title: De novo synthetic short antimicrobial peptides against cariogenic bacteria.
abstract: OBJECTIVE
  Antimicrobial peptides (AMPs) have shown the ability to inhibit planktonic bacteria and biofilms. The objectives of this study were to de novo design and synthesize a series of cationic, amphipathic α-helical AMPs that would be shorter, less cytotoxic, and more potent than existing AMPs against cariogenic bacteria.
  
  
  METHODS
  Three short AMPs (GH8, GLLWHLLH-NH2; GH12, GLLWHLLHHLLH-NH2; and GH16, GLLWHLLHHLLHLLHH-NH2) were designed, synthesized and characterized structurally. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against eight major cariogenic bacteria were tested to select the most promising peptide. Scanning electron microscopy (SEM) was used to observe the bacterial membrane after treatment with selected peptides. The bactericidal kinetics, effects on biofilm and cytotoxity were further investigated.
  
  
  RESULTS
  Of the three AMPs, GH12 had the most balanced structural parameters and a high content of α-helical structure. GH12 had a MIC of 4.0-8.0μg/mL and MBC of 8.0-32.0μg/mL. The corresponding values for the other two AMPs were 2- to 64- fold higher. In time-kill assays, GH12 killed all bacterial strains within 60min at 4- fold MBC. SEM observed lysis and pore formation of the cytomembrane after treatment with GH12. 8.0μg/mL GH12 inhibited Streptococcus mutans biofilm formation. Confocal laser scanning microscopy showed that GH12 effectively reduced the biomass of 1-day-old S. mutans biofilm. Cytotoxicity assays indicated that GH12 showed little toxic effect on the viability of human gingival fibroblasts.
  
  
  CONCLUSIONS
  These results indicate that GH12 shows antimicrobial activity against cariogenic bacteria and biofilms in vitro.
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Fan
authors.affiliation: The First People's Hospital of Yunnan Province, Kunming, China.
authors.forename: Zhengli
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Huanxin
authors.initials: H
authors.lastname: Tu
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Longjiang
authors.initials: L
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
authors.forename: Xuedong
authors.initials: X
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China. Electronic address: zhanglinglin_sc@163.com.
authors.forename: Linglin
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D018441:Biofilms / Q000187:drug effects*; D003731:Dental Caries / Q000188:drug therapy* / Q000382:microbiology*; D017886:Durapatite / Q000494:pharmacology; D005881:Gingiva / Q000166:cytology / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D017886:Durapatite
keywords: Antimicrobial activity; Antimicrobial peptide; Biofilms; Dental caries; Streptococcus mutans