The presence of common motifs in PR-39, dermaseptins and ceratotoxins, suggests

that the antimicrobial activity of pleurocidin is due to only a portion of the pleurocidin sequence. SGI-1776 in vivo Furthermore, to make Plc useful as a therapeutic drug requires delineating the feature responsible for its activities as an AMP. There are examples of peptide and protein fragments retaining the antimicrobial activity of the parent molecule and, in some instance, their activities even exceed that of a close relative molecule [5] and [21]. In addition, the N- and C-terminal regions of antimicrobial peptides play an important role in the organism-specific interaction process or pore formation in plasma membrane [4] and [23]. AMPs are not only click here an interest against human pathogens, they are also excellent candidates for serving as biologically based pesticides for agriculture. To capitalize on their potential use, studies are in

progress to elucidate the mechanisms of their action with an ongoing search to identify the particular residues and structural elements responsible. Such endeavors can lead to modifications towards more selective compounds with lower intrinsic toxicity and reduced negative environmental impacts [27]. Towards this goal, an analysis of the peptide fragments in pleurocidin was initiated. In this study, the activity of the peptides was examined against bacteria and filamentous phytopathogenic fungi. We discovered that a small sequence of the 12 amino acid C-terminus (KHVGKAALTHYL) possed a high percentage (≥80%) of the precursor’s lytic activity against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and no effect or very small effect against Enterococcus faecalis. In Resveratrol fungi of agronomical interest, a high activity was observed against all the fungi evaluated,

except Aspergillus ochraceus. The measured MIC values were close to those of commercial fungicides. Four other synthetic peptides, spanning the whole pleurocidin sequence, were tested, but a reduced growth inhibition was obtained for P. aeruginosa and for the three other bacteria species compared to pleurocidin. Amino acids for peptide synthesis were acquired from Calbiochem-Novabiochem Corp. (Germany). The sequencing reagents and HPLC columns were from Shimadzu (Kyoto, Japan). Piperidine, acetonitrile and trifluoroacetic acid were purchased from Fluke. Brain heart infusion broth (BHI), trifluoroethanol and all other analytical reagents were purchased from Merck (Darmstad, Germany). Sytox green (SG) was acquired from Molecular Probes (Invitrogen Corp, Carlsbad, CA, USA) and calcofluor white (CFW) (Fluorescent Brightener 28) from Sigma–Aldrich (St Louis, MO, USA). Potato dextrose broth (PDB) and potato dextrose agar (PDA) were purchased from HiMedia (Mumbai, India) and Oxoid (Hampshire, England), respectively.