RESUMO
Sulfated polysaccharides are known to display activity against enveloped viruses, such as herpes and dengue. The aim of this work was to assess the antiviral activity of botryosphaeran, a fungal exocellular (1â¯ââ¯3)(1â¯ââ¯6)-ß-d-glucan devoid of sulfate groups, and its chemically sulfonated derivatives, against herpes simplex virus (HSV), dengue virus (DENV) and poliovirus (PV). The natural parent polysaccharide inhibited acyclovir-sensitive HSV (HSV-KOS) infection in Vero cells (IC50 of 39.3⯵gâ¯mL-1), while the IC50 against acyclovir-resistant HSV (HSV-AR) was 47.5⯵gâ¯mL-1. Botryosphaeran was derivatized by sulfonylation with chlorosulfonic acid to prepare two sulfonated derivatives, S1 and S2, with degrees of substitution (DS) of 0.4 and 1.1, respectively. Antiviral evaluation of S1 and S2 gave the IC50 of 3.0 and 2.4⯵gâ¯mL-1 against HSV-KOS, and 7.3 and 2.7⯵gâ¯mL-1 against HSV-AR, respectively. This study demonstrated for the first time that native botryosphaeran inhibited HSV infection, albeit moderately, while its sulfonated derivatives developed high activity against viral infection. DENV inhibition was weak for botryosphaeran, but remarkably stronger for S1 and S2. All compounds were inactive against PV, as it lacked a viral envelope. The presence of sulfate groups and the DS were confirmed to be important features for antiviral activity.
Assuntos
Antivirais/química , Antivirais/farmacologia , Vírus da Dengue/efeitos dos fármacos , Glucanos/química , Glucanos/farmacologia , Simplexvirus/efeitos dos fármacos , Ácidos Sulfônicos/química , Animais , Chlorocebus aethiops , Poliovirus/efeitos dos fármacos , Células VeroRESUMO
Laccase was immobilized on a glassy carbon electrode layered with multi-walled carbon nanotubes using a film of botryosphaeran, a fungal (1â¯ââ¯3)(1â¯ââ¯6)-ß-D-glucan. This novel biosensing platform was characterized by electrochemical impedance spectroscopy and scanning electron microscopy, and applied for the determination of dopamine. Experimental variables such as enzyme concentration, pH value and operational parameters of the electroanalytical technique were optimized. Using square-wave voltammetry, there was a linear dependence of peak current and dopamine concentration within the range of 2.99-38.5⯵molâ¯L-1 with a limit of detection of 0.127⯵molâ¯L-1. The biosensor was successfully applied in the determination of dopamine in pharmaceutical injection and synthetic biological samples, and presented good selectivity even in the presence of uric acid and ascorbic acid, as well as other phenolic compounds. The different aspects regarding the operational stability of the laccase biosensor were evaluated, demonstrating good intra-day and inter-day repeatability, and long-storage stability. Furthermore, this biosensor was evaluated in the indirect determination of spironolactone by using the analytical signal of dopamine, presenting a limit of detection of 0.94⯵molâ¯L-1. The results obtained in the analysis of spironolactone in commercial pharmaceutical samples were satisfactory.
Assuntos
Técnicas Biossensoriais/métodos , Dopamina/análise , Glucanos/química , Lacase/química , Espironolactona/análise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Enzimas Imobilizadas/química , Limite de Detecção , Nanotubos de Carbono/químicaRESUMO
AIMS: Obesity is associated with comorbidities such as diabetes and hepatic steatosis. ß-Glucans have been described as effective in treating conditions including dyslipidaemia and diabetes. Thus, the objective of this study was to evaluate the effects of botryosphaeran [(1â¯ââ¯3)(1â¯ââ¯6)-ß-D-glucan] on obesity and its comorbidities, and understand its mechanism of action. MAIN METHODS: Obesity was induced in adult male Wistar rats by ingestion of a high-fat diet and water with sucrose (300â¯g/L) for 8â¯weeks. Control rats received standard diet. After six weeks, treatment commenced with botryosphaeran (12â¯mg/kg.b.w., via gavage, 15â¯days), respective controls received water. Rats were divided into 3 groups: control (C), obese (O), and obeseâ¯+â¯botryosphaeran (OB). In the 8th week, obesity was characterized. Feed-intake, glucose and lipid profiles, glucose tolerance, and concentrations of glycogen and lipids in liver were analyzed. Protein expression was determined by Western blotting. KEY FINDINGS: Obese rats showed significant increases in weight gain and adipose tissue, presented glucose intolerance, dyslipidaemia, and hepatic steatosis. Botryosphaeran significantly reduced feed intake, weight gain, periepididymal and mesenteric fat, and improved glucose tolerance. Botryosphaeran also reduced triglyceride and VLDL, and increased HDL levels. Furthermore, botryosphaeran increased glycogen and reduced total lipids, triglycerides and cholesterol in liver, and increased AMP-activated protein kinase(AMPK) activity and Forkhead transcription factor 3a(FOXO3a) protein expression in adipose tissue. SIGNIFICANCE: This study demonstrated that botryosphaeran was effective in reducing obesity, hepatic steatosis, dyslipidaemia insulin resistance and glucose intolerance in diet-induced obese rats, and these effects were, at least in part, associated with reduced feed intake, and AMPK and FOXO3a activities.