Novel 1,2,3-triazolium-functionalized starch derivatives: Synthesis, characterization, and evaluation of antifungal property

Four novel 1,2,3-triazolium-functionalized starch derivatives were synthesized by N-alkylating the precursor starch derivatives with 1,2,3-triazole with iodomethane based on cuprous-catalyzed azide-alkyne cycloaddition (CuAAC). The detailed structural characterization was investigated by means of FTIR, UV-vis, 1H NMR, and 13C NMR spectra. The antifungal activities of starch derivatives against Colletotrichum lagenarium, Fusarium oxysporum, and Watermelon fusarium, were then assayed by hypha measurement in vitro. The fungicidal assessment revealed that compared with starch and starch derivatives with 1,2,3-triazole, 1,2,3-triazolium-functionalized starch derivatives displayed tremendously enhanced antifungal activity. Especially, the inhibitory indices of 6-(4-hydroxymethyl-3-methyl-1,2,3-triazolium-1-yl)-6-deoxy starch iodine (2a) with against the tested plant threatening fungi attained 70% above at 1.0 mg/mL. It was also found that their antifungal activity profiles were dependent on the variation in alkyl chain length. As novel 1,2,3-triazolium-functionalized starch derivatives could be prepared efficiently and exhibited superduper antifungal activity, this synthetic strategy might provide an effective way and notion to prepare novel antifungal biomaterials.