Browsing by Author "Djamel Eddine Khatmi"

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Host-guest inclusion complex between b-cyclodextrin and paeonol: A theoretical approach
(2013) Sakina Haiahem; Leila Nouar; Imen Djilani; Abdelazize Bouhadiba; Fatiha Madi; Djamel Eddine Khatmi
Host-guest interactions of b-cyclodextrin (b-CD) with paeonol (PAE) were simulated using semi-empirical PM3 and both ONIOM2 [(B3LYP/6-31G*:PM3), (HF/6-31G*:PM3)] methods. The results obtained with PM3 method clearly indicate that the complexes formed are energetically favored with or without solvent, the model 1 (PAE entering into the cavity of b-CD from its wide side by OCH3 group) is found more favored than the model 2 (PAE entering into the cavity of b-CD from its wide side by COCH3 group). Finally, natural bonding orbital (NBO) analysis was performed based on ONIOM2 optimized complexes to quantify the donor–acceptor interactions between PAE and b-CD.
Molecular docking study on b-cyclodextrin Interactions of metobromuron and [3-(p-bromophenyl)-1-methoxy-1- methylurea]
(2012-03-04) sakina haiahem; Abdelaziz Bouhadiba; Leila Nouar; Imene Djilani; Fatiha Madi; Djamel Eddine Khatmi
The inclusion process involving b-cyclodextrin (b-cyclodextrin-CD) and phenylurea herbicide metobromuron (MB) has been investigated by using the MM?, PM3, B3LYP, HF, ONIOM2 and NBO methods. The binding and complexation energies for both orientations considered in this research are reported. The geometry of the most stable complex shows that the aromatic ring is deeply selfincluded inside the hydrophobic cavity of b-CD also an intermolecular hydrogen bond is established between hostand guest molecules. This suggests that hydrophobic effect and hydrogen bond play an important role in the complexation process. The statistical thermodynamic calculations by PM3 demonstrate that 1:1 MB/b-CD complex is favored by a negative enthalpy change. Moreover, NBO calculations proved also that are a very useful means to quantify the interaction energies of the hydrogen bonds.
Theoretical investigation to characterize the inclusion complex of a-lipoic acid and b-cyclodextrin
(2015) Imene Djilani; Fatiha Madi; Leila Nouar; Sakina Haiahem; Mohamed Rahim; Djamel Eddine Khatmi; Abdelaziz Bouhadiba
We simulated the docking of a-lipoic acid (a-LA) in b-cyclodextrin (b-CD) using two models. We considered in this study complexes formed by 1:1 host–guest stoichiometry in vacuo and in aqueous phase, using PM6, DFT and ONIOM2 hybrid calculations. The results obtained with PM6 method clearly indicate that the complexes formed are energetically favored with or without solvent, model 2 (a-LA entering the cavity of b-CD from its wide side by COOH group) is found more favored than model 1 (a-LA entering into the cavity of b-CD from its wide side by cyclic group), the preference being greater in the case of ONIOM2 calculations. In addition, NBO analysis gives that mutual interactions between the donor and acceptor orbitals of a-lipoic acid and b-CD plays an important role to the stabilization of such a complex. Finally, 1H nuclear magnetic resonance (NMR) chemical shifts of free and complexed a-LA were calculated by the Gauge-Including Atomic Orbital (GIAO) method and compared with available experimental data. The results of GIAO calculations were analyzed and discussed.