Conformational Analysis of Mefenamic Acid in scCO2-DMSO by the 2D NOESY Method

Belov, Konstantin V.; Carvalho, Luís A. E. Batista de; Dyshin, A. A.; Киселев, М. Г.; Sobornova, V.V.; Khodov, Ilya A.

doi:10.1134/s1990793122070028

Cited by 6 publications

(4 citation statements)

References 44 publications

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“…This interring distance was observed to be ~3.3 Å for mefenamic and tolfenamic acids and ~3.9 Å for flufenamic acid under the same condition. This ratio of conformers relative to the interring distance is 70:30 for mefenamic acid, and 20:80 for flufenamic acid, respectively [ 82 , 83 ]. This difference in distances was attributed to the conformational lability of flufenamic acid due to the influence of the methyl group [ 84 ].…”

Section: Resultsmentioning

confidence: 99%

Exploring the Conformational Equilibrium of Mefenamic Acid Released from Silica Aerogels via NMR Analysis

Khodov

Sobornova

Mulloyarova

et al. 2023

IJMS

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This study examines the influence of mefenamic acid on the physical and chemical properties of silica aerogels, as well as its effect on the sorption characteristics of the composite material. Solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and high-pressure 13C NMR kinetic studies were conducted to identify the presence of mefenamic acid and measure the kinetic rates of CO2 sorption. Additionally, a high-pressure T1–T2 relaxation-relaxation correlation spectroscopy (RRCOSY) study was conducted to estimate the relative amount of mefenamic acid in the aerogel’s pores, and a high-pressure nuclear Overhauser effect spectoscopy (NOESY) study was conducted to investigate the conformational preference of mefenamic acid released from the aerogel. The results indicate that mefenamic acid is affected by the chemical environment of the aerogel, altering the ratio of mefenamic acid conformers from 75% to 25% in its absence to 22% to 78% in the presence of aerogel.

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Section: Resultsmentioning

confidence: 99%

Exploring the Conformational Equilibrium of Mefenamic Acid Released from Silica Aerogels via NMR Analysis

Khodov

Sobornova

Mulloyarova

et al. 2023

IJMS

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“…The peak amplitude normalization for an improved cross-relaxation (PANIC) approach [ 23 , 48 , 49 , 50 ], the isolated spin-pair approximation (ISPA) model [ 51 , 52 , 53 , 54 ], and the two-position exchange model [ 23 ] were used to calculate the proportions of fenamate conformer groups in a lipid membrane modeled by POPC. The volume of the cross-peak between two spin systems I and S in the spin-pair interaction model could be determined by the formula in [ 55 ].…”

Section: Resultsmentioning

confidence: 99%

Conformational State of Fenamates at the Membrane Interface: A MAS NOESY Study

et al. 2023

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The present work analyzes the 1H NOESY MAS NMR spectra of three fenamates (mefenamic, tolfenamic, and flufenamic acids) localized in the lipid–water interface of phosphatidyloleoylphosphatidylcholine (POPC) membranes. The observed cross-peaks in the two-dimensional NMR spectra characterized intramolecular proximities between the hydrogen atoms of the fenamates as well as intermolecular interactions between the fenamates and POPC molecules. The peak amplitude normalization for an improved cross-relaxation (PANIC) approach, the isolated spin-pair approximation (ISPA) model, and the two-position exchange model were used to calculate the interproton distances indicative of specific conformations of the fenamates. The results showed that the proportions of the A+C and B+D conformer groups of mefenamic and tolfenamic acids in the presence of POPC were comparable within the experimental error and amounted to 47.8%/52.2% and 47.7%/52.3%, respectively. In contrast, these proportions for the flufenamic acid conformers differed and amounted to 56.6%/43.4%. This allowed us to conclude that when they bind to the POPC model lipid membrane, fenamate molecules change their conformational equilibria.

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“…Moreover, we found that the population of conformer II correlates with the mole fraction of polymorph II that exists in the bottom phase. The authors of [ 20 , 21 ] also mentioned that adding a small amount of a co-solvent (DMSO) to heterogeneous mixtures of mefenamic or tolphenamic acid with scCO 2 (used to increase the acids solubility in the scCO 2 phase) does not change this conformational equilibrium. In work [ 8 ], we also demonstrated that a temperature-induced change in the polymorphic composition of the bottom phase of a heterogeneous MA–scCO 2 mixture shifts the conformational equilibrium of MA molecules in the fluid phase of this mixture.…”

Section: Introductionmentioning

confidence: 99%

Molecular Mechanism of Conformational Crossover of Mefenamic Acid Molecules in scCO2

et al. 2023

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In this work, we studied conformational equilibria of molecules of mefenamic acid in its diluted solution in scCO2 under isochoric heating conditions in the temperature range of 140–210 °С along the isochore corresponding to the scCO2 density of 1.1 of its critical value. This phase diagram range totally covers the region of conformational transitions of molecules of mefenamic acid in its saturated solution in scCO2. We found that in the considered phase diagram region, the equilibrium of two conformers is realized in this solution. In the temperature range of 140–180 °C, conformer I related to the first, most stable polymorph of mefenamic acid prevails. In the temperature range of 200–210 °C, conformer II, which is related to the second metastable polymorph becomes dominant. Based on the results of quantum chemical calculations and experimental IR spectroscopy data on the mefenamic acid conformer populations, we classified this temperature-induced conformational crossover as an entropy-driven phenomenon.

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Conformational Analysis of Mefenamic Acid in scCO2-DMSO by the 2D NOESY Method

Cited by 6 publications

References 44 publications

Exploring the Conformational Equilibrium of Mefenamic Acid Released from Silica Aerogels via NMR Analysis

Exploring the Conformational Equilibrium of Mefenamic Acid Released from Silica Aerogels via NMR Analysis

Conformational State of Fenamates at the Membrane Interface: A MAS NOESY Study

Molecular Mechanism of Conformational Crossover of Mefenamic Acid Molecules in scCO2

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