Development and Antifungal Efficacy of Hydrocarbon-Stapled Peptide Analogs Based on Human Antimicrobial Peptides for Candidiasis Therapy

KR-12, derived from the human antimicrobial peptide LL-37, maintains the antimicrobial properties of LL-37 while minimizing human cell toxicity.The KR-12 analog, named KR-12-pa, is characterized by its amphipathic -helical structure, contributing to its strong antimicrobial and antiinflammatory effects.In this study, we designed hydrocarbon-stapled peptide analogs based on KR-12-pa incorporating chiral non-natural amino acids at positions i and i+4.All stapled peptides were synthesized by solidphase peptide synthesis method, verified by LC-MS.The stapled peptides showed broad-spectrum antifungal activities, with minimum inhibitory concentrations (MIC) ranging from 2 to 32 g/mL, against pathogenic Candida strains including the fluconazole-resistant Candida krusei strain.Notably, a subset of these analogs, specifically S3, S5, and S7, demonstrated low human cell toxicity comparable to the original KR-12 peptide.Among these, S3 stood out for its balance of potent antifungal activity and minimal toxicity, making it a promising candidate for further development.Further structural analysis through circular dichroism indicated that S3 maintains an -helical conformation in buffer solutions, differing from the wild-type peptide.Preliminary in vivo assessments using the Galleria mellonella model underscored S3's reduced toxicity and heightened antifungal efficacy.Altogether, these results position the S3 stapled analog of KR-12-pa as a viable and effective option for treating candidiasis, highlighting its potential as a therapeutic innovation.