Modification of carboxymethyl inulin with heterocyclic compounds: Synthesis, characterization, antioxidant and antifungal activities

Abstract

A series of novel inulin derivatives were designed and synthesized by the introduction of amino heterocyclic moieties onto carboxymethyl inulin with the aid of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide. The target products were prepared via three - step chemical synthesis, and structures were identified by FTIR and 1H NMR spectroscopy. Antioxidant activities of inulin derivatives including DPPH - radical scavenging assay, superoxide - radical scavenging assay, hydroxyl - radical scavenging assay, and reducing power were estimated. Meanwhile, their antifungal activities, including Colletotrichum lagenarium and Botrytis cinerea, were also explored by hyphal measurement. In particular, inulin derivatives bearing heterocyclic moieties exhibited a remarkable improvement over inulin on antioxidant and antifungal activities, and their bioactivities decreased roughly in the order of 2ATCMI > 4APCMI > 3APCMI > 2APCMI > 3ATCMI > CMI > inulin. Furthermore, the cytotoxicities of inulin derivatives against L929 cells were evaluated by CCK-8 in vitro, and all samples showed weak cytotoxicities. In a nutshell, the paper provides a practical approach to synthesize novel inulin derivatives with dramatically enhanced bioactivity and good biocompatibility. The product described in paper might serve as a new leading structure for further design of antioxidants or antifungal agents in biomedicine, cosmetics, and other fields.