RESUMEN
Targeting viral polymerases has been a proven and attractive strategy for antiviral drug discovery. Herein we describe our effort in improving the antiviral activity and physical properties of a series of benzothienoazepine compounds as respiratory syncytial virus (RSV) RNA polymerase inhibitors. The antiviral activity and spectrum of this class was significantly improved by exploring the amino substitution of the pyridine ring, resulting in the discovery of the most potent RSV A polymerase inhibitors reported to date.
Asunto(s)
ARN Polimerasas Dirigidas por ADN/antagonistas & inhibidores , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Virus Sincitiales Respiratorios/enzimología , Proteínas Virales/antagonistas & inhibidores , Antivirales/síntesis química , Antivirales/química , Antivirales/farmacología , Azepinas/síntesis química , Azepinas/química , Azepinas/farmacología , Línea Celular , ARN Polimerasas Dirigidas por ADN/metabolismo , Evaluación Preclínica de Medicamentos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/síntesis química , Humanos , Relación Estructura-Actividad , Proteínas Virales/metabolismo , Replicación Viral/efectos de los fármacosRESUMEN
A series of inhibitors with a squaramide core was synthesized following its discovery in a high-throughput screen for novel inhibitors of a transcription-coupled translation assay using Escherichia coli S30 extracts. The inhibitors were inactive when the plasmid substrate was replaced with mRNA, suggesting they interfered with transcription. This was confirmed by their inhibition of purified E. coli RNA polymerase. The series had antimicrobial activity against efflux-negative strains of E. coli and Haemophilus influenzae. Like rifampin, the squaramides preferentially inhibited synthesis of RNA and protein over fatty acids, peptidoglycan, and DNA. However, squaramide-resistant mutants were not cross-resistant to rifampin. Nine different mutations were found in parts of rpoB or rpoC that together encode the so-called switch region of RNA polymerase. This is the binding site of the natural antibiotics myxopyronin, corallopyronin, and ripostatin and the drug fidaxomicin. Computational modeling using the X-ray crystal structure of the myxopyronin-bound RNA polymerase of Thermus thermophilus suggests a binding mode of these inhibitors that is consistent with the resistance mutations. The squaramides are the first reported non-natural-product-related, rapidly diversifiable antibacterial inhibitors acting via the switch region of RNA polymerase.