DSpace Communidade:
http://repositorio.ufc.br/handle/riufc/24045
2024-03-19T04:30:30ZFitossíntese e caracterização de nanopartículas de ouro sintetizadas com extrato aquoso de Anacardium occidentale e avaliação do seu efeito antibacteriano
http://repositorio.ufc.br/handle/riufc/75614
Título: Fitossíntese e caracterização de nanopartículas de ouro sintetizadas com extrato aquoso de Anacardium occidentale e avaliação do seu efeito antibacteriano
Autor(es): Figueira, Ciro Siqueira
Abstract: The use of nanobiotechnology is changing the way in which various types of materials are used. The biosynthesis of nanoparticles is a very simple, effective, and relatively low-cost method compared to other methods of producing metallic nanoparticles (NPs). Their behavior is related to the reaction medium in which they are found, their stability, chemical composition, degree of aggregation, morphology, and size, which is why modulations at the time of synthesis are decisive for their biological activity. Most of the routes traditionally used to produce metal nanoparticles use toxic solvents, which generate waste that is harmful to health and the environment. Studies on NPs have shown that they have high antimicrobial potential, drug delivery, among others. The aim of this study was to develop a sustainable methodology for the synthesis of gold nanoparticles, using an aqueous extract of Anacardium occidentale leaves as a reducing agent, and to evaluate their antimicrobial activity. The gold nanoparticles (AuNPs) were synthesized by oxirreduction, based on a design in which the variable observed was the concentration of the reducing agent. Characterization was carried out using UV-Vis, microscopy, zeta potential, ICP-MS and infrared analyses. Antibacterial activity was tested against Staphylococcus aureus 1117 and Escherichia coli DH5α using the broth microdilution technique, and rapid interaction by shaking, followed by Transmission Electron Microscopy analysis. The lyophilized cashew leaf extract was able to reduce gold as effectively as sodium citrate (the commonly used reducing agent). The concentration of the reducing agent was relevant in determining the characteristics of the nanoparticles. The absorbance peak occurred between 519 and 529nm. Together with this data, the microscopy images confirm the presence of gold nanoparticles with an average size of 13 - 23 nm. From the green synthesis the AuNPs had varied shapes and the zeta potential showed that the AuNPs were stable. ICP-MS analysis showed that the concentration of AuNPs with the green synthesis was higher than with citrate. The gold nanoparticles showed antibacterial potential and were able to inhibit the growth of S. aureus by interacting with the membrane. The plant extract proved to be an excellent alternative for the synthesis of AuNPs, resulting in particles with effective antimicrobial activity in inhibiting S. aureus.
Tipo: Tese2023-01-01T00:00:00ZEfeito de calcogenol ésteres em células planctônicas e biofilmes de bactérias orais
http://repositorio.ufc.br/handle/riufc/74852
Título: Efeito de calcogenol ésteres em células planctônicas e biofilmes de bactérias orais
Autor(es): Sousa, Leonardo Silva de
Abstract: Bacteria have a natural tendency to develop communities of cells surrounded by a polysaccharide matrix called a biofilm. Biofilms are formed on the surfaces of teeth (dental plaque) and are the main etiological factor for most dental problems such as caries, gingivitis and periodontitis. Dental plaque is made up of multiple species of bacteria that participate in the complex ecosystems of the human oral cavity. The genus Streptococcus is commonly found in the oral cavity, with emphasis on the species S. mutans and S. parasanguinis. In this context, research into new compounds capable of preventing or eradicating oral biofilms was intensified with these bacteria. This study aimed to evaluate the antibacterial and antibiofilm activity of 5 synthetic chalcogenol esters (S501, S502, S503, S505, S506) on S. mutans ATCC 25175 and S. parasanguinis ATCC 903. The effect of chalcogenol esters on planktonic cultures was determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Regarding biofilm formation, the compounds were added to bacteria at different concentrations (7.80 to 250 μg/mL) in microtiter plates. The plates were incubated for 24 h at 37°C on an orbital shaker at 120 rpm under atmospheric pressure, with 5% CO2. Biofilm formation was characterized by total biomass, using crystal violet staining, and the number of viable cells was expressed as log CFU/mL. Tests were also carried out with pre-formed biofilms with chalcogenol esters. The results showed that chalcogenol esters S505 and S506 presented MICs of 125 and 62.50 μg/mL, respectively, for S. mutans, while S501, S502 and S506 presented MICs of 62.50, 31.25 and 250 μg/ml for S. parasanguinis. Regarding biofilm formation, in general, all compounds effectively reduced the formation of biomass and the number of viable cells, mainly in S. parasanguinis and interfered with the pre-formed biofilm of both species. It was concluded that the tested chalcogenol esters have the potential to be an effective alternative against oral biofilms involving the species S. mutans and S. parasanguinis.
Tipo: Dissertação2015-01-01T00:00:00ZConsórcio microbiano isolado a partir do óleo derramado no nordeste brasileiro: biorremediação de áreas contaminadas
http://repositorio.ufc.br/handle/riufc/74768
Título: Consórcio microbiano isolado a partir do óleo derramado no nordeste brasileiro: biorremediação de áreas contaminadas
Autor(es): Castro, Luzia Gabrielle Zeferino de
Abstract: August 2019, a mysterious oil spill affected coastal ecosystems in the Northeast of Brazil,
considered the largest oil disaster in the last 30 years. The diversity of affected environments
made it clear that there is no universal impact mitigation solution. However, one promising
approach is the use of bioremediation technology by bioaugmentation. This study aimed to
isolate, characterize, and evaluate cultivable microbiota associated with heavy oil, with the goal
of selecting a customized consortium to accelerate the degradation of hydrocarbons. The
bacterial isolation process used the enrichment technique on Bushnell Haas medium with + 3%
m/v NaCl and 1% m/v from oiled samples collected on beaches in Ceará. The isolates were
then identified from the analysis of the 16S rRNA gene sequences by Sanger sequencing. The
biodegradation potential of oil fractions from each isolate was evaluated by the 2,6Dichlorophenolindophenol
indicator method (DCPIP), using six hydrocarbon fractions as the
sole carbon source. In addition, the prospection of biosurfactants was also evaluated through
the kerosene emulsification index, surface tension reduction and oil dispersion. The
biocompatibility between the isolates was evaluated using the antibiosis technique. After the
evaluation process, 24 strains of bacteria were isolated and identified, from 14 different genera,
belonging to the phyla Proteobacteria, Actinobacteria, and Bacteriodetes. Among these, the
strains of Acinetobacter sp., Alcanivorax sp. and Martellella sp. stood out for their ability to
degrade the largest number of hydrocarbons, emerging as the most promising to compose the
consortium. Culture supernatants of Alcanivorax sp. FOR1501 and Acinetobacter sp.
AMO1502 promoted kerosene emulsification, being candidates for the possible production of
biosurfactants. The degradation assay with the consortia demonstrated that Acinetobacter sp.
FLE1503 was the best strain for the degradation of alkanes (C4C25),
while Alcanivorax sp.
FOR1501 and Martelella sp. FOR1507 combined showed superior aromatic hydrocarbon
degradation. Therefore, this study is the first record of microbial isolates associated with the oil
spill, pointing to a customized consortium for alkanes and aromatic hydrocarbons as a
promising approach to accelerate the cleaning of affected environments. The results of this
study can be used to develop more effective and sustainable strategies for the management of
oil spills in the future.
Tipo: Dissertação2023-01-01T00:00:00ZFruticulosina: uma nova proteína inativadora de ribossomos (rip tipo 2) de sementes de Abrus fruticulosus com ação antifúngica e antileishmania
http://repositorio.ufc.br/handle/riufc/74752
Título: Fruticulosina: uma nova proteína inativadora de ribossomos (rip tipo 2) de sementes de Abrus fruticulosus com ação antifúngica e antileishmania
Autor(es): Penha, Samara Sena da
Abstract: The type 2 Ribosome-Inactivating Proteins (type 2 RIPs) are heterodimeric proteins consisting of a RNA-N-glicosydase catalytic subunit linked to a galactose-binding subunit to allow cell surface binding and toxin entry in most mammalian cells, showing a high toxicity. Although their potency to kill cells is remarkable, these RIPs have been explored in the chemical constrution of immunotoxins and diagnostic tools. This work report the isolation, biochemistry characterization, antifungal and antileshimanial action of the fruticulosin, a type 2 RIP of seeds from Abrus fruticulosus. Initially, the fruticulosin was purified by precipitation with ammonium sulfate followed by affinity chromatographic using Sepharose-4B. The protein showed of a single band with an apparent molecular mass of 63 KDa under nonreducing conditions and two bands (30 and 28 KDa, respectively) under reducing conditions, suggesting the presence of disulfide bond. The new RIP strongly agglutinated rabbit erythrocyte and was inhibited by D-galactose, N-acetyl-D-galactosamine and D-lactose. The secondary structure of fruticulosin showed contain predominace of -sheet and tryptophan residues in the most internal regions of the molecule. Moreover, fruticulosin showed high toxicity in vivo on mice (LD50 3.0 μg/kg) and inhibit in vitro protein synthesis by a cell-free system with similar activity to ricin. In addition, fruticulosin showed antifungal activity and exhibited toxic effect on promastigote forms of Leishmania major.
Tipo: Dissertação2015-01-01T00:00:00Z