scholarly journals Elucidating Tricin-Lignin Structures: Assigning Correlations in HSQC Spectra of Monocot Lignins

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 916 ◽  
Author(s):  
Wu Lan ◽  
Fengxia Yue ◽  
Jorge Rencoret ◽  
José del Río ◽  
Wout Boerjan ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Model Compounds ◽  
Heteronuclear Correlation ◽  
Nmr Methods ◽  
Nuclear Magnetic ◽  
Lignin Structure

Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4′–O–β coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H–13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4′–O–β-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cβ/Hβ of 4′–O–β unit, producing peaks at around δC/δH 82.5–83.5/4.15–4.45, that differ from the Cβ/Hβ correlations from normal 4–O–β units formed solely by monolignols, and that have to date been unassigned.

scholarly journals Identification and analysis of N-alkyl-N’-arylalkylureas by nuclear magnetic resonance

2020 ◽  
Vol 130 (1) ◽  
pp. 18-22
Author(s):  
A.A. Bakibaev ◽  
◽  
М.Zh. Sadvakassova ◽  
R.Sh. Еrkasov ◽  
А.Е. Аtagulova ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Systematic Analysis ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Methods ◽  
Nuclear Magnetic

This paper presents the results that allow one to reliably identify N-alkyl- (10 compounds) and N-alkyl-N’- arylalkylureas (12 compounds) based on the data of 1H and 13C nuclear magnetic resonance (NMR) methods. A systematic analysis has been carried out of chemical shifts in the NMR spectra of the compounds. Additionally, the authors have investigated the effect of the nitrogen atoms substituents on the chemical shifts in the NH2, NH, and C = O groups of urea.

Sesquiterpene alkaloids from Tripterygiumwilfordii (Hook): a nuclear magnetic resonance study of 1-desacetylwilfordine, 1-desacetylwilfortrine, and 2-debenzoyl-2-nicotinoylwilforine

1990 ◽  
Vol 68 (3) ◽  
pp. 371-374 ◽  
Author(s):  
Li Ya ◽  
George M. Strunz ◽  
Larry A. Calhoun
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Chemical Shift Assignments ◽  
Magnetic Resonance Study ◽  
Root Extracts ◽  
C Nmr ◽  
Nuclear Magnetic

1-Desacetylwilfordine, 8, 1-desacetylwilfortrine, 9, and 2-debenzoyl-2-nicotinoylwilforine, 10, have been isolated from root extracts of the Chinese medicinal and insecticidal plant Tripterygiumwilfordii. Analysis of the 1H and 13C NMR spectra of 8 and 10, with the aid of COSY, HCCOSY, and COLOC experiments, has allowed unambiguous chemical shift assignments of all protons and carbons of these alkaloids. Keywords: alkaloids, sesquiterpene, Celastraceae, Tripterygium, NMR.

scholarly journals P052 Nuclear magnetic resonance metabolomic profiling of IBD patients under anti-TNF treatment. Are the pathways network deregulated?

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S160-S160
Author(s):  
S Notararigo ◽  
M Martin-Pastor ◽  
J E Dominguez Munoz ◽  
M Barreiro-de Acosta
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Mononuclear Cells ◽  
High Rate ◽  
Resonance Spectroscopy ◽  
Serum Samples ◽  
Spectral Window ◽  
Metabolomic Study ◽  
Nuclear Magnetic

Abstract Background The deregulation of immune system cell response implies loss of T-cell apoptosis, high rate of proinflammatory cytokines production and subsequent exacerbate activation of TNF-α pathway. The use of biologic antibody decrease inflammation rate and symptoms, but it remains unclear if it has a direct effect on the pathways activation/inactivation on peripheral blood mononuclear cells (PBMCs). The aim of this study is evaluate the role of nuclear magnetic resonance spectroscopy (NMR) applied to the metabolomic study of serum samples isolated from fresh blood from inflammatory bowel disease (IBD) patients under IFX treatment to understand the activated/inactivated pathways of PBMCs. Methods A case–control study was performed. Inclusion criteria were IBD patients under IFX treatment. Blood samples were obtained in Crohn’s disease (CD) and ulcerative colitis (UC) patients before IFX and in healthy controls (CTRL). CD patients were divided into subgroups according to the gut affected, in Ileocolic (IC), ileum and colon. NMR samples of the serum were collected and measured according to Standard Operation Procedures. Three types of NMR spectra were measured for each serum sample (1Hnoepresat, 1Hcpmgpresat and 1HDfilterpresat). The signal in each NMR spectrum was integrated in a series of equidistant little portion of the spectrum called buckets of a constant width of 0.04 ppm, covering the complete 1H NMR spectral window from −5 to 14 ppm. Buckets in regions depleted from signal at the two extremes of the spectrum were discarded as well as those in the proximity of the water peak at ca. 4.7 ppm which was affected by the presaturation. The vectors corresponding to a number of samples of two or more groups can be rapidly analysed using Multivariant Statistical Analysis methods. Results Twenty-two IBD patients (12 CD and nine UC) were included, 10 CTRL were also included. The metabolomic analyses of the NMR spectra of the serum of the different patients and control groups by the fingerprinting and targeting profiling strategies provided OPLS-DA statistical models (Figure 1) that permitted the successful classification of certain groups of samples which are summarised in Table 1. Conclusion The results of this pilot NMR metabolomic study of serum samples of IBD found a series of spectral fingerprints that are able to discriminate between groups of patients CTRL and CD, which underlines its potential use for the diagnosis of the disease.

The metal nuclear magnetic resonance spectra of some tin(II) and lead(II) complexes with polydentate phosphines

1983 ◽  
Vol 61 (8) ◽  
pp. 1795-1799 ◽  
Author(s):  
Philip A. W. Dean
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Narrow Range ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The previously reported 1:1 complexes formed in MeNO2, between M(SbF6)2 (M = Sn or Pb) and Ph2P(CH2)2PPh2, PhP[(CH2)2PPh2]2, MeC(CH2PPh2)3, P[(CH2)2PPh2]3, and [Formula: see text] have been studied by metal (119Sn or 207Pb) nmr. The metal chemical shifts span the comparatively narrow range of −586 to −792 ppm and 60 to −269 ppm, relative to the resonance of MMe4, for 119Sn and 207Pb nmr, respectively. The implications of these data regarding the denticity of the ligand in M(P[(CH2)2PPh2]3)2+ are discussed, and a comparison with the metal nmr spectra of related stannous and plumbous complexes is made.

NUCLEAR MAGNETIC RESONANCE STUDIES: IX. THE CHEMICAL SHIFT OF THE FORMYL PROTON IN ALIPHATIC ALDEHYDES

1966 ◽  
Vol 44 (1) ◽  
pp. 45-51 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Aliphatic Aldehydes ◽  
Magnetic Resonance Studies ◽  
Unsaturated Aldehydes ◽  
Potential Use ◽  
Nuclear Magnetic

The effects of structure on the shielding of formyl protons of aliphatic aldehydes have been examined. The survey included examples of acyclic, alicyclic, and α, β-unsaturated aldehydes. The potential use of these results as an aid for structural elucidations is discussed, and the limitations are noted.

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