CGD-1, a defensin-related peptide derived from marine Chinese medicine Ostreae concha, inhibits the Gram-negative bacteria by membrane attack

Abstract

There is an increasing interest in discovering new antibacterial agents derived from nature to enhance the treatment of various bacterial infections. Defensins and their derived peptide fragments exhibit significant antibacterial activity without any cytotoxic effects, making them attractive features for potential novel antibacterial therapeutics. Crassostrea gigas , a traditional seafood that has been used worldwide for centuries, has its shells applied in Chinese medicine as Ostreae concha . In this study, bioinformatics analysis was used to obtain a novel antibacterial peptide, CGD-1, derived from marine Chinese medicine Ostreae concha . The physicochemical characterization and circular dichroism analysis results demonstrated that CGD-1 assembled into an α -helical structure in a simulated membrane environment, and it displayed antibacterial action against Gram-negative bacteria. The minimal inhibitory concentrations against both Pseudomonas aeruginosa ATCC27853 and Escherichia coli ATCC25922 were 25 μ M. CGD-1 was able to efficiently permeate the cell membrane. Changes in bacterial cell morphology were evaluated using a field emission scanning electron microscope. The results suggested that CGD-1 exerted its antibacterial activity through permeabilizing and disrupting the bacterial cell membrane. Therefore, CGD-1 may have potential applications in fighting against pathogenic bacteria such as P. aeruginosa and E. coli .