Conjugation of CRAMP 18-35 Peptide to Chitosan and Hydroxypropyl Chitosan via Copper-Catalyzed Azide-Alkyne Cycloaddition and Investigation of Antibacterial Activity

• Published in: International journal of molecular sciences 2024-08, Vol.25 (17)
• Main Authors: Rathinam, Sankar, Sørensen, Kasper K, Hjálmarsdóttir, Martha Á, Thygesen, Mikkel B, Másson, Már
• Format: Article
• Language: English
• Subjects: Alkynes - chemistry; Animals; Anti-Bacterial Agents - chemical synthesis; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - pharmacology; Azides - chemistry; Catalysis; Cathelicidins; Chitosan - analogs & derivatives; Chitosan - chemistry; Chitosan - pharmacology; Copper - chemistry; Cycloaddition Reaction; Enterococcus faecalis - drug effects; Enterococcus faecalis - growth & development; Mice; Microbial Sensitivity Tests; Staphylococcus aureus - drug effects
• ISSN: 1422-0067
• DOI: 10.3390/ijms25179440

We developed a synthesis strategy involving a diazo transfer reaction and subsequent click reaction to conjugate a murine cathelicidin-related antimicrobial peptide (CRAMP ) to chitosan and hydroxypropyl chitosan (HPC), confirmed the structure, and investigated the antimicrobial activity. Chitosan azide and HPC-azide were prepared with a low degree of azidation by reacting the parent chitosan and HPC with imidazole sulfonyl azide hydrochloride. CRAMP carrying an N-terminal pentynoyl group was successfully grafted onto chitosan and HPC via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The chitosan-peptide conjugates were characterized by IR spectroscopy and proton NMR to confirm the conversion of the azide to 1,2,3-triazole and to determine the degree of substitution (DS). The DS of the chitosan and HPC CRAMP conjugates was 0.20 and 0.13, respectively. The antibacterial activity of chitosan-peptide conjugates was evaluated for activity against two species of Gram-positive bacteria, ( ) and ( ), and two species of Gram-negative bacteria ( ) and ( ). The antimicrobial peptide conjugates were selectively active against the Gram-negative bacteria and lacking activity against Gram-positive bacteria.