Enhencemnet of solubility and photostability of rutin by complexation with β-cyclodextrin and (2-hydroxypropyl)-β-cyclodextrin

Rutin is a flavonoid and has found a wide application in the treatment of various chronic diseases such as cancer, diabetes, hypertension and hypercholesterolemia. The pharmaceutical application of rutin is limited due to its poor water solubility. One of the ways to enhance the solubility and stability is the formation of the inclusion complexes. The purpose of this study was to improve the solubility, antioxidative activity and photostability of rutin by preparation of the inclusion complexes with beta-cyclodextrin (beta-CD) and (2-hydroxypropyl)-beta-cyclodextrin (HP-beta-CD). The inclusion complexes were structurally characterized using FT-IR, XRD, H-1 NMR methods. The obtained results indicated that the complexation between rutin and cyclodextrins were successfully achieved in the mixture of ethanol and water 2:3 (v/v) at room temperature for 24 h. The study of phase-solubility was showed that the solubility of rutin was linearly increased in the solution of increasing amount of cyclodextrins, i.e. that the molar ratio was 1:1 in the complexes. The calculated values of stability constants were found to be 508.4 and 488.9 M-1 for rutin:beta-CD and rutin:HP-beta-CD complexes, respectively. After preparation of inclusion complexes, the antioxidant activity of rutin was improved due to the increase of its scavenge capacity. The photostability study indicates that the complexed rutin was a more stable and protected from the effect of irradiation in compared with free rutin. The improvement in the physicochemical properties provide the opportunities to the inclusion complexes of rutin to use for design of the new pharmaceutical products with modified characteristics of active substance.