Metabolomics is defined as a matrix of studies on the methodologies and analytical technologies related to data analysis in microorganisms, plants, and animals. In humans, about 50–200 metabolites have been identified, improving our understanding of the metabolome and genomics. A broad range of fields commonly apply metabolomics studies, including those related to the effects of drugs, cellular function, and drug discovery, as well as to the search for biomarkers of diseases. It is possible to divide a well-designed metabolomics study into phases, including ethical approval, sample collection and preparation, sample analysis (Liquid or Gas Chromatography Coupled to Mass Spectrometry - LC-MS/GC-MS, High or Ultrahigh Performance Liquide Chromatography - HPLC/UPLC, or Nuclear Magnetic Resonance - NMR), identification/quantification of metabolites, statistical analysis, and biochemical interpretation. In studies involving biological samples, the use of NMR has increased, in comparison with GC-MS and LC-MS, because NMR presents advantages, including the fact that it is nondestructive to samples, no chromatographic separation is needed, and there is a possibility of determining unknown metabolites. In addition to discussing NMR-based metabolomics studies involving biological samples from humans, in this chapter, we discuss essential aspects in early stages, including sample preparation in phosphate buffer, utilization of internal standards, the importance of water suppression, and the use of 1D and 2D NMR spectroscopies for identification of metabolites. Thereafter, the most often-used multivariate analysis in chemometrics will also be presented, demonstrating which OPLS-DA method is the best option for group discrimination.Some metabolites identified in human biofluids will be described, especially those associated with pathological conditions or dysregulation in metabolic pathways for different types of cancer. Finally, we present the results of a preliminary NMR-based metabolomics study involving patients with colorectal cancer and healthy volunteers.
The importance of nuclear magnetic resonance (NMR) spectroscopy for the food industry, including the coffee industry, has led to several studies using this analytical tool to assess coffee in different scenarios. In this context, this chapter presents an overview of 1H NMR-based metabolomics analysis used in coffee quality control. Several articles using 1H NMR associated with multivariate data analysis have been published to investigate aspects related to quality, authenticity, sensory quality, production processes, and origin of coffee. In addition, the present review reports the main chemical shifts of the constituents present in the extracts of green and roasted coffee beans. The results presented confirm the potential and versatility of 1H NMR combined with chemometric tools for coffee analysis, playing an important role in distinguishing and identifying the origins, quality, and purity of coffee. Exploratory data analysis, classification, and calibration are the most used chemometric methods in metabolomics applied in the coffee field. The results show the potential of NMR and multivariate data analysis for coffee authentication.
Cyanobacteria are ubiquitous in nature as they efficiently tolerate various extreme climatic conditions for survival, such as increasing effects of solar radiation, salinity, temperature, etc. Cyanobacteria are important sources of secondary metabolites, which enable them to withstand these harsh environmental conditions. Small-molecular-weight secondary compounds are primarily implied in the defense mechanisms in case of biotic and abiotic stresses. Various beneficiary secondary compounds are extracted from cyanobacteria, such as UV-screening pigments (mycosporine-like amino acids, scytonemin, carotenoids, etc.), phytohormones, cyanotoxins and antioxidants. Bioactivity-directed isolation techniques are used to identify these molecules from complicated matrices in pharmacognosy (discovery of biologically active compounds from natural sources). NMR spectroscopy has appeared as a specific major analytical technique applied in metabolomics. The easy sample preparation, the expertise to evaluate metabolite quantity, the notable investigational reliability, and the innately non-destructive quality of NMR spectroscopy have made it the first-line option for significant scientific metabolic analyses. Unlike some mass spectrometry methods, NMR is not discriminatory, depending on the metabolites' precursors or their ionization potential. Screening of metabolites needs maximum sensitivity, and it is a process with a broad scope. In this chapter, we have discussed the usage of NMR spectroscopy in the identification of photoprotective compounds and its advantages and disadvantages for metabolomic studies. We have also explored several new NMR techniques that have recently become available in order to fortify its advantages and overcome its inherent limitations in metabolomics applications.
Nuclear magnetic resonance (NMR) spectroscopy is one of the mostimportant spectroscopic methods for lignin characterization, playing a key role in itsstructural elucidation and the choice of its suitable application. This chapter intends tocover a wide range of matters regarding the NMR utilization in the lignin field from thebiorefinery up to lignin valorization through different chemical modifications in orderto produce high-added-value products with potential technological applications. Thechapter is divided into four main sections, in which the first and second ones willprovide a review of the main structural properties, NMR experiments used for lignincharacterization, and the recent advances of this technique. The third section iscomposed of topics about biorefinery with a focus on microwave-assisted organosolvdelignification (MWAOD) and how the main pulping parameters affect the ligninstructure, besides the use of NMR as a quality control tool for MWAOD up-scaling.Finally, the fourth section discusses NMR as a tool for determining structure-propertyrelationship by performing some chemical modifications in lignin structure aiming itsvalorization, such as glycidylation, microwave-assisted phosphorylation, microwaveassistedselective acetylation, and the performance of lignins from different pulpingprocesses as antioxidant compounds and the influence of their structure on it.Therefore, this chapter contributes to the development of the lignin field by reviewingthe recent advances provided by NMR spectroscopy.
Objective: The objective of this chapter is to highlight the current developments in NMR spectroscopy for chiral recognition of pharmaceuticals reported during the past five years. Introduction: NMR spectroscopy is an effective technique to contextualize structural characteristics and chirality discrimination of various compounds. During the past few decades, extensive studies have been carried out on chirality recognition (CR) of organic compounds, including pharmaceuticals. The assessment of enantiomeric drugs and related methods have become a customary assignment in most NMR labs, enabling the identification of molecular connectivity as well as the development of conceptual frameworks. Background: Various NMR active nuclei (1H, 13C, 19F, & 31P, etc.) can be used to strengthen the CR abilities of NMR spectroscopy. NMR active nuclei are isochronic in the optically inactive environment and thus unable to exhibit CR. However, certain nuclei are anisochronic in a chiral atmosphere making CR feasible. CR capabilities of NMR are dependent on the application of chiral discriminating agents such as chiral derivatizing agents (CDAs), chiral lanthanide shift reagents (CLSRs), and chiral solvating agents (CSAs) that essentially contain a chiral auxiliary. CDAs tend to bind covalently with a functional group of the analytes, whereas CSAs bind vis non-covalent associations, like dipoledipole and ion-pair, etc. However, CLSRs, like CSAs, do not bind covalently with the enantiomers of analytes. However, CLSRs, like CSAs, do not bind covalently with the enantiomers of analytes rather they comprise a paramagnetic center that can bring chemical shift difference of diastereotopic nuclei. Method: Herein, the recent developments in methods based on NMR spectroscopy for CR of certain chiral drugs using various chiral discriminating agents are discussed. Application: The methods described herein can be an assessment tool to provide details of molecular geometry and the construction of spatial relationships of chiral molecules.
