LasB-IN-1 (compound 5f) is a potent and orally active inhibitor of LasB ( IC 50 = 8.7 μM). LasB-IN-1 effectively attenuates elastase production and biofilm formation by P. aeruginosa while alleviating the inflammatory response through downregulating MAPK and NF-κB pathways. LasB-IN-1 is potential to be a novel anti-infective candidate against drug-resistant infections.