Synthesis and anti-fungi/oomycetes activity of cuminic acid derivatives containing thiourea group for crop protection.

In search of novel natural product-based fungicides,twenty-four cuminic acid derivatives containing thiourea group were synthesized and characterized by 1H-NMR, 13C-NMR and HRMS spectra. The anti-fungi/oomycete activity bioassay showed that the some of the title compounds displayed moderate to good anti-fungi activity against Botryosphaeria dothidea (B. dothidea), Sclerotinia sclerotiorum (S. sclerotiorum) and Valsa mali (V. mali). Compound 4k exhibited the best in vitro anti-fungi activity toward V. mali. The in vivo experiment identified that 4k possessed considerable anti-V. mali protective and curative effect at 200 mg/L. Antifungal mechanism study showed that 4k could destroy morphology of V. mali mycelia, increase the cell membrane permeability, inhibit the dry weight of V. mali mycelia and led to the increase of reactive oxygen species(ROS) level. The phytotoxicity experiment revealed that compound 4k showed good safety on mung bean. This cuminic acid derivatives would be potential fungicide for controlling apple canker disease.