Determination of antifungal activity and action mechanism of the modified Aurein 1.2 peptide derivatives

Abstract

BackgroundWith the emergence of drug-resistant fungi and the increased population prone to fungal infections, more effective antifungal drugs are needed. Aurein 1.2 is a potent antimicrobial peptide. Here, we designed a novel derivative of Aurein 1.2, called Aurein N3, which is a modified form of Aurein N2 (another Aurein 1.2 derivative), in which Lys 8 residue was replaced with Leu 13, and was also modified by creating two other mutations. MethodsAurein N3 was designed using several algorithms and docking studies. All peptides were synthesized and some of their bio-activity indices such as antifungal properties on 11 fungi, cytotoxicity, hemolysis, and time of the killing were investigated. Electron microscopy, lived/dead staining, and ergosterol binding assay were performed to study their mechanism of action. ResultsIn comparison to Aurein 1.2 and N2, the docking studies showed that Aurein N3 has reduced binding energy toward ergosterol. The antifungal assessments showed that both Aurein N2 and N3 had strong activity against many fungi. Aurein N3 had lower cytotoxicity and higher binding capability to ergosterol. The hemolytic activity of Aurein N2 and N3 was less than parental Aurein 1.2. All peptides were able to attack the cell wall/membrane and enter the fungi cells. ConclusionHere we introduced a novel derivative of Aurein 1.2 which has lower cytotoxicity, higher ergosterol-binding capability, and comparable antifungal activity compared to the original peptides. It can bind to ergosterol and can also attack the cell wall/membrane of fungi, although more studies are required to find its accurate mechanism of action.