Indole Acetylated High-Amylose Maize Starch: Synthesis, Characterization and Application for Amelioration of Colitis

Abstract

Recent studies have found tryptophan metabolites such as indole-3-acetic acid (IAA) play a critical role in intestinal homeostasis. HAMSIAA, IAA esterified high amylose maize starch (HAMS), was synthesized with different degrees of substitution (DSs) by controlling the molar ratio of IAA vs HAMS. The changes in structure, physicochemical properties and colon-targeted delivery effect of modified starch were investigated. The new 1H NMR characteristic peaks related to NH (10.83 ppm), aromatic CH (7.50, 7.35, 7.27, 7.08 and 6.99 ppm), and FTIR characteristic absorption at 1725 cm−1 related to stretching of C=O at ester group indicating the occurrence of indole acetylation at HAMSIAA. In vivo experiments found that HAMSIAA could significantly increase the concentration of IAA in colon, as well as improve dextran sodium sulfate-induced colitis in mice. Taken together, HAMSIAA could serve as a useful tool for colon-targeted delivery of IAA and a promising candidate for amelioration of inflammatory bowel diseases.

Keywords: High amylose maize starch, Indole-3-acetic acid, Colon-targeted delivery, Colitis, Intestinal homeostasis