scholarly journals NMR Spectroscopy of Human Eye Tissues: A New Insight into Ocular Biochemistry

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Tomasz Kryczka ◽  
Edward Wylęgała ◽  
Dariusz Dobrowolski ◽  
Anna Midelfart
Keyword(s):  
Nmr Spectroscopy ◽  
Human Eye ◽  
H Nmr ◽  
Biochemical Compounds ◽  
Eye Tissues ◽  
Metabolic Properties ◽  
Human Eyes ◽  
First Time ◽  
Insight Into ◽  
Complex Organ

Background. The human eye is a complex organ whose anatomy and functions has been described very well to date. Unfortunately, the knowledge of the biochemistry and metabolic properties of eye tissues varies. Our objective was to reveal the biochemical differences between main tissue components of human eyes.Methods. Corneas, irises, ciliary bodies, lenses, and retinas were obtained from cadaver globes 0-1/2 hours postmortem of 6 male donors (age: 44–61 years). The metabolic profile of tissues was investigated with HR MAS1H NMR spectroscopy.Results. A total of 29 metabolites were assigned in the NMR spectra of the eye tissues. Significant differences between tissues were revealed in contents of the most distant eye-tissues, while irises and ciliary bodies showed minimal biochemical differences. ATP, acetate, choline, glutamate, lactate, myoinositol, and taurine were identified as the primary biochemical compounds responsible for differentiation of the eye tissues.Conclusions. In this study we showed for the first time the results of the analysis of the main human eye tissues with NMR spectroscopy. The biochemical contents of the selected tissues seemed to correspond to their primary anatomical and functional attributes, the way of the delivery of the nutrients, and the location of the tissues in the eye.

Isolierungen und 11C-NMR-Spektroskopie von Indoleninalkaloiden / Isolation and 13C NMR Spectroscopy of Indolenine Alkaloids

1982 ◽  
Vol 37 (4) ◽  
pp. 494-498 ◽  
Author(s):  
Mohammad Ataullah Khan ◽  
Hans Horn ◽  
Wolfgang Voelter
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
H Nmr ◽  
First Time

The indolenine alkaloids raucaffricine and perakine were isolated from Rauwolfia caffra Sonder and their PFT 13C{1H}-NMR spectra studied for the first time. The interpretations of their spectra were accomplished in correlating with those of quinuclidine, indole, methyl-α-D-galactopyranoside, methyl-β-D-galactopyranoside, methyl-2,6-di-O-methyl-α-D-galactopyranoside and methyl-3-O-methyl-β-D-galactopyranoside.

Carbon versus oxygen nucleophilic selectivity in the reaction of the aryloxide ions, 2,6- and 3,5-di-tert-butylphenoxide, with the 2-[(nitro)\dn6 xaryl]-4,6-dinitrobenzotriazole 1-oxide series of super-electrophiles. Stereoelectronic factors on C-7 Meisenheimer complex formation versus C-1' SNAr displacement

1998 ◽  
Vol 76 (6) ◽  
pp. 662-671 ◽  
Author(s):  
Julian M Dust ◽  
Richard A Manderville
Keyword(s):  
Nmr Spectroscopy ◽  
Nucleophilic Aromatic Substitution ◽  
Nucleophilic Attack ◽  
Aromatic Substitution ◽  
Factors Affecting ◽  
H Nmr ◽  
Sterically Demanding ◽  
Biphenyl Derivative ◽  
First Time ◽  
Electrophilic Site

The 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides (1, Pi-DNBT (x = 3); 2, DNP-DNBT (x = 2); 3, NP-DNBT (x = 1)) are electron-deficient nitro-substituted heteroaromatic substrates that possess two sites for nucleophilic attachment: C-7 and C-1'. Generally, attack at the super-electrophilic C-7 site yields spectroscopically observable anionic sigma -bonded adducts, whereas attack at C-1' leads to displacement products in an overall process of nucleophilic aromatic substitution (SNAr). To gain an understanding of the factors affecting C-1' versus C-7 attack by potentially ambident aryloxide (C- and O-)nucleophiles, we have monitored the reactions of 1-3 with 2,6-di-tert-butylphenoxide (2,6-ArO-) and 3,5-di-tert-butylphenoxide (3,5-ArO-) using 400 MHz 1H NMR spectroscopy (deuterated dimethyl sulfoxide solvent at ambient temperature). The results indicate that 2,6-ArO- acts only as a C-nucleophile with O-attack precluded, presumably by the sterically demanding tert-butyl groups flanking the O-nucleophilic centre. Although 2,6-ArO- reacts preferentially at C-7 of 1-3, the biphenyl derivative that arises from C-1' attack is also observed with 1, the first time that C-nucleophilic attack has been seen at this electrophilic site. In contrast, 3,5-ArO- acts only as an O-nucleophile, also as a consequence of the steric hindrance to the C-4 position; this aryloxide reacts entirely at C-1' of Pi-DNBT but also exclusively at C-7 of 3. However, with DNP-DNBT, 2, both the C-7 O-adduct and C-1' displacement products are noted; attack at C-1' is dominant. The selectivity (C-7 versus C-1') found in these reactions is discussed with emphasis given to stereoelectronic factors that may stabilize the putative C-1' O-adducts.Key words: aryloxides, super-electrophiles, Meisenheimer complexes, 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides.

scholarly journals Biochemical Effects of Routine Gonadectomy on Blood of Domestic Ferrets (Mustela putorius furo)

2020 ◽  
Vol 59 (5) ◽  
pp. 567-574
Author(s):  
Michelle C Whitehead ◽  
Olivia A Petritz ◽  
Mary Doerr ◽  
Michael K Stoskopf ◽  
Tara M Harrison
Keyword(s):  
Nmr Spectroscopy ◽  
Whole Blood ◽  
Clinical Chemistry ◽  
Mustela Putorius ◽  
Plasma Biochemistry ◽  
H Nmr ◽  
Duration Of Surgery ◽  
Methylbutyric Acid ◽  
Insight Into ◽  
Mustela Putorius Furo

We studied domestic ferrets (Mustela putorius furo) to evaluate the physiologic effects of routine surgery. Standard plasma biochemistry panels and 1H-NMR spectroscopy of heparinized whole blood were performed on samples taken 24 h prior to and immediately after surgery from female and male ferrets undergoing routine gonadectomy. Increases in plasma glucose, phosphorus, potassium, and creatine kinase concentrations associated with the duration of surgery were identified on plasma biochemistry panels. Whole-blood NMR spectra allowed us to identify 42 metabolites and one drug residue. Variations between pre- and postoperative metabolite concentrations were most pronounced for female ferrets, which underwent more prolonged surgery than males. Affected metabolites included organic acids and osmolytes (betaine, methylmalonate, <small>D</small>-lactate), fatty acids and lipids (2-hydroxy-3-methylbutyric acid), and amino acid groups (acetylglycine, alloisoleucine, leucine, and isoleucine). These findings indicate that 1H-NMR spectroscopy of whole blood provides insight into metabolic perturbations in domestic ferrets undergoing surgery that are not detected in routine clinical chemistry panels.

Lignin analysis with benchtop NMR spectroscopy

Holzforschung ◽  
2020 ◽  
Vol 74 (2) ◽  
pp. 226-231
Author(s):  
Jerk Rönnols ◽  
Ernesto Danieli ◽  
Hélène Freichels ◽  
Fredrik Aldaeus
Keyword(s):  
Nmr Spectroscopy ◽  
High Field ◽  
Nmr Spectra ◽  
Molar Mass ◽  
Industrial Applications ◽  
H Nmr ◽  
Low Magnetic Field ◽  
Insight Into ◽  
Good Agreement ◽  
Gaining Insight

AbstractBenchtop nuclear magnetic resonance (NMR) spectroscopy is an emerging field with an appealing profile for industrial applications. The instrumentation offers the possibility to measure NMR spectra in situations where high-field NMR spectroscopy is considered too expensive or complicated. In this study, we investigated the scope and limitations of 1H NMR measurements on kraft lignins and black liquors at low magnetic field strengths (1.0 and 1.5 T). The ability to quantify different classes of compounds was investigated and found to be promising. NMR-based diffusion measurements were performed, with the aim of gaining insight into the molar mass of the lignins at hand. These measurements were fast, repeatable and in good agreement with established methods.

scholarly journals Copolymer chain formation of 2-oxazolines by in situ1H-NMR spectroscopy: dependence of sequential composition on substituent structure and monomer ratios

RSC Advances ◽  
2021 ◽  
Vol 11 (18) ◽  
pp. 10468-10478
Author(s):  
Sabina Abbrent ◽  
Andrii Mahun ◽  
Miroslava Dušková Smrčková ◽  
Libor Kobera ◽  
Rafał Konefał ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Polymer Chains ◽  
Chain Formation ◽  
Molar Ratios ◽  
H Nmr ◽  
Copolymer Chain ◽  
Nmr Characterization ◽  
Insight Into

In situ1H NMR characterization of copolymerization reactions of various 2-oxazoline monomers at different molar ratios offers detailed insight into the build-up and composition of the polymer chains.

Synthese von cis-und trans-4-Cyanocyclohexanol / Synthesis of cis-and trans-4-Cyanocyclohexanol

1980 ◽  
Vol 35 (11) ◽  
pp. 1451-1454 ◽  
Author(s):  
Klaus Praefcke ◽  
Dietmar Schmidt
Keyword(s):  
Nmr Spectroscopy ◽  
H Nmr ◽  
Cis And Trans ◽  
First Time

Abstract The synthesis of cis-and trans-4-cyanocyclohexanol 2 a and 2 b is described for the first time. Their stereochemistry has been determined by 1H NMR spectroscopy.

Das 2-Halogen-5,6-benzo-1,3,2-dioxaphosphorinan-4-on-Ringsystem / The 2-Halogeno-5,6-benzo-1,3,2-dioxaphosphorinan-4-one Ring System

1993 ◽  
Vol 48 (7) ◽  
pp. 867-874 ◽  
Author(s):  
Rainer Gast ◽  
Thomas Kaukorat ◽  
Ion Neda ◽  
Reinhard Schmutzler
Keyword(s):  
Nmr Spectroscopy ◽  
Ring System ◽  
Phosphorus Trichloride ◽  
Secondary Amines ◽  
Methyl Substituent ◽  
Exchange Reactions ◽  
H Nmr ◽  
Rotational Isomers ◽  
First Time ◽  
Iodo Derivative

The reaction of salicylic acid with phosphorus trichloride furnished the previously known 2-chloro-5,6-benzo-1,3,2-dioxaphosphorinan-4-one heterocycle 1 which was unambiguously characterized, for the first time, by NMR spectroscopy and mass spectrometry. The fluorine and bromine analogues of 1, 2 and 3 were synthesized from 1, using exchange reactions. The iodo derivative, 4, owing to its instability, could be identified only in the reaction mixture by 1H and 31P NMR spectroscopy. The amine derivatives 5-8 were obtained from 1 using standard exchange reactions, either with silylated amines or with secondary amines in the presence of base. There was no evidence by 1H NMR spectroscopy for intramolecular Me2N→P coordination in 6. The 31P NMR investigation of 7 revealed the presence of two rotational isomers, presumably as a result of steric hindrance at the P–N bond by the methyl substituent of the piperidine group. The reaction of 6 with methyl iodide led to methylation at the nitrogen atom of the Me2N group, producing the ammonium iodide, 9. The reactions of 5,6 and 8 with norbornadiene tetracarbonyl molybdenum failed to furnish isolable products.

scholarly journals Identification of lower-order inositol phosphates (IP<sub>5</sub> and IP<sub>4</sub>) in soil extracts as determined by hypobromite oxidation and solution <sup>31</sup>P NMR spectroscopy

2020 ◽  
Vol 17 (20) ◽  
pp. 5079-5095
Author(s):  
Jolanda E. Reusser ◽  
René Verel ◽  
Daniel Zindel ◽  
Emmanuel Frossard ◽  
Timothy I. McLaren
Keyword(s):  
Nmr Spectroscopy ◽  
Lower Order ◽  
Inositol Phosphates ◽  
Organic Phosphorus ◽  
31P Nmr Spectroscopy ◽  
Organic P ◽  
Soil Extracts ◽  
Broad Signal ◽  
First Time ◽  
Insight Into

Abstract. Inositol phosphates (IPs) are a major pool of identifiable organic phosphorus (P) in soil. However, insight into their distribution and cycling in soil remains limited, particularly of lower-order IP (IP5 and IP4). This is because the quantification of lower-order IP typically requires a series of chemical extractions, including hypobromite oxidation to isolate IP, followed by chromatographic separation. Here, for the first time, we identify the chemical nature of organic P in four soil extracts following hypobromite oxidation using solution 31P NMR spectroscopy and transverse relaxation (T2) experiments. Soil samples analysed include A horizons from a Ferralsol (Colombia), a Cambisol and a Gleysol from Switzerland, and a Cambisol from Germany. Solution 31P nuclear magnetic resonance (NMR) spectra of the phosphomonoester region in soil extracts following hypobromite oxidation revealed an increase in the number of sharp signals (up to 70) and an on average 2-fold decrease in the concentration of the broad signal compared to the untreated soil extracts. We identified the presence of four stereoisomers of IP6, four stereoisomers of IP5, and scyllo-IP4. We also identified for the first time two isomers of myo-IP5 in soil extracts: myo-(1,2,4,5,6)-IP5 and myo-(1,3,4,5,6)-IP5. Concentrations of total IP ranged from 1.4 to 159.3 mg P per kg soil across all soils, of which between 9 % and 50 % were comprised of lower-order IP. Furthermore, we found that the T2 times, which are considered to be inversely related to the tumbling of a molecule in solution and hence its molecular size, were significantly shorter for the underlying broad signal compared to for the sharp signals (IP6) in soil extracts following hypobromite oxidation. In summary, we demonstrate the presence of a plethora of organic P compounds in soil extracts, largely attributed to IPs of various orders, and provide new insight into the chemical stability of complex forms of organic P associated with soil organic matter.

scholarly journals Synthesis of photoresponsive cholesterol-based azobenzene organogels: dependence on different spacer lengths

2015 ◽  
Vol 11 ◽  
pp. 1089-1095 ◽  
Author(s):  
Yuchun Ren ◽  
Bin Wang ◽  
Xiuqing Zhang
Keyword(s):  
Nmr Spectroscopy ◽  
Crucial Role ◽  
Molecular Structures ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
Thermal Phase ◽  
Reversible Gel ◽  
Phase Behaviors ◽  
Insight Into ◽  
C Nmr

A series of azobenzene–cholesterol organogel compounds (M 0 –M 12 ) with different spacers were designed and synthesized. The molecular structures were confirmed by 1H NMR and 13C NMR spectroscopy. The rapid and reversible photoresponsive properties of the compounds were investigated by UV–vis spectroscopy. Their thermal phase behaviors were studied by DSC. The length of the spacer plays a crucial role in the gelation. Compound M 6 is the only one that can gelate in ethanol, isopropanol and 1-butanol and the reversible gel–sol transitions are also investigated. To obtain visual insight into the microstructure of the gels, the typical structures of the xerogels were studied by SEM. Morphologies of the aggregates change from flower-like, network and rod with different sizes. By using IR and XRD characterization, it is found that intermolecular H-bonding, the solvents and van der Waals interaction are the main contributions to the specific superstructure.

Characterization of technical lignins by NMR spectroscopy: optimization of functional group analysis by 31P NMR spectroscopy

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 807-814 ◽  
Author(s):  
Philipp Korntner ◽  
Ivan Sumerskii ◽  
Markus Bacher ◽  
Thomas Rosenau ◽  
Antje Potthast
Keyword(s):  
Nmr Spectroscopy ◽  
Analytical Data ◽  
Group Analysis ◽  
Hydroxyl Group ◽  
Solution Technique ◽  
31P Nmr Spectroscopy ◽  
Nmr Analysis ◽  
H Nmr ◽  
Functional Group Analysis ◽  
First Time

Abstract31P nuclear magnetic resonance (NMR) based on the derivatization reagent 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane is a common approach for the hydroxyl group determination of lignins, but the results are sometimes less reproducible compared to other methods. In the present work, common pitfalls in31P NMR analysis of kraft lignin (KL) and lignosulfonates (LS) are addressed and the results are compared to those obtained by1H NMR spectroscopy. Several experimental parameters are revisited in terms of the reliability of the obtained data, such as the choice of relaxation delay, internal standards, and the best solution technique for the31P NMR analysis of LS. For the first time,31P NMR data of LS are presented based on a new dissolution protocol. The analytical data of a set of lignins consisting of three KLs, one LS, and one milled wood lignin are presented based on the optimized31P NMR approach.

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