Investigation of curcumin encapsulation in amino-β-cyclodextrin: Insights from spectroscopic and molecular dynamic simulation techniques

Journal article, 2026

Curcumin (Cur) is a bioactive compound found in turmeric that is and widely used in pharmaceutical applications. However, it has poor water solubility and low chemical stability. In this work, amino-β-cyclodextrin (ACD) was used to form an inclusion complex with curcumin. The photophysical properties of curcumin in the ACD inclusion complex were studied at various pH values. The steady-state absorption spectrum of the Cur: ACD inclusion complex showed a blue shift of the absorption band at 340 nm In addition, ACD enhanced the otherwise weak fluorescence of curcumin in aqueous solutions. Time-resolved fluorescence decay analysis revealed that the excited state consisted of three components which tentatively correspond to the c is -diketo form, the excited-state intramolecular proton transfer (ESIPT) of the keto-enol tautomer and solvent reorganization of curcumin. The average fluorescence lifetime of curcumin increased in the presence of ACD. Molecular dynamic (MD) simulations showed that the amino moiety blocked the narrow rim of ACD, resulting in a difference in the orientation and non-linear extended conjugation of the curcumin molecule when bound to ACD at different pH values. Moreover, the photostability of curcumin was significantly improved upon inclusion complex formation with ACD. These results demonstrated that amino-β-cyclodextrin inclusion enhanced effectively the photophysical and photochemical properties of curcumin.