High potency and broad-spectrum antimicrobial peptides synthesized via ring-opening polymerization of alpha-aminoacid-N-carboxyanhydrides.
Antimicrobial peptides (AMPs), particularly those effective against methicillin-resistant Staphylococcus aureus ( S. aureus ) and antibiotic-resistant Pseudomonas aeruginosa ( P. aeruginosa ), are important alternatives to antibiotics. Typical peptide synthesis methods involving solid-phase sequential synthesis are slow and costly, which are obstacles to their more widespread application. In this paper, we synthesize peptides via ring-opening polymerization of alpha-amino acid N-carboxyanhydrides (NCA) using a transition metal initiator. This method offers high potential for inexpensive synthesis of substantial quantities of AMPs. Lysine (K) was chosen as the hydrophilic amino acid and alanine (A), phenylalanine (F), and leucine (L) as the hydrophobic amino acids. We synthesized five series of AMPs (i.e., P(KA), P(KL), P(KF), P(KAL), and P(KFL)), varied the hydrophobic amino acid content from 0 to 100%, and determined minimal inhibitory concentrations (MICs) against clinically important Gram-negative and Gram-positive bacteria and fungi (i.e., Escherichia coli ( E. coli ), P. aeruginosa , Serratia marcescens ( S. marcescens ), and Candida albicans ( C. albicans ). We found that P(K(10)F(7.5)L(7.5)) and P(K(10)F(15)) show the broadest activity against all five pathogens and have the lowest MICs against these pathogens. For P(K(10)F(7.5)L(7.5)), the MICs against E. coli , P. aeruginosa , S. marcescens , S. aureus , and C. albicans are 31 microg/mL, 31 microg/mL, 250 microg/mL, 31 microg/mL, and 62.5 microg/mL, while for P(K(10)F(15)) the respective MICs are 31 microg/mL, 31 microg/mL, 250 microg/mL, 31 microg/mL, and 125 microg/mL. These are lower than the MICs of many naturally occurring AMPs. The membrane depolarization and SEM assays confirm that the mechanism of microbe killing by P(K(10)F(7.5)L(7.5)) copeptide includes membrane disruption, which is likely to inhibit rapid induction of AMP-resistance in pathogens.
Zhou
Chuncai
C
School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore.
Qi
Xiaobao
X
Li
Peng
P
Chen
Wei Ning
WN
Mouad
Lamrani
L
Chang
Matthew W
MW
Leong
Susanna Su Jan
SS
Chan-Park
Mary B
MB
D000596:Amino Acids / Q000737:chemistry*; D000812:Anhydrides / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002942:Circular Dichroism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D005658:Fungi / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D011108:Polymers / Q000138:chemical synthesis*
D000596:Amino Acids; D000812:Anhydrides; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D006454:Hemoglobins; D011108:Polymers