The Discovery of HNPC-A0073: A Novel Thiazol-5-ylmethyl-Based 3-Nitropyridin-2-amine Fungicide

Botrytis cinerea is one of the most destructive pathogens that cause serious damage to fruits and vegetables. The effective management of B. cinerea thus requires the continuous development of new fungicides with novel structures or distinct modes of action. This study on nitropyridine chemistry led to the discovery of 6Bc-5 (HNPC-A0073 ). 6Bc-5 exhibits excellent fungicidal potency against B. cinerea (EC 50 = 0.47 mg/L), superior to or comparable to the commercial products, such as procymidone, boscalid, and fluopyram. Notably, 6Bc-5 probably operates through a distinct fungicidal mechanism that does not affect energy metabolism but instead potently suppresses the ribosome biogenesis pathway of pathogenic fungi. This mechanism also allows 6Bc-5 to demonstrate a low toxicity to mammals, bees, and birds.