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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

(A) Extracted ion current chromatograms of a standard solution containing all-trans-β-carotene and target CPs at 1.0 μg/L. Identity of peaks: A, β-apo-12’-carotenal, B, β-apo-10’-carotenal, C, β-apo-8’-carotenal, D, β-apo-4’-carotenal, E, 5,6-epoxy-β-carotene (BC), and F, β-carotene (BC). (B) Detected masses and isotope distribution for β-carotene and target β-apocarotenals including a comparison with theoretical masses and theoretical isotope distribution by means of the software option provided. Reprinted from [116], under the terms of Creative Commons Attribution License.
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Related In: Results  -  Collection


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Figure 0008: (A) Extracted ion current chromatograms of a standard solution containing all-trans-β-carotene and target CPs at 1.0 μg/L. Identity of peaks: A, β-apo-12’-carotenal, B, β-apo-10’-carotenal, C, β-apo-8’-carotenal, D, β-apo-4’-carotenal, E, 5,6-epoxy-β-carotene (BC), and F, β-carotene (BC). (B) Detected masses and isotope distribution for β-carotene and target β-apocarotenals including a comparison with theoretical masses and theoretical isotope distribution by means of the software option provided. Reprinted from [116], under the terms of Creative Commons Attribution License.

Mentions: Characterization of β-carotene and related CPs by their retention times and UV-Vis spectra might be inadequate for their unequivocal identification [156]. Highly accurate mass information is mostly indispensable. In this context, hyphenation of chromatographic separation systems to MS is progressively applied. Fragmentation of analytes by MS/MS or higher order MS (MSn), and the comparison with theoretical isotope patterns in case of high-resolution MS systems, offer further decisive tools for an improved reliability of data in analyte identification (Figure 8) [89,116]. A discussion of the principles of electrospray ionization (ESI) in MS is beyond the scope of this review. The interested reader is thus directed to comprehensive reviews that tackle this aspect [157–160]. Unfortunately, β-carotene, like other non-polar analytes, lacks protonation and deprotonation sites and thus ionization in ESI-MS is cumbersome [117,123]. Frequently, this prevents adequate sensitivity or even detection at all [161].


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

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

(A) Extracted ion current chromatograms of a standard solution containing all-trans-β-carotene and target CPs at 1.0 μg/L. Identity of peaks: A, β-apo-12’-carotenal, B, β-apo-10’-carotenal, C, β-apo-8’-carotenal, D, β-apo-4’-carotenal, E, 5,6-epoxy-β-carotene (BC), and F, β-carotene (BC). (B) Detected masses and isotope distribution for β-carotene and target β-apocarotenals including a comparison with theoretical masses and theoretical isotope distribution by means of the software option provided. Reprinted from [116], under the terms of Creative Commons Attribution License.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4487603&req=5

Figure 0008: (A) Extracted ion current chromatograms of a standard solution containing all-trans-β-carotene and target CPs at 1.0 μg/L. Identity of peaks: A, β-apo-12’-carotenal, B, β-apo-10’-carotenal, C, β-apo-8’-carotenal, D, β-apo-4’-carotenal, E, 5,6-epoxy-β-carotene (BC), and F, β-carotene (BC). (B) Detected masses and isotope distribution for β-carotene and target β-apocarotenals including a comparison with theoretical masses and theoretical isotope distribution by means of the software option provided. Reprinted from [116], under the terms of Creative Commons Attribution License.
Mentions: Characterization of β-carotene and related CPs by their retention times and UV-Vis spectra might be inadequate for their unequivocal identification [156]. Highly accurate mass information is mostly indispensable. In this context, hyphenation of chromatographic separation systems to MS is progressively applied. Fragmentation of analytes by MS/MS or higher order MS (MSn), and the comparison with theoretical isotope patterns in case of high-resolution MS systems, offer further decisive tools for an improved reliability of data in analyte identification (Figure 8) [89,116]. A discussion of the principles of electrospray ionization (ESI) in MS is beyond the scope of this review. The interested reader is thus directed to comprehensive reviews that tackle this aspect [157–160]. Unfortunately, β-carotene, like other non-polar analytes, lacks protonation and deprotonation sites and thus ionization in ESI-MS is cumbersome [117,123]. Frequently, this prevents adequate sensitivity or even detection at all [161].

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