Mono-Dendronized beta-Cyclodextrin Derivatives as Multitasking Containers for Curcumin. Impacting Its Solubility, Loading, and Tautomeric Form

In this study, three mono-dendronized beta-cyclodextri n (beta CD) derivatives (beta CD-1G, beta CD-2G, and beta CD-3G) were used as multitasking containers of curcumin (CUR) to influence its aqueous solubility and tautomerism, both of which are related to its biological activity. We evaluated the relevant physicochemical properties of these containers associated with their potential hosting capacity. All mono-dendronized derivatives exhibited enhanced solubility in different solvents, including water, in comparison with native beta CD. Gas-phase geometry optimizations by density functional theory (DFT) confirmed that none of the dendrons blocked the passage of CUR into the beta CD cavity, and depending on the generation, different preorganization scenarios were promoted before complex-ation. Phase solubility diagrams showed that all the dendronized containers have superior performance for solubilizing CUR compared to native beta CD. We proved that coprecipitation is most efficient than lyophilization for forming inclusion complexes (ICs) with dendronized containers. Even though beta CD-3G with the largest 3G dendron exhibited the highest CUR loading, the complexation of CUR with beta CD-2G provided the supramolecular system that contains CUR preferentially in its diketo tautomer, which is known for its antioxidant activity.