Spectroscopic study to assess the integrity of chemically modified curcumin: Hyaluronic acid-curcumin conjugate as a proof of the method

A hyaluronan-curcumin conjugate was synthesized by employing a green procedure, the final aim was to improve the aqueous solubility and the bioavailability of the curcumin by reducing its hydrolytic degradation. A comprehensive study on the obtained macromolecular system was carried out in order to investigate the integrity and the stability of the curcumin bound to the polysaccharide. These findings may help for the evaluation of the therapeutic potential of the developed curcumin vehicle. In particular, comparative spectroscopic studies were performed in different system solvents for both, pure curcumin and curcumin conjugated to hyaluronic acid, at different temperature and different pH values. An increased stability for the curcumin bound to the hyaluronic acid was found under slightly basic aqueous solution, while the Uv–vis as well as the fluorescence spectral features ensures that the chemical structure of the curcumin is fully retained. The self-assembling behavior of the developed hyaluronan-curcumin conjugate (HA-CUR) was also investigated. It is likely that the micellar self-aggregation is able to protect the curcumin, embedded in the inner core, from the hydrolitic decomposition.