Synthesis, Characterization and Antifungal Activities of Amide and Acylthiourea of Substituted 2-Amino-1,3-Benzothiazole

Objective: To search new antifungal compounds for effectively controling vital plant diseases, we designed and synthesized series of N-acyl and acylthiourea of substituted 2-amino-1,3-benzothiazole. Methods: The in vitro antifungal activities of the target compounds were screened against the mycelium growth rate of Valsa mali and Botrytis cinerea. The in vivo antifungal activities were evaluated on grape fruit against B. cinerea. Microscopic inspection and electrical conductivity detection were used to explore the effects of screened compound on the mycelium growth of B. cinerea. Results: The results showed that the most active compounds against V. mali were A12 and B9, while the most active compounds against B. cinerea were B9 and B10. Structure activity relationship (SAR) indicates that 6-NO 2 on benzothiazole ring and electron withdrawing substitutes (-NO 2 , -CF 3 ) on the aryl ring of acyl group are benefical to the activity of benzothiazole acylthiourea. Meanwhile, compounds B9 and B10 exhibited 80%–95% control effects on grape fruit against B. cinerea at 200 μg/mL. Compound B9 could destroy the structure of mycelium by increasing the permeability of cell membrane to inhibit the growth of B. cinerea. Conclusions: The structure activity relationship and the action mechanism of the title compounds are helpful to design new fungicide.