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Analytical tools for the analysis of β-carotene and its degradation products.

Stutz H, Bresgen N, Eckl PM - Free Radic. Res. (2015)

Bottom Line: Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs).For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed.The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Bioanalytics, Department of Molecular Biology, University of Salzburg , Salzburg , Austria.

ABSTRACT
β-Carotene, the precursor of vitamin A, possesses pronounced radical scavenging properties. This has centered the attention on β-carotene dietary supplementation in healthcare as well as in the therapy of degenerative disorders and several cancer types. However, two intervention trials with β-carotene have revealed adverse effects on two proband groups, that is, cigarette smokers and asbestos-exposed workers. Beside other causative reasons, the detrimental effects observed have been related to the oxidation products of β-carotene. Their generation originates in the polyene structure of β-carotene that is beneficial for radical scavenging, but is also prone to oxidation. Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs). Due to their instability and hydrophobicity, the handling of standards and real samples containing β-carotene and related CPs requires preventive measures during specimen preparation, analyte extraction, and final analysis, to avoid artificial degradation and to preserve the initial analyte portfolio. This review critically discusses different preparation strategies of standards and treatment solutions, and also addresses their protection from oxidation. Additionally, in vitro oxidation strategies for the generation of oxidative model compounds are surveyed. Extraction methods are discussed for volatile and non-volatile CPs individually. Gas chromatography (GC), (ultra)high performance liquid chromatography (U)HPLC, and capillary electrochromatography (CEC) are reviewed as analytical tools for final analyte analysis. For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed. The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation.

No MeSH data available.


Related in: MedlinePlus

HPLC separation profiles of β-carotene and its oxidation products. (A) All-trans-β-carotene standard, (B) β-carotene oxidation products and (C) total ion current chromatograms of corn oils showing control, and oxidized samples for 10, 12 and 14 h in the Rancimat at 110°C. Reprinted from [67], © 2011, with permission from Elsevier.
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Figure 0003: HPLC separation profiles of β-carotene and its oxidation products. (A) All-trans-β-carotene standard, (B) β-carotene oxidation products and (C) total ion current chromatograms of corn oils showing control, and oxidized samples for 10, 12 and 14 h in the Rancimat at 110°C. Reprinted from [67], © 2011, with permission from Elsevier.

Mentions: Others have oxidized β-carotene and β-IO by thermal degradation and a combined thermal-ozone treatment [36,66]. This procedure is of particular relevance in the food industry, where ozone is applied as an antimicrobial agent and food processing frequently includes heating steps. If food contains β-carotene either naturally, added as an antioxidant, or as a colorant additive, β-carotene breakdown products might be generated by these treatments and also consumed. Treatment was conducted with 0.80–2.54 ppm ozone at flow rates of 1 L/min for 7 h. CPs identified by HPLC-ion-trap mass spectrometry (MS) comprised epoxides and carbonyl compounds as major oxidation classes, including β-apo-14´-carotenal, β-apo-12´-carotenal, and their respective 5,6-epoxides. Moreover, β-apo-15-carotenal and 3,7,11,11-tetramethyl-10,15-dioxo-hexadec-2,4,6, 8-tetraenal were identified as intermediates that were further oxidized. Criegee´s biradical also takes a prominent role in ozone-driven oxidative degradation, for example, by degradation of β-CC to pyruvic acid. Detailed degradation pathways are given elsewhere [66]. Zeb and Murkovic [67] have oxidized β-carotene dissolved in corn oil at 110°C in a Rancimat system, at an air flow of 20 L/h for 1–4 h. The CPs identified after this treatment comprised β-apo-8´-carotenal, β-apo-6´-carotenal, 5,6-epoxy-β-apo-8´-carotenal, β-carotene-2,2´-dione, 5,6-epoxy-β-carotene, 5,8-epoxy-β-carotene and 5,6,5´,6´-diepoxy-β-carotene (Figures 3A and B). Furthermore, triacylglycerols of the corn oil were also oxidized under these conditions promoted by β-carotene, producing various hydroperoxide degradation products (Figure 3C). Analysis was done by HPLC-APCI-MS for β-carotene and its CPs, whereas HPLC-ESI-MS was applied for the characterization of the products of triacylglycerol degradation [67].


Analytical tools for the analysis of β-carotene and its degradation products.

Stutz H, Bresgen N, Eckl PM - Free Radic. Res. (2015)

HPLC separation profiles of β-carotene and its oxidation products. (A) All-trans-β-carotene standard, (B) β-carotene oxidation products and (C) total ion current chromatograms of corn oils showing control, and oxidized samples for 10, 12 and 14 h in the Rancimat at 110°C. Reprinted from [67], © 2011, with permission from Elsevier.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4487603&req=5

Figure 0003: HPLC separation profiles of β-carotene and its oxidation products. (A) All-trans-β-carotene standard, (B) β-carotene oxidation products and (C) total ion current chromatograms of corn oils showing control, and oxidized samples for 10, 12 and 14 h in the Rancimat at 110°C. Reprinted from [67], © 2011, with permission from Elsevier.
Mentions: Others have oxidized β-carotene and β-IO by thermal degradation and a combined thermal-ozone treatment [36,66]. This procedure is of particular relevance in the food industry, where ozone is applied as an antimicrobial agent and food processing frequently includes heating steps. If food contains β-carotene either naturally, added as an antioxidant, or as a colorant additive, β-carotene breakdown products might be generated by these treatments and also consumed. Treatment was conducted with 0.80–2.54 ppm ozone at flow rates of 1 L/min for 7 h. CPs identified by HPLC-ion-trap mass spectrometry (MS) comprised epoxides and carbonyl compounds as major oxidation classes, including β-apo-14´-carotenal, β-apo-12´-carotenal, and their respective 5,6-epoxides. Moreover, β-apo-15-carotenal and 3,7,11,11-tetramethyl-10,15-dioxo-hexadec-2,4,6, 8-tetraenal were identified as intermediates that were further oxidized. Criegee´s biradical also takes a prominent role in ozone-driven oxidative degradation, for example, by degradation of β-CC to pyruvic acid. Detailed degradation pathways are given elsewhere [66]. Zeb and Murkovic [67] have oxidized β-carotene dissolved in corn oil at 110°C in a Rancimat system, at an air flow of 20 L/h for 1–4 h. The CPs identified after this treatment comprised β-apo-8´-carotenal, β-apo-6´-carotenal, 5,6-epoxy-β-apo-8´-carotenal, β-carotene-2,2´-dione, 5,6-epoxy-β-carotene, 5,8-epoxy-β-carotene and 5,6,5´,6´-diepoxy-β-carotene (Figures 3A and B). Furthermore, triacylglycerols of the corn oil were also oxidized under these conditions promoted by β-carotene, producing various hydroperoxide degradation products (Figure 3C). Analysis was done by HPLC-APCI-MS for β-carotene and its CPs, whereas HPLC-ESI-MS was applied for the characterization of the products of triacylglycerol degradation [67].

Bottom Line: Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs).For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed.The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation.

View Article: PubMed Central - PubMed

Affiliation: Division of Chemistry and Bioanalytics, Department of Molecular Biology, University of Salzburg , Salzburg , Austria.

ABSTRACT
β-Carotene, the precursor of vitamin A, possesses pronounced radical scavenging properties. This has centered the attention on β-carotene dietary supplementation in healthcare as well as in the therapy of degenerative disorders and several cancer types. However, two intervention trials with β-carotene have revealed adverse effects on two proband groups, that is, cigarette smokers and asbestos-exposed workers. Beside other causative reasons, the detrimental effects observed have been related to the oxidation products of β-carotene. Their generation originates in the polyene structure of β-carotene that is beneficial for radical scavenging, but is also prone to oxidation. Depending on the dominant degradation mechanism, bond cleavage might occur either randomly or at defined positions of the conjugated electron system, resulting in a diversity of cleavage products (CPs). Due to their instability and hydrophobicity, the handling of standards and real samples containing β-carotene and related CPs requires preventive measures during specimen preparation, analyte extraction, and final analysis, to avoid artificial degradation and to preserve the initial analyte portfolio. This review critically discusses different preparation strategies of standards and treatment solutions, and also addresses their protection from oxidation. Additionally, in vitro oxidation strategies for the generation of oxidative model compounds are surveyed. Extraction methods are discussed for volatile and non-volatile CPs individually. Gas chromatography (GC), (ultra)high performance liquid chromatography (U)HPLC, and capillary electrochromatography (CEC) are reviewed as analytical tools for final analyte analysis. For identity confirmation of analytes, mass spectrometry (MS) is indispensable, and the appropriate ionization principles are comprehensively discussed. The final sections cover analysis of real samples and aspects of quality assurance, namely matrix effects and method validation.

No MeSH data available.


Related in: MedlinePlus