Ulteriori evidenze di attivit\ue0 antimicrobiche in invertebrati marini

The antimicrobial molecules are an abundant group of molecules that are amply distributed in nature, from plants and insects to vertebrate animals, including humans. They are an essential component of the innate immune system for host defence against pathogenic agents of different types. They are often the products of individual genes and circulating cells. In this thesis, based on a bioinformatic analysis, we identified three peptides, members to the family of cathelicidins and to the class of peptides rich in proline (PR-AMPs), that may be generally be considered as the first effectors of the interior defense, acting as natural antibiotics (Scocchi et al., 2011; Reddy et al., 2004). We investigate, also, about the possibility of use four extracts from marine invertebrates as possible natural antibiotics. Their small size makes them able to spread rapidly at sites of infection, they are also cheap to synthesize, relatively resistant to denaturation and are less likely to induce resistance. The objective of this doctoral thesis was to deepen the knowledge on the ability of peptides and molecules with antimicrobial activity, initially identified or isolated from different marine invertebrates. The studied peptides show a broad spectrum of activity against a variety of microorganisms such as Gram-positive bacteria, Gram-negative bacteria and fungi. Furthermore, it was interesting to determine the cytotoxic activity of peptides and antimicrobial molecules versus the murine monocytic cell line J774-A1 coming from sarcoma of Balb / c mice. The surprising results, especially on the analysis of peptides, make them interesting to understand the mechanisms of innate immunity evolution and trace an original point of view on a new frontier for the control of microbial infections that could, therefore, be a good alternative for their use in biotechnology and in the pharmaceutical field (Schnapp et al., 1996)