Design, synthesis of novel starch derivative bearing 1,2,3-triazolium and pyridinium and evaluation of its antifungal activity

Based on cuprous-catalyzed azide-alkyne cycloaddition (CuAAC), starch derivative bearing 1,2,3-triazole and pyridine (II) was prepared and subsequently followed by alkylation with iodomethane to synthesize starch derivative bearing 1,2,3-triazolium and pyridinium (III). The antifungal activities of starch derivatives against Colletotrichum lagenarium, Watermelon fusarium, and Phomopsis asparagi, were then assayed by hypha measurement in vitro. Apparently, starch derivatives showed enhanced antifungal activity against three fungi at the tested concentrations compared with starch. Especially, the best inhibitory index of starch derivative (III) against Colletotrichum lagenarium attained 97% above at 1.0 mg/mL. Meanwhile, starch derivative (III) had stronger antifungal activity than starch derivative (II), which was reasonable to propose that the alkylation of 1,2,3-triazole and pyridine was significant for enhanced antifungal activity. As this novel starch derivative bearing 1,2,3-triazolium and pyridinium could be prepared efficiently and exhibited superduper antifungal activity, this material might provide an effective way and notion to prepare novel antifungal agents.