Nguelefack T B, Dimo T, Mbuyo E P Nguelefack, Tan P V, Rakotonirina S V, Kamanyi A
Department of Animal Biology, Faculty of Sciences, P.O. Box 67, University of Dschang, Cameroon.
Phytother Res. 2005 Mar;19(3):207-10. doi: 10.1002/ptr.1646.
The long-lasting antihypertensive effect of a neutral extract of Bidens pilosa has been suggested to be due to vasodilation. The present work was undertaken to assess this hypothesis. The vasorelaxant effect of a neutral extract (NBp) of the leaves of B. pilosa was evaluated in vitro on isolated rat aorta contracted with KCl or norepinephrine. NBp induced a concentration-dependent vasorelaxation of the rat aorta precontracted with KCl (60 mM) by 25%-105% at the respective concentrations of 0.25-1.5 mg/mL. The maximal concentration of 1.5 mg/mL provoked 88% relaxation of norepinephrine-induced contractions. There were no significant differences between the effects of the extract on the aorta strips with or without endothelium. In the presence of indomethacin or pyrilamine maleate, the relaxant response induced by the plant extract was significantly inhibited at the lower concentrations. The plant extract was able to reduce the aorta resting tone, inhibit the KCl-induced contractions (90% at 1.5 mg/mL) and the CaCl2-induced contractions by 95% at a concentration of 0.75 mg/mL. These results demonstrate the vasodilating properties of the neutral extract of Bidens pilosa and indicate that it may act as a calcium antagonist.
三叶鬼针草中性提取物的持久降压作用被认为是由于血管舒张。开展本研究以评估这一假说。在体外对用氯化钾或去甲肾上腺素预收缩的离体大鼠主动脉评估三叶鬼针草叶中性提取物（NBp）的血管舒张作用。NBp在0.25 - 1.5 mg/mL的相应浓度下，使用60 mM氯化钾预收缩的大鼠主动脉产生25% - 105%的浓度依赖性血管舒张。1.5 mg/mL的最大浓度使去甲肾上腺素诱导的收缩产生88%的舒张。提取物对有或无内皮的主动脉条的作用之间无显著差异。在吲哚美辛或马来酸氯苯那敏存在的情况下，植物提取物诱导的舒张反应在较低浓度时受到显著抑制。植物提取物能够降低主动脉静息张力，抑制氯化钾诱导的收缩（1.5 mg/mL时为90%）以及在0.75 mg/mL浓度下抑制氯化钙诱导的收缩达95%。这些结果证明了三叶鬼针草中性提取物的血管舒张特性，并表明它可能作为一种钙拮抗剂起作用。
