Ambient ionization mass spectrometry allows for analysis of samples in their natural state, i.e., with no sample pre-treatment. It can be viewed as a fast, simple, and economical analysis, but its main disadvantages include a lower analytical performance due to the presence of complex sample matrix and the lack of chromatographic separation prior to the introduction of the sample into the mass spectrometer. Here we present an application of two ambient ionization mass spectrometry techniques, i.e., Desorption Atmospheric Pressure Photoionization and Dielectric Barrier Discharge Ionization, for the analysis of known Selective Androgen Receptor Modulators, which represent common compounds of abuse in professional and semiprofessional sport. Eight real samples of illegal food supplements, seized by the local law enforcement, were used to test the performance of the ambient mass spectrometry and the results were validated against a newly developed targeted LC-UV-MS/MS method performed in multiple reaction monitoring mode with an external calibration for each analyte. In order to decide whether or not the compound can be declared as present, we proposed a system of rules for the interpretation of the obtained spectra. The criteria are based on mass spectrum matching (5-10 ppm accuracy from the theoretical exact mass and a correct isotopic pattern), duration of the mass signal (three or five consecutive scans, depending on the instrumentation used), and intensity above the background noise (threefold increase in intensity and absolute intensity above 5E4 or 1E5, depending on the instrumentation). When applying these criteria, good agreement was found between the tested methods. Ambient ionization techniques were effective at detecting SARMs at pharmacologically relevant doses, i.e., approximately above 1 mg per capsule, although they may fail to detect lower levels or isomeric species. It is demonstrated that when adhering to a set of clear and consistent rules, ambient mass spectrometry can be employed as a qualitative technique for the screening of illegal SARMs with sufficient confidence and without the necessity to perform a regular LC-MS analysis.
- MeSH
- androgenní receptory * metabolismus MeSH
- antagonisté androgenních receptorů analýza MeSH
- chromatografie kapalinová metody MeSH
- doping ve sportu prevence a kontrola MeSH
- hmotnostní spektrometrie metody MeSH
- lidé MeSH
- odhalování abúzu drog metody MeSH
- potravní doplňky analýza MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Lipidy hrají klíčové role v mnoha biologických procesech. Většina lipidů obsahuje dlouhé alifatické řetězce, jejichž variabilní struktura přispívá k rozmanitým fyzikálně-chemickým vlastnostem a biologickým funkcím těchto molekul. Alifatické řetězce lipidů mohou být rovné nebo rozvětvené, s dvojnými či trojnými vazbami, případně s různými funkčními skupinami. V posledních letech došlo k významnému pokroku ve strukturní analýze lipidů pomocí hmotnostní spektrometrie. Nové metody jsou založeny na využití netradičních fragmentačních technik a nových derivatizačních reakcí. S jejich pomocí lze určovat podrobnou strukturu alifatických řetězců, včetně určení polohy násobných vazeb, funkčních skupin a uspořádání alifatických řetězců v komplexních lipidech. Tento přehledový článek navazuje na dva předchozí, které se zabývaly určováním poloh dvojných vazeb (Chem. Listy 117, 684 (2023), Chem. Listy 117, 747 (2023)). Tento text je zaměřen na určení polohy methylového větvení, kyslíkatých funkčních skupin, karbocyklů a stereospecifické polohy acylového řetězce na glycerolu.
Lipids play key roles in many biological processes. Most lipids contain long aliphatic chains whose variable structure contributes to diverse physicochemical properties and biological functions of these molecules. The aliphatic chains of lipids can be straight or branched, with double or triple bonds, or with various functional groups. In recent years, mass spectrometry has made significant progress in the structural analysis of lipids. New methods are based on unconventional fragmentation techniques and new derivatization reactions. They can be used to determine the detailed structure of aliphatic chains, including the position of multiple bonds, functional groups, and the arrangement of aliphatic chains in complex lipids. This review article is a follow-up to two previous articles that dealt with the determination of double bond positions (Chem. Listy 117, 684 (2023), Chem. Listy 117, 747 (2023)). Here, we focus on determining the position of methyl branching, oxygen-containing functional groups, carbocyclic structures, and the stereospecific position of the acyl chain on glycerol.
Alzheimer's disease (AD) is a progressive brain disorder characterized by extracellular amyloid-β (Aβ) plaques, intracellular neurofibrillary tangles formed by hyperphosphorylated Tau protein and neuroinflammation. Previous research has shown that obesity and type 2 diabetes mellitus, underlined by insulin resistance (IR), are risk factors for neurodegenerative disorders. In this study, obesity-induced peripheral and central IR and inflammation were studied in relation to AD-like pathology in the brains and periphery of APP/PS1 mice, a model of Aβ pathology, fed a high-fat diet (HFD). APP/PS1 mice and their wild-type controls fed either a standard diet or HFD were characterized at the ages of 3, 6 and 10 months by metabolic parameters related to obesity via mass spectroscopy, nuclear magnetic resonance, immunoblotting and immunohistochemistry to quantify how obesity affected AD pathology. The HFD induced substantial peripheral IR leading to central IR. APP/PS1-fed HFD mice had more pronounced IR, glucose intolerance and liver steatosis than their WT controls. The HFD worsened Aβ pathology in the hippocampi of APP/PS1 mice and significantly supported both peripheral and central inflammation. This study reveals a deleterious effect of obesity-related mild peripheral inflammation and prediabetes on the development of Aβ and Tau pathology and neuroinflammation in APP/PS1 mice.
- MeSH
- Alzheimerova nemoc * etiologie MeSH
- amyloidní beta-protein MeSH
- diabetes mellitus 2. typu * MeSH
- dieta s vysokým obsahem tuků škodlivé účinky MeSH
- inzulinová rezistence * MeSH
- myši MeSH
- neurozánětlivé nemoci MeSH
- zánět MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Human amniotic and amniochorionic membranes (AM, ACM) represent the most often used grafts accelerating wound healing. Palmitoylethanolamide, oleoylethanolamide and anandamide are endogenous bioactive lipid molecules, generally referred as N-acylethanolamines. They express analgesic, nociceptive, neuroprotective and anti-inflammatory properties. We assessed the distribution of these lipid mediators in placental tissues, as they could participate on analgesic and wound healing effect of AM/ACM grafts. METHODS: Seven placentas were collected after caesarean delivery and fresh samples of AM, ACM, placental disc, umbilical cord, umbilical serum and vernix caseosa, and decontaminated samples (antibiotic solution BASE 128) of AM and ACM have been prepared. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used for N-acylethanolamines analysis. RESULTS: N-acylethanolamines were present in all studied tissues, palmitoylethanolamide being the most abundant and the anandamide the least. For palmitoylethanolamide the maximum average concentration was detected in AM (350.33 ± 239.26 ng/g), while oleoylethanolamide and anandamide were most abundant in placenta (219.08 ± 79.42 ng/g and 30.06 ± 7.77 ng/g, respectively). Low levels of N-acylethanolamines were found in serum and vernix. A significant increase in the levels of N-acylethanolamines (3.1-3.6-fold, P < 0.001) was observed in AM when the tissues were decontaminated using antibiotic solution. The increase in decontaminated ACM was not statistically significant. CONCLUSIONS: The presence of N-acylethanolamines, particularly palmitoylethanolamide in AM and ACM allows us to propose these lipid mediators as the likely factors responsible for the anti-hyperalgesic, but also anti-inflammatory and neuroprotective, effects of AM/ACM grafts in wound healing treatment. The increase of N-acylethanolamines levels in AM and ACM after tissue decontamination indicates that tissue processing is an important factor in maintaining the analgesic effect.
- MeSH
- analgetika MeSH
- endokanabinoidy * MeSH
- ethanolaminy MeSH
- lidé MeSH
- placenta * MeSH
- polynenasycené alkamidy MeSH
- těhotenství MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Prolactin-releasing peptide (PrRP) is an anorexigenic neuropeptide that has potential for the treatment of obesity and its complications. Recently, we designed a palmitoylated PrRP31 analog (palm11-PrRP31) that is more stable than the natural peptide and able to act centrally after peripheral administration. This analog acted as an anti-obesity and glucose-lowering agent, attenuating lipogenesis in rats and mice with high-fat (HF) diet-induced obesity. In Wistar Kyoto (WKY) rats fed a HF diet for 52 weeks, we explored glucose intolerance, but also prediabetes, liver steatosis and insulin resistance-related changes, as well as neuroinflammation in the brain. A potential beneficial effect of 6 weeks of treatment with palm11-PrRP31 and liraglutide as comparator was investigated. Liver lipid profiles, as well as urinary and plasma metabolomic profiles, were measured by lipidomics and metabolomics, respectively. Old obese WKY rats showed robust glucose intolerance that was attenuated by palm11-PrRP31, but not by liraglutide treatment. On the contrary, liraglutide had a beneficial effect on insulin resistance parameters. Despite obesity and prediabetes, WKY rats did not develop steatosis owing to HF diet feeding, even though liver lipogenesis was enhanced. Plasma triglycerides and cholesterol were not increased by HFD feeding, which points to unincreased lipid transport from the liver. The liver lipid profile was significantly altered by a HF diet that remained unaffected by palm11-PrRP31 or liraglutide treatment. The HF-diet-fed WKY rats revealed astrogliosis in the brain cortex and hippocampus, which was attenuated by treatment. In conclusion, this study suggested multiple beneficial anti-obesity-related effects of palm11-PrRP31 and liraglutide in both the periphery and brain.
- MeSH
- dieta s vysokým obsahem tuků škodlivé účinky MeSH
- hormon uvolňující prolaktin farmakologie MeSH
- hypoglykemika farmakologie terapeutické užití MeSH
- inzulinová rezistence * MeSH
- krysa rodu rattus MeSH
- lipidy MeSH
- liraglutid farmakologie terapeutické užití MeSH
- myši MeSH
- obezita farmakoterapie MeSH
- porucha glukózové tolerance * farmakoterapie MeSH
- potkani inbrední WKY MeSH
- prediabetes * farmakoterapie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
In mass spectrometry imaging (MSI), the essential steps in sample preparation include collection and storage. The most widely used preservation procedure for MSI consists in freezing samples and storing them at temperatures below -80 °C. On the other hand, the most common method for preserving biological samples in clinical practice is their fixation in paraformaldehyde. The storage of free-floating sections is a particular type of the preservation of paraformaldehyde-fixed tissues that is used in immunohistochemistry. This chapter describes the approach of the multimodal imaging of free-floating brain sections using the MSI of lipids and the immunohistochemistry of neurodegeneration markers.
Double and triple bonds have significant effects on the biological activities of lipids. Determining multiple bond positions in their molecules by mass spectrometry usually requires chemical derivatization. This work presents an HPLC/MS method for pinpointing the double and triple bonds in fatty acids. Fatty acid methyl esters were separated by reversed-phase HPLC with an acetonitrile mobile phase. In the APCI source, acetonitrile formed reactive species, which added to double and triple bonds to form [M + C3H5N]+• ions. Their collisional activation in an ion trap provided fragments helpful in localizing the multiple bond positions. This approach was applied to fatty acids with isolated, cumulated, and conjugated double bonds and triple bonds. The fatty acids were isolated from the fat body of early-nesting bumblebee Bombus pratorum and seeds or seed oils of Punicum granatum, Marrubium vulgare, and Santalum album. Using the method, the presence of the known fatty acids was confirmed, and new ones were discovered.
- MeSH
- acetonitrily chemie MeSH
- estery chemie izolace a purifikace MeSH
- hmotnostní spektrometrie MeSH
- mastné kyseliny chemie izolace a purifikace MeSH
- molekulární struktura MeSH
- včely chemie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
RATIONALE: Hyphenation of atmospheric pressure chemical ionization (APCI) mass spectrometry with capillary and micro high-performance liquid chromatography (HPLC) is attractive for many applications, but reliable ion sources dedicated to these conditions are still missing. There are a number of aspects to consider when designing such an ion source, including the susceptibility of the ionization processes to ambient conditions. Here we discuss the importance of ion source housing for APCI at low flow rates. METHODS: Selected compounds dissolved in various solvents were used to study ionization reactions at 10 μL/min flow rate. APCI spectra were generated using the Ion Max-S source (Thermo Fisher Scientific) operated with or without the ion source housing. RESULTS: The APCI spectra of most compounds measured in the open and enclosed ion sources were markedly different. The differences were explained by water and oxygen molecules that entered the plasma region of the open ion source. Water tended to suppress charge transfer processes while oxygen diminished electron capture reactions and prevented the formation of acetonitrile-related radical cations useful for localizing double bonds in lipids. The effects associated with the ion source housing were significantly less important for compounds that are easy to protonate or deprotonate. CONCLUSIONS: The use of ion source housing prevented alternative ionization channels leading to unwanted or unexpected ions. Compared with the conventional flow rate mode (1 mL/min), the effects of ambient air components were significantly higher at 10 μL/min, emphasizing the need for ion source housing in APCI sources dedicated to low flow rates.
- Publikační typ
- časopisecké články MeSH
Fatty acid esters of long-chain hydroxy fatty acids or (O-acyl)-hydroxy fatty acids (OAHFAs) were identified for the first time in vernix caseosa and characterized using chromatography and mass spectrometry. OAHFAs were isolated from the total lipid extract by a two-step semipreparative TLC. The general structure of OAHFAs was established using high-resolution and tandem mass spectrometry of intact lipids and their transesterification and derivatization products. Two isomeric lipid classes were identified: O-acyl esters of ω-hydroxy fatty acids (ωOAHFA) and O-acyl esters of α-hydroxy fatty acids (αOAHFAs). To the best of our knowledge, αOAHFAs have never been detected in any biological sample before. Chromatographic separation and identification of OAHFAs species were achieved using non-aqueous reversed-phase HPLC coupled to electrospray ionization hybrid linear ion trap-Orbitrap mass spectrometry. The lipid species were detected as deprotonated molecules, and their structures were elucidated using data-dependent fragmentation in the negative ion mode. More than 400 OAHFAs were identified in this way. The most abundant ωOAHFAs species were 28:0/ω-18:2, 29:0/ω-18:2, 30:0/ω-18:2, 32:0/ω-18:2, and 30:0/ω-18:3, while αOAHFAs comprised saturated species 21:0/α-24:0, 22:0/α-24:0, 23:0/α-24:0, 24:0/α-24:0, and 26:0/α-24:0. OAHFAs were estimated to account for approximately 0.04% of vernix caseosa lipids. Graphical Abstract.
The queens of advanced social insects maintain their reproductive monopoly by using exocrine chemicals. The chemistry of these "queen pheromones" in termites is poorly known. We show that primary queens of four higher termites from the subfamily Syntermitinae (Embiratermes neotenicus, Silvestritermes heyeri, Labiotermes labralis, and Cyrilliotermes angulariceps) emit significant amounts of the sesquiterpene alcohol (E)-nerolidol. It is the dominant analyte in queen body washes; it is present on the surface of eggs, but absent in kings, workers, and soldiers. In E. neotenicus, it is also produced by replacement neotenic queens, in quantities correlated with their fertility. Using newly synthesised (3R,6E)-nerolidol, we demonstrate that the queens of this species produce only the (R) enantiomer. It is distributed over the surface of their abdomen, in internal tissues, and in the haemolymph, as well as in the headspace of the queens. Both (R) and (S) enantiomers are perceived by the antennae of E. neotenicus workers. The naturally occurring (R) enantiomer elicited a significantly larger antennal response, but it did not show any behavioural effect. In spite of technical difficulties encountered in long-term experiments with the studied species, (3R,6E)-nerolidol remains among eventual candidates for the role in queen fertility signalling.
