MRL-494 hydrochloride, an antibacterial agent, is a inhibitor of β-barrel assembly machine A (BamA) impervious to efflux and the outer membrane permeability barrier. MRL-494 hydrochloride can inhibits Gram-positive (MIC of 12.5 μM for Staphylococcus aureus COL) and Gram-negative (MIC of 25 μM for E. coli JCM158) bacterias.