Antibiotic-Based Conjugates Containing Antimicrobial HLopt2 Peptide: Design, Synthesis, Antimicrobial and Cytotoxic Activities

ACS Chem Biol. 2019 Oct 18;14(10):2233-2242. doi: 10.1021/acschembio.9b00538. Epub 2019 Sep 25.

Abstract

Recent studies have shown that modified human lactoferrin 20-31 fragment, named HLopt2, possesses antibacterial and antifungal activity. Thus, we decided to synthesize and evaluate the biological activity of a series of conjugates based on this peptide and one of the antimicrobials with proven antibacterial (ciprofloxacin, CIP, and levofloxacin, LVX) or antifungal (fluconazole, FLC) activity. The drugs were covalently connected to the peptide via amide, methylenecarbonyl moieties, or a disulfide bridge. The antibacterial and antifungal activities were evaluated under Clinical and Laboratory Standard Institute (CLSI) recommended conditions or in a low-salt brain-heart infusion diluted medium (BHI1/100). Results showed that conjugation of the peptide with the drug increased its antimicrobial activity up to 4-fold. Under CLSI-recommended conditions, all the compounds revealed rather low efficiency. Among conjugates, the highest antibacterial activity was recorded for the CIP-Cys-S-S-HLopt2-NH2 (III). In BHI1/100, which had lower differentiating properties, all of the conjugates revealed low MIC and MMC (minimum inhibitory and microbicidal concentrations) values. The disulfide bridge used as a linker in the most active conjugate (III) upon incubation with S. aureus cells is reduced, releasing constituent peptide and CIP-Cys. In addition, we showed that its fluorescently labeled analogue and constituent peptide are able to be internalized into both C. albicans and S. aureus cells. Moreover, the invaluable advantage of the presented conjugates was their low toxicity to mammalian cells and very low hemolytic activity. The current research can form a solid basis for further in vivo studies and drug development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemical synthesis
  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / toxicity
  • Antifungal Agents / chemical synthesis
  • Antifungal Agents / pharmacology*
  • Antifungal Agents / toxicity
  • Candida albicans / drug effects
  • Ciprofloxacin / chemical synthesis
  • Ciprofloxacin / pharmacology
  • Ciprofloxacin / toxicity
  • Drug Stability
  • Escherichia coli / drug effects
  • Fluconazole / chemical synthesis
  • Fluconazole / pharmacology
  • Fluconazole / toxicity
  • HEK293 Cells
  • Hep G2 Cells
  • Humans
  • Immunoconjugates / pharmacology*
  • Immunoconjugates / toxicity
  • Lactoferrin / chemical synthesis
  • Lactoferrin / pharmacology*
  • Lactoferrin / toxicity
  • Levofloxacin / chemical synthesis
  • Levofloxacin / pharmacology
  • Levofloxacin / toxicity
  • Male
  • Microbial Sensitivity Tests
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / pharmacology*
  • Peptide Fragments / toxicity
  • Staphylococcus aureus / drug effects
  • Swine

Substances

  • Anti-Bacterial Agents
  • Antifungal Agents
  • Immunoconjugates
  • LTF protein, human
  • Peptide Fragments
  • Ciprofloxacin
  • Levofloxacin
  • Fluconazole
  • Lactoferrin