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

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 alpha-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.