1Westerdijk, Fungal Biodiversity Institute, Netherlands
2CBMR Scientific Inc, Canada
3BioAware Life Sciences Data Management Software, Belgium
4Department of Pharmaceutical sciences, University of Perugia, Italy
3CEMIN Research Centre of Excellence, University of Perugia, Italy
4Department of Radiology, Interventional Molecular Imaging Laboratory, Leiden University Medical Center, Netherlands
*Corresponding author: Carlo PJM Brouwer, Westerdijk, Fungal Biodiversity Institute, Uppsalalaan 8, Utrecht 3584 CT, Netherlands, CBMR Scientific Inc., Edmonton, Alberta, Canada, BioAware Life Sciences Data Management Software, Rue du Henrifontaine 20, B-4280 Hannut, Belgium, Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, Utrecht 3584 CT, Netherlands, Fax: +31 (0)30 2122601, Tel: +31 (0)30 2122600; Email: firstname.lastname@example.org
Submission: January 31, 2018; Published: March 13, 2018
ISSN: 2578-0190 Volume1 Issue3
Antimicrobial peptides are omnipresent in nature and act as the first line of defence of the host against infectious agents. A synthetic antimicrobial peptide derived from the N-terminus of human lactoferrin hLF(1-11) (GRRRRSVQWCA), displays antibacterial as well as antifungal activity in vitro and in vivo. In order to elucidate the mechanism of antimicrobial action of hLF(1-11), we have synthesised several peptides analogues derived from hLF(1- 11) to test their activity against various fungal and bacterial strains. In this way, a general trend on the importance of the order and position of amino acid residues for biological activity against various organisms could be drawn.
In this study, the full Ala-scan has been synthesised (i.e. series of structural variants where a different residue is replaced with an alanine residue); the affinity of the analogue peptide was assessed and compared with that of the original. Additionally, we performed combination therapy with hLF(1-1) peptides and classical antibiotics as this may serve as an alternative approach to improve antimicrobial treatment outcome in drug resistant strains. The biological tests showed a decrease in the activity of the peptide when one out of the first three arginine residues, the tryptophan or the cysteine residue were replaced by alanine. Replacement of the cysteine residue by a serine residue or by a methylated cysteine led to peptides that were significantly less potent than the reference peptide hLF(1 11). However, the peptide containing a cysteine residue; the disulphide dimer showed the same activity as the monomer. Finally, it was also possible to replace the tryptophan residue by another aromatic residue phenylalanine without any loss of activity. Amidation of the C-terminus did not negatively affect the biological activity of the peptide but even increased, while acetylation of the N-terminus led to a significant loss of antimicrobial activity. The synthesis of analogues from hLF(1 11) and their use in biological tests revealed the importance of some amino acid residues for antimicrobial activity; that are arginine (position 2), tryptophan (position 9) and cysteine (position 10). Secondly, in combination with classical antibiotics even for the drug resistant species we found synergistic interactions between the peptide and antibiotics in vivo. In conclusion, some amino acid sequences/places of hLF(1-11)are important for the antimicrobial actions and in synergistic processes.
Keywords: AMP; Biological activity; Synergism; Fungal infections