Thermodynamic Study of Cyclodextrins Complexation with Benzimidazolic Antihelmintics in Different Reaction Media

Abstract

The main purpose of this work was to accomplish a comparative study about cyclodextrins complexation equilibria with three benzimidazolic antihelmintics: albendazole (Alb), mebendazole (Meb) and thiabendazole (Thiab). The complexation process with four different cyclodextrins (alpha-, beta-, gamma-, and HP-beta-CDs) was investigated under various temperatures and different reaction media (aqueous solution buffered at pH 7.5, dimethylsulfoxide (DMSO) and DMSO/water at 25/75, 50/50, 75/50 (w/w) mixtures). It was studied by electronic absorption and 1H NMR (NOESY) spectroscopy. Binding constants were determined by electronic absorption spectroscopic method, the DeltaH and DeltaS complexation values were evaluated and discussed according to the diverse factors that affect the chemical interactions in these systems. Solubility has also been determined by the Higuchi and Connors method. In general, albendazole and mebendazole exhibit similar complexation behavior, while thiabendazole acts differently. Classic and non-classic solvophobic effects are mainly the driving and stabilizing forces for complex formation, with the exception in some Thiab-CDs interactions. In all cases, DMSO, an aprotic solvent, should be considered as an active component of the reaction systems.

Magnetic β-Cyclodextrin Nanosponges for Potential Application in the Removal of the Neonicotinoid Dinotefuran from Wastewater

“…The H3 and H5 signals also showed chemical shifts, which confirmed inclusion, as these signals correspond to the internal protons of the NSs. These results are consistent with previous studies with native CDs and NSs [10,[30][31][32][33][34].…”

“…As NSs are insoluble in deuterated water/chloroform, deuterated DMSO was used as a solvent for the 1 H-NMR analyses. Previous studies have shown that DMSO does not interfere with the formation of the inclusion compound [10,[30][31][32][33][34]. As seen in Figure 3, 1 H-NMR spectra show that some of the signals in the NS-DTF complex are sharper than that of NSs alone.…”

Effect of Dimethyl Sulfoxide on the Binding of 1-Adamantane Carboxylic Acid to β- and γ-Cyclodextrins

“…In some cases, a high concentration of DMSO can prevent a complexation from taking place, like for the binding of puerarin with β-CD, which does not occur at 100% DMSO. 20 Finally, Bernad-Bernad et al 19 showed that the binding constant of albendazole and mebendazole to α, β-, and γ-CD drastically decreases when 25%, 50%, or 75% DMSO is added, but at 100% DMSO, if the binding constant is smaller than that in water it is larger than that in a mixture of water and DMSO. However, the behavior is different for thianedazole: while additions of DMSO continuously increase the binding constant for β-CD, it first increases it for α- and γ-CD at 36% and 50% DMSO and then decreases it for 75% and 100%.…”

“…To the best of our knowledge, the effect of a few percent of DMSO on the binding of chemically unmodified cyclodextrins has never been investigated. All previous studies dealt with large concentrations, ranging from 25% to 100% DMSO. − …”

Structure–Binding Effects: Comparative Binding of 2-Anilino-6-naphthalenesulfonate by a Series of Alkyl- and Hydroxyalkyl-Substituted β-Cyclodextrins

“…Some binding studies of guests by CDs in nonaqueous or mixed organic–aqueous solvents have been reported. − Organic solvent systems studied include DMSO, , DMF, , mixed alcohol–water, − and various other organic solvents . In all these studies, a significant decrease of the binding constant for a specific guest was observed in organic solvents as compared to aqueous solvent, or upon increase in organic solvent proportion in organic–aqueous solvent mixtures.…”