The synergistic anti-inflammatory effects of lycopene, lutein, β-carotene, and carnosic acid combinations via redox-based inhibition of NF-κB signaling

Inflammatory mediators and cytokines play important roles in the pathogenesis of a vast number of human diseases; therefore much attention is focused on blunting their proinflammatory modes of action. The aims of the present research were to assess the effectiveness of combinations of carotenoids and phenolics, at concentrations that can be achieved in blood, to inhibit the release of inflammatory mediators from macrophages exposed to lipopolysaccharide (LPS) and to determine what the anti-inflammatory effect of the phytonutrient combinations was in an in vivo mouse model of peritonitis. Preincubation of mouse peritoneal macrophages with lycopene (1μM) or Lyc-O-Mato (1μM) and carnosic acid (2μM), lutein (1μM), and/or β-carotene (2μM) 1h before addition of LPS for 24h caused a synergistic inhibition of NO, prostaglandin E(2), and superoxide production derived from downregulation of iNOS, COX-2, and NADPH oxidase protein and mRNA expression and synergistic inhibition of TNFα secretion. We surmise that the anti-inflammatory action of the phytonutrient combinations used probably resides in their antioxidant properties, because they caused an immediate, efficient, and synergistic inhibition of LPS-induced internal superoxide production leading to a marked decrease in ERK and NF-κB activation. The anti-inflammatory effects of the selected phytonutrient combinations were also demonstrated in a mouse model of peritonitis: their supplementation in drinking water resulted in attenuation of neutrophil recruitment to the peritoneal cavity and in inhibition of inflammatory mediator production by peritoneal neutrophils and macrophages.     

Effect of β-carotene on catechol-induced genotoxicity in vitro: Evidence of both enhanced and reduced DNA damage

Abstract

Intake of antioxidants from the diet has been recognized to have beneficial health effects, but the potential benefit of taking antioxidants such as β-carotene as supplements is controversial. The aim of the present study was to evaluate the potential protective effects of a physiologically relevant concentration (2 μM) of β-carotene on the DNA damaging effects of catechol in mouse lymphoma L5178Y cells. Two different exposure protocols were used: simultaneous exposure to β-carotene and catechol for 3 h; and exposure to catechol for 3 h after 18 h pre-treatment with the vitamin. DNA damage was evaluated using the comet assay (employing one procedure for general damage, and another procedure, which also included oxidative DNA damage). Independent of exposure protocol and procedure for comet assay, β-carotene did not increase the basal level of DNA damage. However, at the highest concentration of catechol (1 mM), β-carotene was found to clearly increase the level of catechol-induced DNA damage, especially in the pre-treated cells. Interestingly, an opposite effect was observed at lower concentrations of catechol, but the β-carotene related reduction of catechol-induced genotoxicity was significant (P < 0.05) only for the procedure including oxidative damage induced by 0.5 mM catechol. Taken together our results indicate that β- carotene can both reduce and enhance the DNA damaging effects of a genotoxic agent such as catechol. This indicates that it is the level of catechol-induced DNA damage that seems to determine whether β-carotene should be regarded as a beneficial or detrimental agent when it comes to its use as a dietary supplement.     

Retinol-deficient rats can convert a pharmacological dose of astaxanthin to retinol: antioxidant potential of astaxanthin, lutein, and β-carotene

Retinol (ROH) and provitamin-A carotenoids are recommended to treat ROH deficiency. Xanthophyll carotenoids, being potent antioxidants, can modulate health disorders. We hypothesize that nonprovitamin-A carotenoids may yield ROH and suppress lipid peroxidation under ROH deficiency. This study aimed to (i) study the possible bioconversion of astaxanthin and lutein to ROH similar to β-carotene and (ii) determine the antioxidant potential of these carotenoids with reference to Na(+)/K(+)-ATPase, antioxidant molecules, and lipid peroxidation (Lpx) induced by ROH deficiency in rats. ROH deficiency was induced in rats (n = 5 per group) by feeding a diet devoid of ROH. Retinol-deficient (RD) rats were gavaged with astaxanthin, lutein, β-carotene, or peanut oil alone (RD group) for 7 days. Results show that the RD group had lowered plasma ROH levels (0.3 μmol/L), whereas ROH rose in astaxanthin and β-carotene groups (4.9 and 5.7 μmol/L, respectively), which was supported by enhanced (69% and 70%) intestinal β-carotene 15,15'-monooxygenase activity. Astaxanthin, lutein, and β-carotene lowered Lpx by 45%, 41%, and 40% (plasma), respectively, and 59%, 64%, and 60% (liver), respectively, compared with the RD group. Lowered Na(+)/K(+)-ATPase and enhanced superoxide dismutase, catalase, and glutathione-S-transferase activities support the lowered Lpx. To conclude, this report confirms that astaxanthin is converted into β-carotene and ROH in ROH-deficient rats, and the antioxidant potential of carotenoids was in the order astaxanthin > lutein > β-carotene.     

Lipid-dissolved γ-carotene, β-carotene,and lycopene in globular chromoplasts of peach palm (Bactris gasipaes Kunth) fruits

Main conclusion

High levels of β-carotene, lycopene, and the rare γ-carotene occur predominantly lipid-dissolved in the chromoplasts of peach palm fruits. First proof of their absorption from these fruits is reported. The structural diversity, the physical deposition state in planta, and the human bioavailability of carotenoids from the edible fruits of diverse orange and yellow-colored peach palm (Bactris gasipaes Kunth) varieties were investigated. HPLC–PDA–MSⁿ revealed a broad range of carotenes, reaching total carotenoid levels from 0.7 to 13.9 mg/100 g FW. Besides the predominant (all-E)-β-carotene (0.4–5.4 mg/100 g FW), two (Z)-isomers of γ-carotene (0.1–3.9 mg/100 g FW), and one (Z)-lycopene isomer (0.04–0.83 mg/100 g FW) prevailed. Approximately 89–94 % of total carotenoid content pertained to provitamin A carotenoids with retinol activity equivalents ranging from 37 to 609 µg/100 g FW. The physical deposition state of these carotenoids in planta was investigated using light, transmission electron, and scanning electron microscopy. The plastids found in both orange and yellow-colored fruit mesocarps were amylo-chromoplasts of the globular type, containing carotenoids predominantly in a lipid-dissolved form. The hypothesis of lipid-dissolved carotenoids was supported by simple solubility estimations based on carotenoid and lipid contents of the fruit mesocarp. In our study, we report first results on the human bioavailability of γ-carotene, β-carotene, and lycopene from peach palm fruit, particularly proving the post-prandial absorption of the rarely occurring γ-carotene. Since the physical state of carotenoid deposition has been shown to be decisive for carotenoid bioavailability, lipid-dissolved carotenoids in peach palm fruits are expected to be highly bioavailable, however, further studies are required.     

Spectroscopy analysis for simultaneous determination of lycopene and β-carotene in fungal biomass of Blakeslea trispora

Blakeslea trispora is a good alternative source for producing such carotenoids as lycopene and β-carotene. The objective of this research was to elaborate a method for the simultaneous determination of lycopene and β-carotene in Blakeslea trispora products using a usual UV-vis spectrophotometer. The standard solutions of the mixture of different concentrations of β-carotene and lycopene were measured with the UV-vis method and correlation formula for the extinction coefficients of 1% standard solution of lycopene in the solvent (hexane) and the ratios of the optical densities at the character peaks of 470 and 502 nm was elaborated. This gives a possibility to calculate the concentrations of lycopene and β-carotene in the mixture. The prediction quality of the UV-vis method was sufficient and the obtained results were very close to the ones, being measured with the HPLC technique. The proposed method can be used for both routine industrial work and academic research, providing the rapid analysis for simultaneous measurements of lycopene and β-carotene.     

Flavonoids protect against oxidative damage to LDL in vitro: use in selection of a flavonoid rich diet and relevance to LDL oxidation resistance ex vivo?

The ability of a range of dietary flavonoids to inhibit low-density lipoprotein (LDL) oxidation in vitro was tested using a number of different methods to assess oxidative damage to LDL. Overall quercetin was the most effective inhibitor of oxidative damage to LDL in vitro. On this basis, a diet enriched with onions and black tea was selected for a dietary intervention study that compared the effect on the Cu²⁺ ion-stimulated lag-time of LDL oxidation ex vivo in healthy human subjects of a high flavonoid diet compared with a low flavonoid diet. No significant difference was found in the Cu²⁺ ion-stimulated lag-time of LDL oxidation ex vivo between the high flavonoid and low flavonoid dietary treatments (48 ± 1.6 min compared to 49 ± 2.1 min).     

Effects of catecholamines and β-alanine on tanning of pupal cuticle of Manduca sexta in vitro

When epidermis from wandering stage tobacco hornworm (Manduca sexta) larvae was exposed to 5 μg/ml 20-hydroxyecdysone for 3 days, then exposed to hormone-free Grace's medium, the newly formed pupal cuticle tanned slowly up to 35% of its area by day 12. The addition of 1.3 mM dopamine on either day 4 or 5 slightly increased the area tanned and addition of β-alanine (to 11.2 mM) on days 3–5 enhanced tanning 2–2.5-fold by day 8. Later addition had no effect. When pharate pupal cuticle about 24 h before ecdysis was explanted to Grace's medium, little tanning occurred in 24 h unless dopa or dopamine or their derivatives were added; β-alanine up to 4.4 mM had no effect. Partial tanning occurred in 10 mM dopa or dopamine. More effective were N-β-alanylnorepinephrine and N-β-alanyldopamine which produced nearly maximal tanning at 1 and 5 mM respectively. Up to 10 mM N-β-acetylnorepinephrine had little effect. Thus, dopamine and β-alanine are important to cuticular tanning in vitro and apparently need to be incorporated into the exocuticle during its synthesis. Maximal tanning of this exocuticle then requires further incorporation of β-alanyl conjugates.     

Effect of β-carotene,lutein and violaxanthin on structural properties of dipalmitoyl-phosphatidylcholine liposomes as studied by ultrasound absorption technique

The effect of three carotenoid pigments, -carotene, lutein, and violaxanthin, on structural properties of dipalmitoylphosphatidylcholine liposomes was studied by means of ultrasound absorption technique. It was found that the polar carotenoid-lutein enhances drastically ultrasound absorption related to energy consumption during phase transition of a lipid component. The effect of apolar -carotene was not so much evident. No differences between the sample and control were found in the case of violaxanthin presence in liposomes. The effect of a polar carotenoid is discussed in terms of the reinforcement of the lipid matrix. Physiological aspects of carotenoid action in membranes are also briefly discussed.     

Effects of hydrogenated fat-spray-coated β-carotene supplement on plasma β-carotene concentration and conception rate after embryo transfer in Hanwoo beef cows

We hypothesised that hydrogenated fat (HF)-spray-coated β-carotene (βC) supplement could be used to increase plasma βC concentration and conception rates after embryo transfer (ET) in Hanwoo beef cows. In Experiment 1, 12 multiparous Hanwoo cows were fed one of four experimental diets in a triplicate 4 × 4 Latin square design for a 28-day period. Treatments included no βC addition (control), HF-uncoated βC (HFuβC), HF-spray-coated βC (HFβC), and HF-spray-coated βC and vitamin A (HFβCA). The cows under βC-supplemented treatments were fed 400 mg/day of βC, and a daily intake for vitamin A of HFβCA treatment was 30 000 IU/day as retinyl acetate. Blood was collected on days 0, 26, 27, and 28 to analyse βC and other metabolite concentrations. In Experiment 2, 199 Hanwoo cows with low fertility were randomly assigned to either control (n = 99) or HFβC treatments (n = 100) based on the results of Experiment 1. The oestrus of the cows was synchronised for ET. The HFβC group was fed from 4 weeks before to 4 weeks after ET with a daily intake of 400 mg βC. Pregnancy for conception rates was diagnosed on day 60 after ET, and blood was collected for βC concentrations on the day before ET. Supplementing βC resulted in a high plasma βC concentration (P < 0.001). Supplementing HFβC or HFβCA resulted in higher βC concentrations than HFuβC (P < 0.001); however, there was no difference between HFβC and HFβCA groups. Plasma retinol concentration was lower in the HFβCA treatment than in the control and HFβC groups (P < 0.05). Blood metabolites were unaffected by the treatments. The retinol:βC ratio was lower in the βC-supplemented treatments than in the controls, and was lower in HFβC and HFβCA than in HFuβC groups (P < 0.001). Plasma βC concentration was positively correlated with plasma high-density lipoprotein, low-density lipoprotein, and total cholesterol (P < 0.05). Plasma retinol concentration was negatively associated with plasma protein (P < 0.01), but positively associated with plasma creatinine (P < 0.001) and urea (P < 0.01). Supplementing HFβC to low-fertility cows resulted in higher plasma βC concentration (P < 0.001) and conception rates (P = 0.024) than those in the controls. In conclusion, HFβC had a better bioavailability than HFuβC, and an increase in conception rates by supplementing HFβC may be beneficial for producing more calves given the low pregnancy rates of bovine ET in Korea.     

Effects of β-alanine supplementation on performance and body composition in collegiate wrestlers and football players

The purpose of this study was to examine the effectiveness of β-alanine as an ergogenic aid in tests of anaerobic power output after 8 weeks of high-intensity interval, repeated sprint, and resistance training in previously trained collegiate wrestlers (WR) and football (FB) players. Twenty-two college WRs (19.9 ± 1.9 years, age ± SD) and 15 college FB players (18.6 ± 1.5 years) participated in this double-blind, placebo-controlled study. Each subject ingested either 4 g·d β-alanine or placebo in powdered capsule form. Subjects were tested pre and posttreatment in timed 300-yd shuttle, 90° flexed-arm hang (FAH), body composition, and blood lactate after 300-yd shuttle. Although not statistically significant (p > 0.05) subjects taking β-alanine achieved more desirable results on all tests compared to those on placebo. Performance improvements were greatest in the FB supplement group, decreasing 300 shuttle time by 1.1 seconds (vs. 0.4-second placebo) and increasing FAH (3.0 vs. 0.39 seconds). The wrestlers, both placebo and supplement, lost weight (as was the goal, i.e., weight bracket allowance); however, the supplement group increased lean mass by 1.1 lb, whereas the placebo group lost lean mass (-0.98 lb). Both FB groups gained weight; however, the supplement group gained an average 2.1-lb lean mass compared to 1.1 lb for placebo. β-Alanine appears to have the ability to augment performance and stimulate lean mass accrual in a short amount of time (8 weeks) in previously trained athletes. Training regimen may have an effect on the degree of benefit from β-alanine supplementation.     

Effects of Schisandrin B and α-tocopherol on lipid peroxidation, in vitro and in vivo

Effects of Schisandrin B (Sch B) and -tocopherol (-TOC) on ferric chloride (Fe³⁺) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl₄) induced lipid peroxidation in vivo were examined. While -TOC could produce prooxidant and antioxidant effect on Fe³⁺-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with -TOC (3 mmol/kg/day × 3) did not protect against CCl₄-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day × 3) produced a dose-dependent protective effect on the CCl₄-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.Abbreviations ALT alanine aminotransferase - CCl₄ carbon tetrachloride - Fe³⁺ ferric chloride - MDA malondialdehyde - Sch B Schisandrin B - TBA 2-thiobarbituric acid - TBARS thiobarbituric acid reactive substances - -TOC dl--tocopherol     

Effects of cold stress on juvenile Piaractus mesopotamicus and the mitigation by β-carotene

This study investigated the effects of cold stress on morphometrical and hematological biomarkers, energy metabolism, and oxidative stress in different tissues of P. mesopotamicus, and the protective role of β-carotene. Fish were fed with a control diet (CD) and the same diet supplemented with 105 mg/kg β-carotene (BD) for 60 days. After the feeding trial, fish fed CD or BD diets were exposed to control (24 °C) and low temperature (14 °C) for 24 h. Fish (CD and BD) exposed to thermal stress showed lower hepatosomatic index. The hemoglobin increased only in CD-fed fish exposed to 14 °C. Increased glycemia, plasmatic protein depletion, and decreased hepatic glycogen were observed in fish fed the CD, while only the lipid levels in liver were augmented in BD-fed fish exposed at 14 °C. Regarding the oxidative stress, increased antioxidant enzymes activity and lipid peroxidation were observed in CD-fed fish exposed to cold. The two-way ANOVA showed an interaction between dietary treatment and temperature for glucose and oxidative stress biomarkers, with the highest values recorded in 14 °C-exposed fish fed with the CD. Our study demonstrated that cold stress had the greatest impact on fish oxidative status, and β-carotene reduces harmful effects induced by cold in P. mesopotamicus.     

Effects of curvature and composition on α-synuclein binding to lipid vesicles

Parkinson's disease is characterized by the presence of intracellular aggregates composed primarily of the neuronal protein α-synuclein (αS). Interactions between αS and various cellular membranes are thought to be important to its native function as well as relevant to its role in disease. We use fluorescence correlation spectroscopy to investigate binding of αS to lipid vesicles as a function of the lipid composition and membrane curvature. We determine how these parameters affect the molar partition coefficient of αS, providing a quantitative measure of the binding energy, and calculate the number of lipids required to bind a single protein. Specific anionic lipids have a large effect on the free energy of binding. Lipid chain saturation influences the binding interaction to a lesser extent, with larger partition coefficients measured for gel-phase vesicles than for fluid-phase vesicles, even in the absence of anionic lipid components. Although we observe variability in the binding of the mutant proteins, differences in the free energies of partitioning are less dramatic than with varied lipid compositions. Vesicle curvature has a strong effect on the binding affinity, with a >15-fold increase in affinity for small unilamellar vesicles over large unilamellar vesicles, suggesting that αS may be a curvature-sensing protein. Our findings provide insight into how physical properties of the membrane may modulate interactions of αS with cellular membranes.     

The two faces of α- and γ-tocopherols: an in vitro and ex vivo investigation into VLDL, LDL and HDL oxidation

BackgroundVitamin E and its derivatives, namely, the tocopherols, are known antioxidants, and numerous clinical trials have investigated their role in preventing cardiovascular disease; however, evidence to date remains inconclusive. Much of the in vitro research has focused on tocopherol's effects during low-density lipoprotein (LDL) oxidation, with little attention being paid to very LDL (VLDL) and high-density lipoprotein (HDL). Also, it is now becoming apparent that γ-tocopherol may potentially be more beneficial in relation to cardiovascular health.ObjectivesDo α- and γ-tocopherols become incorporated into VLDL, LDL and HDL and influence their oxidation potential in an in vitro and ex vivo situation?DesignFollowing (i) an in vitro investigation, where plasma was preincubated with increasing concentrations of either α- or γ-tocopherol and (ii) an in vivo 4-week placebo-controlled intervention with α- or γ-tocopherol. Tocopherol incorporation into VLDL, LDL and HDL was measured via high-pressure liquid chromatography, followed by an assessment of their oxidation potential by monitoring conjugated diene formation.ResultsIn vitro: Both tocopherols became incorporated into VLDL, LDL and HDL, which protected VLDL and LDL against oxidation. However and surprisingly, the incorporation into HDL demonstrated pro-oxidant properties. Ex vivo: Both tocopherols were incorporated into all three lipoproteins, protecting VLDL and LDL against oxidation; however, they enhanced the oxidation of HDL.ConclusionsThese results suggest that α- and γ-tocopherols display conflicting oxidant activities dependent on the lipoprotein being oxidized. Their pro-oxidant activity toward HDL may go some way to explain why supplementation studies with vitamin E have not been able to display cardioprotective effects.     

Autolysis of glycoproteins in rat kidney lysosomes in vitro. Effects on the isoelectric focusing behaviour of glycoproteins, arylsulphatase and β-glucuronidase

1. Rat kidney lysosomal glycoproteins, prelabelled in the N-acetylneuraminic acid and polypeptide portions with N-acetyl[(3)H]mannosamine and [(14)C]lysine, or with N-acetyl-[(14)C]glucosamine, were incubated under various conditions. Autolytic cleavage of labelled N-acetylneuraminic acid and peptide was maximum at pH5.0. 2. N-Acetylneuraminic acid was released more rapidly than peptide during incubation at 37 degrees or 4 degrees C at pH5. p-Nitrophenyloxamic acid, an inhibitor of bacterial neuraminidase (Edmond et al., 1966), inhibited the cleavage of N-acetylneuraminic acid and peptide, and also inhibited cathepsin D activity. 3. Galactono-, mannono-, and glucono-lactone, inhibitors of the corresponding glycosidases, blocked the autolytic cleavage of N-acetyl[(14)C]glucosamine and protein without inhibiting beta-N-acetylhexosaminidase or cathepsin D activity. These findings suggest that the carbohydrate side chains protect the polypeptide portion of the lysosomal glycoproteins against proteolytic attack by lysosomal cathepsins. 4. In electrofocusing experiments, autolysis was minimized by adding 0.1% p-nitrophenyloxamic acid to the media used for extraction and electrofocusing, and by maintaining an alkaline pH (pH8.8-9) during extraction and dialysis. Arylsulphatase occurred in two forms with pI values of 4.4 and 6.4-6.7, and beta-glucuronidase in two forms with pI values of 4.4 and 6.1. When [(14)C]lysine and N-acetyl[(3)H]mannosamine were given to rats 1.5 and 1 h before killing, (14)C and (3)H were largely restricted to highly acidic glycoprotein species with pI values of 2.1-5.1. 5. When a lysosomal extract was adjusted to pH5 and incubated at 20 degrees C for 16h and then at 37 degrees C for 1 h before electrofocusing, 32 and 58% of the labelled peptide and N-acetylneuraminic acid was cleaved and the pI values of the labelled glycoproteins were markedly increased. About 80% of the acidic form of arylsulphatase and beta-glucuronidase was recovered with the basic form, and the pI of the basic form of both enzymes rose to 7.0. Similar, though less marked changes, were observed when a lysosomal extract was kept at pH5 for 2h at 4 degrees C before electrofocusing. 6. When an acidic lysosomal fraction (pI4.2-4.6) was incubated at pH5 for 2.5h and refocused, 80% of the arylsulphatase now occurred in two forms with pI values of 5 and 6.4. When a basic lysosomal fraction (pI5.8-6.4) was similarly incubated, the pI of arylsulphatase increased from 6.4 to 7.2. The relative increase in pI of arylsulphatases was accompanied by a proportional loss of N-acetylneuraminic acid from the glycoprotein associated with these forms. 7. These experiments show that lysosomal glycoproteins and two representative hydrolases, when exposed to a mildly acidic pH, readily undergo autolytic degradation and their pI values increase. These observations may have a bearing on the origin of the molecular heterogeneity of the lysosomal enzymes.     

Induction of oxidative DNA damage in human foreskin fibroblast Hs68 cells by oxidized β-carotene and lycopene

Two recent clinical trials suggest that β-carotene may be harmful to smokers. In this study we examined the hypothesis that β-carotene may become toxic when degradation occurs. β-Carotene (BC) and lycopene (LP) with or without prior heat treatment (60°C for 1h in open air) were incubated at 20 and 40 μM with calf thymus DNA or human fibroblasts Hs68 cells. The heat treatment resulted in ca. 80% and 35% bleaching of BC and LP, respectively. When Hs68 cells were incubated with the oxidized β-carotene (OBC) or oxidized lycopene (OLP) at 37°C for 20h, cell viability was significantly and dose-dependently decreased whereas cell viability was not affected by BC or LP. Cell death, which was already evident at 4h after incubation with OBC or OLP, was possibly attributable to apoptosis, as shown by the increased histone-associated DNA fragmentation. However, cell lysis, measured as release of lactate dehydrogenase, also occurred at 4h after incubation with OBC and OLP, although the extent was relatively small and was greater for OLP than for OBC. When calf thymus DNA was incubated with OBC or OLP at 37°C for 20h, the 8-hydroxy-2-deoxyguanosine (8-OH-dG) level was significantly and dose-dependently increased by OLP whereas the increase by OBC was only significant at 40 μM. When Hs68 cells were incubated with OBC and OLP for 20h, both compounds increased the 8-OH-dG level, but the effect was only significant for 40 μM OLP. Comet (single-cell gel electrophoresis) assay of DNA damage in Hs68 cells was determined at 2h after incubation with OBC or OLP because of its high sensitivity. Both OBC and OLP significantly and dose-dependently increased DNA breakage while BC and LP had no effect. Inclusion of BHT during incubation of cells with 40 μM OBC or OLP partially inhibited (ca. 40%, p<.05) the extent of comet formation. Intriguingly, OBC and OLP neither induce lipid peroxidation in Hs68 cells (measured as thiobarbituric acid-reactive substances released into the medium) nor increased the intracellular level of reactive oxygen species. Although it is presently unclear about what degradation products are formed, this study has demonstrated that, when oxidized, BC and LP lead to oxidative damage to both purified DNA and cellular DNA. The results suggest that such damage may contribute to the adverse effects of β-carotene reported in recent clinical studies and caution that it is important to prevent oxidation of BC and LP for human uses such as in supplemental studies.     

Photoreceptor-specific efficiencies of β-carotene,zeaxanthin and lutein for photopigment formation deduced from receptor mutant Drosophila melanogaster

Summary Drosophila rearing media had only -carotene, zeaxanthin or lutein as precursors for photopigment chromophores. Zeaxanthin and lutein are potentially optimum sources of the 3-hydroxylated retinoids of visual and accessory photopigments. Mutants made the electroretinogram in white (w) eyes selective for compound eye photoreceptors R1–6, R7 and R8: R1–6 domiantes w's electroretinogram; R7/8 generates w;ora's (ora = outer rhabdomeres absent); R8 generates w sev;- ora's (sev = sevenless). Microspectrophotometry revealed R1-6's visual pigment. In w, all 3 carotenoids yielded monotonic dose-responses for sensitivity (Fig. 4) or visual pigment (Fig. 7). An ultraviolet sensitivity peak from R1-6's sensitizing pigment was present at high but not low doses (Fig. 1). In w;ora, all 3 carotenoids gave similar spectra dominated by R7's high ultraviolet sensitivity (Fig. 2). For w sev;ora, all spectra were the shape expected for R8, peaking around 510 nm (Fig. 3). The sensitivity dose-response was at its ceiling except for low doses in w;ora (Fig. 5) and zero supplementation in w sev;ora (Fig. 6). Hence, without R1-6, most of our dose range mediated maximal visual pigment formation. In Drosophila, -carotene, zeaxanthin and lutein mediate the formation of all major photopigments in R1-6, R7 and R8.Abbreviations ERG electroretinogram - MSP microspectrophotometry - HPLC high pressure liquid chromatography - n.a. numerical aperture - w, sev, ora Drosophila mutants - y, p, r marg types of R7 and R8     

Transport and distribution of α-tocopherol in lymph,serum and liver cells in rats

Rats were cannulated in the major mesenteric lymph duct and given an intraduodenal bolus of unlabeled and α-[³H]tocopherol, and [¹⁴C]oleic acid in soybean oil. The appearance of α-tocopherol in lymph was negligible during the first 2 h and peaked 4–15 h after feeding, whereas no detectable amount was recovered in the portal vein. Intestinal absorption via the lymphatic pathway was 15.4 ± 8.9% (n = 10) and 45.9 ± 10.8% (n = 4) for α-tocopherol and [¹⁴C]oleic acid, respectively. About 99% of α-tocopherol in lymph was associated with the chylomicron fraction (d < 1.006 g/ml). In non-fasting rats, 51% of serum α-tocopherol was associated with chylomicrons/VLDL (very-low-density lipoprotein, d < 1.006 g/ml) and 47% with HDL (high-density lipoprotein, 1.05 < d < 1.21 g/ml). Our study revealed that the liver, skeletal muscle and adipose tissue contain approx. 92% of the total mass of α-tocopherol measured in ten different organs. Parenchymal and nonparenchymal liver cells contributed to 75% and 25% of the total mass of α-tocopherol in the liver, respectively.