Mechanism of endothelium-dependent vasodilation induced by a proanthocyanidin-rich fraction from Ouratea semiserrata.
The vasodilator effects of Ouratea semiserrata stem hydroethanolic extract (OSE) and its ethyl acetate fraction (OSR) were evaluated in endothelium-intact aortic rings. OSR produced a more potent vasodilatation (IC(50) = 3.5 +/- 0.8 microg/ml) than OSE (IC(50) > 30 microg/ml). OSR also presented a higher content of total proanthocyanidins (21.8 +/- 1.5 %) in comparison to OSE (6.5 +/- 0.4 %), suggesting that compounds of this class play a role in the vasorelaxing activity. The vasodilatation mechanism of OSR was further investigated. In endothelium-intact aortic rings, its vasorelaxing effect was completely abolished by L-NAME (300 microM), a nitric oxide (NO) synthase inhibitor, but not by a muscarinic antagonist (atropine, 1 microM) nor by a cyclo-oxygenase inhibitor (indomethacin, 10 microM). The OSR vasodilator effect was completely abolished in endothelium-denuded vessels. Furthermore, OSR did not change the vasodilatation produced by SIN-1, an NO donor, in endothelium-denuded vessels. These findings led us to conclude that OSR, a proanthocyanidin rich fraction of O. semiserrata, induces vasodilatation by a mechanism dependent on endothelium-derived factors, likely NO.
Côrtes
Steyner F
SF
Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Valadares
Ydia M
YM
de Oliveira
Alaíde Braga
AB
Lemos
Virgínia S
VS
Barbosa
Marco P T
MP
Braga
Fernão Castro
FC
D000085:Acetates / Q000494:pharmacology; D000818:Animals; D000872:Anthocyanins / Q000494:pharmacology*; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D001938:Brazil; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D007213:Indomethacin / Q000494:pharmacology; D019684:Magnoliopsida; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018547:Plant Stems / Q000737:chemistry; D044945:Proanthocyanidins; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D000085:Acetates; D000872:Anthocyanins; D010936:Plant Extracts; D044945:Proanthocyanidins; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C013221:proanthocyanidin; C007650:ethyl acetate; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin