Carbon-carbon double bond position elucidation in fatty acids using ozone-coupled direct analysis in real time mass spectrometry

Recent advances in the application of direct analysis in real time-mass spectrometry (DART-MS) in food analysis

Direct analysis in real time-mass spectrometry (DART-MS) has evolved as an effective analytical technique for the rapid and accurate analysis of food samples. The current advancements of DART-MS in food analysis are described in this paper. We discussed the DART principles, which include devices, ionization mechanisms, and parameter settings. Numerous applications of DART-MS in the fields of food and food products analysis published during 2018-2023 were reviewed, including contamination detection, food authentication and traceability, and specific analyte analysis in the food matrix. Furthermore, the challenges and limitations of DART-MS, such as matrix effect, isobaric component analysis, cost considerations and accessibility, and compound selectivity and identification, were discussed as well.

Quantitative mass spectrometry imaging: therapeutics & biomolecules

Mass spectrometry imaging (MSI) has become increasingly utilized in the analysis of biological molecules. MSI grants the ability to spatially map thousands of molecules within one experimental run in a label-free manner. While MSI is considered by most to be a qualitative method, recent advancements in instrumentation, sample preparation, and development of standards has made quantitative MSI (qMSI) more common. In this feature article, we present a tailored review of recent advancements in qMSI of therapeutics and biomolecules such as lipids and peptides/proteins. We also provide detailed experimental considerations for conducting qMSI studies on biological samples, aiming to advance the methodology.

The Biological and Molecular Action of Ozone and Its Derivatives: State-of-the-Art, Enhanced Scenarios, and Quality Insights

The ultimate objective of this review is to encourage a multi-disciplinary and integrated methodological approach that, starting from the recognition of some current uncertainties, helps to deepen the molecular bases of ozone treatment effects on human and animal well-being and to optimize their performance in terms of reproducibility of results, quality, and safety. In fact, the common therapeutic treatments are normally documented by healthcare professionals' prescriptions. The same applies to medicinal gases (whose uses are based on their pharmacological effects) that are intended for patients for treatment, diagnostic, or preventive purposes and that have been produced and inspected in accordance with good manufacturing practices and pharmacopoeia monographs. On the contrary, it is the responsibility of healthcare professionals, who thoughtfully choose to use ozone as a medicinal product, to achieve the following objectives: (i) to understand the molecular basis of the mechanism of action; (ii) to adjust the treatment according to the clinical responses obtained in accordance with the principles of precision medicine and personalized therapy; (iii) to ensure all quality standards.

Plasma-based ambient mass spectrometry: Recent progress and applications

Ambient mass spectrometry (AMS) has grown as a group of advanced analytical techniques that allow for the direct sampling and ionization of the analytes in different statuses from their native environment without or with minimum sample pretreatments. As a significant category of AMS, plasma-based AMS has gained a lot of attention due to its features that allow rapid, real-time, high-throughput, in vivo, and in situ analysis in various fields, including bioanalysis, pharmaceuticals, forensics, food safety, and mass spectrometry imaging. Tens of new methods have been developed since the introduction of the first plasma-based AMS technique direct analysis in real-time. This review first provides a comprehensive overview of the established plasma-based AMS techniques from their ion source configurations, mechanisms, and developments. Then, the progress of the representative applications in various scientific fields in the past 4 years (January 2017 to January 2021) has been summarized. Finally, we discuss the current challenges and propose the future directions of plasma-based AMS from our perspective.

Positional Assignment of C-C Double Bonds in Fatty Acyl Chains of Intact Arsenosugar Phospholipids Occurring in Seaweed Extracts by Epoxidation Reactions

Water-soluble diacyl arsenosugar phospholipids (As-PL) are natural products widespread in marine animals and algae, including the brown alga Undaria pinnatifida, also known as wakame. The systematic recognition of As-PL has been hampered by the lack of standard and of qualitative methods to establish the carbon-carbon double bond positions of unsaturated fatty acyl chains. Here, the epoxidation reaction of fatty acyl substituents of As-PL was carried out with high selectivity by meta-chloroperoxybenzoic acid and the C-C double bond localization was established by collision-induced dissociation of epoxidized species as deprotonated molecules, [epoM - H]-. Reversed-phase liquid chromatography (RPLC) separation and a sequential triple-stage MS (i.e., MS3) analysis of unsaturated and epoxidized As-PL were very helpful to characterize the carbon-carbon double bond locations of both sn-1 and sn-2 fatty acyl chains, starting from a diagnostic product ion pair with 16.0 Da mass difference. These results indicate that intact As-PL can be annotated in terms of fatty acyl chain composition and in terms of their C-C double bond position(s). Interestingly, hexadecenoic (16:1 Δ9) and octadecenoic (18:1 Δ9) along with octadecadienoic (18:2 Δ9,12) and octadecatrienoic (18:3 Δ9,12,15) were found to be the most abundant unsaturated fatty acyl chains of As-PL in the brown alga wakame, thus confirming it as a good source of essential fatty acids with a balanced ω6/ω3 ratio. Although the toxicity of As-including metabolites of algal As-PL is still a matter of debate and needs to be studied in more detail, the described approach can be exploited to assess if As-PL could contribute to the supply of essential fatty acids related to the use of algae as nutritious food.

In situ lipid profiling of insect pheromone glands by direct analysis in real time mass spectrometry

Analysis of biological tissues by Direct Analysis in Real Time mass spectrometry produces semi-quantitative lipid profiles that can be used to distinguish insect species and identify abnormal phenotypes in genetic screens.

Review of Recent Advances in Lipid Analysis of Biological Samples via Ambient Ionization Mass Spectrometry

The rapid and direct structural characterization of lipids proves to be critical for studying the functional roles of lipids in many biological processes. Among numerous analytical techniques, ambient ionization mass spectrometry (AIMS) allows for a direct molecular characterization of lipids from various complex biological samples with no/minimal sample pretreatment. Over the recent years, researchers have expanded the applications of the AIMS techniques to lipid structural elucidation via a combination with a series of derivatization strategies (e.g., the Paternò–Büchi (PB) reaction, ozone-induced dissociation (OzID), and epoxidation reaction), including carbon–carbon double bond (C=C) locations and sn-positions isomers. Herein, this review summarizes the reaction mechanisms of various derivatization strategies for C=C bond analysis, typical instrumental setup, and applications of AIMS in the structural elucidation of lipids from various biological samples (e.g., tissues, cells, and biofluids). In addition, future directions of AIMS for lipid structural elucidation are discussed.

Toward Quantitative Sequencing of Deuteration of Unsaturated Hydrocarbon Chains in Fatty Acids

No general method currently is available for the quantitative determination of deuterium (D) at C positions along a hydrocarbon chain. Bis-allylic deuterated highly unsaturated fatty acids (D-HUFA) are a novel class of drugs stabilized against H-abstraction-mediated oxidation by deuteration at the most labile positions. Ru-based catalytic deuteration overcomes the limited scale of bis-allylic D-HUFA production by total organic synthesis; however, it produces a complex mixture of bis-allylic D isotopologues and isotopomers, requiring detailed sequencing for characterization. We report here adaptation and application of the Paternó-Büchi (PB) reaction of 2-acetylpyridine to a series of D-HUFA with analysis by shotgun lipidomics to determine position-specific quantitative D abundances. Sodiated ^PBD-HUFA result in diagnostic ions of high abundance upon collision-induced dissociation (CID) activation, enabling sensitive differentiation and quantification of D fraction at each bis- and mono-allylic position for each isotopologue. Catalytically deuterated isotopologues D5-7 linolenic acid (D5-7 LnA), D6-8 arachidonic acid (D6-8 ARA), D7-9 eicosapentaenoic acid (D7-9 EPA), and D9-11 docosahexaenoic acid (D9-11 DHA) incorporate 80-98, 95-100, 81-100, and 83-100% D at their bis-allylic positions, respectively. D-HUFA isotopologues having D number greater than or equal to bis-allylic sites (e.g., D10-DHA or D11-DHA) deuterated >95% at bis-allylic positions, except for D-LnA. The mono-allylic position near the methyl end deuterates to a much greater extent than the mono-allylic position near the carboxyl end, and both positions deuterate only when bis-allylic D is near-saturated. This method enables rapid, accurate characterization of position and isotopomer-specific D composition and enables sequencing along the chain.

Lipids: chemical tools for their synthesis, modification, and analysis

Lipids remain one of the most enigmatic classes of biological molecules. Whereas lipids are well known to form basic units of membrane structure and energy storage, deciphering the exact roles and biological interactions of distinct lipid species has proven elusive. How these building blocks are synthesized, trafficked, and stored are also questions that require closer inspection. This tutorial review covers recent advances on the preparation, derivatization, and analysis of lipids. In particular, we describe several chemical approaches that form part of a powerful toolbox for controlling and characterizing lipid structure. We believe these tools will be helpful in numerous applications, including the study of lipid-protein interactions and the development of novel drug delivery systems.

Natural Product Discovery by Direct Analysis in Real Time Mass Spectrometry

Direct analysis in real time mass spectrometry (DART MS) is one of the first ambient ionization methods to be introduced and commercialized. Analysis by DART MS requires minimal sample preparation, produces nearly instantaneous results, and provides detection over a broad range of compounds. These advantageous features are particularly well-suited for the inherent complexity of natural product analysis. This review highlights recent applications of DART MS for species identification by chemotaxonomy, chemical profiling, genetic screening, and chemical spatial analysis from plants, insects, microbes, and metabolites from living systems.

Structure–reactivity relationship of probes based on the H2S-mediated reductive cleavage of the CC bond

The structure–reactivity relationship of H₂S-mediated reductive cleavage of CC bond was studied and utilized to develop probes for detecting H₂S.