A computational study of the interactions between anthocyans and cyclodextrins.

The interactions between six anthocyans (cyanidin-3-O-glucoside, delphinidin-3-O-glucoside, malvidin-3-O-glucoside, cyanidin-3-O-rutinoside, delphinidin-3-O-rutinoside, malvidin-3-O-rutinoside) and cyclodextrins were investigated by means of computational techniques. Four different structures of the aforementioned anthocyans were considered, as a result of the dependence structure - pH value (flavylium cations in acidic medium, hemiketals in neutral solutions and two tautomeric quinones in alkaline environment). The results outlined that the anthocyanidin-3-O-rutinoside are favored for the obtaining of inclusion complexes with the cyclodextrins, mostly due to the larger number of OH groups involved in the formation of hydrogen bonds. For all the four types of structures, best results have been obtained for β- and γ-cyclodextrins.