[Vasorelaxation effects of homoisoflavonoids from Caesalpinia sappan in rat thoracic aortic rings].
OBJECTIVE
To identify and elucidate the vasorelaxant activity of homoisoflavonoids, the main chemical components from Lignum Sappan (the stems of Caesalpinia sappan), in isolated rat thoracic aortic rings pre-contracted with phenylephrine (PE, 1 micromol x L(-1)) and KCl (60 mmol x L(-1)).


METHODS
The tension of rat thoracic aorta rings was used to evaluated the vasorelaxant activities of four homoisoflavonoids, brazlin (1), (E)-3-(3,4-dihydroxybenzylidene)-7-hydroxychroman-4-one (2), sappanone B (3), 3-deoxysappanone B (4).


RESULTS
Cumulative addition of homoisoflavonoids (2, 3 and 4) (50-1000 micromol x L(-1)) exhibited an acute relaxation either in endothelium-intact or endothelium-denuded rings in a concentration-dependent manner. However, this relaxation was significantly inhibited in endothelium-denuded condition and in the presence of endothelial nitric oxide synthase (eNOS) inhibitor, N(W)-nitro-L-arginine methyl ester (L-NNA, 100 micromol x L(-1)), and a soluble guanylate cylcase (sGC) inhibitor, methylene blue (MB, 10 micromol x L(-1)) when addition of variation homoisoflavonoids brazlin (1) (50-1000 micromol x L(-1)).


CONCLUSIONS
These results indicate that normo-homoisoflavonoids (2, 3 and 4) from Caesalpinia sappan mediates endothelium-independent vasodilator action in rat thoracic aortic rings, while the variation homoisoflavonoids brazlin elicits endothelium-dependent relaxation might via nitric oxide (NO)-cGMP pathway. This research could explain the pharmacological activities of homoisoflavonoids to a certain degree.
He
Wenjun
W
Department of Pharmacology, School of Pharmaceutical Sciences, Nanjing University of Traditional Chinese Medicine, Nanjing 210029, China.
Fang
Taihui
T
Zhang
Ke
K
Tu
Pengfei
P
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D029911:Caesalpinia / Q000737:chemistry*; D004727:Endothelium / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors; D000071756:Soluble Guanylyl Cyclase; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000737:chemistry* / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D005419:Flavonoids; D018160:Receptors, Cytoplasmic and Nuclear; D014665:Vasodilator Agents; C000601539:deoxysappanone B; D010656:Phenylephrine; D011189:Potassium Chloride; D052250:Nitric Oxide Synthase Type III; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D019331:NG-Nitroarginine Methyl Ester