Synthesis and Evaluation of Benzylamine Inhibitors of Neuropathogenic Naegleria fowleri "Brain-Eating" Amoeba

Current therapy for primary amoebic meningoencephalitis (PAM), a highly lethal brain infection in humans caused by Naegleria fowleri amoeba, is restricted to repurposed drugs with limited efficacy and success. Discovery of an antiamoebic benzylamine scaffold 2 precipitated a medicinal chemistry effort to improve potency, cytotoxicity profile, and drug-like properties. Thirty-four compounds were prepared, leading to compound 28 with significant gains in potency (EC50 = 0.92 mu M), solubility, and microsomal stability and a demonstrated absence of cytotoxicity in SH-SY5Y human neuroblastoma cells (CC50 > 20 mu M). The compounds demonstrated excellent blood-brain barrier permeability in an in vitro assay, thereby providing a new structural scaffold that inhibits N. fowleri viability and permits the investigation of therapeutic interventions in an understudied neglected disease.