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Zhang YD, Ma C, Zheng KW, Han SQ, Ha W, Shi YP. Direct and Rapid Visualization of the Spatial Distribution of Cholesterol in Alzheimer's and Cancer Tissue via MALDI Mass Spectrometry Imaging. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1756-1767. [PMID: 39001840 DOI: 10.1021/jasms.4c00130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/15/2024]
Abstract
Cholesterol is a vital component of the central nervous system and tissues, and understanding its spatial distribution is crucial for biology, pathophysiology, and diagnostics. However, direct imaging of cholesterol using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) remains challenging and time-consuming due to the difficulty in ionizing the sterol molecule. To tackle this issue, a MALDI-MSI method is established for direct and rapid analysis of the spatial distribution of cholesterol in Alzheimer's disease (AD), different cancer tissues and organs via MALDI-MSI. This excellent imaging performance depends on the study and systemic optimization of various conditions that affect the imaging of MALDI-MSI. In this case, we report the distribution and levels of cholesterol across specific structures of the AD mouse brain and different tumor tissue and organs. According to the results, the content of cholesterol in the AD mouse cerebellum, especially in the arborvitae, was significantly higher than that in the wild type (WT) model. Furthermore, we successfully visualize the distribution of cholesterol in other organs, such as the heart, liver, spleen, kidney, pancreas, as well as tumor tissues parenchyma and interstitium using MALDI-MSI. Notably, the attribution of cholesterol MS/MS hydrocarbon fragments was systematically investigated. Our presented optimization strategy and established MALDI-MSI method can be easily generalized for different animal tissues or live samples, thereby facilitating the potential for applications of MALDI-MSI in clinical, medical and biological research.
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Affiliation(s)
- Yi-Da Zhang
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, P. R. China
| | - Chen Ma
- Gansu Province Key Laboratory of Evidence Science Techniques Research and Application, Gansu University of Political Science and Law, Lanzhou 730070, P. R. China
| | - Kai-Wen Zheng
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Si-Qi Han
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Wei Ha
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, P. R. China
| | - Yan-Ping Shi
- CAS Key Laboratory of Chemistry of Northwestern Plant Resources, Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Lanzhou 730000, P. R. China
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Evtyugin DD, Evtuguin DV, Casal S, Domingues MR. Advances and Challenges in Plant Sterol Research: Fundamentals, Analysis, Applications and Production. Molecules 2023; 28:6526. [PMID: 37764302 PMCID: PMC10535520 DOI: 10.3390/molecules28186526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
Plant sterols (PS) are cholesterol-like terpenoids widely spread in the kingdom Plantae. Being the target of extensive research for more than a century, PS have topped with evidence of having beneficial effects in healthy subjects and applications in food, cosmetic and pharmaceutical industries. However, many gaps in several fields of PS's research still hinder their widespread practical applications. In fact, many of the mechanisms associated with PS supplementation and their health benefits are still not fully elucidated. Furthermore, compared to cholesterol data, many complex PS chemical structures still need to be fully characterized, especially in oxidized PS. On the other hand, PS molecules have also been the focus of structural modifications for applications in diverse areas, including not only the above-mentioned but also in e.g., drug delivery systems or alternative matrixes for functional foods and fats. All the identified drawbacks are also superimposed by the need of new PS sources and technologies for their isolation and purification, taking into account increased environmental and sustainability concerns. Accordingly, current and future trends in PS research warrant discussion.
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Affiliation(s)
- Dmitry D. Evtyugin
- CICECO, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; (D.D.E.); (D.V.E.)
- LAQV-REQUIMTE, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Mass Spectrometry Centre, LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
| | - Dmitry V. Evtuguin
- CICECO, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal; (D.D.E.); (D.V.E.)
| | - Susana Casal
- LAQV-REQUIMTE, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Maria Rosário Domingues
- Mass Spectrometry Centre, LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
- CESAM, Centre for Environmental and Marine Studies, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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Feng M, Jin Y, Yang S, Joachim AM, Ning Y, Mori-Quiroz LM, Fromm J, Perera C, Zhang K, Werbovetz KA, Wang MZ. Sterol profiling of Leishmania parasites using a new HPLC-tandem mass spectrometry-based method and antifungal azoles as chemical probes reveals a key intermediate sterol that supports a branched ergosterol biosynthetic pathway. Int J Parasitol Drugs Drug Resist 2022; 20:27-42. [PMID: 35994895 PMCID: PMC9418051 DOI: 10.1016/j.ijpddr.2022.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/27/2022] [Accepted: 07/31/2022] [Indexed: 12/14/2022]
Abstract
Human leishmaniasis is an infectious disease caused by Leishmania protozoan parasites. Current chemotherapeutic options against the deadly disease have significant limitations. The ergosterol biosynthetic pathway has been identified as a drug target in Leishmania. However, remarkable differences in the efficacy of antifungal azoles that inhibit ergosterol biosynthesis have been reported for the treatment of leishmaniasis. To better understand the sterol biosynthetic pathway in Leishmania and elucidate the mechanism underlying the differential efficacy of antifungal azoles, we developed a new LC-MS/MS method to study sterol profiles in promastigotes of three Leishmania species, including two L. donovani, one L. major and one L. tarentolae strains. A combination of distinct precursor ion masses and LC retention times allowed for specific detection of sixteen intermediate sterols between lanosterol and ergosterol using the newly developed LC-MS/MS method. Although both posaconazole and fluconazole are known inhibitors of fungal lanosterol 14α-demethylase (CYP51), only posaconazole led to a substantial accumulation of lanosterol in azole-treated L. donovani promastigotes. Furthermore, a key intermediate sterol accumulated by 40- and 7-fold when these parasites were treated with posaconazole and fluconazole, respectively, which was determined as 4α,14α-dimethylzymosterol by high resolution mass spectrometry and NMR spectroscopy. The identification of 4α,14α-dimethylzymosterol supports a branched ergosterol biosynthetic pathway in Leishmania, where lanosterol C4- and C14-demethylation reactions occur in parallel rather than sequentially. Our results suggest that selective inhibition of leishmanial CYP51 is insufficient to effectively prevent parasite growth and dual inhibitors of both CYP51 and the unknown sterol C4-demethylase may be required for optimal antiparasitic effect.
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Affiliation(s)
- Mei Feng
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, USA
| | - Yiru Jin
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, USA
| | - Sihyung Yang
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, USA
| | - Arline M Joachim
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - Yu Ning
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409, USA
| | - Luis M Mori-Quiroz
- Synthetic Chemical Biology Core Laboratory, The University of Kansas, Lawrence, KS, USA
| | - Jacob Fromm
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, USA
| | - Chamani Perera
- Synthetic Chemical Biology Core Laboratory, The University of Kansas, Lawrence, KS, USA
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409, USA
| | - Karl A Werbovetz
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - Michael Zhuo Wang
- Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, USA.
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Lim J, Aguilan JT, Sellers RS, Nagajyothi F, Weiss LM, Angeletti RH, Bortnick AE. Lipid mass spectrometry imaging and proteomic analysis of severe aortic stenosis. J Mol Histol 2020; 51:559-571. [PMID: 32794037 DOI: 10.1007/s10735-020-09905-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/09/2020] [Indexed: 12/19/2022]
Abstract
Severe aortic stenosis (AS) is prevalent in adults ≥ 65 years, a significant cause of morbidity and mortality, with no medical therapy. Lipid and proteomic alterations of human AS tissue were determined using mass spectrometry imaging (MSI) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) to understand histopathology, potential biomarkers of disease, and progression from non-calcified to calcified phenotype. A reproducible MSI method was developed using healthy murine aortic valves (n = 3) and subsequently applied to human AS (n = 2). Relative lipid levels were spatially mapped and associated with different microdomains. Proteomics for non-calcified and calcified microdomains were performed to ascertain differences in expression. Increased pro-osteogenic and inflammatory lysophosphatidylcholine (LPC) 16:0 and 18:0 were co-localized with calcified microdomains. Proteomics analysis identified differential patterns in calcified microdomains with high LPC and low cholesterol as compared to non-calcified microdomains with low LPC and high cholesterol. Calcified microdomains had higher levels of: apolipoproteins (Apo) B-100 (p < 0.001) and Apo A-IV (p < 0.001), complement C3 and C4-B (p < 0.001), C5 (p = 0.007), C8 beta chain (p = 0.013) and C9 (p = 0.010), antithrombotic proteins alpha-2-macroglobulin (p < 0.0001) and antithrombin III (p = 0.002), and higher anti-calcific fetuin-A (p = 0.02), while the osteoblast differentiating factor transgelin (p < 0.0001), extracellular matrix proteins versican, prolargin, and lumican ( p < 0.001) and regulator protein complement factor H (p < 0.001) were higher in non-calcified microdomains. A combined lipidomic and proteomic approach provided insight into factors potentially contributing to progression from non-calcified to calcific disease in severe AS. Additional studies of these candidates and protein networks could yield new targets for slowing progression of AS.
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Affiliation(s)
- Jihyeon Lim
- Janssen Research and Development, Malvern, PA, USA
| | - Jennifer T Aguilan
- Laboratory for Macromolecular Analysis & Proteomics, Bronx, NY, USA.,Department of Pathology, Montefiore Health System and Albert Einstein College of Medicine, Bronx, NY, USA
| | | | - Fnu Nagajyothi
- Department of Pathology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Louis M Weiss
- Laboratory for Macromolecular Analysis & Proteomics, Bronx, NY, USA
| | - Ruth Hogue Angeletti
- Laboratory for Macromolecular Analysis & Proteomics, Bronx, NY, USA.,Department of Biochemistry, Montefiore Health System and Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Developmental and Molecular Biology, Montefiore Health System and Albert Einstein College of Medicine, Bronx, NY, USA
| | - Anna E Bortnick
- Department of Medicine, Division of Cardiology, Montefiore Health System and Albert Einstein College of Medicine, Bronx, NY, USA. .,Department of Medicine, Division of Geriatrics, Montefiore Health System and Albert Einstein College of Medicine, Bronx, NY, USA. .,Jack D. Weiler Hospital, 1825 Eastchester Road, Suite 2S-46, Bronx, NY, 10461, USA.
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Prochazka M, Stupavska M, Halaszova S, Jerigova M, Velic D. Ultraviolet photocatalytic degradation of cholesterol on TiO 2: secondary ion mass spectrometry. SURF INTERFACE ANAL 2017. [DOI: 10.1002/sia.6129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Michal Prochazka
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences; Comenius University; Ilkovičova 6 Mlynská dolina 842 15 Bratislava Slovakia
- Department of Composite Materials; Polymer Institute SAS; Dúbravská cesta 9 845 41 Bratislava Slovakia
| | - Monika Stupavska
- Department of Physical Electronics, Faculty of Science; Masaryk University; Kotlářská 2 611 37 Brno Czech Republic
| | - Sona Halaszova
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences; Comenius University; Ilkovičova 6 Mlynská dolina 842 15 Bratislava Slovakia
| | - Monika Jerigova
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences; Comenius University; Ilkovičova 6 Mlynská dolina 842 15 Bratislava Slovakia
- International Laser Centre; Ilkovičova 3 812 19 Bratislava Slovakia
| | - Dusan Velic
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences; Comenius University; Ilkovičova 6 Mlynská dolina 842 15 Bratislava Slovakia
- International Laser Centre; Ilkovičova 3 812 19 Bratislava Slovakia
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6
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van Agthoven MA, Barrow MP, Chiron L, Coutouly MA, Kilgour D, Wootton CA, Wei J, Soulby A, Delsuc MA, Rolando C, O'Connor PB. Differentiating Fragmentation Pathways of Cholesterol by Two-Dimensional Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:2105-14. [PMID: 26184984 DOI: 10.1007/s13361-015-1226-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 05/18/2015] [Accepted: 05/20/2015] [Indexed: 05/21/2023]
Abstract
Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry is a data-independent analytical method that records the fragmentation patterns of all the compounds in a sample. This study shows the implementation of atmospheric pressure photoionization with two-dimensional (2D) Fourier transform ion cyclotron resonance mass spectrometry. In the resulting 2D mass spectrum, the fragmentation patterns of the radical and protonated species from cholesterol are differentiated. This study shows the use of fragment ion lines, precursor ion lines, and neutral loss lines in the 2D mass spectrum to determine fragmentation mechanisms of known compounds and to gain information on unknown ion species in the spectrum. In concert with high resolution mass spectrometry, 2D Fourier transform ion cyclotron resonance mass spectrometry can be a useful tool for the structural analysis of small molecules. Graphical Abstract ᅟ.
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Affiliation(s)
| | - Mark P Barrow
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Lionel Chiron
- NMRTEC, Bld. Sébastien Brandt, Bioparc - Bat. B, 67400, Illkirch-Graffenstaden, France
| | - Marie-Aude Coutouly
- NMRTEC, Bld. Sébastien Brandt, Bioparc - Bat. B, 67400, Illkirch-Graffenstaden, France
| | - David Kilgour
- School of Pharmacy, University of Maryland, Baltimore, MD, 21201, USA
| | | | - Juan Wei
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Andrew Soulby
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Marc-André Delsuc
- NMRTEC, Bld. Sébastien Brandt, Bioparc - Bat. B, 67400, Illkirch-Graffenstaden, France
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, INSERM, U596; CNRS, UMR7104, Université de Strasbourg, 1 rue Laurent Fries, 67404, Illkirch-Graffenstaden, France
| | - Christian Rolando
- Miniaturisation pour la Synthèse, l'Analyse & la Protéomique (MSAP), USR CNRS 3290, and Protéomique, Modifications Post-traductionnelles et Glycobiologie, IFR 147 and Institut Eugène-Michel Chevreul, FR CNRS 2638, Université de Lille 1 Sciences et Technologies, 59655, Villeneuve d'Ascq Cedex, France
| | - Peter B O'Connor
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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Georgiou CA, Constantinou MS, Andreou R, Hapeshi E, Fatta-Kassinos D, Kapnissi-Christodoulou CP. Novel approach to fast determination of cholesterol oxidation products in Cypriot foodstuffs using ultra-performance liquid chromatography-tandem mass spectrometry. Electrophoresis 2015; 37:1101-8. [DOI: 10.1002/elps.201500196] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Revised: 07/23/2015] [Accepted: 08/10/2015] [Indexed: 12/14/2022]
Affiliation(s)
| | | | | | - Evroula Hapeshi
- Department of Civil and Environmental Engineering; University of Cyprus; Nicosia Cyprus
| | - Despo Fatta-Kassinos
- Department of Civil and Environmental Engineering; University of Cyprus; Nicosia Cyprus
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Zardetto S, Barbanti D, Rosa MD. Formation of cholesterol oxidation products (COPs) and loss of cholesterol in fresh egg pasta as a function of thermal treatment processing. Food Res Int 2014. [DOI: 10.1016/j.foodres.2014.02.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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9
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van de Merbel NC, Bronsema KJ, van Hout MW, Nilsson R, Sillén H. A validated liquid chromatography–tandem mass spectrometry method for the quantitative determination of 4β-hydroxycholesterol in human plasma. J Pharm Biomed Anal 2011; 55:1089-95. [DOI: 10.1016/j.jpba.2011.03.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 03/10/2011] [Accepted: 03/11/2011] [Indexed: 11/25/2022]
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10
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Jin Z, Daiya S, Kenttämaa HI. Characterization of Nonpolar Lipids and Selected Steroids by Using Laser-Induced Acoustic Desorption/Chemical Ionization, Atmospheric Pressure Chemical Ionization, and Electrospray Ionization Mass Spectrometry. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2011; 301:234-239. [PMID: 21528012 PMCID: PMC3081587 DOI: 10.1016/j.ijms.2010.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Laser-induced acoustic desorption (LIAD) combined with ClMn(H(2)O)(+) chemical ionization (CI) was tested for the analysis of nonpolar lipids and selected steroids in a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR). The nonpolar lipids studied, cholesterol, 5α-cholestane, cholesta-3,5-diene, squalene, and β-carotene, were found to solely form the desired water replacement product (adduct-H(2)O) with the ClMn(H(2)O)(+) ions. The steroids, androsterone, dehydroepiandrosterone (DHEA), estrone, estradiol, and estriol, also form abundant adduct-H(2)O ions, but less abundant adduct-2H(2)O ions were also observed. Neither (+)APCI nor (+)ESI can ionize the saturated hydrocarbon lipid, cholestane. APCI successfully ionizes the unsaturated hydrocarbon lipids to form exclusively the intact protonated analytes. However, it causes extensive fragmentation for cholesterol and the steroids. The worst case is cholesterol that does not produce any stable protonated molecules. On the other hand, ESI cannot ionize any of the hydrocarbon analytes, saturated or unsaturated. However, ESI can be used to protonate the oxygen-containing analytes with substantially less fragmentation than for APCI in all cases except for cholesterol and estrone. In conclusion, LIAD/ClMn(H(2)O)(+) chemical ionization is superior over APCI and ESI for the mass spectrometric characterization of underivatized nonpolar lipids and steroids.
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Affiliation(s)
- Zhicheng Jin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Shivani Daiya
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Hilkka I. Kenttämaa
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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Nogueira GC, Costa BZ, Crotti AEM, Bragagnolo N. Synthesis of 7-hydroperoxycholesterol and its separation, identification, and quantification in cholesterol heated model systems. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:10226-10230. [PMID: 20799691 DOI: 10.1021/jf102252r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
7-Hydroperoxycholesterol is considered to be an intermediate compound of the cholesterol oxidation path as the first product formed when cholesterol is oxidized by triplet oxygen. However, there is a limitation on cholesterol mechanism studies because of the lack of 7-hydroperoxycholesterol analytical standard due to its low stability. To verify the formation of hydroperoxides in cholesterol model systems heated at 140, 180, and 220 °C, 7α-hydroperoxycholesterol was synthesized by cholesterol photooxidation followed by rearrangement at room temperature in chloroform. Its structure was confirmed on the basis of 13C NMR and mass spectra obtained by APCI-LC-MS. The synthesized compound was also used as standard for the quantification of 7-hydroperoxycholesterol as the sum of 7α- and 7β-hydroperoxycholesterol. The results demonstrated that 7-hydroperoxycholesterol is the first compound formed when the temperature is lower (140 °C). However, the concentration of the 7-hydroperoxycholesterol depends on the temperature and time of exposure: the higher the time, the higher the amount of 7-hydroperoxycholesterol at lower temperatures, and the lower the time, the lower the amount of 7-hydroperoxycholesterol at higher temperatures (180 and 220 °C). By the formation of 7-hydroperoxycholesterol, the known cholesterol oxidation mechanism in three phases (initiation, propagation, and termination) could be confirmed; once at lower temperatures, the stage of cholesterol oxidation is at initiation, at which hydroperoxide formation predominates.
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Affiliation(s)
- Gislaine C Nogueira
- Department of Food Science, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
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