title: Design of novel antimicrobial peptide dimer analogues with enhanced antimicrobial activity in vitro and in vivo by intermolecular triazole bridge strategy.
abstract: Currently, antimicrobial peptides have attracted considerable attention because of their broad-sprectum activity and low prognostic to induce antibiotic resistance. In our study, for the first time, a series of side-chain hybrid dimer peptides J-AA (Anoplin-Anoplin), J-RR (RW-RW), and J-AR (Anoplin-RW) based on the wasp peptide Anoplin and the arginine- and tryptophan-rich hexapeptide RW were designed and synthesized by click chemistry, with the intent to improve the antimicrobial efficacy of peptides against bacterial pathogens. The results showed that all dimer analogues exhibited up to a 4-16 fold increase in antimicrobial activity compared to the parental peptides against bacterial strains. Furthermore, the antimicrobial activity was confirmed by time-killing kinetics assay with two strains which showed that these dimer analogues at 1, 2×MIC were rapidly bactericidal and reduced the initial inoculum significantly during the first 2-6h. Notably, dimer peptides showed synergy and additivity effects when used in combination with conventional antibiotics rifampin or penicillin respectively against the multidrug-resistant strains. In the Escherichia coli-infected mouse model, all of hybrid dimer analogues had significantly lower degree of bacterial load than the untreated control group when injected once i.p. at 5mg/kg. In addition, the infected mice by methicillin-resistant (MRSA) strain could be effectively treated with J-RR. All of dimer analogues had membrane-active action mode. And the membrane-dependent mode of action signifies that peptides functions freely and without regard to conventional resistant mechanisms. Circular dichroism analyses of all dimer analogues showed a general predominance of α-helix conformation in 50% trifluoroethanol (TFE). Additionally, the acute toxicities study indicated that J-RR or J-AR did not show the signs of toxicity when adult mice exposed to concentration up to 120mg/kg. The 50% lethal dose (LD50) of J-AA was 53.6mg/kg. In conclusion, to design and synthesize side chain-hybrid dimer analogues via click chemistry may offer a new strategy for antibacterial therapeutic option.
authors.affiliation: Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; School of Pharmacy, Lanzhou University, Lanzhou 730000, China. Electronic address: liubj12@lzu.edu.cn.
authors.forename: Beijun
authors.initials: B
authors.lastname: Liu
authors.affiliation: Shaanxi Provincial People's Hospital, Shanxi 710068, China.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Huang
authors.affiliation: Key Laboratory of Entomological Biopharmaceutical R&D of Yunnan Province, Dali University, Dali 671000, China.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Affiliated Hospital of Gansu University of Chinese Medicine, Lanzhou 730000, China.
authors.forename: Beiyin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China.
authors.forename: Sanhu
authors.initials: S
authors.lastname: Gou
authors.affiliation: School of Pharmacy, Lanzhou University, Lanzhou 730000, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhong
authors.affiliation: School of Pharmacy, Lanzhou University, Lanzhou 730000, China.
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Han
authors.affiliation: School of Pharmacy, Lanzhou University, Lanzhou 730000, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; School of Pharmacy, Lanzhou University, Lanzhou 730000, China. Electronic address: nijm@lzu.edu.cn.
authors.forename: Jingman
authors.initials: J
authors.lastname: Ni
authors.affiliation: Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: wangrui@lzu.edu.cn.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects* / Q000472:pathogenicity; D007144:Immunoglobulin J-Chains / Q000737:chemistry / Q000494:pharmacology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000472:pathogenicity; D051379:Mice; D008826:Microbial Sensitivity Tests; D055503:Protein Multimerization; D012293:Rifampin / Q000494:pharmacology; D014230:Triazoles / Q000737:chemistry; D014862:Wasp Venoms / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D014863:Wasps / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D007144:Immunoglobulin J-Chains; D014230:Triazoles; D014862:Wasp Venoms; C443041:anoplin; C406672:triazole-dione; D012293:Rifampin
keywords: Antimicrobial activity; Click chemistry; Dimer analogues; Drug resistance; α Helical structure