As propriedades da prata são conhecidas há muitos anos. Recentemente, as nanopartículas de prata têm chamado a atenção por sua atividade antimicrobiana que oferece a possibilidade de uso com propósitos médicos e de higiene. Estas nanopartículas de prata em diferentes formulações, com diferentes formas e tamanhos, exibem atividades antimicrobianas diferentes. Entretanto, os mecanismos da atividade antimicrobiana de íons e de nanopartículas, assim como sua toxicidade em tecidos humanos não estão totalmente esclarecidos. Esta revisão avalia o uso potencial de nanopartículas de prata no controle de patogênicos com ênfase sobre sua ação contra bactérias patogênicas, sua toxicidade e possíveis mecanismos de ação.The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity. However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action.

The dyestuff industry is suffering from the increases in costs of feedstock and energy for dye synthesis, and they are under increasing pressure to minimize the damage to the environment. The industries are continuously looking for cheaper, more environmentally friendly routes to existing dyes. The aim of this minireview is to discuss the most important advances in the fungal pigment area and its interest in biotechnological applications. Characteristic pigments are produced by a wide variety of fungi and the chemical composition of natural dyes are described. These pigments exhibit several biological activities besides cytotoxicity. The synthetic pigments authorized by the EC and in USA and the natural pigments available in the world market are discussed. The obstacle to the exploitation of new natural pigments sources is the food legislation, requesting costly toxicological research, manufacturing costs, and acceptance by consumers. The dislike for novel ingredients is likely to be the biggest impediment for expansion of the pigment list in the near future. If the necessary toxicological testing and the comparison with accepted pigments are made, the fungal pigments, could be acceptable by the current consumer. The potentiality of pigment production in Brazil is possible due to tremendous Amazonian region biodiversity.

Many efforts in these last years have dedicated in the development of new drugs due to an increase of microbial organisms resistant to multiple antibiotics, and silver nanoparticles appears as a novel antimicrobial agent. The aim of our work was to evaluate the in vitro and in vivo antileishmanial activity of the silver nanoparticles prepared by chemical process and by biosynthesis from Fusarium oxysporum. In vitro antipromastigote activity of L. amazonensis showed that silver nanoparticles chemically synthesized (AgCHEM), biogenic silver nanoparticles (AgBIO) and amphotericin B decreased the parasite load up to 13%, 61%, and 68%, respectively. The IC50 of AgCHEM and AgBIO was 103.5 ± 11.5 μM and 31.6 ± 8.2 μM respectively. The assay of antileishmanial effect of these nanoparticles was evaluated in vivo (BALB/c mice) against L. amazonensis. The mice infected with promastigotes of L. amazonensis in the ear showed that after 10 days of treatment (twice a week for four weeks) the wound in the control (mice treated with PBS solution) was large, while the wound of the mice treated with amphotericin B (positive control) exhibited low size of lesion. The same parasitemia inhibition with amphotericin B was observed when AgBIO were used at 300 fold lower concentration, and 100 fold less concentration of AgCHEM than amphotericin B. Thus, these nanoparticles can be used in wound helping like cutaneous leishmaniasis.

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Bioreduction of methyleneketones was carried out with Rhizopus arrhizus, Pseudomonas fluorescens and immobilized Saccharomyces cerevisae. The α-substituted enones were enantioselectively reduced to saturated ketones with good to excellent ee, depending of microorganism. With the S. cerevisae good ee (12-93%) was obtained while excellent ee (99 %) was achieved with P. fluorescens.

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