Magnetic Resonance in Chemistry最新文献

{"title":"Structural elucidation and complete NMR spectral assignments of Monascus monacolin analogues","authors":"Jiachen Liu,&nbsp;Qingjiang Xu,&nbsp;Xin Wang,&nbsp;Xiaoya Shang,&nbsp;Nan Wang","doi":"10.1002/mrc.5447","DOIUrl":"10.1002/mrc.5447","url":null,"abstract":"<p>Three new monacolin analogues, 3,6-dihydroxy-monacolin P (<b>1</b>), 6-methoxy monacolin S (<b>2</b>), and 6-methoxy dehydromonacolin S (<b>3</b>), were isolated from a fraction that strongly inhibited 3-hydroxy-3-methylglutaryl-CoA reductase from the ethyl acetate portion of red yeast rice ethanol extract. Their structures were determined through a combination of 1D and 2D NMR experiments, mass spectrometry analysis, and known literature reports.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 8","pages":"605-609"},"PeriodicalIF":1.9,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140625001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Full configurational and conformational analysis of artemisinin by one-bond carbon–carbon residual dipolar couplings at natural abundance","authors":"Clemens Anklin,&nbsp;Roberto R. Gil","doi":"10.1002/mrc.5443","DOIUrl":"10.1002/mrc.5443","url":null,"abstract":"<p>Configurational and conformational analysis of the biologically relevant natural product artemisinin was conducted using carbon–carbon residual dipolar couplings (¹<i>D</i>_CC RDCs) at natural abundance. These RDCs were measured through the 2D-INADEQUATE NMR experiment using a sample aligned in a compressed poly (methyl methacrylate) (PMMA) gel swollen in CDCl₃. Singular value decomposition (SVD) fitting analysis of all carbon–carbon bonds, ¹<i>D</i>_CC RDCs, in relation to the full configuration/conformational space (32 diastereoisomers) of artemisinin, unambiguously identified the correct configuration of artemisinin.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 8","pages":"599-604"},"PeriodicalIF":1.9,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5443","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140336171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering molecular structures: NMR spectroscopy and quantum mechanical insights of halogenated 4H-Chromenediones","authors":"Lucas M. O. S. Martins,&nbsp;Francielly Thais Souto,&nbsp;Thomas R. Hoye,&nbsp;Elson S. Alvarenga","doi":"10.1002/mrc.5445","DOIUrl":"10.1002/mrc.5445","url":null,"abstract":"<p>Sesquiterpene lactones (SL) represent a class of secondary metabolites found in the <i>Asteraceae</i> family, notable for their unique structures. The SL α-santonin (<b>1</b>) and its derivatives are worthy of mention due to their diverse biological properties. Additionally, 4<i>H</i>-chromenes and 4<i>H</i>-chromones are appealing frameworks holding the capability to be used as structural motifs for new drugs. Furthermore, unambiguous structural elucidation is crucial for developing novel compounds for diverse applications. In this context, it is common to find in the literature molecules erroneously assigned. Therefore, the use of quantum mechanical calculations to simulate NMR chemical shifts has emerged as a valuable strategy. In this work, we conceived the synthesis of two halogenated 4<i>H</i>-chromenediones derived from photosantonic acid (<b>2</b>), a photoproduct arising from irradiation of α-santonin (<b>1</b>) in the ultraviolet region. The structure of the chlorinated and brominated products was determined by NMR analysis, with the aid of quantum mechanical calculations at the B3LYP/6-311 + G(2d,p)//M062x/6-31 + G(d,p) level of theory. All analyses were in agreement and led to the assignment of the brominated 4<i>H</i>-chromene-2,7-dione as (3<i>S</i>,3a<i>S</i>,5a<i>R</i>,9b<i>S</i>)-5a-(2-bromopropan-2-yl)-3-methyl-3,3a,5,5a,8,9b-hexahydro-4<i>H</i>-furo[2,3-<i>f</i>]chromene-2,7-dione (<b>11b</b>) and of the chlorinated 4<i>H</i>-chromene-2,7-dione as (3<i>S</i>,3a<i>S</i>,5a<i>R</i>,9b<i>S</i>)-5a-(2-chloropropan-2-yl)-3-methyl-3,3a,5,5a,8,9b-hexahydro-4<i>H</i>-furo[2,3-<i>f</i>]chromene-2,7-dione (<b>12b</b>). The diastereoselectivities of the reactions were explained based on products and intermediates formation energy calculated using B3LYP/6-31 + G(d,p) as the level of theory. Structures <b>11b</b> and <b>12b</b> were identified as the thermodynamic and kinetic products of the reaction among all candidates. Consequently, the strategy utilized in this study is robust and successfully illustrates the use of quantum mechanical calculations in the structural elucidation of new compounds with potential applications as novel drugs or products.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 8","pages":"583-598"},"PeriodicalIF":1.9,"publicationDate":"2024-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140336170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DFT investigation of coupling constant anomalies in substituted β-lactams","authors":"Emily B. Crull,&nbsp;Alexei V. Buevich,&nbsp;Gary E. Martin,&nbsp;Rohit Mahar,&nbsp;Bo Qu,&nbsp;Chris H. Senanayake,&nbsp;Tadeusz F. Molinski,&nbsp;R. Thomas Williamson","doi":"10.1002/mrc.5444","DOIUrl":"10.1002/mrc.5444","url":null,"abstract":"<p>β-lactams are a chemically diverse group of molecules with a wide range of biological activities. Having recently observed curious trends in ²<i>J</i>_HH coupling values in studies on this structural class, we sought to obtain a more comprehensive understanding of these diagnostic NMR parameters, specifically interrogating ¹<i>J</i>_CH, ²<i>J</i>_CH, and ²<i>J</i>_HH, to differentiate 3- and 4-monosubstituted β-lactams. Further investigation using computational chemistry methods was employed to explore the geometric and electronic origins for the observed and calculated differences between the two substitution patterns.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 8","pages":"573-582"},"PeriodicalIF":1.9,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5444","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140175375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to “A reliable external calibration method for reaction monitoring with benchtop NMR”","authors":"","doi":"10.1002/mrc.5442","DOIUrl":"10.1002/mrc.5442","url":null,"abstract":"<p>\u0000 <span>T. Maschmeyer</span>, <span>B. Conklin</span>, <span>T. C. Malig</span>, <span>D. J. Russell</span>, <span>K. L. Kurita</span>, <span>J. E. Hein</span>, <span>J. G. Napolitano</span>, <i>Magn Reson Chem</i> <span>2024</span>, <span>62</span>(<span>3</span>), <span>169</span>. https://doi.org/10.1002/mrc.5421</p><p>This article, erroneously published in <i>Magnetic Resonance in Chemistry</i>, Volume 62, Issue 3, 2024, is an article from Special Issue: Benchtop/Cryofree NMR.</p><p>We apologize for this error.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 4","pages":"323"},"PeriodicalIF":2.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5442","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140119938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SimpleNMR: An interactive graph network approach to aid constitutional isomer verification using standard 1D and 2D NMR experiments","authors":"Eric Hughes,&nbsp;Alan M. Kenwright","doi":"10.1002/mrc.5441","DOIUrl":"10.1002/mrc.5441","url":null,"abstract":"<p>Despite progress in computer automated solutions, constitutional isomer verification by NMR using one- and two-dimensional data sets is still, in the main, a manual, user-intensive activity that is challenging for a number of reasons. These include the problem of simultaneously keeping track of the information from a number of separate NMR experiments and the difficulty of another researcher subsequently verifying the assignments made without having to independently repeat the whole analysis. This paper describes a graphical interactive approach that overcomes some of these problems. By using concepts used to visualise graph networks, we have been able to represent the NMR data in a manner that highlights directly the link between the different NMR experiments and the molecule of interest. Furthermore, by making the graph networks interactive, a user can easily validate and correct the assignment and understand the decisions made in arriving at the solution. We have developed a usable proof-of-concept computer program, ‘simpleNMR’, written in Python to illustrate the ideas and approach.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 7","pages":"556-565"},"PeriodicalIF":2.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5441","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140039790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methyl α-D-galactopyranosyl-(1→3)-β-D-galactopyranoside and methyl β-D-galactopyranosyl-(1→3)-β-D-galactopyranoside: Glycosidic linkage conformation determined from MA'AT analysis","authors":"Reagan Meredith,&nbsp;Yuping Zhu,&nbsp;Mi-Kyung Yoon,&nbsp;Timothy Tetrault,&nbsp;Jieye Lin,&nbsp;Wenhui Zhang,&nbsp;Margaret McGurn,&nbsp;Evan Cook,&nbsp;Reed Popp,&nbsp;Pradip Shit,&nbsp;Ian Carmichael,&nbsp;Anthony S. Serianni","doi":"10.1002/mrc.5424","DOIUrl":"10.1002/mrc.5424","url":null,"abstract":"<p><i>MA'AT</i> analysis has been applied to two biologically-important <i>O</i>-glycosidic linkages in two disaccharides, α-D-Gal<i>p</i>-(1→3)-β-D-Gal<i>p</i>OMe (<b>3</b>) and β-D-Gal<i>p</i>-(1→3)-β-D-Gal<i>p</i>OMe (<b>4</b>). Using density functional theory (DFT) to obtain parameterized equations relating a group of trans-<i>O</i>-glycosidic NMR spin-couplings to either <i>phi</i> (<i>ϕ'</i>) or <i>psi</i> (<i>ψ'</i>), and experimental ³<i>J</i>_COCH, ²<i>J</i>_COC, and ³<i>J</i>_COCC spin-couplings measured in aqueous solution in ¹³C-labeled isotopomers, probability distributions of <i>ϕ'</i> and <i>ψ'</i> in each linkage were determined and compared to those determined by aqueous 1-μs molecular dynamics (MD) simulation. Good agreement was found between the <i>MA'AT</i> and single-state MD conformational models of these linkages for the most part, with modest (approximately &lt;15°) differences in the mean values of <i>ϕ'</i> and <i>ψ'</i>, although the envelope of allowed angles (encoded in circular standard deviations or CSDs) is consistently larger for <i>ϕ'</i> determined from <i>MA'AT</i> analysis than from MD for both linkages. The <i>MA'AT</i> model of the α-Gal<i>p</i>-(1→3)-β-Gal<i>p</i> linkage agrees well with those determined previously using conventional NMR methods (³<i>J</i>_COCH values and/or ¹H-¹H NOEs), but some discrepancy was observed for the β-Gal<i>p</i>-(1→3)-β-Gal<i>p</i> linkage, which may arise from errors in the conventions used to describe the linkage torsion angles. Statistical analyses of X-ray crystal structures show ranges of <i>ϕ'</i> and <i>ψ'</i> for both linkages that include the mean angles determined from <i>MA'AT</i> analyses, although both angles adopt a wide range of values in the crystalline state, with <i>ϕ'</i> in β-Gal<i>p</i>-(1→3)-β-Gal<i>p</i> linkages showing greater-than-expected conformational variability.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 7","pages":"544-555"},"PeriodicalIF":2.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139983232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ambient temperature 1H/13C NMR spectra of sodium 3-(trimethylsilyl)propane-1-sulfonate (DSS) in D2O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples","authors":"Ryszard B. Nazarski","doi":"10.1002/mrc.5440","DOIUrl":"10.1002/mrc.5440","url":null,"abstract":"<p>This study aimed to obtain the title spectra and verify the temperature dependence of δ_DSS of the HOD signal from D₂O of the NMR sample. However, the analysis of the collected δ_X data, extended by the results of other closely related measurements reported in the literature, provided important guidelines for performing routine ¹H/¹³C NMR spectra in aqueous solvents externally referenced to neat liquid TMS contained in a coaxial capillary. Therefore, it is recommended that the previously proposed correction of δ_X data thus determined, which is mainly due to the difference in volume magnetic susceptibility <i>χ</i>_v between the sample and the external standard used, usually called the bulk magnetic susceptibility (BMS) correction, has been increased by +0.05 ppm (7%). The new value of this correction, +0.73 ppm, based on NMR experiments carried out at a standard temperature of 25°C, was confirmed in a classical approach using critically reviewed <i>χ</i>_m, <i>χ</i>_M, and <i>ρ</i> data for TMS, D₂O, and H₂O. The BMS correction for H₂O solutions is +0.75 ppm. Important issues concerning magnetic susceptibility measurements for D₂O and H₂O, coaxial bulb-ended inserts, and the geometry of two-tube NMR cells (shape factor α_av) are also critically discussed here, partly from a historical perspective.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 7","pages":"535-543"},"PeriodicalIF":2.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139972527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of complex mixtures with benchtop nuclear magnetic resonance: Solvent suppression with T2 and diffusion filters","authors":"Anh Le-McClain,&nbsp;Curt Zanelotti,&nbsp;Hector Robert,&nbsp;Federico Casanova","doi":"10.1002/mrc.5438","DOIUrl":"10.1002/mrc.5438","url":null,"abstract":"<p>Benchtop nuclear magnetic resonance (NMR) spectrometers are being employed in a wide variety of applications from undergraduate teaching and research in academia to quality control and process monitoring in industrial settings. Incorporating benchtop NMR in some of these applications presents opportunities for new practical uses of the technology and challenges that truly test the capabilities of compact NMR spectrometers. For instance, the use of protonated solvents in manufacturing or process monitoring requires separating and quantitating the analyte signals of interest from the strong (overwhelming) response from the solvents. Furthermore, due to the lower field strength available with permanent magnet spectrometers, the NMR spectra of complex mixtures can be more difficult to analyze due to partial or complete signal overlap. To address some of these challenges and to extend the range of applications of benchtop NMR, we investigate NMR techniques that enable quantitative analysis of different components in mixtures. These pulse sequences can be used to suppress one or multiple solvent peaks, to filter out signals by spin–spin relaxation time (<i>T</i>₂), or to separate signal components by a molecule's diffusion coefficient (NMR diffusometry). In this paper, we discuss quantitative analysis of excipients in buffers for therapeutic proteins to highlight the usefulness of these NMR pulse sequences in the analysis of complex samples with benchtop NMR spectrometers.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 7","pages":"497-504"},"PeriodicalIF":2.0,"publicationDate":"2024-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139900201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryogen-free 400-MHz nuclear magnetic resonance spectrometer as a versatile tool for pharmaceutical process analytical technology","authors":"Maria Victoria Silva Elipe,&nbsp;Ikenna Edward Ndukwe,&nbsp;James I. Murray","doi":"10.1002/mrc.5434","DOIUrl":"10.1002/mrc.5434","url":null,"abstract":"<p>The discovery of new ceramic materials containing Ba-La-Cu oxides in 1986 that exhibited superconducting properties at high temperatures in the range of 35 K or higher, recognized with the Nobel Prize in Physics in 1987, opened a new world of opportunities for nuclear magnetic resonance (NMRs) and magnetic resonance imaging (MRIs) to move away from liquid cryogens. This discovery expands the application of high temperature superconducting (HTS) materials to fields beyond the chemical and medical industries, including electrical power grids, energy, and aerospace. The prototype 400-MHz cryofree HTS NMR spectrometer installed at Amgen's chemistry laboratory has been vital for a variety of applications such as structure analysis, reaction monitoring, and CASE-3D studies with RDCs. The spectrometer has been integrated with Amgen's chemistry and analytical workflows, providing pipeline project support in tandem with other Kinetic Analysis Platform technologies. The 400-MHz cryofree HTS NMR spectrometer, as the name implies, does not require liquid cryogens refills and has smaller footprint that facilitates installation into a chemistry laboratory fume hood, sharing the hood with a process chemistry reactor. Our evaluation of its performance for structural analysis with CASE-3D protocol and for reaction monitoring of Amgen's pipeline chemistry was successful. We envision that the HTS magnets would become part of the standard NMR and MRI spectrometers in the future. We believe that while the technology is being developed, there is room for all magnet options, including HTS, low temperature superconducting (LTS) magnets, and low field benchtop NMRs with permanent magnets, where utilization will be dependent on application type and costs.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"62 7","pages":"512-534"},"PeriodicalIF":2.0,"publicationDate":"2024-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5434","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139900202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}