Trialkylamine Derivatives Containing a Triazole Moiety as Promising Ergosterol Biosynthesis Inhibitor: Design, Synthesis, and Antifungal Activity.

As a part of our continuing research on amine derivative antifungal agents, 19 novel target compounds containing 1,2,4-triazole and tertiary amine moieties were designed and synthesized, and their in vitro antifungal activities against six phytopathogenic fungi (Magnaporthe grisea, Alternaria solani, Fusarium solani, Curvularia lunata, A. alternata, F. graminearum) were assayed. All target compounds were elucidated by means of H-NMR, C-NMR, high resolution (HR)-MS, and IR analysis. The results showed that most of the derivatives exhibited obvious activity against each of the fungi at 50 µg/mL. Among them, compounds 7f, l, and o displayed excellent activity against A. solani with median effective concentration values (EC) of 2.88, 8.20, and 1.92 µg/mL. 7o in particular was superior to tebuconazole (EC=2.03 µg/mL), a commercial fungicide. Furthermore, compounds 7j, k, and m also showed good activity against F. graminearum with EC values of 11.60, 5.14, and 16.24 µg/mL, and the value of 7k was extremely close to that of tebuconazole (EC=3.13 µg/mL). The preliminary analysis of the structure-activity relationship (SAR) demonstrated that combination of the active structure of 1,2,4-triazole with the tertiary amine group containing benzene rings effectively increased the antifungal activities. Generally, introducing halogen atoms obviously improved activities against most of the test fungi to varying degrees, while the presence of OMe decreased the activities. Thus, the results strongly indicate that the newly synthesized derivatives should be lead compounds for the development of novel antifungal agents for the effective control of phytopathogenic fungi.