Effect of cyclodextrin types and reagents solvation on the stability of complexes between B-cyclodextrins and rutin in water-ethanol solvents

In this work, the solubility of rutin was first obtained in the water-ethanol solvents with small composition of co-solvent in the mixture at 25 degrees C. The results showed that the solubility of rutin improved with increasing ethanol content in the studied range 0-0.1 mol. fr. Solvation of hydroxypropyl-beta-cydodextrin in binary solvents was first studied by the method of interfacial distribution of the substance between two immiscible phases. It was found that when moving hydroxypropyl-beta-cydodextrin from water to the water-ethanol solvent, a decrease in the solvation of hydroxypropyl-beta-cydodextrin was observed. Complexation between rutin and beta-cyclodextrin or hydroxypropyl-fi-cydodextrin was also studied in water and in the water-ethanol solvents. In the aqueous solution containing hydroxypropyl-beta-cyclodextrin, the solubility of rutin was improved significantly and better than in the solution containing beta-cyclodextrin. The stability of (rutin-hydroxypropyl-beta-cyclodextrin) complex decreased with increasing the ethanol content and was determined by the sum of solvation of rutin (Delta(tr)G(Rut)) and hydroxypropyl-beta-cyclodextrin (Delta(tr)G(Rut)). This effect was also observed for the complexation reaction be- tween quercetin and hydroxypropyl-beta-cydodextrin in our previous study. (C) 2020 Elsevier B.V. All rights reserved.