Inclusion complex of trans-p-coumaroyl-secologanoside (comselogoside) with β-cyclodextrin. Part I. structural characterization and study of solubilization and stabilization.

Abstract

Comselogoside (COM) is a secoiridoid, derivative of p-coumaric acid with a wide range of potential beneficial properties, although its poor aqueous solubility and low stability limit its study and application. The formation of an inclusion complex with β-cyclodextrin (β-CD) could improve the solubility and photostability of COM. The complexation of COM with β-CD in an aqueous solution has been studied for the first time, using the freeze-drying method with high encapsulation yield and efficiency. The formation of the inclusion complex was confirmed by electrospray ionization (ESI) mass and 1H NMR spectroscopy. Phase solubility studies provided an AN-type diagram with an increase in aqueous solubility by 100% and the formation of a high stoichiometric order complex COM: β-CD. The 1H NMR analysis with different COM/β-CD molar ratio established the formation of the 2:1 stoichiometric complex by Job ҆ s plot. In addition, the complexation of COM with β-CD improved the stability of COM against irradiation with UV light at 254 nm. Finally, combined docking and DFT calculations have been performed to study the formation and interactions of the COM: β-CD complexes. The computational results show excellent agreement with experimental observations.