Sulfate-Reducing Bacteria: Biofilm Formation and Corrosive Activity in Endodontic Files.

AIM: This study describes the biofilm formation and the corrosive capacity of sulfate-reducing bacteria (SRB) on the metallic structure of used endodontic files. METHODS: Sulfate-reducing bacteria (SRB) (Desulfovibrio desulfuricans oral and Desulfovibrio fairfieldensis or D. desulfuricans environmental) were inoculated into the culture media (Postgate C culture medium or modified Postgate E culture medium). The biocorrosive potential of these bacteria will be an important component of a biopharmaceutical under development called BACCOR. Afterwards, four used endodontic files (UEFs) were separately inoculated into a specific culture media for 445 days at 30°C in an incubator. The four UEFs were placed in a scanning electron microscope (SEM) and analyzed by the energy-dispersive X-ray spectrometry (EDS). RESULTS: The confocal laser scanning microscopic images indicate the presence of biofilm in the four samples. The SEM and SEM-EDS revealed the presence of rough, irregular structures adhering along the metallic surface of the used endodontic files, suggesting a mature calcified biofilm with a high concentration of Ca, P, C, and S. CONCLUSION: The formation of SRB biofilms on used endodontic files shows characteristics that may contribute to the biocorrosion of these files, and the results may also provide complementary data for a biopharmaceutical, which is still under development to assist in the removal of fractured endodontic files inside root channels.

NF-κB Signaling Pathway Inhibitors as Anticancer Drug Candidates.

Cancer incidence represents an important public health problem worldwide. Nuclear factor kappa B (NF- κB) transcription factor plays a pivotal role in the regulation of genes that control various responses in eukaryotic cells, including proliferation and survival, cytoskeletal remodeling, cellular adhesion and apoptosis. Extensive studies have demonstrated the contribution of NF-κB transcription in the promotion and progression of several hematological malignancies and solid tumors, in which NF-κB constitutive activation and/or overexpression are common clinical features. Moreover, triggering the NF-κB pathway is already considered one of the important mechanisms of resistance development to chemotherapy and radiotherapy, indicating that the inhibition of this signaling cascade is a promising approach to enhancing efficacy and preventing acquired resistance in cancer treatment. In this review, research efforts dedicated to the identification of novel NF-κB signaling pathway inhibitors as promising anticancer drug candidates are described.

Synthesis and antiplatelet activity of antithrombotic thiourea compounds: biological and structure-activity relationship studies.

The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p) displayed IC50 values ranging from 29 to 84 µM with direct influence over in vitro PGE2 and TXA2 formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE2 and TXB2 production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

Preparation and scale up of extended-release tablets of bromopride

Reproducibility of the tablet manufacturing process and control of its pharmaceutics properties depends on the optimization of formulation aspects and process parameters. Computer simulation such as Design of Experiments (DOE) can be used to scale up the production of this formulation, in particular for obtaining sustained-release tablets. Bromopride formulations are marketed in the form of extended-release pellets, which makes the product more expensive and difficult to manufacture. The aim of this study was to formulate new bromopride sustained release formulations as tablets, and to develop mathematical models to standardize the scale up of this formulation, controlling weight and hardness of the tablets during manufacture according to the USP 34th edition. DOE studies were conducted using Minitab(tm) software. Different excipient combinations were evaluated in order to produce bromopride sustained-release matrix tablets. In the scale-up study, data were collected and variations in tableting machine parameters were measured. Data were processed by Minitab(tm) software, generating mathematical equations used for prediction of powder compaction behavior, according to the settings of the tableting machine suitable for scale-up purposes. Bromopride matrix tablets with appropriate characteristics for sustained release were developed. The scale-up of the formulation with the most suitable sustained release profile was established by using mathematical models, indicating that the formulation can be a substitute for the pellets currently marketed.

A reprodutibilidade do processo de fabricação de comprimidos e o controle das suas propriedades farmacotécnicas depende da otimização dos aspectos de formulação e dos parâmetros de processo. O planejamento de experimentos como o Desenho de Experimentos (DOE) pode ser utilizado para acelerar a produção desta formulação, em particular, para a obtenção de comprimidos de liberação prolongada. Formulações de bromoprida são comercializadas sob a forma de péletes de liberação prolongada, o que torna o produto caro e de difícil fabricação. O objetivo deste estudo foi preparar novas formulações de bromoprida de liberação prolongada na forma de comprimidos e desenvolver modelos matemáticos visando ao escalonamento destas formulações, controlando o peso e a dureza dos comprimidos durante a fabricação, de acordo com a 34ª Edição da USP. Estudos de DOE foram realizados utilizando o software Minitab(tm). Diferentes combinações de excipientes foram avaliadas visando à obtenção dos comprimidos de liberação prolongada de bromoprida. No estudo de scale-up, coletaram-se e mediu-se a influência das variações nos parâmetros da máquina de compressão. Processaram-se os dados obtidos pelo software Minitab (tm), gerando equações matemáticas aptas para a previsão do comportamento de compactação do pó em escala industrial. Os comprimidos obtidos apresentavam características adequadas em termos de liberação sustentada, sendo a cinética de liberação estabelecida utilizando modelos matemáticos, indicando que esta formulação pode ser uma substituta aos péletes de bromoprida atualmente comercializados.

Rational use of antioxidants in solid oral pharmaceutical preparations

Antioxidants are currently used as efficient excipients that delay or inhibit the oxidation process of molecules. Excipients are often associated with adverse reactions. Stability studies can guide the search for solutions that minimize or delay the processes of degradation. The ability to predict oxidation reactions in different drugs is important. Methods: This study was conducted to assess the rational use of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), sodium metabisulfite (SMB), propyl gallate (PG) and cysteine (CYS) in tablet formulations of simvastatin and ketoconazole. These antioxidants were evaluated according to stability parameters and the relationship between efficiency of the antioxidant and chemical structure of the drugs. Results were compared with DPPH tests and computational simulations. BHT was most efficient regarding simvastatin stability, and the most effective BHT concentrations for maintaining stability were 0.5 and 0.1%. In relation to ketoconazole, SMB was most efficient for maintaining content and dissolution profile. The evaluation by DPPH showed that the largest percentage of absorbance reduction was observed for PG, while SMB proved most efficient and had lower consumption of DPPH. The same pattern was observed, albeit with lower efficiency, for the other lipophilic antioxidants such as BHT and BHA. The results of the molecular modeling study demonstrated that electronic properties obtained were correlated with antioxidant activity in solution, being useful for the rational development of liquid pharmaceutical formulations but not for solid oral formulations. This study demonstrated the importance of considering stability parameters and molecular modeling to elucidate the chemical phenomena involved in antioxidant activity, being useful for the rational use of antioxidants in the development of pharmaceutical formulations.

Atualmente, antioxidantes são usados como excipientes eficientes, que retardam ou inibem o processo de oxidação de moléculas. Excipientes são frequentemente associados a efeitos adversos. Estudos de estabilidade podem ajudar na busca por possíveis soluções para minimizar ou retardar os processos de degradação. A habilidade de prever as reações de oxidação em diferentes fármacos é importante. O estudo foi conduzido com o objetivo de avaliar o uso racional de hidroxianisol butilado (BHA), hidroxitolueno butilado (BHT), metabissulfito sódico (SMB), galato de propila (PG) e cisteína (CYS) em formulações de comprimidos de sinvastatina e cetoconazol. Eles foram avaliados por parâmetros de estabilidade e pela relação entre a eficiência dos antioxidantes e a estrutura química do fármaco. Os resultados foram comparados com testes de DPPH e simulações em computador. BHT foi mais eficiente com relação a estabilidade da sinvastatina e às concentrações mais eficientes para manutenção de estabilidade foram 0,5 e 0,1%. Com relação ao cetoconazol, SMB foi mais eficiente em manter o conteúdo e o perfil de dissolução. A avaliação por DPPH mostrou que o maior percentual de redução de absorção foi observado para PG, enquanto que SMB mostrou ser mais eficiente e consumir menos DPPH. A mesma tendência foi observada com menos eficiência em todos os outros antioxidantes lipofílicos como o BHT e BHA. Os resultados do estudo de modelagem molecular demonstraram que as propriedades eletrônicas obtidas podem ser correlacionadas com a atividade antioxidante em solução, sendo útil para o desenvolvimento racional de formulações farmacêuticas líquidas, mas não para formulações sólidas orais. Este estudo demonstrou a importância de considerar parâmetros de estabilidade e modelagem molecular para elucidar os fenômenos químicos envolvidos na atividade antioxidante, sendo úteis para o uso racional de antioxidantes no desenvolvimento de formulações farmacêuticas.