Cyclic L27-11 is a cyclic peptide analog antibiotic that exhibits potent antimicrobial activity against specific bacteria, particularly Pseudomonas sp. It is highly effective against Pseudomonas aeruginosa, demonstrating nanomolar-level antibacterial activity. The mechanism of action for Cyclic L27-11 involves interfering with the function of the bacterial outer membrane protein LptD, inhibiting the normal transport of lipopolysaccharide (LPS). This inhibition leads to the accumulation of membrane-like substances within the bacterial cell, adversely affecting bacterial survival. Consequently, Cyclic L27-11 is a promising candidate for antimicrobial agent development.