Vasorelaxant Activity of Sappan Lignum Constituents and Extracts on Rat Aorta and Mesenteric Artery

We investigated the vasorelaxant activity of the methanolic extracts of Sappan Lignum (CSE) and its constituents, brazilin, sappanchalcone, and protosappanins A-E, on rat aorta and mesenteric artery. By comparing the vasorelaxant activity of CSE and brazilin on both blood vessels, we found that CSE contained active constituents other than brazilin. When added to brazilin, sappanchalcone and protosappanin D showed vasorelaxant activity on both blood vessels precontracted with phenylephrine. We clarified that the vasorelaxant activity of brazilin was endothelium-independent, while that of sappanchalcone was endothelium-dependent, on both blood vessels. On the other hand, the vasorelaxant activity of protosappanin D was independent of the endothelium of the aorta and dependent on the endothelium of the mesenteric artery. Experiments on sappanchalcone and protosappanin D using N-G-nitro-L-arginine and indomethacin revealed the involvement of nitric oxide and prostaglandin as endothelium-derived relaxation factors (EDRFs). The anti-oketsu effect of Sappan Lignum might be attributable to the interaction of those compounds. We could partly evaluate the anti-oketsu activity of Sappan Lignum using both the aorta and the mesenteric artery. Through this study, we showed the importance of comparing the effects on the aorta and the mesenteric artery as we found that natural compounds showed different mechanisms of action on the two blood vessels.