RESUMO
Lectins are a class of proteins or glycoproteins capable of recognizing and interacting with carbohydrates in a specific and reversible manner. Owing to this property, these proteins can interact with glycoconjugates present on the cell surface, making it possible to decipher the glycocode, as well as elicit biological effects, such as inflammation and vasorelaxation. Here, we report a structural and biological study of the mannose/glucose-specific lectin from Dioclea lasiophylla seeds, DlyL. The study aimed to evaluate in detail the interaction of DlyL with Xman and high-mannose N-glycans (MAN3, MAN5 and MAN9) by molecular dynamics (MD) and the resultant in vitro effect on vasorelaxation using rat aortic rings. In silico analysis of molecular docking was performed to obtain the initial coordinates of the DlyL complexes with the carbohydrates to apply as inputs in MD simulations. The MD trajectories demonstrated the stability of DlyL over time as well as different profiles of interaction with Xman and N-glycans. Furthermore, aortic rings assays demonstrated that the lectin could relax pre-contracted aortic rings with the participation of the carbohydrate recognition domain (CRD) and nitric oxide (NO) when endothelial tissue is preserved. These results confirm the ability of DlyL to interact with high-mannose N-glycans with its expanded CRD, supporting the hypothesis that DlyL vasorelaxant activity occurs primarily through its interaction with cell surface glycosylated receptors.Communicated by Ramaswamy H. Sarma.
Assuntos
Dioclea , Animais , Carboidratos/química , Dioclea/química , Dioclea/metabolismo , Lectinas , Manose/química , Simulação de Acoplamento Molecular , Lectinas de Plantas/análise , Lectinas de Plantas/química , Lectinas de Plantas/farmacologia , Polissacarídeos/farmacologia , Ratos , Sementes/química , Sementes/metabolismo , Vasodilatadores/análise , Vasodilatadores/química , Vasodilatadores/farmacologiaRESUMO
We aimed to develop a standardized methodology to determine the metabolic profile of organic extracts from Malvaviscus arboreus Cav. (Malvaceae), a Mexican plant used in traditional medicine for the treatment of hypertension and other illnesses. Also, we determined the vasorelaxant activity of these extracts by ex vivo rat thoracic aorta assay. Organic extracts of stems and leaves were prepared by a comprehensive maceration process. The vasorelaxant activity was determined by measuring the relaxant capability of the extract to decrease a contraction induced by noradrenaline (0.1â µM). The hexane extract induced a significant vasorelaxant effect in a concentration- and endothelium-dependent manner. Secondary metabolites, such as polyunsaturated fatty acids, terpenes and one flavonoid, were annotated by liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS) in positive ion mode. This exploratory study allowed us to identify bioactive secondary metabolites from Malvaviscus arboreus, as well as identify potentially-new vasorelaxant molecules and scaffolds for drug discovery.
Assuntos
Aorta Torácica/química , Malvaceae/química , Extratos Vegetais/metabolismo , Vasodilatadores/metabolismo , Animais , Aorta Torácica/metabolismo , Cromatografia Líquida , Masculino , Malvaceae/metabolismo , Espectrometria de Massas , Estrutura Molecular , Extratos Vegetais/análise , Ratos , Ratos Wistar , Vasodilatadores/análiseRESUMO
The vasorelaxing effect of the methanol extract of the flowers of Crataegus gracilior, a Mexican medicinal plant used to treat some cardiovascular diseases, was assessed, and its possible chemical markers identified. The extract produced a potent vasodilator effect on isolated rat aortic rings (EC50 = 1.83 ± 1.39 µg/mL; Emax = 100 ± 3.4%). Vitexin, the most commonly identified flavonoid in the flowers and used to standardise some Crataegus species, was not found at all in this plant sample. Instead, daucosterol, and corosolic and euscapic acids were purified. The two triterpene acids have been reported to possess beneficial effects on cardiovascular diseases. These results indicate that the vasodilator effect might induce the hypotensive effect claimed by users, and that euscapic and corosolic acids may be the main vasodilator compounds, and can then be employed as the chemical markers towards the future standardisation of the extract.
Assuntos
Crataegus/química , Flores/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Vasodilatadores/farmacologia , Animais , Aorta/efeitos dos fármacos , Apigenina/análise , Relação Dose-Resposta a Droga , Flavonoides/análise , Masculino , Metanol , México , Plantas Medicinais/química , Ratos Wistar , Triterpenos/análise , Triterpenos/farmacologia , Vasodilatadores/análise , Vasodilatadores/químicaRESUMO
Grapes and its derivatives (wines and juices) are rich in polyphenols that have high antioxidant and vasodilator capacity. These biological activities may vary in the juices marketed and produced in different regions of Brazil. Objectives: To determine the antioxidant and vasorelaxant effects of grape juice samples produced in different regions of Brazil. Methods: The content of phenolic compounds and antioxidant capacity were evaluated by the methods of Folin-Ciocalteau, DPPH, ABTS and a new electroanalytical approach (differential pulse voltammetry - DPV). Vasodilator effects were analyzed in isolated aorta from rats in an organ bath. Results: The samples from RJ and SP presented respectively the higher and lower phenolic content and also antioxidant capacity by the methods used (ABTS and DPPH). The results of the electrochemical index corroborate to the other tests, with the best results to RJ (21.69 ± 3.15 µA/V) and worse to the SP sample (11.30 ± 0.52 µA/V). In the vascular reactivity studies, the relaxation induced by each sample presented more distinct differences, following the order: RJ (87.9 ± 4.8%) > RS1 (71.6 ± 8.6%) > GO (56.2 ± 7.2%) > SP (39.9 ± 7.8%) > PR (39.4 ± 9.5%) > RS2 (19.5 ± 6.2%). Inhibition of endothelial NO practically abolished (p < 0.001) the relaxation for all samples, except one. Conclusion: The phenolic content and antioxidant capacity vary greatly among samples. The results obtained for the order of antioxidant activity were: RJ > RS1 > GO > RS2 > PR > SP. The juices were able to induce vascular relaxation at quite varied levels, and the RJ sample the most effective. The L-NAME practically blocked all samples except one (RS2)
Assuntos
Animais , Ratos , Vasodilatação , Vasodilatadores/análise , Brasil/epidemiologia , Vitis , Antioxidantes/farmacologia , Doenças Cardiovasculares/prevenção & controle , Análise de Variância , Ratos Wistar , Modelos Animais , Células Endoteliais , Técnicas Eletroquímicas , Polifenóis , Sucos de Frutas e Vegetais/análise , Hipertensão , Neoplasias/prevenção & controleRESUMO
BACKGROUND: In northeastern Brazil, grape pomace has become a potential alternative byproduct because of the recover phenolic compounds from the vinification process. Comparative analyses were performed between lyophilized extract of grape skins from pomace, described as fermented (FGS), and fresh, unfermented (UGS) grape skins to show the relevant brand's composition upon the first maceration in winemaking. METHODS: The use of in vitro testing such as Folin-Ciocalteu's, DPPH free radical scavenger and HPLC methods were performed to evidence antioxidant effect and phenolic compounds. Additionally, vascular reactivity studies were performed in third-order branches of rat superior mesenteric arteries, which were obtained and placed in organ baths containing Krebs-Henseleit solution, maintained at 37 °C, gassed with a mixture of 95% O2 and 5% CO2, and maintained at pH 7.4. The in situ formation of reactive oxygen species (ROS) was evaluated in small mesenteric rings using oxidative fluorescent dihydroethidium dye. RESULTS: We found higher phenolic content and antioxidant activity in FGS when compared to UGS. HPLC analyses identified a significant number of phenolic compounds with antioxidant potential in both samples. The vasorelaxant effect induced by FGS was more potent than that induced by UGS, and the activity was attenuated after removal of vascular endothelium or by blockade of endothelium-derived relaxing factors, such as NO and EDHF. CONCLUSIONS: The FGS extract may be a great source of natural polyphenol products with potent antioxidant effects and endothelium-dependent vasodilatory actions involving NO and EDHF pathways.
Assuntos
Antioxidantes/farmacologia , Frutas/química , Fenóis/farmacologia , Epiderme Vegetal/química , Extratos Vegetais/farmacologia , Vasodilatadores/farmacologia , Vitis/química , Animais , Antioxidantes/análise , Artérias/efeitos dos fármacos , Artérias/fisiologia , Compostos de Bifenilo/metabolismo , Brasil , Cromatografia Líquida de Alta Pressão , Fermentação , Fenóis/análise , Picratos/metabolismo , Ratos , Espécies Reativas de Oxigênio/metabolismo , Vasodilatadores/análiseRESUMO
Background: Chronic degenerative mitral valve disease (CDMVD) continues to be the most common cause of heart failure (HF) in small breed dogs. Pimobendan (PIMO) is a mixed action drug with inotropic and vasodilator properties and is widely used to treat heart disease in dogs. Therefore, PIMO increases cardiac output, reduces both preload and afterload and increases myocardial contractility without increasing energy consumption and myocardial oxygen. Digoxin (DIG) is a cardiac glycoside acting through inhibition of the sarcolemmal Na+/K+ ATPase pump, hence increasing intracellular calcium. It exerts beneficial effects on left ventricular function, symptoms and exercise tolerance. The purpose of this prospective, randomized, double blind clinical trial was to evaluate the clinical response and QoLQ in heart failure (HF) dogs treated with digoxin or pimobendan in addition to conventional therapy (furosemide and benazepril).Materials, Methods & Results: Inclusion criteria: dogs in class III or stabilized class IV (NYHA). Exclusion criteria: use of positive inotrope and antiarrhythmic, presence of atrial fibrillation, renal or hepatic disease or neoplasia. Thirty three dogs were included and randomly assigned to DIG (n = 11), PIMO (n = 14) and placebo (PL) (n = 8) and followed up weekly. Data was evaluated for days zero, 7, 14 and 28. Increasing score was assigned to...
Assuntos
Animais , Cães , Cardiotônicos/administração & dosagem , Digoxina/administração & dosagem , Insuficiência Cardíaca/terapia , Insuficiência Cardíaca/veterinária , Valva Mitral/patologia , Furosemida , Inibidores da Enzima Conversora de Angiotensina , Vasodilatadores/administração & dosagem , Vasodilatadores/análiseRESUMO
Background: Chronic degenerative mitral valve disease (CDMVD) continues to be the most common cause of heart failure (HF) in small breed dogs. Pimobendan (PIMO) is a mixed action drug with inotropic and vasodilator properties and is widely used to treat heart disease in dogs. Therefore, PIMO increases cardiac output, reduces both preload and afterload and increases myocardial contractility without increasing energy consumption and myocardial oxygen. Digoxin (DIG) is a cardiac glycoside acting through inhibition of the sarcolemmal Na+/K+ ATPase pump, hence increasing intracellular calcium. It exerts beneficial effects on left ventricular function, symptoms and exercise tolerance. The purpose of this prospective, randomized, double blind clinical trial was to evaluate the clinical response and QoLQ in heart failure (HF) dogs treated with digoxin or pimobendan in addition to conventional therapy (furosemide and benazepril).Materials, Methods & Results: Inclusion criteria: dogs in class III or stabilized class IV (NYHA). Exclusion criteria: use of positive inotrope and antiarrhythmic, presence of atrial fibrillation, renal or hepatic disease or neoplasia. Thirty three dogs were included and randomly assigned to DIG (n = 11), PIMO (n = 14) and placebo (PL) (n = 8) and followed up weekly. Data was evaluated for days zero, 7, 14 and 28. Increasing score was assigned to...(AU)
Assuntos
Animais , Cães , Digoxina/administração & dosagem , Insuficiência Cardíaca/terapia , Insuficiência Cardíaca/veterinária , Valva Mitral/patologia , Cardiotônicos/administração & dosagem , Vasodilatadores/administração & dosagem , Vasodilatadores/análise , Inibidores da Enzima Conversora de Angiotensina , FurosemidaRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Artemisia copa Phil. (Asteraceae) is a medicinal plant commonly used in traditional medicine in Argentina. AIM OF THE STUDY: The vasorelaxant and hypotensive activities of the aqueous extract of Artemisia copa have been investigated. MATERIALS AND METHODS: The in vitro effect of the extract and isolated compounds from Artemisia copa was investigated using isolated rat aortic rings. The acute effect caused by the intravenous (i.v.) infusion (0.1-300mg/kg) on blood pressure and heart rate was evaluated in spontaneous hypertensive rats. In addition, a phytochemical analysis of the extract was performed by HPLC. RESULTS: Artemisia copa had a relaxant effect in endothelium-intact aortic rings that had been pre-contracted with 10(-7)M phenylephrine (Emax=96.7±1.3%, EC50=1.1mg/ml), 10(-5)M 5-hydroxytriptamine (Emax=96.7±3.5%, EC50=1.5mg/ml) and 80mM KCl (Emax=97.9± 4.4%, EC50=1.6mg/ml). In denuded aortic rings contracted by phenylephrine, a similar pattern was observed (Emax=92.7±6.5%, EC50=1.8mg/ml). l-NAME, indomethacin, tetraethylammonium and glibenclamide were not able to block the relaxation induced by the extract. Nevertheless, the pre-treatment with Artemisia copa attenuated the CaCl2-induced contraction in a concentration-dependent manner (Emax: 86% of inhibition for 3mg/ml and 52% de-inhibition for 1mg/ml). This pre-treatment also induced a significant attenuation of the norepinephrine-induced contraction in a concentration-dependent manner (Emax: 72.7% of inhibition for 3mg/ml and 27% de inhibition for 1mg/ml) in a Ca(2+) free medium. Upon analyzing the composition of the extract, the presence of p-coumaric acid, isovitexin, luteolin and chrysoeriol were found. Luteolin (CE50: 1.5µg/ml), chrysoeriol (CE50: 13.2µg/ml) and p-coumaric acid (CE50: 95.2µg/ml), isolated from the aqueous extract, caused dilatation of thoracic aortic rings pre-contracted with phenylephrine. Artemisia copa administered i.v. also induced a decrease in the mean arterial pressure but did not affect the heart rate in hypertensive rats. CONCLUSIONS: The aqueous extract of Artemisia copa proved to have vasorelaxing and hypotensive effects through the inhibition of Ca(2+) influx via membranous calcium channels and intracellular stores. The presence of luteolin, chrysoeriol and p-coumaric acid found in this plant could be involved in this effect.
Assuntos
Anti-Hipertensivos/uso terapêutico , Artemisia , Extratos Vegetais/uso terapêutico , Vasodilatadores/uso terapêutico , Animais , Anti-Hipertensivos/análise , Anti-Hipertensivos/farmacologia , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/fisiologia , Argentina , Pressão Sanguínea/efeitos dos fármacos , Hipertensão/tratamento farmacológico , Hipertensão/fisiopatologia , Técnicas In Vitro , Masculino , Medicina Tradicional , Fitoterapia , Extratos Vegetais/análise , Extratos Vegetais/farmacologia , Ratos , Ratos Endogâmicos SHR , Ratos Sprague-Dawley , Vasodilatadores/análise , Vasodilatadores/farmacologiaRESUMO
A lectin from seeds of Dioclea lasiocarpa (DLL) was purified in a single step by affinity chromatography in a Sephadex G-50 column. DLL haemagglutinated rabbit erythrocytes showing stability even after 1 h of exposure to a different pH values (optimal between pH 6.0 and 8.0) but was inhibited after incubation with D-mannose and D-glucose. The pure protein possessed a molecular weight of 25 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and 25,410Da by mass spectrometry. The results analyzed by the software SELCON 3 indicate that ß-sheet secondary structures are predominant in DLL (approximately 40.2% antiparallel ß-sheet, 4.6% parallel ß-sheet, 7.2% α-helices, 17.3% turns, and 28.7% unordered structures). Mechanical activity of isolated aorta from rat measured by cumulative concentration curves of DLL, performed at the contraction plateau induced by phenylephrine in either endothelium-intact or denuded aorta. DLL (IC(50) = 34.12 ± 3.46 µg/ml) relaxed precontracted endothelized aortic rings by 34.61 ± 9.06%, 55.19 ± 11.9%, and 81.33 ± 14.35%, respectively, at 10 µg/ml (initial concentration), 30 µg/ml, and 100 µg/ml (maximum effect). All effects occurred via interaction with lectin domains and participation of nitric oxide.
Assuntos
Dioclea/química , Lectinas de Plantas/isolamento & purificação , Lectinas de Plantas/farmacologia , Sementes/química , Vasodilatadores , Animais , Aorta/efeitos dos fármacos , Aorta/patologia , Aorta/fisiologia , Células Cultivadas , Estabilidade de Medicamentos , Eritrócitos/efeitos dos fármacos , Eritrócitos/fisiologia , Técnicas de Cultura de Órgãos , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Lectinas de Plantas/análise , Lectinas de Plantas/química , Coelhos , Ratos , Ratos Wistar , Vasodilatação/efeitos dos fármacos , Vasodilatadores/análise , Vasodilatadores/química , Vasodilatadores/isolamento & purificação , Vasodilatadores/farmacologiaRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: To optimize the obtention of tilianin, an antihypertensive flavonoid isolated from Agastache mexicana (Lamiaceae), a medicinal plant used in Mexico for the treatment of hypertension. Also, a validated HPLC method to quantify tilianin from different extracts, obtained by several extraction methods, was developed. MATERIALS AND METHODS: The aerial parts of Agastache mexicana were dried at different temperatures (22, 40, 50, 90, 100 and 180°C) and the dry material was extracted with methanol by maceration to compare the content of the active constituent tilianin in the samples. Furthermore, EtOH:H(2)O (7:3), infusion and decoction extracts were prepared from air-dried samples at room temperature to compare the content and composition of the different extraction methods. Moreover, an ex vivo vasorelaxant test on endothelium-intact aortic rat rings was conducted, in order to correlate the presence of tilianin with the activity of each extract. RESULTS: Higher concentration and amounts of tilianin were determined from chromatograms in the obtained methanolic extracts from plant material dried at 90, 50, 40 and 22°C, followed by 100°C; however, lower concentrations were observed in dried at 180°C and EtOH:H(2)O (7:3). It is worth to notice that methanolic extracts with higher amount of tilianin were the most potent vasorelaxant extracts, even though these extracts were less potent than carbachol, a positive control used. Finally, decoction, infusion and EtOH:H(2)O (7:3) extracts did not show any vasorelaxant effect. CONCLUSION: Results suggest that extracts with higher concentration of tilianin possess the best vasorelaxant activity, which allowed us to have a HPLC method for future quality control for this medicinal plant.