice. In brief, the carotenoids canthaxanthin or beta-apo-8'-carotenal induced Cyp1a genes in mice through an Ah receptor-dependent pathway, but did not bind to the Ah receptor.

The carotenoids beta-carotene, canthaxanthin and zeaxanthin inhibit macrophage-mediated LDL oxidation

Human monocyte-macrophages were incubated for 24 h in Ham's F-10 medium with human low-density lipoprotein (LDL) in the presence or absence of beta-carotene, canthaxanthin or zeaxanthin, at final concentrations of 2.5, 12.5 and 25 mg/l. LDL oxidation, measured by agarose gel electrophoresis, the thiobarbituric acid assay and gas chromatography, was inhibited by each of the carotenoids in a concentration-dependent manner. Canthaxanthin was more effective when incorporated into LDL before addition to the cultures whereas beta-carotene and zeaxanthin were more effective when added simultaneously with LDL. The results suggest that dietary carotenoids might help slow atherosclerosis progression.

Effects of provitamin A or non-provitamin A carotenoids on liver xenobiotic-metabolizing enzymes in mice

To determine whether carotenoids can modulate xenobiotic-metabolizing enzymes in mice, catalytic activities of several phase I and phase II enzymes have been measured in liver microsomes and cytosol of male Swiss mice fed diets containing beta-carotene, beta-apo-8'-carotenal, canthaxanthin, or astaxanthin (300 mg/kg diet) or treated with 3-methylcholanthrene (3-MC) (3 times at 50 mg/kg ip) for 15 days. Canthaxanthin increased CYP 1A-dependent activities: ethoxyresorufin O-deethylase (EROD) was increased 3-fold, pentoxyresorufin dealkylase (PROD) was increased 2.5-fold, and methoxyresorufin O-demethylase (MROD) was increased 1.6-fold; these increases were much less than those induced by 3-MC, which induced EROD 49-fold, PROD 10-fold, and MROD 4-fold. 3-MC, but not canthaxanthin, also increased relative liver weight, liver P-450 content, NADH-cytochrome c reductase, and benzoxyresorufin dearylase. The three other carotenoids had little or no effect on phase I enzymes. Among the phase II enzyme activities, only NADPH-quinone reductase was slightly increased by 3-MC and carotenoids, except beta-carotene. Among the three carotenoids that have previously been found to be powerful CYP 1A inducers in the rat, i.e., canthaxanthin, astaxanthin, and beta-apo-8'-carotenal, only canthaxanthin shows some (weak) inducing effect of CYP 1A in the 3-MC-responsive Swiss mice, indicating that the mechanism of CYP 1A induction by carotenoids may not be the same as that by 3-MC. In addition, the fact that beta-carotene has no effect on the tested enzymes does not support the hypothesis that the modulation of xenobiotic metabolism is a possible mechanism for the antimutagenic and anticarcinogenic effects of beta-carotene, which have been demonstrated in several in vivo models in mice.

Possible immunomodulating activities of carotenoids in in vitro cell culture experiments

Immunomodulating activities of beta-carotene and carotene-associated carotenoids such as canthaxanthin (beta, beta-carotene-4,4 dione) and astaxanthin (3,3'-dihydroxyl beta, beta-carotene 4,4-dione) were analyzed by in vitro cell culture experiments. (i) beta-Carotene, canthaxanthin and astaxanthin caused significant stimulatory effects on the cell proliferative response of spleen cells and thymocytes from BALB/c mice at the concentrations of 2 x 10(-8) to 10(-7) M, although they showed the activities different from each other. (ii) Astaxanthin exhibited the highest activity on the polyclonal antibody (immunoglobulin M and G) production of murine spleen cells at the concentrations of 2 x 10(-8) to 10(-7) M but beta-carotene did not cause a significant effect at a low concentration (2 x 10(-8) M) although stimulated at a high concentration (2 x 10(-7) M). Canthaxanthin expressed moderate activities at the same concentrations. (iii) All tested carotenoids significantly enhanced the release of interleukin-1 alpha and tumor necrosis factor-alpha from murine peritoneal adherent cells at the concentrations of 2 x 10(-8) to 10(-7) M and the ranks of cytokine-inducing activities were astaxanthin > canthaxanthin > beta-carotene. These results indicate that carotenoids such as beta-carotene, canthaxanthin and astaxanthin have possible immunomodulating activities to enhance the proliferation and functions of murine immunocompetent cells.

Time course evaluation of carotenoid and retinol concentrations in posthatch chick tissue

Carotenoid and retinol concentrations were determined in chicks hatched from carotenoid-enriched eggs while being fed a carotenoid free starter diet. Single Comb White Leghorn (SCWL) hatching eggs were obtained from breeder hens fed diets enriched with either 0.2% beta-carotene, canthaxanthin, lutein, or basal control. Twenty-five day-old chicks hatched from each treatment group were placed in a battery and fed a carotenoid-free basal diet. At 1, 4, 7, 10, and 13 d, five chicks per treatment were randomly selected, and blood serum, liver, and unabsorbed yolk sac were collected for carotenoid and retinol analysis. There were no significant differences in retinol concentrations in the serum, liver, and unabsorbed yolk sac of the chickens. Only small amounts of beta-carotene were detected in the chick tissues. Concentration of all three carotenoids and retinol were greater in the liver and unabsorbed yolk sac than in serum. In the serum and liver, respective carotenoid concentrations decreased and retinol concentration increased with increasing age, whereas respective carotenoid and retinol concentrations in the unabsorbed yolk sac increased over time. It may be concluded that yolk sac carotenoids are not absorbed well, as unabsorbed yolk sac concentrations increased over time, and that carotenoid in serum and liver decrease linearly with increasing age.

Effect of beta-carotene, canthaxanthin, or lutein on lymphocyte proliferation (in vitro) of newly hatched chicks

The aim of this study was to determine the effect of beta-carotene, canthaxanthin, and lutein on lymphocyte proliferation (in vitro) of newly hatched chicks. Tetrahydrofuran (THF) was used as the vehicle to introduce carotenoids in the culture media. So, we also determined effect of THF on viability of cells. The viabilities of fibroblast cells at 10(-3) dilution were 98% and 96% after 24 and 48 hr of incubation. Therefore, 10(-3) (v/v) THF dilution was decided upon as the vehicle to introduce carotenoids in culture media. Chick bursal lymphocytes were incubated in the presence or absence of beta-carotene, canthaxanthin, or lutein and stimulated with phorbol 12, 13-dibutyrate. The results of this experiment suggested that THF rather than the carotenoids stimulated bursal lymphocyte proliferation. The mechanism by which THF acted as a mitogen is not known. We conclude from this study that beta-carotene, canthaxanthin, and lutein are not effective in enhancing in vitro bursal lymphocyte proliferation at concentrations of less than 10(-6) M in the presence of THF.

beta-Apo-8'-carotenal, but not beta-carotene, is a strong inducer of liver cytochromes P4501A1 and 1A2 in rat

1. The catalytic activities of several phase I and II xenobiotic-metabolizing enzymes and their immunochemical detection have been investigated in liver microsomes and cytosol of the male rat, which had been fed for 15 days with diets containing 300 mg/kg beta-carotene isomers (all-trans beta-carotene or beta-carotene from Dunaliella salina rich in 9-cis isomer or isomerized beta-carotene), or apocarotenoids as beta-apo-8'-carotenal, ethyl beta-apo-8'-carotenoate and citranaxanthin. 2. Beta-carotene, either all-trans or containing cis isomers, did not induce any significant change in the measured activities. By contrast, beta-apo-8'-carotenal increased the liver content of cytochrome P450, the activity of NADH- and NADPH-cytochrome c reductase, and strongly increased some cytochrome P450-dependent activities, particularly ethoxyresorufin O-deethylase (x158), methoxyresorufin O-demethylase (x22), pentoxy- and benzoxyresorufin O-dealkylases, but did not affect erythromycin N-demethylase nor nitrosodimethylamine N-demethylase activities. Phase II p-nitrophenol- and 4-hydroxy- biphenyl-uridine diphosphoglucuronosyl transferase activities were also increased by beta-apo-8'carotenal. Western blots of microsomal proteins clearly showed the induction of CYP1A1 and 1A2 by beta-apo-8'-carotenal. This induction profile resembles that produced by two other carotenoids: canthaxanthin and astaxanthin. Ethyl beta-apo-8'-carotenoate and citranaxanthin showed similar effects to beta-apo-8'-carotenal but of less intensity. 3. Three carotenoids: beta-apo-8'-carotenal, canthaxanthin and astaxanthin, are inducers of CYP1A1 and 1A2 in the rat. These carotenoids form a new class of inducers of CYP1A, structurally very different from the classical inducers as 3-methylcholanthrene, beta-naphtoflavone or dioxin.

Effect of beta-carotene, canthaxanthin, lutein, and vitamin E on neonatal immunity of chicks when supplemented in the broiler breeder diets

The study was designed to assess neonatal immunity of chicks hatched from breeders fed diets supplemented with beta-carotene, canthaxanthin, lutein, or vitamin E. Broiler breeder birds were fed experimental diets consisting of control, 0.04% beta-carotene, 0.04% canthaxanthin, 0.04% lutein, 0.03% alpha-tocopherol acetate, or 0.04% beta-carotene plus 0.03% alpha-tocopherol acetate. Three weeks after initiation of experimental feeding, birds were vaccinated against Newcastle disease virus. Chicks hatched from the eggs of these breeders were used to determine the neonatal immune responses. There were no significant differences in weight gain and antibody titers of 3-wk-old chicks. 3H-Thymidine uptake by bursal lymphocytes when stimulated with tetrahydrofuran was significantly higher for the chicks hatched from breeders fed diets supplemented with vitamin E, or vitamin E plus beta-carotene, than in controls. 3H-Thymidine uptake by splenic lymphocytes when stimulated with concanavalin A and phorbol 12-myristate 13 acetate was significantly higher for the chicks hatched from breeders fed diets supplemented with vitamin E or beta-carotene alone, or vitamin E plus beta-carotene, than for the control chicks. Chicks hatched from hens supplemented with vitamin E had significantly higher antibody titers at 1 and 7 d of age than chicks from the control group. Vitamin E supplementation of breeder birds increased the immune response of their progeny.

Effect of beta-carotene and canthaxanthin on tert-butyl hydroperoxide-induced lipid peroxidation in murine normal and tumor thymocytes

It has been reported that the anticarcinogenic effect of carotenoids could be related to an antioxidant mechanism. The antioxidant efficiency of beta-carotene and canthaxanthin was evaluated in murine normal and tumor thymocytes. Normal and tumor cells were exposed under air to tert-butyl hydroperoxide (t-BOOH) and lipid peroxidation was measured in the absence or in the presence of the two carotenoids. Our results show that: (a) Both carotenoids, added at effective and comparable concentrations (from 1 to 50 microM), were able to inhibit t-BOOH-induced malondialdehyde formation in a dose-dependent manner. (b) Canthaxanthin was a more potent antioxidant that beta-carotene. (c) The inhibition of lipid peroxidation was greater in tumor thymocytes. (d) Carotenoids were consumed differentially during the incubation with the prooxidant. beta-Carotene was consumed faster than canthaxanthin and in a larger amount in tumor than in normal thymocytes. The addition of the iron chelator deferoxamine or the SH group reducing agent dithiothreitol reduced t-BOOH-induced beta-carotene consumption in tumor cells but not in normal ones. (e) The loss of endogeneous alpha-tocopherol induced by t-BOOH was enhanced by the addition of beta-carotene, suggesting the possibility of oxidative interactions between the two antioxidants. These results confirmed the antioxidant effectiveness of carotenoids in normal and tumor cells, although differences depending on the kind of cells and carotenoids used were found.

Effects of various carotenoids on cloned, effector-stage T-helper cell activity

Astaxanthin, a carotenoid without provitamin A activity, enhances murine T-helper (Th) cell clone-mediated antibody (Ab) production with suboptimal antigen (Ag) challenges. It also suppresses interferon-gamma (IFN-gamma) production by cloned murine Th1 cells. beta-Carotene is less effective than astaxanthin. This study evaluates the effects of various carotenoids with various relative polarity, provitamin A activity, and antioxidant activity. Carotenoids tested include astaxanthin, cantaxanthin, zeaxanthin, lutein, and lycopene, and their effects were tested at a concentration at which astaxanthin's effect was most potent. A.E7 and CDC35 cells are used as representative type 1 and type 2 Th cell (Th1 and Th2) clones, respectively. In the Th1 clone, astaxanthin, but not other carotenoids, suppressed IFN-gamma production and increased the number of Ab-secreting cells with the use of primed spleen cells. With cultures of Th1 cells and unprimed spleen cells, astaxanthin and zeaxanthin augmented the number of immunoglobulin M Ab-secreting cells. In the cultures of Th2 clone and primed spleen cells, astaxanthin, but not other carotenoids, enhanced the number of Ab-secreting cells. With unprimed spleen cells, lycopene suppressed Th2 clone-mediated Ab production. Interleukin-5 production by the Th2 clone was not significantly altered with the carotenoids tested, irrespective of the use of unprimed or primed spleen cells. Carotenoid actions on Th cells may vary in each carotenoid and do not seem to be closely associated with carotenoid antioxidant activity or relative polarity.

No evidence for an inhibitory effect of beta-carotene or of canthaxanthin on the initiation of liver preneoplastic foci by diethylnitrosamine in the rat

To test whether beta-carotene or canthaxanthin can modulate the initiation of liver preneoplasia by diethylnitrosamine (DEN) in a sequential protocol of hepatocarcinogenesis, for three weeks male weanling rats were fed diets containing beta-carotene or canthaxanthin (300 mg/kg diet) or excess vitamin A (70,000 IU/kg diet) or were given beta-carotene by injection (9 injections at 10 mg/kg body wt ip). On Day 15, all rats were injected with 200 mg DEN/kg body wt ip; later they were submitted to 2-acetylaminofluorene treatment and to two-thirds hepatectomy, then to phenobarbital treatment, after which gamma-glutamyltranspeptidase- and placental glutathione-S-transferase-positive liver foci were histologically detected. Neither beta-carotene (fed or injected), canthaxanthin, nor an excess of dietary vitamin A had an influence on the number and size of preneoplastic liver foci, despite a significant incorporation and persistence in liver of both carotenoids, especially canthaxanthin, and of supplemental vitamin A. These results are in conflict with another report in which beta-carotene, given to rats during the initiation phase, was found to strongly inhibit DEN-induced hepatocarcinogenesis.

Long-term supplementation of canthaxanthin does not inhibit gastric epithelial cell proliferation in Helicobacter mustelae-infected ferrets

The effect of canthaxanthin (CX), a nonprovitamin A carotenoid, on gastric epithelial proliferation was studied in ferrets colonized with Helicobacter mustelae, which causes a chronic gastritis and an increased gastric epithelial cell proliferation. Seven spayed female ferrets were dosed by gavage with CX beadlets (50 mg/kg body wt, 5 d/wk) over 2 y, whereas seven control animals were given placebo beadlets. At the end of the 2-y-period, ferrets were killed, and gastric tissues were obtained from the antrum and body regions. A cell-proliferating biomarker, proliferating cell nuclear antigen (PCNA), was assayed by immunohistochemistry. The PCNA positivity was measured by a computer-based image analysis system. Serum concentrations of carotenoids, retinoids and tocopherols were analyzed by HPLC. Serum antioxidant status was measured by the oxygen radical absorbance capacity (ORAC) assay. The PCNA positivity in both antrum and body regions was not significantly different between CX-fed ferrets and controls. Serum CX concentrations were significantly higher in CX-fed ferrets vs. controls (P < 0.001), whereas levels of other carotenoids, retinoids and tocopherols were not significantly different. The ORAC values were not significant different between groups. This study does not suggest inhibitory effects of CX on gastric epithelial cell proliferation in H. mustelae infected ferrets.

Protection of vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, coenzyme Q0, coenzyme Q10, beta-carotene, canthaxanthin, and (+)-catechin against oxidative damage to rat blood and tissues in vivo

Male Sprague-Dawley rats were fed either a vitamin E and selenium deficient diet, a diet supplemented with vitamin E and selenium, or a diet supplemented with vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, Beta-carotene, canthaxanthin, coenzyme Q0, coenzyme Q10, and (+)-catechin. Rats were injected with CBrCl3 (0.05 mmol/100 g body weight) intraperitoneally. Oxidative damage to tissues was measured by formation of oxidized heme proteins (OHP) in blood, liver, kidney, heart, lung, and spleen. Diets supplemented with antioxidants showed protection against oxidative damage caused by CBrCl3. The protection was dependent on the diversity and quantity of antioxidants in the diet. In general, diets supplemented with both fat soluble and water soluble antioxidants provided better protection than diets supplemented only with vitamin E and selenium or with vitamin E, selenium, and fat soluble antioxidants.

Efficacy of all-trans-beta-carotene, canthaxanthin, and all-trans-, 9-cis-, and 4-oxoretinoic acids in inducing differentiation of an F9 embryonal carcinoma RAR beta-lacZ reporter cell line

A reporter cell line was established from F9 mouse teratocarcinoma cells containing the RAR beta 2 promoter coupled to the lacZ (beta-galactosidase) reporter gene. All-trans-, 9-cis-, and all-trans-4-oxoretinoic acid were equipotent in inducing cell differentiation at 1 microM, determined by induction of collagen IV mRNA expression, of morphological changes, as well as of beta-galactosidase enzyme activity. By the same criteria, beta-carotene at 10 microM also induced differentiation, but less strongly and more slowly than the retinoic acids. In contrast, the oxocarotenoid (or xanthophyll) canthaxanthin, at 10 microM, had little effect on differentiation, unless preincubated in culture medium, from which 4-oxoretinoic acid was recovered and identified as a decomposition product. This indicates that canthaxanthin can act as an effective inducer of differentiation only after breakdown to active metabolites. Likewise, beta-carotene probably also acts subsequent to breakdown to retinoic acid. Throughout these experiments the response of the RAR beta promoter-lacZ reporter gene correlated well with other parameters of differentiation, making this cell line a useful system for examination of inducers of embryonal carcinoma cell differentiation.

Vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, coenzyme Q, beta-carotene, canthaxanthin, and (+)-catechin protect against oxidative damage to kidney, heart, lung and spleen

Male Sprague-Dawley rats were fed diets that varied qualitatively and quantitatively in antioxidants. Kidney, heart, lung, and spleen homogenates were incubated at 37 degrees C with and without hydroperoxide or Fe+2. Protection of antioxidants against oxidative damage to tissue was determined by measurement of oxidized heme proteins. Tissues from rats supplemented with dietary vitamin E and selenium showed protection compared to tissues from rats on the basal diet. Tissues from rats with diets containing larger quantities of antioxidants and both fat soluble antioxidants: vitamin E, beta-carotene, coenzyme Q10, ascorbic acid 6-palmitate and water soluble antioxidants: selenium, trolox C, acetylcysteine, coenzyme Q0, (+)-catechin, showed the highest protection.

Dietary carotenoids protect human cells from damage

A physical chemistry technique based on singlet oxygen luminescence at about 1270 nm and a biological cell membrane technique were used to study the quenching of singlet oxygen by four carotenoids bound to the surface of lymphoid cells. All the carotenoids studied showed a beneficial effect in cell protection, but there were subtle differences between them.

Effects of beta-carotene and canthaxanthin on liver xenobiotic-metabolizing enzymes in the rat

The activities of several phase I and phase II xenobiotic-metabolizing enzymes have been measured in liver microsomes and cytosol of male rats that had been fed for 15 days with diets containing beta-carotene or canthaxanthin (300 mg/kg diet) or an excess of vitamin A (70,000 IU/kg diet), or to which beta-carotene had been administered by ip injections (7 x 10 mg/kg body weight). Microsomal cytochrome P-450 and the associated NADH- and NADPH-cytochrome c reductases were assayed, as well as several phase I and phase II enzyme activities. Phase I activities were markers of the families 1, 2, 3 and 4 of P-450; phase II activities were microsomal UDP glucuronosyl transferases (UGT) and cytosolic glutathione S-transferase (GST). Canthaxanthin accumulated in liver to a much higher level than did ingested or injected beta-carotene. Canthaxanthin increased the liver content of cytochrome P-450 (control value x 1.7), and the activity of NADH-cytochrome c reductase (x 1.5), and of some P-450-dependent enzymes (ethoxy-, methoxy-, pentoxy- and benzoxyresorufin O-dealkylases; x98, x15, x6.5 and x13, respectively), but not of others (erythromycin N-demethylase, nitrosodimethylamine N-demethylase and laurate omega-hydroxylase). Phase II activities were also increased: UGT1 (x3.4), UGT2 (x1.2) and GST (x1.2). This induction profile, characterized by the very strong increase of the activity associated with P4501A1, and the co-induction of UGT1, closely resemble that of a classical inducer, 3-methylcholanthrene. By contrast, neither beta-carotene (fed or injected), nor an excess of vitamin A induced any significant variation of the enzyme activities measured.

Protection by vitamin E selenium, trolox C, ascorbic acid palmitate, acetylcysteine, coenzyme Q, beta-carotene, canthaxanthin, and (+)-catechin against oxidative damage to liver slices measured by oxidized heme proteins

Male SD rats were fed a vitamin E- and selenium-deficient diet, a diet supplemented with vitamin E and selenium, and diets supplemented with vitamin E, selenium, trolox C, ascorbic acid palmitate, acetylcysteine, beta-carotene, canthaxanthin, coenzyme Q0, coenzyme Q10, and (+)-catechin. Liver slices were incubated at 37 degrees C with and without CBrCl3, t-butyl-hydroperoxide, Fe+2, or Cu+2. The effect of antioxidant nutrients on the oxidative damage to rat liver was studied by measurement of the production of oxidized heme proteins (OHP) during the oxidative reactions. Diet supplemented with vitamin E and selenium showed a strong protection against heme protein oxidation compared to the antioxidant-deficient diet. Furthermore, increasing the diversity and quantity of antioxidants in the diets provided significantly more protection.

Effects of retinoids, beta-carotene, and canthaxanthin on UV- and X-ray-induced transformation of C3H10T1/2 cells in vitro

We observed that various retinoids (including all-trans-retinoic acid, 13-cis-retinoic acid, and the synthetic retinoid Ro-11-1430) have approximately the same ability to suppress ultraviolet light-induced transformation of C3H10T1/2 cells in vitro. Retinoids also suppress X-ray induced transformation in vitro. Ro-11-1430 has no effect when present for only 1 day after the X-ray exposure but does have a suppressive effect on radiation transformation when present for 5 or 10 days after irradiation. Ro-11-1430 has its major suppressive effect on X-ray transformation when present in irradiated cultures in the confluent stationary phase of growth. Natural beta-carotene (type IV) from carrots, but not synthetic beta-carotene, has the ability to suppress radiation (X-ray)-induced transformation when present for the entire transformation assay period. Natural beta-carotene is without effect on the transformation process when present in irradiated cultures only during confluence. For these retinoids, as well as beta-carotene and canthaxanthin, there is a highly significant suppressive effect on radiation transformation and radiation transformation enhanced by 12-O-tetradecanoylphorbol-13-acetate when the compounds are present at toxic levels; when nontoxic levels are utilized, these compounds have the ability to suppress the yield of transformed cells to approximately one-half of that observed in irradiated cultures in the absence of these compounds. A selective toxicity for transformed cells appeared to exist for the beta-carotene-treated F-17 cells. This apparent selective toxicity was not observed in another line of transformed cells. Cl 16 cells, or in human cells. We observed different uptake patterns of beta-carotene by nontransformed C3H10T1/2 cells, F-17 cells, and Cl 16 cells that may account for the observed apparent selective toxicity of one line of transformed cells (F-17 cells) to beta-carotene.

Cancer prevention by carotenoids. Mechanistic studies in cultured cells

In 10T1/2 cells several dietary carotenoids have been shown to be capable of inhibiting carcinogen-induced neoplastic transformation. Their action appears qualitatively similar to the previously documented action of retinoids in this cell system; however, higher concentrations (10-1000-fold) are required. Both types of compound were found to strongly upregulate gap junctional intercellular communication, and these activities were statistically correlated. Upregulation of gap junctional intercellular communication was caused by the increased expression of connexin 43, a structural protein of the gap junction. Increased junctional communication has been proposed to be mechanistically linked to inhibition of transformation in 10T1/2 cells. In this model the gap junction serves as a conduit for growth regulatory signals from normal to initiated cells. These putative signals act to suppress transformation of the carcinogen-initiated cell.

Interactions of oral beta-carotene and canthaxanthin in ferrets

Interactive effects of an oral dose of equal quantities of beta-carotene and either canthaxanthin or lycopene on serum and tissue beta-carotene accumulations were investigated in domestic ferrets. Like humans, ferrets absorb a substantial portion of ingested beta-carotene intact and accumulate it in tissues. After the ferrets ingested a low carotenoid purified diet for 13 d, they were randomly assigned to one of two groups of six animals. One group was dosed with beta-carotene (10 mg/kg body weight) and the other with beta-carotene and either canthaxanthin (Experiment 1) or lycopene (Experiment 2) (10 mg/kg body weight for each). In Experiment 1, ferrets that received a combined dose of beta-carotene and canthaxanthin had serum beta-carotene concentrations that were significantly lower at 8, 12 and 24 h post-dosing (P < 0.05), compared with those that received an individual dose of beta-carotene; liver, adrenal and kidney beta-carotene concentrations were also significantly reduced. In Experiment 2, ferrets that received a combined dose of lycopene and beta-carotene had lower serum and tissue beta-carotene concentrations than in those that received beta-carotene alone; the differences were not statistically significant with the exception of serum beta-carotene concentrations at 24 h post-dosing. The results suggest that, at the doses given, a concurrent oral canthaxanthin dose has a specific antagonistic effect on the bioavailability of a beta-carotene dose in ferrets.