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No description available.

The main goal of this research is to provide a novel bioanalytical approach to better understand α-synuclein (AS) aggregation linked to Parkinson’s disease (PD) and characterize the implications of contributing factors such as the presence of metal ions and potential therapeutics that would inhibit or reverse AS fibrillation. Current bioanalytical techniques have reported the fibrillation process of AS however, the detection of prefibrillar formation or the nucleation phase of AS has yet to be characterized. This research aimed to address this issue and monitor the primary stages of AS fibrillation from natively soluble monomer to fibrillar aggregates. The electrochemical measurement of these processes utilized the intrinsic electroactivity of 4 tyrosine (Tyr) residues in AS observed at ~0.6 V (vs. Ag/AgCl) to monitor its early fibrillation kinetics. The research presented here provided valuable evidence of the conformational changes attributed to prefibrillar forms of AS.

The main goal of this research is to provide a novel bioanalytical approach to better understand α-synuclein (AS) aggregation linked to Parkinson’s disease (PD) and characterize the implications of contributing factors such as the presence of metal ions and potential therapeutics that would inhibit or reverse AS fibrillation. Current bioanalytical techniques have reported the fibrillation process of AS however, the detection of prefibrillar formation or the nucleation phase of AS has yet to be characterized. This research aimed to address this issue and monitor the primary stages of AS fibrillation from natively soluble monomer to fibrillar aggregates. The electrochemical measurement of these processes utilized the intrinsic electroactivity of 4 tyrosine (Tyr) residues in AS observed at ~0.6 V (vs. Ag/AgCl) to monitor its early fibrillation kinetics. The research presented here provided valuable evidence of the conformational changes attributed to prefibrillar forms of AS.

Both in type 1 (T1D) and type 2 diabetes (T2D), the deterioration of glycemic control over time is primarily caused by an inadequate mass and progressive dysfunction of ?-cells, leading to the impaired insulin secretion. Thus, the search for agents to protect b-cell and enhance its function is important for diabetes treatment. Studies have reported that baicalein, a flavone originally isolated from the roots of Chinese herb Scutellaria baicalensis, has various claimed beneficial effects on health, such as anti-oxidant, anti-viral, anti-thrombotic, and anti-inflammatory effects. However, it is unclear whether it exerts an anti-diabetic action. Here, we present evidence that baicalein may be a novel anti-diabetic agent. Specifically, dietary intake of baicalein significantly improved hyperglycemia, glucose tolerance, and blood insulin levels in high-fat diet (HFD)-fed middle-aged diabetic mice, which was associated with the improved isle t?-cell survival and mass. Baicalein treatment had no effect on food intake, body weight gain, circulating lipid profile, and insulin sensitivity in HFD-fed mice. In in-vitro studies, baicalein significantly augmented glucose-stimulated insulin secretion in insulin-secreting cells (INS1) and promotes viability of INS1 cells and human islets. These results demonstrate that baicalein may be a naturally occurring anti-diabetic agent by directly modulating pancreatic?-cell function. / Master of Science

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Gastric ulcer is a disease characterized by bleeding, stenosis and perforations of the gastric mucosa that can lead the patient to death. Many flavonoids have been shown to be promising for the treatment of these gastric lesions. Baicalein, a flavonoid present in Scutellaria baicalensis Georgi root (Lamiaceae), a medicinal plant widely used by Chinese medicine to treat peptic ulcers, has pharmacological properties, such as anti-inflammatory, antinociceptive, anticancer, antioxidant and antimicrobial. However, the effect of baicalein on gastric mucosa has not yet been reported. The objective of this study was to evaluate the protective and antisecretory properties of baicalein on the gastric mucosa of mice. The ethanol/HCl-induced ulcer model (60% ethanol/0.3 M HCl) was used to evaluate the protective effect of baicalein (10, 30 and 100 mg/kg) on the gastric mucosa. The participation of α2-adrenoreceptors, nonprotein sulfhydryl compounds (NP-SH), nitric oxide (NO), prostaglandin (PG), ATP-sensitive K+ channels in the gastroprotective effect of baicalein (30 mg/kg), levels of glutathione (GSH) and myeloperoxidase (MPO) activity in gastric tissue were also evaluated through the acidified ethanol induced ulcer model. The antisecretory effect of gastric acid of baicalein (10-100 mg/kg) was evaluated through the pylorus ligation model, in which the parameters of gastric secretion (volume, [H+] and pH) were evaluated in the presence or absence of the secretagogue agent histamine and mucus in the gastric contents. The in vitro activity of H+, K+-ATPase (proton pump) was also determined. Baicalein (10-100 mg/kg) presented a dose-dependent gastroprotective effect (p <0.001) against gastric lesions induced by acidified ethanol. Pretreatment by the intraperitoneal route with an α2 -adrenoreceptor antagonist (yohimbine, 2 mg/kg), a non-protein sulfide compounds blocker (N-ethylmaleimide, NEM, 10 mg/kg), a nonselective inhibitor of the NO synthase (Nw-nitro-L-arginine, L-NAME, 10 mg/kg), a nonselective cyclooxygenase inhibitor (indomethacin, 10 mg/kg) or an ATP-dependent potassium channel blocker (glibenclamide, 10 mg/kg) inhibited the gastroprotective response caused by baicalein (30 mg/kg) (p<0.001). Baicalein (30 mg/kg, p<0.05) was able to increase GSH levels and decrease MPO activity in stomach tissue exposed to the deleterious effect of acidified ethanol. Treatment with baicalein (30 and 100 mg/kg) significantly increased (p<0.05) gastric mucus secretion. In addition, treatment with baicalein reduced the volume of secretion and total acid secretion (30 and 100 mg/kg, p<0.05) and also increased (10, 30 and 100 mg/kg, p<0.001) the value of pH. Baicalein (30 mg/kg) was also effective to inhibi the effects of histamine on gastric secretion (volume, [H+] and pH, p<0.001). Baicalein 10 and 30 μg/mL demonstrated anti-H+, K+-ATPase activity. The present results provide convincing evidence that baicalein can be used as a cytoprotective agent (preventive effect) and anti-ulcer (antisecretory effect) in gastric ulcers treatment. / A úlcera gástrica é uma doença caracterizada por sangramentos, estenoses e perfurações da mucosa gástrica podendo levar o paciente à morte. Muitos flavonoides demonstraram ser promissores para o tratamento dessas lesões gástricas. A baicaleína, um flavonoide presente na raiz da Scutellaria baicalensis Georgi (Lamiaceae), planta medicinal bastante utilizada pela medicina chinesa para tratamento das úlceras pépticas, possui propriedades farmacológicas como anti-inflamatória, antinociceptiva, anticancerígena, antioxidante e antimicrobiana, entretanto o efeito da baicaleína sobre a mucosa gástrica ainda não foi relatado. Portanto, o objetivo deste estudo foi avaliar as propriedades protetora e antissecretória da baicaleína sobre a mucosa gástrica de camundongos. O modelo de úlcera induzida por etanol acidificado (etanol a 60%/HCl a 0,3 M) foi utilizado para avaliar o efeito protetor da baicaleína (10, 30 e 100 mg/kg) sobre a mucosa gástrica. A participação dos receptores α2-adrenérgicos, compostos sulfidrílicos não proteicos (NP-SH), óxido nítrico (NO), prostaglandina (PG), canais K+ ATP no efeito gastroprotetor da baicaleína (30 mg/kg) e os níveis de glutationa (GSH) e a atividade da enzima mieloperoxidase (MPO) no tecido gástrico também foram avaliados através do modelo de úlcera induzida por etanol acidificado. O efeito antissecretório da baicaleína sobre o ácido gástrico da baicaleína (10, 30 e 100 mg/kg) foi avaliado no modelo de ligadura do piloro, em que os parâmetros da secreção gástrica (volume, [H+] e pH) na presença ou ausência do agente secretagogo histamina, bem como muco no conteúdo gástrico foram avaliados. A atividade in vitro da H+, K+-ATPase (bomba de prótons) também foi determinada. A baicaleína (10-100 mg/kg) apresentou efeito gastroprotetor dose-dependente (p<0,001) contra as lesões gástricas induzidas pelo etanol acidificado. O pré-tratamento pela via intraperitoneal com um antagonista dos receptores α2-adrenérgicos (ioimbina, 2 mg/kg), um bloqueador dos grupamentos sulfidrílicos não proteicos (N-etilmaleimida, NEM, 10 mg/kg), um inibidor não seletivo da sintase do NO (Nw-nitro- L-arginina, L-NAME, 10 mg/kg), um inibidor não seletivo da ciclooxigenase (indometacina, 10 mg/kg) ou um bloqueador de canais para potássio sensíveis a ATP (glibenclamida, 10 mg/kg) inibiram a resposta gastroprotetora causada pela baicaleína (30 mg/kg) (p<0,001). Este flavonoide aumentou a concentração de GSH e diminuiu a atividade da MPO no tecido estomacal exposto ao efeito deletério do etanol acidificado. O tratamento com baicaleína (30 e 100 mg/kg) aumentou significativamente (p<0,05) a secreção do muco gástrico, assim como reduziu (30 e 100 mg/kg, p<0,05) o volume de secreção e secreção ácida total, e também aumentou (10, 30 e 100 mg/kg, p<0,001) o valor do pH. A baicaleína (30 mg/kg) também foi eficaz na inibição dos efeitos da histamina na secreção gástrica (volume, [H+] e pH, p<0,001). A baicaleína 10 e 30 μg/mL demonstrou atividade inibitória da H+, K+- ATPase. Os resultados apresentados fornecem evidências de que a baicaleína pode ser utilizada como um agente citoprotetor e antissecretório no tratamento das úlceras gástricas.

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Background: Human mast cells are capable of a wide variety of inflammatory responses and play a vital role in the pathogenesis of inflammatory diseases such as allergy, asthma, and atherosclerosis. We have reported that cigarette smoke extract (CSE) significantly increased IL-6 and IL-8 production in IL-1β-activated human mast cell line (HMC-1). Baicalein (BAI) has anti-inflammatory properties and inhibits IL-1β- and TNF-α-induced inflammatory cytokine production from HMC-1. The goal of the present study was to examine the effect of BAI on IL-6 and IL-8 production from CSE-treated and IL-1β-activated HMC-1.Methods: Main-stream (Ms) and Side-stream (Ss) cigarette smoke were collected onto fiber filters and extracted in RPMI-1640 medium. Two ml of HMC-1 at 1 × 10 6 cells/mL were cultured with CSE in the presence or absence of IL-1β (10 ng/mL) for 24 hrs. A group of HMC-1 cells stimulated with both IL-1β (10 ng/ml) and CSE was also treated with BAI. The expression of IL-6 and IL-8 was assessed by ELISA and RT-PCR. NF-κB activation was measured by electrophoretic mobility shift assay (EMSA) and IκBα degradation by Western blot.Results: Both Ms and Ss CSE significantly increased IL-6 and IL-8 production (p < 0.001) in IL-1β-activated HMC-1. CSE increased NF-κB activation and decreased cytoplasmic IκBα proteins in IL-1β-activated HMC-1. BAI (1.8 to 30 μM) significantly inhibited production of IL-6 and IL-8 in a dose-dependent manner in IL-1β-activated HMC-1 with the optimal inhibition concentration at 30 μM, which also significantly inhibited the enhancing effect of CSE on IL-6 and IL-8 production in IL-1β-activated HMC-1. BAI inhibited NF-κB activation and increased cytoplasmic IκBα proteins in CSE-treated and IL-1β-activated HMC-1.Conclusions: Our results showed that CSE significantly increased inflammatory cytokines IL-6 and IL-8 production in IL-1β-activated HMC-1. It may partially explain why cigarette smoke contributes to lung and cardiovascular diseases. BAI inhibited the production of inflammatory cytokines through inhibition of NF-κB activation and IκBα phosphorylation and degradation. This inhibitory effect of BAI on the expression of inflammatory cytokines induced by CSE suggests its usefulness in the development of novel anti-inflammatory therapies.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / In this work, gold nanoparticles (AuNPs) and nanoclusters (AuNCLs) were prepared by the reduction in diluted solution method, using the amphiphilic copolymer Pluronic F127(PF127) and thiolated Pluronic F127 (PF127-thiol), respectively. The copolymer was functionalized by sterification reaction using thioglycolic acid (TGA). The investigated parameters of synthesis were concentration of the PF127 solution, temperature, as well as, the UV irradiation. The nanosystems were characterized by UV/Vis absorption spectroscopy and transmission electron microscopy (TEM). Further, the system potentialities were investigated by a catalized reaction and incorporation of a model molecule (baicalein). Morphologies, sizes, polydispersity, amount of reduced ion as welll as kinetics parameters were depedent on the parameters of synthesis. The yeld of the functionalization reaction was 90%, calculated by 1H NMR. Using the PF127-thiol, the surface plasmonic ressonance band (SPR) was undetected and a strong absorption in the UV region observed, which indicated that nanoparticles smaller than 3 nm were obtained (AuNCLs). Catalitic property of the AuNPs were investigated by reduction of p-nitrophenol, in which the AuNPs synthesised by PF127 were more efficent than the systems obtained by citrate reduction. The encapsulation efficiency of the baicalein were around 90%. In conclusion, the synthesis of AuNPs by PF127 is not only adequate to modulate sizes and morphology but also to provide environmental advantage in comparison to some tradicional methods. In addition, these are promissing systems to biologic applications because of the biocompatibility of PF127. / Neste trabalho, nanopartículas e nanoclusters de ouro (AuNPs e AuNCLs, respectivamente) foram obtidos pelo método de redução em solução diluída, empregando o polímero anfifílico Pluronic F 127 não funcionalizado (PF127) e funcionalizado (PF 127-Tiol) como agente redutor/estabilizador, respectivamente. A funcionalização do polímero foi realizada por reação de esterificação com ácido tioglicólico (TGA), inserindo-se grupos tióis terminais. A concentração de PF127 e temperatura de obtenção foram parâmetros variados nos processos, além da incidência ou não de radiação UV. A caracterização dos nanosistemas foi realizada por espectroscopia de absorção no UV-Vis e por microscopia eletrônica de transmissão (MET). Os sistemas foram testados quanto à atividade catalítica, na redução do p-nitrofenol em borohidreto de sódio e na incorporação de uma molécula modelo, a baicaleína. As diferentes condições de síntese influíram sobre a morfologia, tamanho, quantidade, polidispersão e cinética de formação das nanopartículas. O rendimento da reação de funcionalização, estimado por 1H RMN, foi de 90%. O produto obtido (PF127-Tiol) foi empregado na redução do Au3+ e, nanopartículas menores que 3 nm foram obtidas, nesse caso, AuNCLs, evidenciados pelo desaparecimento da banda SPR e surgimento de uma forte absorção no UV, além da observação por MET. Os sistemas a partir do PF127 foram investigados quanto a aplicação em catálise, na qual as AuNPs preparados utilizando Pluronic foi mais eficiente do que as obtidas por redução por citrato. Na investigação da incorporação de uma molécula modelo, as eficiências de encapsulamento foram superiores a 90%. Dessa forma, esses sistemas mostraram-se promissores para uma diversa gama de aplicações de nanopartículas ou clusters de ouro, tais como na catálise de reações químicas e encapsulamamento de bioativos. A síntese por PF127 mostrou-se uma rota ambientalmente amigável e capaz de modulação nos tamanhos e formas das AuNPs,.Os sistemas ainda são promissores para uso em sistemas biológicos, tendo em vista a biocompatibilidade do PF127.