Isomerization of an antimicrobial peptide broadens antimicrobial spectrum to gram-positive bacterial pathogens

Area of Science:

• Microbiology
• Peptide Science
• Drug Discovery

Background:

• The M33 antimicrobial peptide exhibits potent activity against Gram-negative pathogens.
• There is a need for novel antimicrobial agents, particularly against multidrug-resistant strains.

Purpose of the Study:

• To synthesize and evaluate an M33 peptide isomer composed of D-amino acids (M33-D).
• To compare the antimicrobial efficacy of M33-D with the original M33 peptide (M33-L) against Gram-positive and Gram-negative bacteria.

Main Methods:

• Synthesis of the D-amino acid isomer M33-D.
• Antimicrobial activity assays against Gram-positive and Gram-negative bacterial strains.
• Assessment of protease sensitivity.
• Biofilm eradication experiments.
• In vivo efficacy studies in a mouse infection model.

Main Results:

• M33-D demonstrated 4 to 16-fold higher activity against Gram-positive pathogens (e.g., Staphylococcus aureus, Staphylococcus epidermidis) compared to M33-L.
• M33-D retained significant activity against Gram-negative bacteria.
• Differential sensitivity to bacterial proteases influenced peptide activity.
• M33-D showed superior performance in biofilm eradication and in vivo survival studies.

Conclusions:

• M33-D is a potent antimicrobial agent with broad-spectrum activity.
• M33-D represents a promising candidate for developing novel therapeutics against clinically important bacterial pathogens.