Antimicrobial Activity of the Antibacterial Peptide PMAP-GI24 and Its Analogs

Because of the growing problem of antibiotic resistance, the antibacterial activity of antimicrobial peptides (AMPs) has attracted attention. In this study, two PMAP-GI24 peptide analogs, PMAP-24WW and PMAP-24KK, were synthesized by extending the α-helix and increasing the positive charge of the parental peptide. The antibacterial activities of PMAP-GI24 and its analogs were detected in vitro and in vivo. The results showed that after modification, PMAP-24KK displayed an increased zone of inhibition against Escherichia coli ATCC25922 compared to that of PMAP-GI24. PMAP-24WW had inhibition zones against nine bacterial strains, among which, the antibacterial zones were larger than those of PMAP-GI24 against seven bacterial strains. Furthermore, PMAP-24KK had inhibition zones against ten bacterial strains, and the antibacterial zones were larger than those of PMAP-GI24 against seven bacterial strains. Moreover, in the in vivo efficacy assessment of mice infected with Salmonella enterica serovar choleraesuis C78-1 and Listeria monocytogenes CICC21533, the PMAP-GI24 analogs effectively reduced the number of bacterial and decreased the inflammatory damage in the mouse livers and lungs, thus effectively reducing mortality. This study provides reference data for the clinical design of effective antibiotic alternatives.