Preparation of defatted walnut meal hydrolysate-loaded enteric-coated pellets with enhanced oral absorption efficiency

Abstract

The goal of this study was to enhance the absorption efficiency of walnut peptides (WPs) by employing an enteric-coated pellet formulation. Firstly, defatted walnut meal hydrolysate (DWMH) and microcrystalline cellulose (MCC) were mixed with sodium caprate to prepare the core pellets by extrusion/spheronization. The granulation process was optimized by a single-factor experiment and used to obtain uniform and spherical core pellets with a high yield of 74.3%. Afterwards, enteric coating of the core pellets was conducted using a bottom-spray fluid-bed coater. The in vitro release study of the optimum product showed that less than 10% of WPs were released from the enteric-coated pellets in simulated gastric fluid after 2 h, and complete release of WPs was achieved in simulated intestinal fluid after 45 min. Moreover, the bioactivity of WPs was retained following absorption from the enteric-coated formulation. Finally, the absorption efficiency of WPs from DWMH-loaded enteric-coated pellets was investigated in rats using an in situ intestinal perfusion experiment. It was revealed that the enteric-coated pellet formulation can significantly enhance the intestinal absorption of WPs. In conclusion, enteric coating of the pellets and co-delivery of an absorption enhancer could be an effective strategy for producing oral formulations of bioactive peptides.