Antibacterialagent 302 is an antibacterial compound with strong and broad-spectrum activity. It exhibits minimal hemolytic toxicity and cytotoxicity, and has a low tendency to induce resistance. Its mechanism of action involves disrupting the integrity of bacterial cell membranes. Antibacterialagent 302 is applicable for research into bacterial keratitis.

Antibacterial agent 302 (Compound 27) exhibits strong antibacterial activity against both Gram-positive bacteria, such as Staphylococcus epidermidis CMCC 26069 (MIC = 0.39 μg/mL), and Gram-negative bacteria, like Klebsiella pneumoniae ATCC 10031 (MIC = 1.56 μg/mL). It shows low hemolytic toxicity towards rabbit red blood cells (RBC), indicating high safety. The compound has a CC50 of 62.44 μg/mL for HEK 293 cells, 84.46 μg/mL for NCTC clone 929 cells, and 60.99 μg/mL and 61.17 μg/mL for THLE-2 and HSC-T6 cells, respectively. Over 21 days, its minimum inhibitory concentration (MIC) against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 remains stable over more than 20 generations, with low inducibility of resistance. At 8 × MIC for 2 hours, it exerts bactericidal effects by disrupting the cell membranes of Staphylococcus aureus ATCC 29213, methicillin-resistant Staphylococcus aureus NCTC 10442, and Escherichia coli ATCC 25922, causing bacterial morphology damage. Additionally, at 1-8 × MIC for 1 hour, it increases bacterial membrane permeability in methicillin-resistant Staphylococcus aureus NCTC 10442 and Pseudomonas aeruginosa ATCC 9027, leading to content leakage. The outer membrane permeability of Escherichia coli is also increased in a concentration-dependent manner at 1-2 × MIC for 1 hour. Expression of the genes dltB, mprF, and vraG in Staphylococcus aureus ATCC 29213 is upregulated 3.9-fold, 3.1-fold, and 4.9-fold, respectively, at 4 × MIC for 90 minutes. Moreover, it effectively inhibits biofilm formation in Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 at concentrations of 0.39-12.5 μg/mL over 24 hours.

Antibacterial agent 302 (Compound 27) at a concentration of 5 mg/mL, applied topically 4-6 times daily, demonstrates significant efficacy in treating keratitis caused by Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa) in vivo, while no notable toxic symptoms were observed in mice.