Extraction and Analysis of Sterols in Biological Matrices by High Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry

McDonald, Jeffrey G.; Thompson, Bonne M.; McCrum, Erin; Russell, David W.

doi:10.1016/s0076-6879(07)32006-5

Cited by 141 publications

(146 citation statements)

References 25 publications

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“…To overcome this disadvantage, we have developed a new method for the enhancement of the ionization efficiency by derivatizing into picolinyl esters (23,27). Dihydroxy-or epoxysterols are more efficiently ionized by electrospray, and their limit of detection (5-60 fmol oncolumn) was reported to be more than 10 times lower than that of monohydroxysterols (175-2,000 fmol on-column) (22). In this paper, we have studied the usefulness of our derivatization method on dihydroxy-and epoxysterols that are key regulatory oxysterols in biological samples.…”

Section: Discussionmentioning

confidence: 99%

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Highly sensitive quantification of key regulatory oxysterols in biological samples by LC-ESI-MS/MS

Honda

Yamashita

Hara

et al. 2009

Journal of Lipid Research

177

154

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We describe a highly sensitive and specific method for the quantification of key regulatory oxysterols in biological samples. This method is based upon a stable isotope dilution technique by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After alkaline hydrolysis of human serum (5 ml) or rat liver microsomes (1 mg protein), oxysterols were extracted, derivatized into picolinyl esters, and analyzed by LC-MS/MS using the electrospray ionization mode. The detection limits of the picolinyl esters of 4b-hydroxycholesterol, 7a-hydroxycholesterol, 22R-hydroxycholesterol, 24S-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, and 24S,25-epoxycholesterol were 2-10 fg (5-25 amol) on-column (signal-to-noise ratio 5 3). Reproducibilities and recoveries of these oxysterols were validated according to one-way layout and polynomial equation, respectively. The variances between sample preparations and between measurements by this method were calculated to be 1.8% to 12.7% and 2.9% to 11.9%, respectively. The recovery experiments were performed using rat liver microsomes spiked with 0.05 ng to 12 ng of oxysterols, and recoveries of the oxysterols ranged from 86.7% to 107.3%, with a mean recovery of 100.6%. This method provides reproducible and reliable results for the quantification of oxysterols in small amounts of biological samples. Supplementary key words liquid chromatography-tandem mass spec-Biological samples contain a large number of oxysterols (1), and most of them are formed from cholesterol by enzymatic oxidation (2 -6) ( Fig. 1) or autoxidation (7). By contrast, the oxysterol 24S,25-epoxycholesterol is not derived from cholesterol but is produced de novo from acetyl-CoA via a shunt in the mevalonate pathway (8).These oxysterols are important molecules for preserving lipid homeostasis in the body. 7a-Hydroxycholesterol is a product of CYP7A1, which is the rate-limiting enzyme in the classic bile acid biosynthetic pathway. 27-Hydroxycholesterol, 24S-hydroxycholesterol, 4b-hydroxycholesterol, 22R-hydroxycholesterol, and 24S,25-epoxycholesterol are effective endogenous ligands of the nuclear receptors liver X receptor a (LXRa) and LXRb (9-11). In addition, 27-hydroxycholesterol (12), 25-hydroxycholesterol (13), and 24S,25-epoxycholesterol (14) are known to downregulate the cholesterol biosynthetic pathway, presumably by blocking the processing of the sterol-regulatory element binding protein.GC-MS has historically been used for the analyses of oxysterols in serum and tissues (1, 15) because the sensitivity and specificity of conventional GC with flame ionization detector is not sufficient to quantify oxysterols in biological samples. However, GC-MS is still not an ideal method, especially for the analysis of 24S,25-epoxycholesterol, because this epoxycholesterol does not survive the temperature required for GC analysis (16). Another approach to quantifying oxysterols in biological samples was HPLC with ultraviolet (UV) detection after derivatization to the D 4 -3-ketones (16-19). Thi...

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Section: Discussionmentioning

confidence: 99%

“…In addition, LCtandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI) has also been applied to the analysis of oxysterols (22). In general, ESI is not the best ionization method for neutral steroids because of its poor ionization efficiency.…”

mentioning

confidence: 99%

Highly sensitive quantification of key regulatory oxysterols in biological samples by LC-ESI-MS/MS

Honda

Yamashita

Hara

et al. 2009

Journal of Lipid Research

177

154

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“…The HPLC-MS instrument consisted of a Shimadzu binary HPLC system (Shimadzu Scientific Instruments, Columbia, MD) with a CTC LC PAL autosampler (Leap Technologies, Carrboro, NC) coupled to a 4000 Q TRAP mass spectrometer (Applied Biosystems, Foster City, CA) through a Turbo V electrospray ionization source. Samples were resolved with a binary solvent gradient using a Luna C 18 HPLC column (150 × 3 mm, 3-μm particle size; Phenomenex, Torrance, CA). The mobile phases were (A) H 2 O with 5 mM ammonium acetate and (B) methanol with 5 mM ammonium acetate.…”

Section: Instrument Informationmentioning

confidence: 99%

“…Multiple water losses have been observed for analogous compounds such as oxysterols. 18 Each compound exhibited a unique fragment ion resulting from dissociation of the acetal bonds that link the alkyl-benzyl group to the sorbitol backbone. The fragment ion from I differed slightly from the other two compounds in that a loss of benzaldehyde produced a m/z 251 ion.…”

Section: Mass Spectramentioning

confidence: 99%

Identification and Quantitation of Sorbitol-Based Nuclear Clarifying Agents Extracted from Common Laboratory and Consumer Plasticware Made of Polypropylene

et al. 2008

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Reported here is the mass spectral identification of sorbitol-based nuclear clarifying agents (NCAs) and the quantitative description of their extractability from common laboratory and household plasticware made of polypropylene. NCAs are frequently added to polypropylene to improve optical clarity, increase performance properties, and aid in the manufacturing process of this plastic. NCA addition makes polypropylene plasticware more aesthetically pleasing to the user and makes the product competitive with other plastic formulations. We show here that several NCAs are readily extracted with either ethanol or water from plastic labware during typical laboratory procedures. Observed levels ranged from a nanogram to micrograms of NCA. NCAs were also detected in extracts from plastic food storage containers; levels ranged from 1to 10 μg in two of the three brands tested. The electron ionization mass spectra for three sorbitol-based nuclear clarifying agents (1,3:2,4-bis-O-(benzylidene)sorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)sorbitol, 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)sorbitol) are presented for the native and trimethylsilylderivatized compounds together with the collision-induced dissociation mass spectra; gas and liquid chromatographic data are also reported. These NCAs now join other well-known plasticizers such as phthalate esters and bisphenol A as common laboratory contaminants. While the potential toxicity of NCAs in mammalian systems is unknown, the current data provide scientists and consumers the opportunity to make more informed decisions regarding the use of polypropylene plastics.The ubiquitous nature of plasticizers in the laboratory has plagued analytical chemists and other scientists for decades. Plasticizers, slip and mold release agents, antioxidants, and other compounds extractable from plastics can complicate preparation of samples, contaminate analytical instrumentation (e.g., mass spectrometers), confound data interpretation, and consume valuable time and resources during their identification. When reference information is available in the literature or databases, potential contaminants observed in analytical measurements can be rapidly identified with mass spectrometry or other analytical tools. Many laboratories that specialize in analytical chemistry, especially mass spectrometry, minimize contaminants by using only glass and other inert materials (e.g., Teflon, stainless steel, etc.) sources such as stretchable sealing films or plastic tubing. As scientific research becomes more interdisciplinary, adherence to such strict procedures increases in difficulty. In contrast to analytical chemists, biologists often rely heavily on plasticware to conduct their research and it may be impractical to eliminate plastic materials from biological research; therefore, a compromise must be made and the potential for artifacts introduced from plasticware must be considered.While the potential interference in analytical measurements of plasticizers and other contaminants is appreciated, t...

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“…Afterwards, the extracts are introduced to a liquid chromatography tandem mass spectrometry (LC-MSMS) system to achieve optimal separation of lipid species present in the extract prior to MSMS analysis [41,23,42,43,44,45]. This strategy ensures best possible sensitivity by utilizing chromatographic separation and fragmentation producing complete and accurate lipidome profiles.…”

Section: Targeted Lipidomicsmentioning

confidence: 99%

Computational Lipidomics and Lipid Bioinformatics: Filling In the Blanks

Pauling

Klipp

2016

Journal of Integrative Bioinformatics

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SummaryLipids are highly diverse metabolites of pronounced importance in health and disease. While metabolomics is a broad field under the omics umbrella that may also relate to lipids, lipidomics is an emerging field which specializes in the identification, quantification and functional interpretation of complex lipidomes. Today, it is possible to identify and distinguish lipids in a high-resolution, high-throughput manner and simultaneously with a lot of structural detail. However, doing so may produce thousands of mass spectra in a single experiment which has created a high demand for specialized computational support to analyze these spectral libraries. The computational biology and bioinformatics community has so far established methodology in genomics, transcriptomics and proteomics but there are many (combinatorial) challenges when it comes to structural diversity of lipids and their identification, quantification and interpretation. This review gives an overview and outlook on lipidomics research and illustrates ongoing computational and bioinformatics efforts. These efforts are important and necessary steps to advance the lipidomics field alongside analytic, biochemistry, biomedical and biology communities and to close the gap in available computational methodology between lipidomics and other omics sub-branches.

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Extraction and Analysis of Sterols in Biological Matrices by High Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry

Cited by 141 publications

References 25 publications

Highly sensitive quantification of key regulatory oxysterols in biological samples by LC-ESI-MS/MS

Highly sensitive quantification of key regulatory oxysterols in biological samples by LC-ESI-MS/MS

Identification and Quantitation of Sorbitol-Based Nuclear Clarifying Agents Extracted from Common Laboratory and Consumer Plasticware Made of Polypropylene

Computational Lipidomics and Lipid Bioinformatics: Filling In the Blanks

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