Wong I Y, Huang Y, He Z D, Lau C W, Chen Z Y
Department of Biochemistry, Chinese University of Hong Kong, Hong Kong, China.
Planta Med. 2001 Jun;67(4):317-21. doi: 10.1055/s-2001-14324.
The present study describes the effects of an extract obtained from the leaves of Ligstrum purpurascens and acteoside purified from the extract on the contractile response to various agonists in rat isolated aortic rings. L. purpurascens extract relaxed 9,11-dideoxy-11 alpha,9 alpha-epoxymethanoprostaglandin F2 alpha (U46619)-preconstricted rings in a concentration-dependent manner (IC50: 0.14 +/- 0.01 mg/ml with endothelium and 0.16 +/- 0.01 mg/ml without endothelium). The extract also reduced contraction induced by 35 mM K+ or by 1 microM phorbol 12,13-diacetate (PDA) in endothelium-intact rings. The extract (0.1-0.3 mg/ml) reduced the concentration-response to U46619 in normal Krebs solution or to CaCl2 in 35 mM K(+)-containing solution. Acteoside accounts for 2.05% of total L. purpurascens extract in weight. Acteoside induced relaxation of rings preconstricted by U46619 (IC50: 0.22 +/- 0.01 mg/ml) but it caused an increase in 35 mM K(+)-induced tone. Removal of endothelium enhanced the relaxing effect of acteoside. Besides, pretreatment with acteoside inhibited endothelium/nitric oxide-mediated relaxation induced by acetylcholine. These results indicate that acteoside is unlikely the major ingredient responsible for the vasodilator effect of L. purpurascens extract. The extract relaxed the preconstricted aortic rings probably through multiple mechanisms by acting on smooth muscle cells. The inhibitory effect on endothelial nitric oxide-mediated relaxation suggests that acteoside could also act on the endothelial cells to reduce nitric oxide release.
本研究描述了从紫丁香叶中提取的提取物以及从该提取物中纯化得到的毛蕊花糖苷对大鼠离体主动脉环对各种激动剂收缩反应的影响。紫丁香提取物以浓度依赖性方式使9,11-二脱氧-11α,9α-环氧甲烯前列环素F2α（U46619）预收缩的血管环舒张（IC50：有内皮时为0.14±0.01mg/ml，无内皮时为0.16±0.01mg/ml）。该提取物还可减弱内皮完整的血管环中由35mM K⁺或1μM佛波醇12,13-二乙酸酯（PDA）诱导的收缩。提取物（0.1 - 0.3mg/ml）可降低正常Krebs溶液中对U46619或含35mM K⁺溶液中对CaCl₂的浓度-反应。毛蕊花糖苷占紫丁香提取物总重量的2.05%。毛蕊花糖苷可使由U46619预收缩的血管环舒张（IC50：0.22±0.01mg/ml），但会使35mM K⁺诱导的张力增加。去除内皮可增强毛蕊花糖苷的舒张作用。此外，用毛蕊花糖苷预处理可抑制乙酰胆碱诱导的内皮/一氧化氮介导的舒张。这些结果表明，毛蕊花糖苷不太可能是紫丁香提取物血管舒张作用的主要成分。该提取物可能通过多种机制作用于平滑肌细胞使预收缩的主动脉环舒张。对内皮一氧化氮介导的舒张的抑制作用表明，毛蕊花糖苷也可作用于内皮细胞以减少一氧化氮释放。
