Structural modification of tryptamine derivative bearing 2-(thiazol-4-yl)acetamide from Polyphaga plancyi as potential fungicidal agents

A N-phenylacetyl tryptamine derivative, isolated and identified from Polyphaga plancy, was used as a lead compound to carry out structural optimization for the exploration of fungicidal agents. Here we designed and synthesized a series of tryptamine derivatives bearing 2-(thiazol-4-yl)acetamide by a straightforward method. The results of biological experiments showed that most of the title compounds possessed potential fungicidal activities against Fusarium graminearum, Fusarium oxysporumn, Sclerotinia sclerotiorum, and Curvularia mebaldsii. Especially, PLS-12 provided the EC₅₀ values of 23.5 mg/L, 24.7 mg/L, and 27.4 mg/L against F. oxysporumn, F. graminearum, and S. sclerotiorum, respectively, whose activities were superior or similar to those of hymexazol. This is the first report on the application of plant protection using active derivatives from P. plancyi. It provides valuable scientific insights into the structural optimization and development of active substances derived from P. plancyi, and offers a novel structural precursor for the design of fungicidal molecules.