Discovery of a Potent Botulinum Neurotoxin A Inhibitor ZM299 with Effective Protections in Botulism Mice

Comprehensive Summary 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 effective anti‐BoNT/A analogs, and compound ZM299 is worthy of further preclinical evaluation as a drug candidate for the treatment of botulism.