Plain 1 H NMR Analysis Streamlines the Quality Control of Antiviral Favipiravir and Congeneric WHO Essential Medicines

2021 ◽  
Author(s):  
Prabhakar S. Achanta ◽  
Shao‐Nong Chen ◽  
Guido F. Pauli
Keyword(s):  
Quality Control ◽  
Essential Medicines ◽  
Nmr Analysis ◽  
H Nmr

scholarly journals Analysis of solid-state heparin samples by ATR-FTIR spectroscopy

2019 ◽  
Author(s):  
Anthony Devlin ◽  
Courtney J. Mycroft-West ◽  
Marco Guerrini ◽  
Edwin A. Yates ◽  
Mark A. Skidmore
Keyword(s):  
Quality Control ◽  
Multivariate Analysis ◽  
Cost Effective ◽  
World Health Organisation ◽  
Essential Medicines ◽  
World Health ◽  
Sulphated Polysaccharides ◽  
H Nmr ◽  
Alternative Approach ◽  
Alternative Approaches

AbstractThe widely used anticoagulant pharmaceutical, heparin, is a polydisperse, heterogeneous polysaccharide. Heparin is one of the essential medicines defined by the World Health Organisation but, during 2007-2008, was the subject of adulteration. The intrinsic heterogeneity and variability of heparin makes it a challenge to monitor its purity by conventional means. This has led to the adoption of alternative approaches for its analysis and quality control, some of which are based on multivariate analysis of 1H NMR spectra, or exploit correlation techniques. Such NMR spectroscopy-based analyses, however, require costly and technically demanding NMR instrumentation. Here, an alternative approach based on the use of attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR) combined with multivariate analysis is proposed. FTIR-ATR employs more affordable and easy-to-use technology and, when combined with multivariate analysis of the resultant spectra, readily differentiates between glycosaminoglycans of different types, between heparin samples of distinct animal origins and enables the detection of both known heparin contaminants, such as over-sulphated chondroitin sulfate (OSCS), as well as other alien sulphated polysaccharides in heparin samples to a degree of sensitivity comparable to that achievable by NMR. The approach will permit the rapid and cost-effective monitoring of pharmaceutical heparin at any stage of the production process and indeed, in principle, the quality control of any heterogeneous or variable material.

Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Glucopyranoside Enantiomers

2006 ◽  
Vol 71 (10) ◽  
pp. 1470-1483 ◽  
Author(s):  
David Šaman ◽  
Pavel Kratina ◽  
Jitka Moravcová ◽  
Martina Wimmerová ◽  
Zdeněk Wimmer
Keyword(s):  
Analytical Data ◽  
Chiral Hplc ◽  
Nmr Analysis ◽  
Target Structure ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
H Nmr ◽  
Structure Assignment ◽  
Related Compounds ◽  
C Nmr

Glucosylation of the cis- and trans-isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol (1a/1b, 2a/2b, 1a or 2a) was performed to prepare the corresponding alkyl β-D-glucopyranosides, mainly to get analytical data of pure enantiomers of the glucosides (3a-6b), required for subsequent investigations of related compounds with biological activity. One of the employed modifications of the Koenigs-Knorr synthesis resulted in achieving 85-95% yields of pure β-anomers 3a/3b, 4a/4b, 3a or 4a of protected intermediates, with several promoters and toluene as solvent, yielding finally the deprotected products 5a/5b, 6a/6b, 5a or 6a as pure β-anomers. To obtain enantiomerically pure β-anomers of the target structure (3a, 4a, 5a and 6a) for unambiguous structure assignment, an enzymic reduction of 2-(4-methoxybenzyl)cyclohexan-1-one by Saccharomyces cerevisiae whole cells was performed to get (1S,2S)- and (1S,2R)-enantiomers (1a and 2a) of 2-(4-methoxybenzyl)cyclohexan-1-ol. The opposite enantiomers of alkyl β-D-glucopyranosides (5b and 6b) were obtained by separation of the diastereoisomeric mixtures 5a/5b and 6a/6b by chiral HPLC. All stereoisomers of the products (3a-6b) were subjected to a detailed 1H NMR and 13C NMR analysis.

1H-NMR Analysis of Degree of Substitution in N,O-Carboxymethyl Chitosans from Various Chitosan Sources and Types

2012 ◽  
Vol 506 ◽  
pp. 158-161 ◽  
Author(s):  
A. Jaidee ◽  
Pornchai Rachtanapun ◽  
S. Luangkamin
Keyword(s):  
Chemical Structure ◽  
Carboxymethyl Chitosan ◽  
Degree Of Substitution ◽  
Resonance Spectroscopy ◽  
Nmr Analysis ◽  
Reaction Conditions ◽  
H Nmr ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Chitosan Oligomer ◽  
Ft Ir

N,O-Carboxymethyl chitosans were synthesized by the reaction between shrimp, crab and squid chitosans with monochloroacetic acid under basic conditions at 50°C. The mole ratio of reactants was obtained from various reaction conditions of shrimp chitosan polymer and oligomer types. The mole ratio 1:12:6 of chitosan:sodium hydroxide:monochloroacetic acid was used for preparing carboxymethyl of chitosan polymer types while carboxymethyl of chitosan oligomer types were used the mole ratio 1:6:3 of chitosan:sodium hydroxide:monochloroacetic acid. The chemical structure was analyzed by fourier transformed infrared spectroscopy (FT-IR) and proton nuclear magnatic resonance spectroscopy (1H-NMR). The FT-IR was used for confirm the insertion of carboxymethyl group on chitosan molecules. The 1H-NMR was used for determining the degree of substitution (DS) of carboxymethylation at hydroxyl and amino sites of chitosans. Carboxymethyl chitosan samples had the total DS of carboxymethylation ranging from 1.0-2.2. The highest of DS of carboxymethylation was from shrimp chitosan oligomer type.

Prediction of physical-chemical properties of crude oils by 1 H NMR analysis of neat samples and chemometrics

2012 ◽  
Vol 50 (11) ◽  
pp. 729-738 ◽  
Author(s):  
Alice Masili ◽  
Sonia Puligheddu ◽  
Lorenzo Sassu ◽  
Paola Scano ◽  
Adolfo Lai
Keyword(s):  
Chemical Properties ◽  
Crude Oils ◽  
Nmr Analysis ◽  
H Nmr ◽  
Physical Chemical

Lactose quantification in bovine milk by nuclear magnetic resonance without deuterated solvent (No-D qNMR)

2020 ◽  
Vol 12 (40) ◽  
pp. 4892-4898
Author(s):  
Danyelle Alves da Cunha ◽  
Thays Cardoso Valim ◽  
Paulo Roberto Filgueiras ◽  
Valdemar Lacerda Junior ◽  
Alvaro Cunha Neto
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Bovine Milk ◽  
Nmr Analysis ◽  
H Nmr ◽  
Nuclear Magnetic

Validation of a method to quantify low lactose content in commercial lactose-free milk by 1H NMR analysis.

NMR analysis of budding yeast metabolomics: a rapid method for sample preparation

2015 ◽  
Vol 11 (2) ◽  
pp. 379-383 ◽  
Author(s):  
C. Airoldi ◽  
F. Tripodi ◽  
C. Guzzi ◽  
R. Nicastro ◽  
P. Coccetti
Keyword(s):  
Nmr Spectroscopy ◽  
Sample Preparation ◽  
Rapid Method ◽  
Budding Yeast ◽  
Yeast Cells ◽  
Intracellular Metabolite ◽  
Nmr Analysis ◽  
H Nmr ◽  
Metabolite Extraction

We present a rapid and reproducible protocol for intracellular metabolite extraction from yeast cells analyzed by1H-NMR spectroscopy.

Folded conformations due to arene interactions in dissymmetric and symmetric butylidene-linker models based on pyrazolo[3,4-d]pyrimidine, purine and 7-deazapurine

2014 ◽  
Vol 70 (6) ◽  
pp. 555-561 ◽  
Author(s):  
Kamlakar Avasthi ◽  
Lakshmi Shukla ◽  
Ruchir Kant ◽  
Krishnan Ravikumar
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Crystalline State ◽  
Nmr Analysis ◽  
First Report ◽  
Π Interactions ◽  
H Nmr

The butylidene-linker models 1-[2-(2,6-dimethylsulfanyl-9H-purin-9-yl)-2-methylidenepropyl]-4,6-bis(methylsulfanyl)-1H-pyrazolo[3,4-d]pyrimidine, C18H20N8S4, (XI), 7,7′-(2-methylidenepropane-1,3-diyl)bis[3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one], C20H22N6O2S2, (XIV), and 7-[2-(4,6-dimethylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-methylidenepropyl]-3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one, C19H21N7OS3, (XV), show folded conformations in solution, as shown by1H NMR analysis. This folding carries over to the crystalline state. Intramolecular π–π interactions are observed in all three compounds, but only (XIV) shows additional intramolecular C—H...π interactions in the solid state. As far as can be established, this is the first report incorporating the pyrrolo[2,3-d]pyrimidine nucleus for such a study. In addition to the π–π interactions, the crystal structures are also stabilized by other weak intermolecular C—H...S/N/O and/or S...N/S interactions.

Quantitative 2 H NMR analysis of deuterium distribution in petroselinic acid isolated from parsley seed

2003 ◽  
Vol 64 (1) ◽  
pp. 227-233 ◽  
Author(s):  
Sébastien Guiet ◽  
Richard J. Robins ◽  
Michele Lees ◽  
Isabelle Billault
Keyword(s):  
Petroselinic Acid ◽  
Nmr Analysis ◽  
H Nmr ◽  
Deuterium Distribution

13 C and 1 H NMR analysis of structural defects in PVC: Application to the production of defects at various polymerization stages

1989 ◽  
Vol 29 (1) ◽  
pp. 171-184 ◽  
Author(s):  
Marie-France Llauro-Darricades ◽  
Naima Bensemra ◽  
Alain Guyot ◽  
Roger Petiaud
Keyword(s):  
Structural Defects ◽  
Nmr Analysis ◽  
H Nmr

scholarly journals Erratum: Investigation of drug release and 1 H-NMR analysis of the in situ forming systems based on poly(lactide-co-glycolide)

2009 ◽  
Vol 20 (5) ◽  
pp. 507-507
Author(s):  
Z. Mohamadnia ◽  
E. Ahmadi ◽  
M. Rafienia ◽  
H. Mirzadeh ◽  
H. Mobedi
Keyword(s):  
Drug Release ◽  
Nmr Analysis ◽  
H Nmr ◽  
In Situ Forming
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