Antibacterialagent 200 (pyridyl HH 7) is a unique hydrazine-based hydroxycoumarin (HH) characterized by potent and broad-spectrum antibacterial activity, with minimum inhibitory concentration (MIC) values ranging from 0.5-32 μg/mL against both Gram-positive and Gram-negative bacteria. It effectively inhibits Pseudomonas aeruginosa 27853 with an MIC of 0.5 μg/mL. Antibacterialagent 200 disrupts bacterial membrane integrity, leading to leakage of intracellular proteins, and interacts with bacterial DNA gyrase through non-covalent binding.