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dc.creatorDiniz, Thiago Frederico-
dc.creatorPereira, Aline Carvalho-
dc.creatorCapettini, Luciano-
dc.creatorSantos, Marcelo Rodrigues dos-
dc.creatorNagem, Tanus Jorge-
dc.creatorLemos, Virgínia Soares-
dc.creatorCôrtes, Steyner de França-
dc.date.accessioned2016-09-01T19:13:40Z-
dc.date.available2016-09-01T19:13:40Z-
dc.date.issued2013-
dc.identifier.citationDINIZ, T. F. et al. Mechanism of the vasodilator effect of mono-oxygenated xanthones: a structure-activity relationship study. Planta Medica, Stuttgart, v. 79, n. 16, p. 1495-1500, 2013.pt_BR
dc.identifier.urihttps://www.thieme-connect.com/products/ejournals/pdf/10.1055/s-0033-1350803.pdfpt_BR
dc.identifier.urihttp://repositorio.ufla.br/jspui/handle/1/11722-
dc.description.abstractThe present study characterized the mechanisms involved in the vasodilator effect of two mono-oxygenated xanthones, 4-hydroxyxanthone and 4-methoxyxanthone. 9-Xanthenone, the base structure of xanthones, was used for comparison. 4-Hydroxyxanthone and 9-xanthenone induced a concentration-dependent and endothelium-independent vasodilator effect in arteries precontracted with phenylephrine (0.1 µmol · L−1) or KCl (50 mmol · L−1). 4-Methoxyxanthone induced a concentration-dependent vasodilator effect in arteries precontracted with phenylephrine, which was partially endothelium-dependent, and involved production of nitric oxide. In endothelium-denuded arteries precontracted with KCl, the vasodilator effect of 4-methoxyxanthone was abolished. The vasodilator effect of 4-hydroxyxanthone (96.22 ± 2.10 %) and 4-methoxyxanthone (96.57 ± 12.40 %) was significantly higher than observed with 9-xanthenone (53.63 ± 8.31 %). The presence of an oxygenated radical in position 4 made 4-hydroxyxanthone (pIC50 = 4.45 ± 0.07) and 4-methoxyxanthone (pIC50 = 5.04 ± 0.09) more potent as a vasodilator than 9-xanthenone (pIC50 = 3.92 ± 0.16). In addition, 4-methoxyxanthone was more potent than the other two xanthones. Ca2+ transients in vascular smooth muscle cells elicited by high K+ were abolished by 4-hydroxyxanthone and 9-xanthenone. The endothelium-independent effect of 4-methoxyxanthone was abolished by inhibition of K+ channels by tetraethylammonium. The current work shows that an oxygenated group in position 4 is essential to achieve Emax and to increase the potency of xanthones as vasodilators. Substitution of an OH by OCH3 in position 4 increases the potency of the vasodilator effect and changes the underling mechanism of action from the blockade of L-type calcium channels to an increase in NO production and activation of K+ channels.pt_BR
dc.languageen_USpt_BR
dc.publisherThieme Medical Publisherspt_BR
dc.rightsrestrictAccesspt_BR
dc.sourcePlanta Medicapt_BR
dc.subjectXanthonespt_BR
dc.subject4-hydroxyxanthonept_BR
dc.subject4-methoxyxanthonept_BR
dc.subjectVasodilationpt_BR
dc.subjectCa2+ channelspt_BR
dc.subjectNitric oxidept_BR
dc.subjectK+ channelspt_BR
dc.titleMechanism of the vasodilator effect of mono-oxygenated xanthones: a structure-activity relationship studypt_BR
dc.typeArtigopt_BR
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