The comparison of the relaxant effects of two methoxylated flavones in rat aortic rings


Uydes-Dogan B. S. , Takir S. , ÖZDEMİR O. , Kolak U. , Topçu G. , Ulubelen A.

VASCULAR PHARMACOLOGY, vol.43, no.4, pp.220-226, 2005 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 4
  • Publication Date: 2005
  • Doi Number: 10.1016/j.vph.2005.07.002
  • Title of Journal : VASCULAR PHARMACOLOGY
  • Page Numbers: pp.220-226

Abstract

The vascular effect of salvigenin (6-hydroxyapigenin 6,7,4'-trimethyl other) (1), a natural flavone, was investigated in comparison with another flavone, 6-hydroxyluteolin 6,7,3', 4'-tetramethyl ether (2) in rat aotic rings. Cumulative addition of their increasing concentrations (10(-9)-10(-4)M) produced graded relaxations on rings precontracted with noradrenaline (10(-6) M) and KCl (40 mM). The maximal relaxations induced by flavones were similar, however, based on their pEC(50) values salvigenin displayed a higher potency than 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether. Endothelium removal markedly reduced the relaxations to salvigenin while the responses to 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether were partially affected. In addition, a significant decrease was observed in maximal responsiveness and sensitivity to flavones in the presence of L-NOARG, a NO synthase inhibitor. The cyclooxygenase inhibitor indomethacin significantly inhibited the relaxations to salvigenin, but not altered the responses to 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether. Our results provide evidence that salvigenin is an effective flavone in causing vasorelaxation which appears to be mediated by endothelium derived NO and prostacyclin. Whereas, the other flavone, 6-hydroxyluteolin 6,7,3',4'-tetramethyt ether induced relaxant responses are partially endothelium, presumably NO mediated. (c) 2005 Published by Elsevier Inc.