Identification and Optimization of a Truncated Hs-1-Derived Antimicrobial Peptide for Enhanced Broad-Spectrum Antiviral Activity.

Antimicrobial peptides (AMPs) represent promising scaffolds for the development of novel broad-spectrum antiviral therapeutics. Based on structural modeling data, we applied a systematic sequence downsizing approach to the 20-amino-acid AMP Hs-1 from Hypsiboas semilineatus to identify its minimal active region. A series of N- and C-terminally truncated derivatives was synthesized to preserve the predicted amphipathic α-helical core. Circular dichroism showed that the peptides adopt a random-coil conformation in aqueous solution and transition to an α-helical structure in hydrophobic environments, which is essential for membrane disruption. Antiviral screening against enveloped viruses revealed that the peptides interfere with the early stages of infection while maintaining a favorable safety profile. Notably, variant Hs-1[7-20] showed a two-to-four-fold potency enhancement over the parent peptide, indicating the successful removal of a detrimental N-terminal segment. Further optimization via N-terminal acetylation and C-terminal amidation yielded Hs-1[7-20]mod, which exhibited increased antiviral efficacy and serum stability, achieving low-micromolar IC50 values (0.5-0.7 µM) under virus pretreatment conditions while maintaining low toxicity (CC50 > 100 µM). In conclusion, Hs-1 was successfully optimized into a potent, stable, and safe antiviral candidate Hs-1[7-20]mod.