Broad-Spectrum Antimicrobial Activity and Low Cytotoxicity against Human Cells of a Peptide Derived from Bovine αS1-Casein.

Juncai Hou,Haimei Wang,Chenggang Jiang,Muhammad Hussain,Shiyue Pang,Songsong Cao,Zhijing Liu

doi:10.3390/molecules23051220

Abstract

The primary objective of this study was to improve our understanding of the antimicrobial mechanism of protein-derived peptides and to provide evidence for protein-derived peptides as food bio-preservatives by examining the antimicrobial activities, low cytotoxicity, stabilities, and mechanism of Cp1 (LRLKKYKVPQL). In this study, the protein-derived peptide Cp1 was synthesized from bovine αS1-casein, and its potential use as a food biopreservative was indicated by the higher cell selectivity shown by 11-residue peptide towards bacterial cells than human RBCs. It also showed broad-spectrum antimicrobial activity, with minimum inhibitory concentrations (MICs) of 64–640 μM against both gram-positive and gram-negative bacteria. The peptide had low hemolytic activity (23.54%, 512 μM) as well as cytotoxicity. The results of fluorescence spectroscopy, flow cytometry, and electron microscopy experiments indicated that Cp1 exerted its activity by permeabilizing the microbial membrane and destroying cell membrane integrity. We found that Cp1 had broad-spectrum antimicrobial activity, low hemolytic activity, and cytotoxicity. The results also revealed that Cp1 could cause cell death by permeabilizing the cell membrane and disrupting membrane integrity. Overall, the findings presented in this study improve our understanding of the antimicrobial potency of Cp1 and provided evidence of the antimicrobial mechanisms of Cp1. The peptide Cp1 could have potential applications as a food biopreservative.

Highlights

The rapid emergence of antibiotic resistance and microbial contamination in recent years has become a crucial problem worldwide in food safety as well as in food industries [1,2,3]
Melittin in sodium buffer exhibited an unordered conformation, it showed an αin sodiummelittin phosphate buffer phosphate exhibited an unordered conformation, it showed an α-helix structure in helix structure in the membrane-like environment of solutions, confirming that the the membrane-like environment of trifluoroethyl alcohol (TFE) and Sodium dodecyl sulfate (SDS) solutions, confirming that the structure of melittin structure of melittin disrupted cell formation membranes formationasofthe α-helix as thesodium buffer disrupted cell membranes through of through α-helix structures bufferstructures changed from changed from sodium phosphate buffer to SDS, similar to the results described by Pandey phosphate buffer to TFE and SDS, similar to the results described by Pandey et al [24] and Asthana et al
We found that Cp1 and melittin killed bacteria by damaging cytoplasmic membrane integrity

Summary

Introduction

The rapid emergence of antibiotic resistance and microbial contamination in recent years has become a crucial problem worldwide in food safety as well as in food industries [1,2,3]. The development of new classes of antimicrobial agents has become a primary focus of many researchers [4]. Antimicrobial peptides (AMPs), called host defense peptides, are primordial constituents of the innate immune system found in eukaryotic organisms and indicate broad-spectrum antimicrobial activity against microorganisms like viruses, bacteria, parasites, and fungi [5,6,7]. Antimicrobial peptides have been isolated from a wide range of sources including animals, plants, and bacteria [8]. Most of the AMPs show common characteristics because of having a positive charge. AMPs generally consist of 12–50 amino acids, with 2–9 cationic residues and up to 50% hydrophobic amino acids [9,10]

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