New Biodegradable Hydrogels Based on Inulin and α,β-Polyaspartylhydrazide Designed for Colonic Drug Delivery: In Vitro Release of Glutathione and Oxytocin.

Succinic derivatives of inulin (INU-SA) with two different degrees of derivatization (20% and 30%, mol/mol) were cross-linked with α,β-polyaspartylhydrazide (PAHy) to obtain INUPAHy hydrogels. Cross-linking was performed using N-ethyl-N-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (NHSS) as coupling agents and by varying the reaction time (4 h, 8 h and 24 h). All samples prepared were characterized by FT-IR analysis and swelling measurements in different media. In vitro assays, performed in the presence of inulinase, demonstrated the degradability of the prepared hydrogels. Cell compatibility was evaluated using Caco-2 cells through both direct and indirect assay. Glutathione (GSH) and oxytocin (OT), both potential agents for the treatment of colonic inflammation, were entrapped into a INUPAHy hydrogel and their release was evaluated in simulated gastrointestinal fluids. The obtained results suggest that GSH- and OT-loaded INUPAHy hydrogels are potentially useful for the oral treatment of inflammatory bowel disease.