There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. All authors have approved the final article. This work was supported by grants Natural Product Library concentration from Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG – APQ01525) to L.M. Botion. E.G.M. was recipient of scholarship from Coordenadoria de Aperfeiçoamento do Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). “
“Eukaryotic antimicrobial peptides (AMPs) are a promising class of molecular tools that have

tremendous potential to be clinically relevant due to their activity against a wide spectrum of microorganisms. Over the last few decades, intense research has been focused on their biosynthesis and the mechanisms of their activity [6] and [16]. They are important components of the natural defenses of most living organisms and have been isolated from a wide variety of animals, plants and bacteria (http://www.bbem.univ.triest.it/-tossi/search.htm). Many of these AMPs are genetically

encoded, while others are secondary metabolites. Yet, both avenues generate peptides that display positive, negative or neutral net charge in physiological pH. The positive charge of the vast majority of AMPs allows the initial interaction with the negatively charged lipopolysacharides (LPS) in the outer membrane, and later, with negatively charged phospholipids in the inner membrane. Forskolin in vitro However, there are exceptions such as the magainins and cecropins, which do not show any interaction with chiral centers in the membrane since the L and D enantiomers of these peptides have similar antimicrobial this website activity. In contrast, apidaecin kills bacteria by a mechanism that involves stereospecificity. The selectivity of these peptides for bacterial membranes over eukaryotic membranes has been ascribed to the lack of cholesterol and cationic lipids in the bacterial membranes and the limited amounts of anionic lipids in the eukaryotic membranes.

The skin and skin mucus of several fish species have been shown to contain AMPs. A number of those show sequence similarity to AMPs isolated from other organisms. Pleurocidin (Plc), a α-helical cationic peptide isolated from the skin-secreted mucous of the winter flounder Pleuronectes americanus [6] and [7] is predicted as a 60 or 68 residue precursor prepropolypeptide that undergoes proteolytic cleavage of its amino-terminal signal and carboxy-terminal anionic propiece to form the active peptide [8] and [9]. The resulting active peptide consists of 25 amino acid residues and possesses a net positive charge at physiological pH. The activity has been extensively explored and has shown a broad spectrum of antimicrobial and hemolytic activity [14], [17], [40] and [42].