Estudo de três peptídeos sintéticos com atividade antimicrobiana, derivados da toxina LyeTx I da aranha Lycosa erythrognatha (Lucas, 1836)

Abstract

Infectious disease is one big cause to death, where bacterium infections show among some 10 mainly death´s causes in the world. Fungi can cause severe diseases too, particularly in imunossupressed people. However, although there are a vast antimicrobial arsenal, as antibiotics antimicrobials and antimycotic against fungi is important to develop new medicines, considering the growing of resistence by microorganisms. Antimicrobial peptides found in many multicellular organisms could be good candidates to this aim. In this work, the antimicrobial peptide, LyeTx I, from the spider Lycosa erythrognatha´s venom was used as a model. Part of this molecule (LyeTxI minimized) was synthesized by the Fmoc method. Three derivatives were obtained: LyeTxImn, LyeTxImnΔK and LyeTxImnΔKAc. They showed different antimicrobial activities as well as different hemolytic activities. This last activity is an important indicator to verify if the antimicrobial peptide is also active in cells from mammals. A high hemolytic activity is not a good indicator for a peptide as a good antibiotic. But only LyeTxImnΔK was more effective than the native peptide (LyeTx I), when compared therapeutic index among them. The structuration of these peptides was also investigated in mimetic media such as trifluorethanol, sodium dodecyl sulfate and dodecyl phosphocholine, being found structuration patterns consistent with α-helix profiles, similar to the original peptide LyeTx I. Therefore, was possible the synthesis of a peptide derivative from the a spider toxin LyeTxI with higher antimicrobial activities, as well as with lower production cost, some, essential characteristics to a candidate to newtherapeutic drugs.