Navegando por Palavras-chave "antimicrobial peptides"
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- ItemSomente MetadadadosCrotamine toxicity and efficacy in mouse models of melanoma(Informa Healthcare, 2011-09-01) Pereira, Alexandre; Kerkis, Alexandre; Hayashi, Mirian A. F. [UNIFESP]; Pereira, Aparecida S. P.; Silva, Fernando S.; Oliveira, Eduardo B.; Prieto da Silva, Alvaro R. B.; Yamane, Tetsuo; Radis-Baptista, Gandhi; Kerkis, Irina; Butantan Inst; Vet Act Ltda Genet Aplicada; Virol Lab; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP); Univ Estado Amazonas; Univ Fed CearaObjectives: Selective anticancer cell activity for both cell-penetrating and cationic antimicrobial peptides has previously been reported. As crotamine possesses activities similar to both of these, this study investigates crotamine's anticancer toxicity in vitro and in vivo.Research design and methods: in vitro cancer cell viability was evaluated after treatment with 1 and 5 mu g/ml of crotamine. in vivo crotamine cytotoxic effects in C57Bl/6J mice bearing B16-F10 primary cutaneous melanoma were tested, with two groups each containing 35 mice. the crotamine-treated group received 1 mu g/day of crotamine per animal, subcutaneously which was well tolerated; the untreated group received a placebo.Results: Crotamine at 5 mu g/ml was lethal to B16-F10, Mia PaCa-2 and SK-Mel-28 cells and inoffensive to normal cells. in vivo crotamine treatment over 21 days significantly delayed tumor implantation, inhibited tumor growth and prolonged the lifespan of the mice. Mice in the crotamine-treated group survived at significantly higher rates (n = 30/35) than those in the untreated group (n = 7/35) (significance calculated with the Kaplan-Meier estimator). the average tumor weight in the untreated group was 4.60 g but was only about 0.27 g in the crotamine-treated mice, if detectable.Conclusions: These data warrant further exploration of crotamine as a tumor inhibition compound.
- ItemEmbargoEstudos comparativos do mecanismo de ação de peptídeos antimicrobianos(Universidade Federal de São Paulo (UNIFESP), 2012) Martins, Marta Natividade Crizol [UNIFESP]; Miranda, Antonio [UNIFESP]Os peptideos antimicrobianos (PAMs) sao componentes importantes do sistema de defesa inato de plantas e animais contra micro-organismos, bacterias e fungos. A maioria dos PAMs sao cationicos e anfipaticos, caracteristicas que sao essenciais para a sua interacao nao especifica com a membrana de micro-organismos. Neste trabalho, comparamos as atividades antimicrobianas e hemoliticas, assim como o indice terapeutico (IT) dos peptideos gomesina, magainina II, protegrina I, taquiplesina I, polifemusina II e seus analogos lineares. A atividade antimicrobiana foi avaliada contra S. aureus, E. coli e C. albicans. As atividades hemoliticas dos peptideos foram avaliadas contra eritrocitos humanos. A microscopia optica foi empregada para estudar a interacao destes peptideos com vesiculas unilamelares gigantes (GUVs), compostas por misturas de um lipidio neutro (POPC) com um lipidio carregado negativamente (POPG). Os resultados mostraram que a gomesina e protegrina I tem a mesma potencia, enquanto que os outros peptideos foram menos ativos contra C. albicans. Protegrina I e taquiplesina I foram os mais potentes contra E.coli e protegrina I foi o mais ativo contra S. aureus (2 a 4 vezes). A maioria dos PAMs estudados apresentaram atividades hemoliticas significativas com excessao da magainina II, que nao foi hemolitica mesmo na concentracao de 100 μM. A magainina II apresentou o melhor IT contra todos os micro-organismos testados. Curiosamente, a gomesina, taquiplesina I, polifemusina II e seus analogos lineares e o analogo linear da protegrina I parecem atuar atraves do modelo de carpete, enquanto a magainina II e a protegrina I formam poros estaveis nas membranas das GUVs. Recentemente, estudos que envolvem a acao de PAMs contra celulas do cancer tem aumentado significatimente. No entanto os mecanismos pelos quais os PAMs regulam a morte celular em mamiferos nao estao bem esclarecidos. Diante do fato, no presente trabalho investigamos a atuacao destes peptideos contra as celulas eritroleucemicas humanas K562. Os resultados mostraram que a gomesina e protegrina I exibiram atividades citotoxicas nao mostradas pelos seus analogos lineares. Taquiplesina I e polifemusina II tambem induziram morte celular e seus analogos lineares nao perderam os efeitos. Atraves dos experimentos realizados foi possivel distinguir duas maneiras que os peptideos induzem morte celular, dependendo da concentracao empregada. Baixas concentracoes dos PAMs induzem mecanismos de morte celular de forma controlada, tais como apoptose, necrose secundaria e necrose/necroptose. Cada PAM testado promoveu morte celular controlada por um mecanismo intracelular diferente. Gomesina, taquiplesina I e [Trp0, Ser3,7,12,16]-taquiplesina I promoveram apoptose que foi caracterizada por anexina, sensibilidade a Z-VAD, e ativacao da caspase-3. Gomesina e protegrina I induziram morte celular que tambem foi dependente de mecanismos intracelulares de Ca2+. Necrostatina-1 tambem foi capaz de inibir a morte celular provocada pela gomesina, taquiplesina I e [Trp0, Ser4,8,13,17]-polifemusina II. Por outro lado o tratamento com concentracoes mais elevadas dos PAMs, acima da EC50, resultou principalmente em ruptura da membrana com diferentes acoes na membrana celular. Assim, em concentracoes de PAMs abaixo da EC50, a morte celular controlada pode ser induzida, mas em altas concentracoes ocorrem perturbacoes direta na membrana
- ItemAcesso aberto (Open Access)Juruin: an antifungal peptide from the venom of the Amazonian Pink Toe spider, Avicularia juruensis, which contains the inhibitory cystine knot motif(Frontiers Research Foundation, 2012-01-01) Ayroza, Gabriela; Ferreira, Ivan L. C.; Sayegh, Raphael S. R.; Tashima, Alexandre Keiji [UNIFESP]; Silva, Pedro I. da; Inst Butantan; Coordenadoria Controle Doencas; Universidade Federal de São Paulo (UNIFESP)The aim of this study was to screen the venom of the theraposid spider Avicularia juruensis for the identification of antimicrobial peptides (AMPs) which could be further used as prototypes for drug development. Eleven AMPs, named juruentoxins, with molecular weight ranging from 3.5 to 4.5 kDa, were identified by mass spectrometry after the soluble venom was separated by high performance liquid chromatography. Juruentoxins have a putative inhibitory cystine knot (ICK) motif, generally found in neurotoxins, which are also resistant to proteolysis. One juruentoxin that has 38 amino acid residues and three disulfide bonds were characterized, to which we proposed the name Juruin. Based on liquid growth inhibition assays, it has potent antifungal activity in the micromolar range. Importantly, Juruin lacks haemolytic activity on human erythrocytes at the antimicrobial concentrations. Based on the amino acid sequence, it is highly identical to the insecticidal peptides from the theraposid spiders Selenocosmia huwena, Chilobrachys jingzhao, and Haplopelma schmidti from China, indicating they belong to a group of conserved toxins which are likely to inhibit voltage-gated ion channels. Juruin is a cationic AMP and Lys22 and Lys23 show maximum positive charge localization that might be important for receptor recognition. Although it shows marked sequence similarity to neurotoxic peptides, Juruin is a novel exciting molecule with potent antifungal activity, which could be used as a novel template for development of drugs against clinical resistant fungi strains.
- ItemSomente MetadadadosThe role of hemocytes in the immunity of the spider Acanthoscurria gomesiana(Elsevier B.V., 2008-01-01) Fukuzawa, Aline H.; Vellutini, Bruno C.; Lorenzini, Daniel M.; Silva, Pedro I.; Mortara, Renato A. [UNIFESP]; Silva, Jose M. C. da; Daffre, Sirlei; Universidade de São Paulo (USP); Inst Butantan; Universidade Federal de São Paulo (UNIFESP)Invertebrates protect themselves against microbial infection through cellular and humoral immune defenses. Since the available information on the immune system of spiders is scarce, the main goat of the present study was to investigate the role of hemocytes and antimicrobial peptides (AMPs) in defense against microbes of spider Acanthoscurria gomesiana. We previously described the purification and characterization of two AMPs from the hemocytes of naive spider A. gomesiana, gomesin and acanthoscurrin. Here we show that 57% of the hemocytes store both gomesin and acanthoscurrin, either in the same or in different granules. Progomesin labeling in hemocyte granules indicates that gomesin is addressed to those organelles as a propeptide. in vivo and in vitro experiments showed that lipopolysaccharide (LPS) and yeast caused the hemocytes to migrate. Once they have reached the infection site, hemocytes may secrete coagulation cascade components and AMPs to cell-free hemolymph. Furthermore, our results suggest that phagocytosis is not the major defense mechanism activated after microbial challenge. Therefore, the main reactions involved in the spider immune defense might be coagulation and AMP secretion. (C) 2007 Elsevier B.V. All rights reserved.
- ItemSomente MetadadadosTruncation of amidated fragment 33-61 of bovine alpha-hemoglobin: Effects on the structure and anticandidal activity(Wiley-Blackwell, 2007-01-01) Machado, Alessandra; Sforca, Mauricio L.; Miranda, Antonio; Daffre, Sirlei; Pertinhez, Thelma A.; Spisni, Alberto; Miranda, M. Teresa M.; Universidade de São Paulo (USP); Ctr Struct Mol Biol; Universidade Federal de São Paulo (UNIFESP); Univ ParmaPeptides derived from endogenous hemoglobin play important biological roles in a variety of living systems. in previous works we showed that the fragment 33-61 of bovine alpha=hemoglobin (Hb33-61) and its C-terminus amidated analogue (Hb33-61a) exhibit antimicrobial activity and we determined the 3D structure of HB33-61a bound to sodium dodecyl sulfate micelles. Here we report that Hb33-61a is lethal to Candida albicans at 625 mu M probably through disruption of its plasma membrane. in addition, we show that, even when used at 50 mu M, Hb33-61a produces low hemolysis (16% +/- 3.0%). Recognizing that one of the key steps to study new compounds with potential pharmaceutical application is to identify the structural elements essential to express biological activity, we also investigated the anticandidal activity of HB33-61a fragments. the results indicated that Hb40-61a exhibits the same minimal inhibitory concentration as Hb33-61a, whereas HB33-52a and Hb48-61a are significantly less astive. Noteworthy, for all the peptides tested, we observed that C-terminus amidation produces a potentiation of their anticandidal activity and we associate that increased biological activity and we associate that increased biological activity to a preferred structural and spatial organization of the C-terminal region favored by amidation. Finally, the data show that the most active peptides (Hb33-61a and Hb40-61a) are characterized by a central hinge joining the C-terminal region (containing a beta-turn followed by a helical element) to the N-terminal region (that presents only a beta-turn). We hypothesize that these two structured regions, by fluctuating independently in the lipid environment, may act in a coordinated fashion disrupting the yeast plasma membrane. (c) 2007 Wiley Periodicals, Inc.