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Biologically active polymers from spontaneous carotenoid oxidation: a new frontier in carotenoid activity.

Johnston JB, Nickerson JG, Daroszewski J, Mogg TJ, Burton GW - PLoS ONE (2014)

Bottom Line: Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges.An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system.Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.

View Article: PubMed Central - PubMed

Affiliation: National Research Council of Canada, Charlottetown, Prince Edward Island, Canada.

ABSTRACT
In animals carotenoids show biological activity unrelated to vitamin A that has been considered to arise directly from the behavior of the parent compound, particularly as an antioxidant. However, the very property that confers antioxidant activity on some carotenoids in plants also confers susceptibility to oxidative transformation. As an alternative, it has been suggested that carotenoid oxidative breakdown or metabolic products could be the actual agents of activity in animals. However, an important and neglected aspect of the behavior of the highly unsaturated carotenoids is their potential to undergo addition of oxygen to form copolymers. Recently we reported that spontaneous oxidation of ß-carotene transforms it into a product dominated by ß-carotene-oxygen copolymers. We now report that the polymeric product is biologically active. Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges. An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system. Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.

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Effect of OxC-beta treatment on CYP26A gene expression in MCF-7 cells.Cells were incubated in the presence of the indicated concentrations of OxC-beta or vehicle control for 24 hours. For vehicle controls the concentrations of DMSO used were equivalent to the concentration of DMSO in the OxC-beta treatment groups, i.e., control groups labeled as 0.025%, 0.05% and 0.25% DMSO had the same DMSO concentration (v/v) as was used in the 2.5 µM, 5.0 µM and 25 µM OxC-beta treatment groups, respectively. Untreated cells were used as negative controls and cells treated with 1.0 µM of all trans retinoic acid (RA) served as positive controls. CYP26A gene expression was measured relative to β-actin using quantitative real-time PCR with the two standard curve method. Bars represent the mean ratio of CYP26A expression relative to β-actin from 4 separate experiments. Error bars represent the standard error of the mean. One-way ANOVA with Tukey’s test for multiple comparisons indicated no significant difference in relative CYP26A expression between cells treated with OxC-beta, DMSO, or untreated control cells. Treatment with 1.0 µM RA induced a significant increase in CYP26A gene expression compared to all other treatment groups. CYP26A expression ratios are shown calibrated to untreated control cells. *** p<0.001.
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pone-0111346-g004: Effect of OxC-beta treatment on CYP26A gene expression in MCF-7 cells.Cells were incubated in the presence of the indicated concentrations of OxC-beta or vehicle control for 24 hours. For vehicle controls the concentrations of DMSO used were equivalent to the concentration of DMSO in the OxC-beta treatment groups, i.e., control groups labeled as 0.025%, 0.05% and 0.25% DMSO had the same DMSO concentration (v/v) as was used in the 2.5 µM, 5.0 µM and 25 µM OxC-beta treatment groups, respectively. Untreated cells were used as negative controls and cells treated with 1.0 µM of all trans retinoic acid (RA) served as positive controls. CYP26A gene expression was measured relative to β-actin using quantitative real-time PCR with the two standard curve method. Bars represent the mean ratio of CYP26A expression relative to β-actin from 4 separate experiments. Error bars represent the standard error of the mean. One-way ANOVA with Tukey’s test for multiple comparisons indicated no significant difference in relative CYP26A expression between cells treated with OxC-beta, DMSO, or untreated control cells. Treatment with 1.0 µM RA induced a significant increase in CYP26A gene expression compared to all other treatment groups. CYP26A expression ratios are shown calibrated to untreated control cells. *** p<0.001.

Mentions: Given that activation of the retinoic acid receptor (RAR) pathway is known to affect immune function [22], it was important to rule out the possibility that unidentified compounds within OxC-beta possessed RAR agonist activity. Treatment of MCF-7 cells with OxC-beta failed to induce expression of CYP26A, a known RAR responsive gene [23] (Fig. 4). This result is consistent with the reported absence of retinoic acid and closely related compounds in OxC-beta [17].


Biologically active polymers from spontaneous carotenoid oxidation: a new frontier in carotenoid activity.

Johnston JB, Nickerson JG, Daroszewski J, Mogg TJ, Burton GW - PLoS ONE (2014)

Effect of OxC-beta treatment on CYP26A gene expression in MCF-7 cells.Cells were incubated in the presence of the indicated concentrations of OxC-beta or vehicle control for 24 hours. For vehicle controls the concentrations of DMSO used were equivalent to the concentration of DMSO in the OxC-beta treatment groups, i.e., control groups labeled as 0.025%, 0.05% and 0.25% DMSO had the same DMSO concentration (v/v) as was used in the 2.5 µM, 5.0 µM and 25 µM OxC-beta treatment groups, respectively. Untreated cells were used as negative controls and cells treated with 1.0 µM of all trans retinoic acid (RA) served as positive controls. CYP26A gene expression was measured relative to β-actin using quantitative real-time PCR with the two standard curve method. Bars represent the mean ratio of CYP26A expression relative to β-actin from 4 separate experiments. Error bars represent the standard error of the mean. One-way ANOVA with Tukey’s test for multiple comparisons indicated no significant difference in relative CYP26A expression between cells treated with OxC-beta, DMSO, or untreated control cells. Treatment with 1.0 µM RA induced a significant increase in CYP26A gene expression compared to all other treatment groups. CYP26A expression ratios are shown calibrated to untreated control cells. *** p<0.001.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4216090&req=5

pone-0111346-g004: Effect of OxC-beta treatment on CYP26A gene expression in MCF-7 cells.Cells were incubated in the presence of the indicated concentrations of OxC-beta or vehicle control for 24 hours. For vehicle controls the concentrations of DMSO used were equivalent to the concentration of DMSO in the OxC-beta treatment groups, i.e., control groups labeled as 0.025%, 0.05% and 0.25% DMSO had the same DMSO concentration (v/v) as was used in the 2.5 µM, 5.0 µM and 25 µM OxC-beta treatment groups, respectively. Untreated cells were used as negative controls and cells treated with 1.0 µM of all trans retinoic acid (RA) served as positive controls. CYP26A gene expression was measured relative to β-actin using quantitative real-time PCR with the two standard curve method. Bars represent the mean ratio of CYP26A expression relative to β-actin from 4 separate experiments. Error bars represent the standard error of the mean. One-way ANOVA with Tukey’s test for multiple comparisons indicated no significant difference in relative CYP26A expression between cells treated with OxC-beta, DMSO, or untreated control cells. Treatment with 1.0 µM RA induced a significant increase in CYP26A gene expression compared to all other treatment groups. CYP26A expression ratios are shown calibrated to untreated control cells. *** p<0.001.
Mentions: Given that activation of the retinoic acid receptor (RAR) pathway is known to affect immune function [22], it was important to rule out the possibility that unidentified compounds within OxC-beta possessed RAR agonist activity. Treatment of MCF-7 cells with OxC-beta failed to induce expression of CYP26A, a known RAR responsive gene [23] (Fig. 4). This result is consistent with the reported absence of retinoic acid and closely related compounds in OxC-beta [17].

Bottom Line: Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges.An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system.Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.

View Article: PubMed Central - PubMed

Affiliation: National Research Council of Canada, Charlottetown, Prince Edward Island, Canada.

ABSTRACT
In animals carotenoids show biological activity unrelated to vitamin A that has been considered to arise directly from the behavior of the parent compound, particularly as an antioxidant. However, the very property that confers antioxidant activity on some carotenoids in plants also confers susceptibility to oxidative transformation. As an alternative, it has been suggested that carotenoid oxidative breakdown or metabolic products could be the actual agents of activity in animals. However, an important and neglected aspect of the behavior of the highly unsaturated carotenoids is their potential to undergo addition of oxygen to form copolymers. Recently we reported that spontaneous oxidation of ß-carotene transforms it into a product dominated by ß-carotene-oxygen copolymers. We now report that the polymeric product is biologically active. Results suggest an overall ability to prime innate immune function to more rapidly respond to subsequent microbial challenges. An underlying structural resemblance to sporopollenin, found in the outer shell of spores and pollen, may allow the polymer to modulate innate immune responses through interactions with the pattern recognition receptor system. Oxygen copolymer formation appears common to all carotenoids, is anticipated to be widespread, and the products may contribute to the health benefits of carotenoid-rich fruits and vegetables.

Show MeSH
Related in: MedlinePlus