Botulinum neurotoxins serotype A(BoNT/A)is the deadliest toxins known to humans and the“Category A”agent for bioterrorism.Over the past 20 years,significant efforts have been put forth to develop effective inhibitors of BoNT/A.Unfortunately,few identified inhibitors possess noteworthy efficacy against BoNT/A in vivo.Here,we performed a high-throughput virtual screening based on the structure-based docking simulations and found a novel potent scaffold 2-thionicotinate that inhibits the BoNT/A light chain(LC).We then synthesized and optimized a novel series of 2-thionicotinate derivatives and comprehensively evaluated their activity against BoNT/A in vitro and in vivo.An optimized compound ZM299 effectively exhibits anti-BoNT/A activity in primary neurons and displayed remarkably therapeutic efficacy against BoNT/A in vivo,which could raise the survival rate of intoxicated mice to 100％(12/12)after lethal doses of BoNT/A exposures.These findings demonstrate that 2-thionicotinates is a promising scaffold for producing more effec-tive anti-BoNT/A analogs,and compound ZM299 is worthy of further preclinical evaluation as a drug candidate for the treatment of botulism.