Encapsulation in chitosan-based polyelectrolyte complexes enhances antidiabetic activity of curcumin

Low bioavailability, poor aqueous stability and lack of appropriate delivery systems delimit the chemotherapeutic effect of curcumin. In this study, curcumin was encapsulated in chitosan-based polyelectrolyte complexes and its antidiabetic activities were assessed using in vitro α-amylase inhibitory assay and in vivo antihyperglycaemic effect in alloxan-induced rats. Microscopic examination showed nanoformulations (<50 nm) of curcumin loaded in chitosan-alginate complex. Improved encapsulation efficiency (64-76%), loading capacity (20-26%) and yield (50-72%) were achieved. Complexation of chitosan with alginate reduced loss of curcumin by 20% and extended mean release time by 40 min in simulated gastric fluid. Time dependent study showed that the α-amylase inhibitory activity of curcumin was enhanced via nanoencapsulation. Oral administration of sub-therapeutic dosage of curcumin (50 mg/kg b.wt.) nanoencapsulated in chitosan-based complexes caused significant reduction in hyperglycaemia within 7 days of treatment. Overall, chemotherapeutic effectiveness of curcumin was enhanced via nanoencapsulation in chitosan-based polyelectrolyte complexes.