Review
Artifact generation and monitoring in analysis of cholesterol oxide products

https://doi.org/10.1016/j.ab.2008.12.034Get rights and content

Section snippets

Defining artifacts and sampling

Cholesterol with its single double bond is vulnerable to oxidation, including enzymatic oxidation, autoxidation, and photooxidation [2], [10], [46]. The resulting oxidation products are COPs. During autoxidation, cholesterol can break down in a series of reactions. Primary products are various cholesterol hydroperoxides (CHPs), which can react to yield epoxy-cholesterols or can be converted to cholesterol-diols and keto-cholesterols. These secondary products can be further altered by

Artifact generation

How are artifacts generated? The same factors that initiate autoxidation and photooxidation contribute to artifact generation. Exposure to air, light, or metals propagates oxidation of cholesterol and COPs and these oxidative factors may be limited during analysis. Artifacts are also generated by experimental conditions which compromise the stability of cholesterol and existing COPs. Experimental conditions such as elevated saponification and evaporation temperatures or the alkaline

Is total artifact prevention possible?

Can artifacts be prevented? Are they truly inherent since artifacts can be generated by both oxidative processes and experimental conditions? Artifact generation can be limited through careful measures to control oxidative processes and experimental conditions; but, several investigators acknowledge that it may be impossible to entirely prevent them. For Rose-Sallin and colleagues, the belief that artifacts from cholesterol are “essentially impossible to avoid” led to the development of an

Artifact monitoring

Artifact monitoring is important and should be addressed in COP papers as many investigators do not monitor artifacts or report monitoring methods. There are several methods in use for artifact monitoring: using unlabeled/labeled cholesterol and multiple individually labeled COPs.

Reports on artifacts in the literature

Despite all of the controversy surrounding artifact generation during saponification and other causes, articles involving unrecognized artifacts are still being published. As COPs become better understood and their ubiquitous presence acknowledged, they are being studied or used as markers/measures of oxidative damage in various disease states. Use of COPs as markers/measures is relatively new in some disease conditions, indicating that the complex history of artifact generation methodology is

Application of knowledge of COPs to phytosterol oxidation products

Recently, phytosterols have become commercial nutraceutical ingredients present in several types of foods and as a result, phytosterol oxidation and analysis of its products (POPs) are an emerging, rapidly growing field of investigation. Because phytosterols share a similar structure with cholesterol, they, too, are subject to oxidation leading to the same spate of oxidation products. Fig. 3 compares the structure of the most common phytosterol, β-sistosterol, to cholesterol. The similarities

Future of sterol oxide products analysis

One of the many challenges scientist face is ensuring that newcomers to the field and clinicians know about artifact generation during analysis. Investigators who specialize in disease states and are looking for new markers may come to the field of SOPS unaware of artifact issues. COPs are now under investigation in several new areas, such as for antifungal activity and the questionable oxidation of cholesterol in arterial plaques by ozone [99], [100], [101]. Many aspects of POPs and their

First page preview

First page preview
Click to open first page preview
View PDF

References (102)

  • F. Guardiola et al.

    Comparison of three methods for the determination of oxysterols in spray-dried egg

    J. Chromatogr. A

    (1995)
  • J.A. Garcia Regueiro et al.

    Procedure for the determination of eight cholesterol oxides in poultry meat using on-column and solvent venting capillary gas chromatography

    J. Chromatogr. A

    (1997)
  • S.J.K.A. Ubhayasekera et al.

    Evaluation of GC and GC–MS methods for the analysis of cholesterol oxidation products

    Food Chem.

    (2004)
  • R.G. Dyer et al.

    Simultaneous measurement of phytosterols (campesterol and beta-sitosterol) and 7-ketocholesterol in human lipoproteins by capillary column gas chromatography

    J. Chromatogr. B

    (1995)
  • E. Boselli et al.

    Pressurized liquid extraction of lipids for the determination of oxysterols in egg-containing food

    J. Chromatogr. A

    (2001)
  • A.-M. Lampi et al.

    Determination of thermo-oxidation products of plant sterols

    J. Chromatogr. B

    (2002)
  • J. Plat et al.

    Oxidized plant sterols in human serum and lipid infusions as measured by combined gas–liquid chromatography–mass spectrometry

    J. Lipid Res.

    (2001)
  • V. Leoni et al.

    Levels of 7-oxocholesterol in cerebrospinal fluid are more than one thousand times lower than reported in multiple sclerosis

    J. Lipid Res.

    (2005)
  • I. Burkard et al.

    Determination of 24S- and 27-hydroxycholesterol in plasma by high-performance liquid chromatography–mass spectrometry

    J. Lipid Res.

    (2004)
  • H. Shan et al.

    Chromatographic behavior of oxygenated derivatives of cholesterol

    Steroids

    (2003)
  • C.J.W. Brooks et al.

    The use of trimethylsilyl ethers in the characterization of natural sterols and steroid diols by gas chromatography–mass spectrometry

    Biochim. Biophys. Acta

    (1973)
  • F. Guardiola et al.

    Adsorption of oxysterols on different microtube materials during silanization prior to gas chromatographic determination

    J. Chromatogr. A

    (1995)
  • O. Breuer

    Identification and quantitation of cholest-5-ene-3 beta, 4 beta-diol in rat liver and human plasma

    J. Lipid Res.

    (1995)
  • I. Björkhem et al.

    Assay of unesterified cholesterol-5,6-epoxide in human serum by isotope dilution mass spectrometry, Levels in the healthy state and in hyperlipoproteinemia

    J. Lipid Res.

    (1988)
  • A.J. Brown et al.

    Free and esterified oxysterol: formation during copper-oxidation of low density lipoprotein and uptake by macrophages

    J. Lipid Res.

    (1996)
  • L. Kritharides et al.

    A method for defining the stages of low-density lipoprotein oxidation by the separation of cholesterol and cholesteryl ester-oxidation products using HPLC

    Anal. Biochem.

    (1993)
  • P.B. Addis et al.

    Capillary GC quantification of cholesterol oxidation products in plasma lipoproteins of fasted humans

    Free Radic. Biol. Med.

    (1989)
  • A. Grau et al.

    Cholesterol oxidation in frozen dark chicken meat: influence of dietary fat source, and alpha-tocopherol and ascorbic acid supplementation

    Meat Sci.

    (2001)
  • A. Grandgirard et al.

    Gas chromatographic separation and mass spectrometric identification of mixtures of oxyphytosterol and oxycholesterol derivatives application to a phytosterol-enriched food

    J. Chromatogr. A

    (2004)
  • S. Li et al.

    Preparation and characterization of fluorinated and deuterated analogs of oxygenated derivatives of cholesterol

    Chem. Phys. Lipids

    (1999)
  • A. Sevanian et al.

    Analysis of plasma cholesterol oxidation products using gas- and high-performance liquid chromatography/mass spectroscopy

    Free Radic. Biol. Med.

    (1994)
  • R.G. Dyer et al.

    7-Ketocholesterol, a specific indicator of lipoprotein oxidation, and malondialdehyde in non-insulin dependent diabetes and peripheral vascular disease

    Clin. Chim. Acta

    (1997)
  • S. Miwa et al.

    Relationship between carotid atherosclerosis and erythrocyte membrane cholesterol oxidation products in type 2 diabetic patients

    Diabetes Res. Clin. Pract.

    (2003)
  • A.J. King et al.

    Concerns about methodology and use of 3,5,7-cholestatriene as a marker of oxidative stress. Response to relationship between carotid atherosclerosis and erythrocyte membrane cholesterol oxidation products in type 2 diabetic patients

    Diabetes Res. Clin. Pract.

    (2006)
  • J. Lembcke et al.

    Rapid quantification of free and esterified phytosterols in human serum using APPI-LC–MS/MS

    J. Lipid Res.

    (2005)
  • J.M. Brunel et al.

    Synthesis and antifungal activity of oxygenated cholesterol derivatives

    Steroids

    (2005)
  • L.L. Smith

    Cholesterol Autoxidation

    (1981)
  • L.L. Smith

    Cholesterol autoxidation 1981–1986

    Chem. Phys. Lipids

    (1987)
  • S.-K. Peng et al.

    Effects of cholesterol oxides on atherogenesis

  • S.-K. Peng et al.

    Effects of cholesterol oxides on cell membranes

  • S.-K. Peng et al.

    Cytotoxicity of cholesterol oxides

  • R.J. Morin et al.

    Effects of cholesterol oxides on cholesterol metabolism

  • R.J. Morin et al.

    Cholesterol oxidation and cancer

  • L.L. Smith

    Review of progress in sterol oxidations: 1987–1995

    Lipids

    (1996)
  • J. Linseisen et al.

    Origin, metabolism, and adverse health effects of cholesterol oxidation products

    Fett/Lipid

    (1988)
  • G.J. Schroepfer

    Oxysterols: modulators of cholesterol metabolism and other processes

    Physiol. Rev.

    (2000)
  • I. Björkhem et al.

    Oxysterols: friends, foes, or just fellow passengers?

    Arterioscler. Thromb. Vasc. Biol.

    (2002)
  • P.S.W. Park et al.

    Cholesterol oxide content of foods

  • P. Paniangvait et al.

    Cholesterol oxides in foods of animal origin

    J. Food Sci.

    (1995)
  • L.A. Appelqvist

    Oxidized sterols

    Bull. Int. Dairy Fed.

    (1996)

    • Cited by (0)

    View full text
    Copyright © 2009 Elsevier Inc. All rights reserved.