scholarly journals Inclusion Complexes of Sunscreen Agents withβ-Cyclodextrin: Spectroscopic and Molecular Modeling Studies

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Nathir A. F. Al-Rawashdeh ◽  
Khaled S. Al-Sadeh ◽  
Mohammad Bassam Al-Bitar
Keyword(s):  
Molecular Modeling ◽  
Molecular Mechanics ◽  
Inclusion Complexes ◽  
Dynamic Features ◽  
Scanning Calorimetry ◽  
Molecular Mechanics Calculations ◽  
Vis Spectroscopy ◽  
Nmr Techniques ◽  
Sunscreen Agents ◽  
C Nmr

The inclusion complexes of selected sunscreen agents, namely, oxybenzone (Oxy), octocrylene (Oct), and ethylhexyl-methoxycinnamate (Cin) withβ-cyclodextrin (β-CD) were studied by UV-Vis spectroscopy, differential scanning calorimetry (DSC),13C NMR techniques, and molecular mechanics (MM) calculations and modeling. Molecular modeling (MM) study of the entire process of the formation of 1 : 1 stoichiometry sunscreen agent/β-cyclodextrin structures has been used to contribute to the understanding and rationalization of the experimental results. Molecular mechanics calculations, together with13C NMR measurements, for the complex withβ-CD have been used to describe details of the structural, energetic, and dynamic features of host-guest complex. Accurate structures of CD inclusion complexes have been derived from molecular mechanics (MM) calculations and modeling. The photodegradation reaction of the sunscreen agents' molecules in lotion was explored using UV-Vis spectroscopy. It has been demonstrated that the photostability of these selected sunscreen agents has been enhanced upon forming inclusion complexes withβ-CD in lotion. The results of this study demonstrate thatβ-CD can be utilized as photostabilizer additive for enhancing the photostability of the selected sunscreen agents' molecules.

scholarly journals Conformational Analysis in 18-Membered Macrolactones Based on Molecular Modeling

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Salah Belaidi ◽  
Dalal Harkati
Keyword(s):  
Molecular Dynamics ◽  
Molecular Modeling ◽  
Conformational Analysis ◽  
Molecular Mechanics ◽  
Conformational Flexibility ◽  
Molecular Mechanics Calculations

Conformational analysis of 18-ring membered macrolactones has been carried out using molecular mechanics calculations and molecular dynamics. A high conformational flexibility of macrolactones was obtained, and an important stereoselectivity was observed for the complexed macrolides. For 18d macrolactone, which was presented by a most favored conformer with 20.1% without complex, it was populated with 50.1% in presence of Fe(CO)3.

Molecular Modeling of Slip Supposed to Occur in the Shock Initiation of Crystalline PETN

1992 ◽  
Vol 296 ◽  
Author(s):  
James P. Ritchie
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Molecular Modeling ◽  
Molecular Mechanics ◽  
Molecular Mechanics Calculations ◽  
Rigid Displacement ◽  
Shock Initiation ◽  
Flexible Molecules ◽  
Finite Lattices ◽  
Molecular Deformations

AbstractSome molecular modeling of slip using both rigid and flexible molecules of PETN in perfect, but finite, lattices has been performed. Studies of rigid displacement show slip on (001)<010> to be relatively unhindered. The shock orientation with a maximum resolved shear stress in this direction would, therefore, be expected to be insensitive. Molecular mechanics calculations have also been performed. The results show that it is likely that molecular deformations occur and have an important effect in determining the shear strength of crystalline PETN.

scholarly journals Formation of Rutin–β-Cyclodextrin Inclusion Complexes by Supercritical Antisolvent Precipitation

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 246
Author(s):  
Paola Franco ◽  
Iolanda De Marco
Keyword(s):  
Inclusion Complexes ◽  
Point Of View ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cyclodextrin Inclusion Complexes ◽  
Antisolvent Precipitation ◽  
Supercritical Antisolvent ◽  
Dissolution Tests ◽  
Vis Spectroscopy ◽  
Supercritical Antisolvent Precipitation

In this work, rutin (RUT)–β-cyclodextrin (β-CD) inclusion complexes are prepared by Supercritical AntiSolvent (SAS) precipitation. Well-defined composite microparticles are obtained at guest:host ratios equal to 1:2 and 1:1 mol:mol. The dimensions of composite particles range between 1.45 ± 0.88 µm and 7.94 ± 2.12 µm. The formation of RUT–β-CD inclusion complexes has been proved by different analyses, including Fourier transform infrared spectroscopy, Differential Scanning Calorimetry, X-ray diffraction, and UV-vis spectroscopy. The dissolution tests reveal a significant improvement in the release rate of RUT from inclusion complexes. Indeed, compared to the unprocessed RUT, the dissolution rate is about 3.9 and 2.4 times faster in the case of the complexes RUT–β-CD 1:2 and 1:1 mol:mol, respectively. From a pharmaceutical/nutraceutical point of view, CD-based inclusion complexes allow the reduction of the polymer amount in the SAS composite formulations.

Conformational Analysis of 2,4-Disubstituted 9-Oxobicyclo[3.3.1]nonane Derivatives

1995 ◽  
Vol 60 (2) ◽  
pp. 216-223
Author(s):  
Pelayo Camps ◽  
Joan Castañé ◽  
Carlos Jaime ◽  
Francesc Pérez ◽  
Santiago Vázquez
Keyword(s):  
Nmr Spectroscopy ◽  
Conformational Analysis ◽  
Dicarboxylic Acid ◽  
Molecular Mechanics ◽  
Molecular Mechanics Calculations ◽  
C Nmr

The conformational analysis of several 2,4-disubstituted 9-oxobicyclo[3.3.1]nonane derivatives (diesters IIIb and IIIc, and dihalo compounds IV, Va, Vb and VI) derived from 9-oxobicyclo[3.3.1]nonane-exo-2, exo-4-dicarboxylic acid has been studied by 1H and 13C NMR spectroscopy with the aid of Molecular Mechanics Calculations (MM3 program).

Molecular Modeling of a Functionalized Aib-Based Octapeptide by Molecular Mechanics Calculations Restrained by NMR and Fluorescence Data in DMSO

1997 ◽  
Vol 30 (17) ◽  
pp. 4905-4910 ◽  
Author(s):  
B. Pispisa ◽  
A. Palleschi ◽  
M. E. Amato ◽  
A. L. Segre ◽  
M. Venanzi
Keyword(s):  
Molecular Modeling ◽  
Molecular Mechanics ◽  
Molecular Mechanics Calculations

Conformational analysis and complete assignment of the proton and carbon NMR spectra of ouabain and ouabagenin

1990 ◽  
Vol 68 (8) ◽  
pp. 1263-1270 ◽  
Author(s):  
Deane D. McIntyre ◽  
Markus W. Germann ◽  
Hans J. Vogel
Keyword(s):  
Conformational Analysis ◽  
Molecular Mechanics ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
X Ray Diffraction ◽  
Proton Proton ◽  
Proton Coupling ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolide ouabain and its aglycon ouabagenin have been completely assigned by two-dimensional NMR techniques, including phase-sensitive COSY and carbon–proton correlation (HETCOR, HMQC, and COLOC) spectra. The major conformer of these two compounds in solution is all-chair as determined from proton–proton coupling constants and is similar to that in the crystal lattice as previously determined by X-ray diffraction. The conformations of the A and D rings of ouabain in water are somewhat different than in DMSO/CDCl3 (2:1). At lower temperatures (−20 °C) signals from two conformers in slow exchange were readily observed in the 13C spectra, with an approximate ratio of 1:7. Molecular mechanics and dynamics calculations indicate that the conformational process responsible for this involves a chair/twist-boat interconversion of the A ring, with the all-chair conformer highly preferred. Keywords: ouabain, conformational analysis, 2-D NMR, molecular mechanics, molecular dynamics.

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