title: Salivary peptidomic as a tool to disclose new potential antimicrobial peptides.
abstract: Antimicrobial peptides (AMPs) and peptidomimetics are among the new generation of antibiotics due to their broad spectrum of activity towards pathogenic agents. Considering the fact that the oral cavity is a relevant entryway for pathogenic microorganisms, it must be armed with several defenses in order to maintain homeostasis. Thus, we aimed at disclosing potential AMPs in saliva from humans, pigs and mice. We enriched salivary peptides by filtration and then separated and identified multiple peptides by nanoHPLC-MALDI-TOF/TOF. Using this approach, we identified 45 different peptides from mice's saliva and 94 from pig's saliva. Almost all peptides from pig and mice saliva were new assignments, encouraging the application of this technique to other mammals' saliva. The potential antimicrobial activity was then calculated in silico with an available CAMP's algorithm. Eight peptides from pig's basic proline-rich protein, as well as 6 peptides resulting from human's P-B peptide, 1 from P-C peptide fragmentation and 1 from statherin were found to have potential antimicrobial activity. Therefore, the peptides GPPPQGGRPQG and RFGYGYGPYQPVPEQPLYPQ were synthetically obtained and their antimicrobial properties evaluated in vitro for different bacterial strains. These showed to exert an antibacterial effect in Staphylococcus aureus. This report validates the prospection of mammal's saliva to find new alternatives to antibiotics.
  
  
  CONCLUSIONS
  With the growing problem of antibiotic resistance, the identification of new routes in antibiotic therapy is on the scientific agenda worldwide. Antimicrobial peptides (AMPs) and peptidomimetics are among the new generation of antibiotics due to their broad spectrum of activity towards pathogenic agents and owing to a less probable microbial resistance that can arise from their use. Thus, we explored the saliva from humans, pigs and mice to identify potential AMPs using a peptidomic approach. At the end, eight peptides from pig's basic proline-rich protein, six peptides resulting from human's P-B peptide, one from P-C peptide fragmentation and one from statherin were found to have potential antimicrobial activity. From this, the peptides GPPPQGGRPQG and RFGYGYGPYQPVPEQPLYPQ were tested showing to have antibacterial effect in S. aureus which highlights the potential of mammal's saliva to find new alternatives to antibiotics.
authors.affiliation: QOPNA, Mass Spectrometry Center, Department of Chemistry, University of Aveiro, Portugal.
authors.forename: Fábio
authors.initials: F
authors.lastname: Trindade
authors.affiliation: School of Health Sciences, University of Aveiro, Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Amado
authors.affiliation: QOPNA, Mass Spectrometry Center, Department of Chemistry, University of Aveiro, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Pinto da Costa
authors.affiliation: QOPNA, Mass Spectrometry Center, Department of Chemistry, University of Aveiro, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Ferreira
authors.affiliation: Department of Biology & CESAM, University of Aveiro, Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Maia
authors.affiliation: Department of Biology & CESAM, University of Aveiro, Portugal; Institute for Research in Biomedicine-iBiMED, Health Sciences Program, University of Aveiro, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Henriques
authors.affiliation: Department of Zootechnics, CECAV, University of Trás-os-Montes and Alto Douro, Vila Real, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Colaço
authors.affiliation: QOPNA, Mass Spectrometry Center, Department of Chemistry, University of Aveiro, Portugal; Institute for Research in Biomedicine-iBiMED, Health Sciences Program, University of Aveiro, Portugal. Electronic address: rvitorino@ua.pt.
authors.forename: Rui
authors.initials: R
authors.lastname: Vitorino
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D020543:Proteome / Q000737:chemistry* / Q000235:genetics; D012463:Saliva / Q000737:chemistry*; D012471:Salivary Proteins and Peptides / Q000737:chemistry* / Q000235:genetics; D013211:Staphylococcus aureus / Q000254:growth & development*; D034421:Sus scrofa
chemical_list: D023181:Antimicrobial Cationic Peptides; D020543:Proteome; D012471:Salivary Proteins and Peptides
keywords: Antimicrobial peptides; Human saliva; Mouse saliva and pig saliva; Peptidomics