Evaluating the Impact of High-Esterified Pectin on Retrogradation and Film-Forming Properties of High-Amylose Starch

Abstract

Achieving precise drug release in the colon remains a key objective in therapies for inflammatory bowel disease (IBD). Natural polysaccharides, including high-amylose starch (HAS) and pectin, offer relevant characteristics for localized drug delivery due to their biocompatibility, biodegradability, and adaptability. In this work, high-esterified pectin (HEP) was incorporated during the retrogradation of HAS to further form cohesive films without the need for organic solvents or high temperatures. The resulting matrices showed improved mucoadhesive performance, particularly under colonic conditions, where hydrophobic ester groups in HEP enhanced tissue adherence. This feature is critical for prolonged residence time in inflamed mucosa. Variations in HEP content directly influenced matrix density, fluid interaction, and mechanical resistance, without compromising film integrity. The high degree of esterification limited pH-dependent swelling and promoted alternative release mechanisms potentially related to enzymatic degradation. Such behavior contrasts with traditional low-esterified pectin (LEP) systems, suggesting that HEP may act as a structural modifier rather than a neutral excipient. Despite its widespread use in food systems, HEP remains underexplored in pharmaceutical matrices, especially in combination with retrograded starch (RS). The physicochemical and biointerfacial properties observed here underscore their applicability for the rational design of colonic delivery systems and provide a foundation for formulation strategies tailored to chronic intestinal disorders.