In Vitro Evaluation of Cytotoxicity and Permeation Study on Lysine- and Arginine-Based Lipopeptides with Proven Antimicrobial Activity

Abstract

Owing to their excellent antimicrobial activities with a relatively low cost of production, lipopeptides are being intensively investigated as potential alternatives to popular antimicrobials. However, a critical obstacle for their application is a relatively high toxicity, hence a lot of attention has been paid to designing new molecules with optimal properties. In this study we synthesized the following lipopeptides: C16-KK-NH2, C16-KεK-NH2, C16-KKK-NH2, C16-KRK-NH2, C16-RR-NH2, C16-RRR-NH2, (C10)2-KKKK-NH2 and (C12)2-KKKK-NH2. Their antimicrobial activity against representative strains of Gram-positive bacteria, Gram-negative bacteria and fungi has been confirmed. The compounds have been evaluated with regard to the safety of their application in dermatology. The cytotoxicity was determined in HaCaT keratinocytes using MTT assay, whereas Strat M membranes placed in Franz diffusion cells were used to assess their ability to skin permeation. The compounds containing one hexadecanoic acid chain turned out to be very toxic towards human keratinocytes, while lipopeptides containing two fatty acid chains (decanoic and dodecanoic) demonstrated much lower cytotoxicity. For the most promising lipopeptide, (C10)2-KKKK-NH2, the measured IC50 on HaCaT keratinocytes was few times higher as compared to MICs obtained for the tested bacteria. Both groups of lipopeptides did not permeate the model membranes and therefore lack of permeation through human skin could be expected. The results of this work encourage further research on the potential application of lipopeptides with two fatty acids as novel antimicrobials.

Antibacterial mechanisms of GN‐2 derived peptides and peptoids against Escherichia coli

“…Increase in peptide/peptoid hydrophobicity due to the introduction of the aromatic residues Phe and N pm, has been shown to correlate with enhancement of hemolysis since hydrophobicity enables the partitioning in lipid bilayers of erythrocytes . This is corroborated by other investigations on both cationic lipo‐peptides and anti‐cancer peptides . However, when comparing GN‐2 with the all arginine peptide GN‐2‐Arg 1,3,4,7 , the hemolytic potential dropped with the increase of the hydrophobicity (Figure ).…”

Ultrashort Cationic Lipopeptides–Effect of N-Terminal Amino Acid and Fatty Acid Type on Antimicrobial Activity and Hemolysis

“…In general, lipopeptides have dispersing, foaming, de-emulsificating, and moisturizing properties [1]. Furthermore, it is worth nothing that USCLs offer promising antimicrobial activities against planktonic cells and biofilms of bacteria and fungi [2][3][4][5]. USCLs were also applied to modify materials to prevent bacterial colonization crucial to hard-to-treat biomaterial-associated infections [6].…”

“…USCLs seem to be non-specific membrane disruptors and therefore the risk of development of resistance is relatively low especially as compared to that of available antibiotics [15]. Unfortunately, lipopeptides with high antimicrobial activity usually exhibit substantial toxicity against human cells including red blood cells (hRBCs; erythrocytes) [3,5,16]. The aim of this study was to analyze the hydrophobic region of the USCLs to find out how it could be modified to improve selectivity for pathogens over human cells.…”

“…The aim of this study was to analyze the hydrophobic region of the USCLs to find out how it could be modified to improve selectivity for pathogens over human cells. Compounds used in this study were derivatives of USCL with palmitic acid and two arginine residues and a C-terminal amide (C16-RR-NH 2 ) that have proven antimicrobial activity [5,17,18]. Furthermore, arginine was chosen over lysine owing to its extensive H-bonding with phospholipid head-groups in the membrane and thus enhanced membrane perturbations [19].…”

Characteristic of AMP and the effects of chemical modifications on the modulation of their antimicrobial properties

“…Wszystkie dotychczas zaproponowane zmiany obejmowały modyfikacje w obrębie łańcucha peptydowego lub łańcucha bocznego reszt aminokwasowych obecnych w sekwencji. Wprowadzenie reszt D-aminokwasowych, lipidacja oraz cyklizacja przyczyniły się do poprawy selektywności, zwiększenia stabilności metabolicznej oraz aktywności biobójczej [18,42].…”