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| Author(s): |
Welligton de Mattos Santussi
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2007-07-27 |
| Examining board members: |
Eliane Candiani Arantes Braga;
Jose Roberto Giglio;
Sergio Akira Uyemura
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| Advisor: | Eliane Candiani Arantes Braga |
| Abstract | |
Antimicrobial peptides appear to be ubiquitous and multipotent components of the innate immune defense arsenal used by both prokaryotic and eukaryotic organisms. They are used in the first line of immune defense. In this work, we evaluate the effects of Tityus serrulatus venom (Tsv) and its major toxin TsTX-I, a -neurotoxin, on fungi growth. TsTX-I was isolated from Tsv by ion-exchange chromatography. Its purity was confirmed by reverse-phase (C18) high performance liquid chromatography. The growth inhibition of different filamentous fungi (Neurospora crassa, Penicillum ochrochloron, Penicillum verrucosum, Penicillum waksmanii, Penicillum corylophilum, Penicillum veridicatum, Aspergillus terreus, Aspergillus niger, Aspergillus phoenix, Aspergillus fumigatus, and Talaromyces flavus ) was evaluated by quantitative microplate reader assay (Broekaert et al., 1990). Tsv (100 g and 500 g) was more active in inhibiting growth of A. nidulans, A. terreus, P. verrucosum and P. corylophilum. TsTX-I (6 g, 1.5 g and 0.7 g) showed dose-dependent antifungal activity against A. nidulans, inhibiting 100% of fungal growth at concentration of 3 g/well. The growth inhibition of A. nidulans was more intense when TsTX-I was added to culture medium at the initial time than after 6 h of free germination. The addition of Ca++ ions on culture medium increased TsTX-I action against A. nidulans, P. verrucosum and P. corylophilum. Assays carried out in the presence of tetrodotoxin, a known Na+ channel blocker, showed that it was not able to interfere on TsTX-I antifungal activity against A. nidulans. TsTX-I induces depolarization on nerve endings and it is known that the action of membrane destabilizing peptides in scorpion venoms seems to be part of an antibacterial and antifungal defense system. It is probably that TsTX-I induces depolarization of fungi membranes and this effect is, at least in part, responsible for its antifungal activity. (AU) | |