Broad-Spectrum Antimicrobial Potential of the γ-Core Motif Peptides of Filipendula ulmaria for Practical Applications in Agriculture and Medicine

Antimicrobial peptides (AMPs) are the promising candidates for the development of next-generation antimicrobials for agriculture and medicine; however, their large-scale production is costly. The γ-core motif peptides, functionally significant fragments of AMPs responsible for the antimicrobial activity, provide a more economical and feasible approach for the commercial development of novel antimicrobials. In the present work, we undertook a comprehensive study of antimicrobial properties of several γ-core peptides derived from defensins and snakins of <i>Filipendula ulmaria</i>, a medicinal plant known for its valuable pharmacological properties. The γ-core peptides were produced by solid-phase synthesis and purified by RP-HPLC. Their physicochemical properties underlying biological activity were predicted. All the peptides ranging in size from 14 to 18 amino acid residues were positively charged. All peptides except one were predicted to be α-helical and antimicrobial. The synthetic peptides were in vitro tested against a wide panel of plant and human fungal and bacterial pathogens. A short overview of the pathogens used in antimicrobial assays with a special emphasis on their economic, social, and medicinal impacts is provided. As a result of our work, we identified the peptides with pronounced activity in low-micromolar range against particular pathogens that can serve as prototypes for the development of novel biopesticides and antimicrobials for medicine. We also revealed synergism of action between particular γ-core peptide pairs and demonstrated that interference with membrane permeabilization contributes to the peptides' mode of action. The results obtained broaden our understanding of plant AMPs, the key players in plant immunity, and provide novel highly efficient peptides with high potential in practical applications.