IDENTIFICATION OF ANTIMICROBIAL COMPOUNDS AGAINST BRUCELLOSIS TARGETING RIBOFLAVIN SYNTHASE

MARIELA DEL CARMEN CARRICA; MARÍA INÉS SERER; MARÍA LAURA CERUTTI; JOERG TRAPPE; SANDRA LOPEZ ROMERO; HERNÁN RUY BONOMI; SEBASTIÁN KLINKE; FERNANDO ALBERTO GOLDBAUM

Buenos Aires

Congreso; Reunion Conjunta de Sociedades de Biociencias; 2017

Brucella spp. are facultative intracellular bacteria, that areadapted to life within cells of a large variety of mammals. These bacteria are thecausative agent of brucellosis, a zoonotic infection with the highest incidencein the world affecting livestock and humans and for which a safe and completelyreliable vaccine is still unavailable. Riboflavin (vitamin B2) is the universalprecursor for the biosynthesis of FMN and FAD, two versatile redox cofactors innature. This vitamin is biosynthesized in microorganisms and plants but must beobtained from dietary sources by animals. Owing to the absence of this pathway in animals andhumans and the fact that endogenous riboflavin synthesis is necessary for the growth of many pathogens, thispathway is regarded as a rich resource of targets for the development of new antimicrobial agents for thetreatment of brucellosis. In this work, we describe a High-Throughput Screening(HTS) approach for the identification of inhibitors of the enzymatic activityof Riboflavin Synthase, the last enzyme of the riboflavin biosynthesis pathway,along with its subsequent validation as potential drugs candidates in anin vitro model for brucellosis infection.From a set of 44,000 highly diverse low-molecular weight compounds, a total of 163exhibited a 30% threshold inhibition at 30 µM concentration. Further secondaryscreening with dose-response curves allowed for the identification of tenmolecules with 50% inhibitory concentrations (IC50s) in the low micromolarrange. Interestingly, a subset of five compounds sharing a2-Phenylamidazo[2,1-b][1,3]benzothiazole chemical scaffold also displayed bactericideactivity against B. abortus.Furthermore, we tested the effect of the two most promisingcompounds on the survival of intracellular bacteria and we found that they areable to inhibit Brucella growth in amurine macrophage cell line. These findings represent a promissory advancementin the pursuit of antimicrobial compounds against brucellosis.