Unveiling the mechanism of action of acylated temporin L analogues against multidrug-resistant Candida albicans

Abstract

The increasing resistance of fungi to conventional antifungal drugs has prompted worldwide the search for new compounds. In this work, we investigated the antifungal properties of acylated Temporin L derivatives, Pent-1B and Dec-1B , against Candida albicans , including the multidrug-resistant strains. Acylated peptides resulted to be active both on reference and clinical strains with MIC values ranging from 6.5 to 26 µM, and they did not show cytotoxicity on human keratinocytes. In addition, we also observed a synergistic or additive effect with voriconazole for peptides Dec-1B and Pent-1B through the checkerboard assay on voriconazole-resistant Candida strains. Moreover, fluorescence-based assays, NMR spectroscopy, and confocal microscopy elucidated a potential membrane-active mechanism, consisting of an initial electrostatic interaction of acylated peptides with fungal membrane, followed by aggregation and insertion into the lipid bilayer and causing membrane perturbation probably through a carpeting effect.

Glycosylation and Lipidation Strategies: Approaches for Improving Antimicrobial Peptide Efficacy

“…Indeed, the conjugation of the lipid tails of C13, C10, C7, and C5 at the N- terminus of the peptide [Pro 3 ,DLeu 9 ,DLys 10 ]TL derived from the natural Temporin L peptide caused a reduction in the net positive charge from +4 to +3, with a consequent reduction in the activity of lipopeptides toward S. aureus , K. pneumoniae, and P. aeruginosa. In [ 90 , 91 ], the authors identified the para position of Phe 1 as the optimal position for the attachment of fatty acids, as it preserved the positive charge +4 and demonstrated the best activity against both bacteria and Candida species.…”

Hydrophobicity: The door to drug delivery

“…A subtle balance between cationic groups and hydrophobic side chains located on different sides of the amphiphilic structure is the key to disrupt bacterial cell membranes, causing membrane leakage and ultimately cell death. [143][144][145][146][147][148][149] Interestingly, there is a significant difference between amphiphilic peptides with a perfectly alternating hydrophobic and hydrophilic domain, where inefficient close contact can have a negative impact on lipid membrane disruption, and the conformational amphiphilic peptides, which having a homogeneous allocation of cationic and hydrophobic moieties, lead to improved contacts between the peptide and the membrane. To maximize application efficacy while reducing undesired deleterious effects brought on by hydrophobic interactions and disruptions of the membrane phospholipid bilayer, peptide hydrophobicity must be carefully considered during design.…”

“…While cationic domains are critical for antimicrobial activity, the hydrophobicity is the driving force for lipid membrane binding; both hydrophilicity and hydrophobicity are key for pore formation which eventually triggers cell death through a membrane‐disruption mechanism. A subtle balance between cationic groups and hydrophobic side chains located on different sides of the amphiphilic structure is the key to disrupt bacterial cell membranes, causing membrane leakage and ultimately cell death 143–149 . Interestingly, there is a significant difference between amphiphilic peptides with a perfectly alternating hydrophobic and hydrophilic domain, where inefficient close contact can have a negative impact on lipid membrane disruption, and the conformational amphiphilic peptides, which having a homogeneous allocation of cationic and hydrophobic moieties, lead to improved contacts between the peptide and the membrane.…”

Myxinidin-Derived Peptide against Biofilms Caused by Cystic Fibrosis Emerging Pathogens

“…Large unilamellar vesicles (LUVs) mimicking Gram-negative bacteria (DOPE/DOPG/CL, 63/25/12, ratio in moles) and Candida (PE/PC/PI/Ergosterol, 5:4:1:2, ratio in moles) were prepared according to the extrusion method, as previously reported [ 78 , 79 , 80 ]. LUVs were loaded with ANTs and DPX fluorescent probes to monitor their leakage induced by WMR-4.…”