Theoretical study of the inclusion processes of Venlafaxine with β-cyclodextrin

Enhanced Antioxidant Activity of Fresh Fruits through Salicylic Acid/β-CD Hydroalcoholic Gels

Oxidation is an important cause of fruit spoilage, and therefore improving the antioxidant capacity of fresh fruits is beneficial to their preservation. Herein, fresh-cut bananas were used as a type of fresh fruit and soaked in 75% hydroalcoholic gels containing salicylic acid (SA) or SA/β-CD inclusion complex (SA/β-CD). After treatment, they were placed in an atmosphere at 85% relative humidity at 20 °C for 12 days. A significant reduction in spoilage in bananas treated with the hydroalcoholic gels in the presence of SA/β-CD was observed, compared with those treated with gels in the presence or absence of SA. The free-radical-scavenging performances of SA and its complex were investigated using the DPPH (1,1-diphenyl-2-picryl-hydrazil) method. Based on the results, the significant increase in antioxidant activity was attributed to the fact that the inclusion complex could break the intramolecular hydrogen bonding of SA, thus efficiently eliminating ROS in the fruits. The formation of the inclusion complex was confirmed by experiments and theoretical calculations. Our findings indicate that treatment with SA/β-CD can provide an efficient method of maintaining postharvest quality and extending the shelf life of bananas.

DFT-ONIOM study of the dopamine–β-CD complex: NBO and AIM analysis

In this work, we conducted a systematic search of the minimum energy of a dopamine–β-cyclodextrin complex via different ONIOM approaches using both mixed (DFT-HF) and nonmixed (DFT-DFT) combinations. Different density functionals were employed: B3LYP, MPW1PW91, M05-2X, M06-2X, and ωB97X-D. Two different basis sets were used on the dopamine–β-cyclodextrin complex; a lower basis set (3-21G*) is used on β-cyclodextrin and a higher basis set (6-31G(d)) is used on dopamine. To fulfill this task, complexation and deformation energies were determined. The relative performance of these functionals was compared with that obtained with the DFT method at the M06-2X/6-31G(d) level that is chosen as a reference method. Although we did not clearly establish an assessment of the relative performance of these density functionals, the efficacy of the ONIOM combination (DFT-HF) is shown compared with a nonmixed ONIOM combination (DFT-DFT). The intermolecular hydrogen bond interactions of the complex obtained with the full M06-2X/6-31G(d) have been analyzed with the atoms-in-molecules and natural bond rrbital methodologies.

Theoretical study of inclusion complexes of dopamine with β-cyclodextrin based on PM6, ONIOM, and natural bonding orbital analysis

The inclusion process involving β-cyclodextrin (β-CD) with dopamine (DA) was investigated by using PM6, HF, and ONIOM methods. The most stable structure was obtained at the optimum position and angle. The complex orientation in which the catechol ring of dopamine penetrates into the β-CD cavity near primary hydroxyls is preferred in energy. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital analysis, employed to quantify the donor–acceptor interactions between dopamine and β-CD. A study of these complexes in solution was carried out using the CPCM model to examine the influence of solvation on the stability of the dopamine β-CD complex.