Magnetic Resonance in Chemistry最新文献

Six sesquiterpene derivative compounds (1–6), including one new 7R-sydowic acid (1) and five known compounds (2–6) were isolated from the secondary metabolites of Aspergillus sydowii-HB. The structures were determined by NMR spectroscopy and ESI-MS analysis, and the configuration of compound 1 was confirmed through DP4⁺ calculation and NMR chemical shift. All the isolated compounds (1–6) were tested for their cytotoxic activities. The possible biosynthetic pathways for compounds (1–6) were also postulated.

G-protein–coupled receptors (GPCRs) are the largest and most heterogeneous group of cell membrane receptors dictating various physiological processes. GPCRs are the pivotal points for orchestrating almost every cellular response, making them the most sought-after drug targets. Although the GPCRs have extensively been studied, there are still many aspects that are yet to be understood. The GPCR structures have been characterised using various biophysical techniques like x-ray crystallography, cryo-EM and nuclear magnetic resonance (NMR) techniques. While the conventional techniques enabled a gross understanding of the GPCR structures, ligand interaction and conformational dynamics, the recent developments in NMR methods have unlocked new possibilities to better understand receptor bias, ligand-selectivity determination and ligand-binding characterisation in live cells. In this review, we have attempted to highlight how different NMR approaches can be utilised to add more details to the story of GPCRs.

Characterising drug-binding mechanisms, structural changes and dynamics at atomic resolution remains a challenge due to the dynamic and heterogeneous nature of surfactant supramolecular assemblies. In this context, nuclear magnetic resonance (NMR) is uniquely suited to overcome these complexities by offering precise information on binding, structure, dynamics and transport in native-like conditions. NMR spectroscopy, leveraging the nuclear Overhauser effect (NOE), spin-relaxometry and translational self-diffusometry, offers atomistic-level insights into drug–surfactant interactions. NOE measurements reveal spatial proximities between drug and surfactant molecules, while relaxometry captures local dynamics and facilitates the estimation of rotational correlation times for both free and bound drug species. Diffusometry probes global translational motion and geometric features, enabling quantification of the bound drug fraction (p_b) and partition coefficient (K), both of which are pertinent to pharmaceutical and chromatographic contexts. Together, these NMR approaches provide an integrated view of structure, dynamics and transport, which is critical for understanding the physicochemical behaviour of drug–surfactant systems. This mini-review summarizes key solution-state NMR techniques, supported by theoretical models and selected applications, for incisive characterisation of these interactions.

Determination of the correct 3D structure of regioisomers and other proton-deficient molecules such as the breitfussin analogue is a very challenging task. In the current work, we present the structural differentiation between the two regioisomeric forms of a spiro compound using anisotropic NMR data measured in graphene oxide derivatized cyclopentylamine liquid crystal. The constitution of the regioisomer was first derived from various 2D isotropic NMR data using CASE software, from which other possible regioisomer was generated. Finally, the correct 3D structure is obtained from the anisotropic NMR data, which is also further corroborated with DP4 and DP4+ analysis. We also investigated one proton-deficient breitfussin structural analogue. Finally, results obtained from the anisotropic NMR and DP4+ analysis were compared.

Systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) are chronic and complex autoimmune diseases with shared clinical features complicating differential disease diagnosis. Despite similarities, they exhibit distinct pathophysiological mechanisms and disease progression. This study is an attempt to investigate disease-specific metabolic alterations and identify potential biomarkers for differential diagnosis using a nuclear magnetic resonance (NMR)-based serum metabolomics approach. 1D ¹H Carr–Purcell–Meiboom–Gill (CPMG) NMR spectra were recorded, and a total of 35 serum metabolites were quantified using CHENOMX software across SSc, SLE, and healthy control (HC) groups. Multivariate and univariate statistical analyses revealed significant metabolic distinctions between the diseases. SLE is primarily characterized by disruptions in glycolysis, the tricarboxylic acid (TCA) cycle, and oxidative stress, indicating compromised energy metabolism and immune-mediated mitochondrial dysfunction. In contrast, SSc showed distinct perturbations in inositol and amino acid metabolism linked to fibrosis and endothelial dysfunction. Significantly elevated levels of acetate emerged as a key discriminatory metabolite in SSc patients, implying a shift towards enhanced fatty acid oxidation in SSc, potentially fueling fibrotic processes and contributing to the energy demands of chronic inflammation. Specific metabolic ratios (with acetate as the numerator) demonstrated high accuracy in distinguishing SSc from SLE and HC, highlighting their potential as diagnostic biomarkers; including multivariate and multiclass ROC, supported the diagnostic relevance of these markers. The study underscores the metabolic heterogeneity of SLE and SSc, offering new insights and a deeper understanding into their distinct pathological mechanisms and supporting the development of biomarker-based strategies for improved diagnosis, classification, and personalized therapeutic approaches.

Ten secondary amino alcohols were synthesized through condensation reactions using 3-aminopropanol or 2-aminoethanol with cyclohexanone, adamantanone, norcamphor, benzaldehyde, salicylaldehyde, p-hydroxy-benzaldehyde and m-hydroxy-benzaldehyde under pressure with a monowave reactor. Secondary amino alcohols were characterized by ¹H, ¹³C and ¹⁵N. NMR and two-dimensional experiments were used to determine the correct structures and the relative positions of amino alcohols on cyclohexyl and norbornyl groups. To compare their reactivity, the relative protonation constants were determined for 10 mixtures of two compounds by ¹H NMR in an acidic medium using DCl/CD₃OD solution. The steric effects of cyclic groups such as adamantyl and norbornyl, along with para- and ortho-OH effects in benzyl compounds, were analysed to assess their influence on reactivity. In all cases, compound 1 was the most susceptible to protonation, while compound 4 was the least susceptible. A linear relationship exists between the ¹⁵N NMR chemical shifts of cyclic compounds (1, 2, 8, 9 and 10) and their protonation energies. Theoretical calculations, such as molecular electrostatic potential, natural bond orbital, Fukui function and protonation energy, helped us to support the experimental results.