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Novel hydrogels based on yeast chitin-glucan complex: Characterization and safety assessment
Publication . Araújo, Diana; Delgado Alves, Vitor; Lima, Sofia A.C.; Reis, Salette; Freitas, Filomena; Reis, Maria A.M.
Chitin-glucan complex (CGC) was used for the first time for the preparation of hydrogels. Alkali solvent systems, NaOH and KOH solutions, either at 1 or 5 mol/L, were used for CGC dissolution using a freeze-thaw procedure (freezing at −20 °C and thawing at room temperature; four cycles). The CGC solutions thus obtained were subjected to dialysis that induced the spontaneous gelation of the biopolymer, yielding translucid hydrogels with a yellowish coloration. Although all CGC hydrogels exhibited porous microstructures, high water content (above 97%) and good mechanical properties, their morphology, viscoelastic properties and texture were influenced by the type of solvent system used for CGC dissolution, as well as by their ionic strength. The K-based hydrogels presented a less compact network with larger pores and exhibited lower elastic properties. The Na-based hydrogels, on the other hand, exhibited a denser structure with smaller pores and a stiffer gel structure. These results show that it is possible to prepare CGC hydrogels with differing characteristics that can be suitable for different applications. Furthermore, all hydrogels were non-cytotoxic towards L929 fibroblasts and HaCaT keratinocytes. This study demonstrates CGC can be used to prepare biocompatible hydrogels with properties render them promising biomaterials
Novel ocellatin peptides mitigate LPS-induced ROS formation and NF-kB activation in microglia and hippocampal neurons
Publication . Sousa, Nayara A.; Oliveira, Guilherme A. L.; de Oliveira, Ana Patrícia; Lopes, André Luís F.; Iles, Bruno; Nogueira, Kerolayne M.; Araújo, Thiago S. L.; Souza, Luan K. M.; Araújo, Alyne R.; Ramos-Jesus, Joilson; Plácido, Alexandra; Amaral, Constança Pais Do; Campelo, Yuri D. M.; Barbosa, Eder Alves; Portugal, Camila C.; Socodato, Renato; Lobo, Andrea; Relvas, Joao; Bemquerer, Marcelo; Eaton, Peter; Leite, José Roberto S. A.; Medeiros, Jand Venes R.
Cutaneous secretions of amphibians have bioactive compounds, such as peptides, with potential for biotechnological applications. Therefore, this study aimed to determine the primary structure and investigate peptides obtained from the cutaneous secretions of the amphibian, Leptodactylus vastus, as a source of bioactive molecules. The peptides obtained possessed the amino acid sequences, GVVDILKGAAKDLAGH and GVVDILKGAAKDLAGHLASKV, with monoisotopic masses of [M + H]± = 1563.8 Da and [M + H]± = 2062.4 Da, respectively. The molecules were characterized as peptides of the class of ocellatins and were named as Ocellatin-K1(1-16) and Ocellatin-K1(1-21). Functional analysis revealed that Ocellatin-K1(1-16) and Ocellatin-K1(1-21) showed weak antibacterial activity. However, treatment of mice with these ocellatins reduced the nitrite and malondialdehyde content. Moreover, superoxide dismutase enzymatic activity and glutathione concentration were increased in the hippocampus of mice. In addition, Ocellatin-K1(1-16) and Ocellatin-K1(1-21) were effective in impairing lipopolysaccharide (LPS)-induced reactive oxygen species (ROS) formation and NF-kB activation in living microglia. We incubated hippocampal neurons with microglial conditioned media treated with LPS and LPS in the presence of Ocellatin-K1(1-16) and Ocellatin-K1(1-21) and observed that both peptides reduced the oxidative stress in hippocampal neurons. Furthermore, these ocellatins demonstrated low cytotoxicity towards erythrocytes. These functional properties suggest possible to neuromodulatory therapeutic applications.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/QUI/50006/2013