Novel Pyrazolo[3,4-]pyrimidin-4-one Derivatives as Potential Antifungal Agents: Design, Synthesis, and Biological Evaluation.

Plant pathogenic fungi seriously threaten agricultural production. There is an urgent need to develop novel fungicides with low toxicity and high efficiency. In this study, we designed and synthesized 44 pyrazolo[3,4-]pyrimidin-4-one derivatives and evaluated them for their fungicidal activities. The bioassay data revealed that most of the target compounds possessed moderate to high in vitro antifungal activities. Especially compound exhibited remarkable antifungal activity against with an EC value of 1.25 mg/L, close to that of commercial fungicide (EC = 0.96 mg/L) and (EC = 1.91 mg/L). Moreover, compound possessed prominent protective activity against in vivo for 24 h (95.23%) and 48 h (93.78%), comparable to positive control (24 h (96.63%); 48 h (93.23%)). Subsequent studies indicated that compound may impede the growth and reproduction of by affecting the morphology of mycelium, destroying cell membrane integrity, and increasing cell membrane permeability. In addition, the application of compound did not injure the growth or reproduction of Italian bees. This study revealed that compound is expected to be developed for efficient and safe agricultural fungicides.