In fact, these two nitroheterocycle drugs are limited in that they are highly toxic and rarely find more beneficial during the chronic phase of the disease; moreover, these treatments only cure approximately 20% of all patients (Urbina and Docampo, 2003). These restrictions highlight the necessity for developing
alternative synthetic or natural compounds that are effective for both the clinical treatment of Chagas disease and for the chemoprophylaxis of donated blood. Antimicrobial peptides (AMPs), which are a component of innate immunity, are ancient evolutionary weapons. They have been isolated from virtually every kingdom and phylum, which attests to their role as a mechanism of the primitive immune response (Andreu and Rivas, 1998). They are a unique and diverse group of molecules, and they have been divided into subgroups on the basis of their amino acid composition and structure. AMPs are diverse in length,
overall charge, and conformation, but a large majority of these molecules are cationic and amphipathic (Yeaman and Yount, 2003). They are defined as peptides S3I-201 in vitro of 12–50 amino acids in length, with a molecular mass of less than 10 kDa and a net positive charge ranging from +2 to +7 due to an excess of basic amino acids (arginine, lysine and histidine) over acidic amino acids (aspartate and glutamate). Generally, 50% or more of the AMP amino acids are hydrophobic, a fact reflected by the interaction of such peptides with bacterial membranes as part of their mechanism of action (Hancock and Diamond, 2000; Teixeira et al., 2012). AMPs display certain features that make them appealing as alternatives to conventional pharmaceuticals, including their fast mode of action, low likelihood of resistance development and ability to act in conjunction with existing drug regimens (Zasloff, 2002). AMPs show a high level of toxicity against both Gram-positive and Gram-negative
bacteria, as well as fungi, viruses, metazoans, other parasites, and even cancer cells (Hoskin and Ramamoorthy, 2008; Zasloff, 2002). McGwire and Kulkarni click here (2010) and Harrington (2011) have described the AMPs and synthetic derivatives that are active against the related kinetoplasts T. cruzi, Leishmania spp., and African trypanosomes. The largest group of AMPs currently known consists of the linear cationic α-helical peptides; more than 300 members have been described thus far, and melittin is among the most represented AMPs ( Yeaman and Yount, 2003). Melittin is a naturally and cytolytic occurring AMP, which is a highly basic 26-residue peptide that is almost entirely hydrophobic but with a hydrophilic sequence (Lys-Arg-Lys-Arg) near the C-terminus; with a 2846.