Exploring the antimicrobial potential of crude peptide extracts from Allium sativum and Allium oschaninii against antibiotic-resistant bacterial strains

Abstract

Context: Plant peptides garner attention for their potential antimicrobial properties amid the rising concern over antibiotic-resistant bacteria. Objective: This study investigates the antibacterial potential of crude peptide extracts from 27 Thai plants collected locally. Materials and methods: Peptide extracts from 34 plant parts, derived from 27 Thai plants, were tested for their antimicrobial efficacy against four highly resistant bacterial strains: Streptococcus aureus MRSA, Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli. The stability of these peptide extracts was examined at different temperatures, and the synergistic effects of two selected plant peptide extracts were investigated. Additionally, the time-kill kinetics of the individual extracts and their combination were determined against the tested pathogens. Results: Peptides from Allium sativum L. and Allium oschaninii O. Fedtsch (Amaryllidaceae) were particularly potent, inhibiting bacterial growth with MICs ranging from 1.43 to 86.50 µg/mL. The consistent MICs and MBCs of these extracts across various extraction time points highlight their reliability. Stability tests reveal that these peptides maintain their antimicrobial activity at −20 °C for over a month, emphasizing their durability for future exploration and potential applications in addressing antibiotic resistance. Time-kill assays elucidate the time and concentration-dependent nature of these antimicrobial effects, underscoring their potent initial activity and sustained efficacy over time. Discussion and conclusions: This study highlights the antimicrobial potential of Allium-derived peptides, endorsing them for combating antibiotic resistance and prompting further investigation into their mechanisms.