NMR structure and bactericidal activity of KR-12 analog derived from human LL-37 as a potential cosmetic preservative

Hyosuk Yun,Hye Jung Min,Chul Won Lee

doi:10.1186/s40543-020-00213-x

Abstract

KR-12 was derived from the human antimicrobial peptide, LL-37. KR-12 maintains the antimicrobial activity of LL-37 and has low toxicity against human cells, thereby showing a high potential for various applications. In this study, the three-dimensional structure of KR-12 analog (KR-12-pa) was determined by solution NMR spectroscopy. The NMR structure of KR-12-pa revealed a nearly perfect amphipathic α-helical structure composed of multiple hydrophobic and positively charged residues. The minimal inhibitory concentration of KR-12-pa for various bacterial and yeast cells suggested that KR-12-pa has a much stronger antimicrobial activity than commercial cosmetic preservatives. In addition, KR-12-pa in cosmetic formulations showed much stronger bactericidal effects than conventional cosmetic preservatives and very low cytotoxicity to mammalian cells. These results suggest that KR-12-pa is applicable as a cosmetic preservative.

Highlights

Cosmetics contain many organic compounds such as glycerin and sorbitol, which can serve as a carbon source for microorganisms, and amino acid derivatives and proteins, which are nitrogen sources and may cause growth of microorganisms and lead to alteration in the contents (Kim 2004)
Preparation of KR-12-pa Human cathelicidin LL-37 is known as an attractive Antimicrobial peptide (AMP) for treatment of endotoxin shock and sepsis caused by gram-negative bacterial infection because of its effective binding and neutralization of LPS (Rosenfeld et al 2006)
LL-37 causes significant hemolysis of human red blood cells and it is too long to be developed as a peptide drug for bacterial infection and inflammatory disease (Ciornei et al 2005)

Summary

Introduction

Cosmetics contain many organic compounds such as glycerin and sorbitol, which can serve as a carbon source for microorganisms, and amino acid derivatives and proteins, which are nitrogen sources and may cause growth of microorganisms and lead to alteration in the contents (Kim 2004). Contaminated cosmetics can cause serious problems such as skin irritation, allergic reactions, phototoxicity, and photoallergy. Human cathelicidin LL-37 is a long peptide with 37 amino acids It is structurally cationic and is an amphiphilic α-helical AMP (Johansson et al 1998). A KR-12 analog with a nearly perfect amphipathic α-helical structure (hereinafter named KR-12-pa) showed highly effective antimicrobial and anti-inflammatory activities. The KR-12-pa folds into a symmetric amphipathic α-helical structure in a membrane-like environment. This peptide showed strong antimicrobial activity against various bacteria and fungi and showed excellent antimicrobial activity even when used in cosmetic preparations. KR12-pa shows a potential to be developed as a new stable cosmetic preservative to replace cosmetic preservatives causing side effects

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Results

Conclusion