钾通道开放剂和前列环素在介导菊三七的血管舒张活性中起着至关重要的作用。
Potassium channel openers and prostacyclin play a crucial role in mediating the vasorelaxant activity of Gynura procumbens.
出版信息
BMC Complement Altern Med. 2013 Jul 23;13:188. doi: 10.1186/1472-6882-13-188.
BACKGROUND
Previous studies of Gynura procumbens (G. procumbens) have shown that partially purified fractions of the leaves are capable of lowering the blood pressure of rats by inhibiting angiotensin-converting enzymic activity and causing vasodilatation. The objectives of this study were therefore to further purify the active compounds that exhibited selective effects on blood vessels, determine the mechanism of actions, and to qualitatively analyse the putative compounds present.
METHODS
The butanolic fraction (BU) of the crude ethanolic extract was purified using column chromatography to obtain several sub-fractions of different polarities. The in vitro effects of BU and the sub-fractions on vascular tension were subsequently determined using isolated rat thoracic aortic rings. The most potent sub-fraction (F1) alone was then investigated for its mechanisms of the vasorelaxant activity. In another experiment, thin-layer chromatography was used to qualitatively analyse the active compounds found in F1.
RESULTS
The BU and the sub-fractions ranging from 10-7 to 10-2 g/ml significantly (p < 0.05) inhibited the sustained tonic contractions induced by phenylephrine and potassium chloride in a concentration-dependent manner with various degree of potency. The most potent sub-fraction (F1) antagonised the calcium-induced vasocontractions (1 x 10-4 - 1 x 10-2 M) in calcium-free with high concentration of potassium as well as in calcium- and potassium-free Krebs-Henseleit solutions. Contractions induced by noradrenaline and caffeine were not affected by F1. The vasorelaxing effect caused by F1 was significantly attenuated with preincubation of potassium channel blockers (glibenclamide and 4-aminopyridine) and prostacyclin inhibitor (indomethacin) while it was not affected by preincubation with tetraethylammonium, l-nitro-arginine methyl esther, propanolol, atropine, oxadiazolo quinoxalin one and methylene blue. The qualitative phytochemical analysis of F1 indicated the presence of flavonoids.
CONCLUSION
These results confirm previous findings that G. procumbens causes vasodilatory effects by blocking calcium channels. In addition, the present study further demonstrates that the vasodilatory effect of G. procumbens may also be due to the opening of potassium channels and the stimulation of prostacyclin production. The putative compounds are probably flavonoids in nature.
背景
先前对菊三七（Gynura procumbens）的研究表明，其叶片部分纯化的部分可通过抑制血管紧张素转换酶活性和引起血管扩张来降低大鼠的血压。因此，本研究的目的是进一步纯化对血管具有选择性作用的活性化合物，确定其作用机制，并对存在的假定化合物进行定性分析。
方法
使用柱层析法对粗乙醇提取物的丁醇部分（BU）进行纯化，以获得不同极性的几个亚组分。随后，使用分离的大鼠胸主动脉环测定 BU 和亚组分对血管张力的体外作用。然后单独研究最有效的亚组分（F1）对血管舒张活性的机制。在另一个实验中，使用薄层色谱法对 F1 中发现的活性化合物进行定性分析。
结果
BU 和 10-7 至 10-2 g/ml 的亚组分浓度依赖性地显著（p < 0.05）抑制由苯肾上腺素和氯化钾诱导的持续紧张性收缩，其抑制作用具有不同的效力。最有效的亚组分（F1）拮抗钙诱导的血管收缩（1 x 10-4 - 1 x 10-2 M），包括在高钾和无钙-无钾 Krebs-Henseleit 溶液中。F1 对去甲肾上腺素和咖啡因引起的收缩没有影响。F1 引起的血管舒张作用在预先孵育钾通道阻滞剂（格列本脲和 4-氨基吡啶）和前列腺素抑制剂（吲哚美辛）后显著减弱，而预先孵育四乙铵、l-硝基-精氨酸甲酯、丙醇、阿托品、恶二唑并喹喔啉和亚甲蓝对其没有影响。F1 的定性植物化学分析表明存在黄酮类化合物。
结论
这些结果证实了先前的发现，即菊三七通过阻断钙通道引起血管舒张作用。此外，本研究进一步表明，菊三七的血管舒张作用可能还归因于钾通道的开放和前列腺素的产生刺激。假定的化合物可能是天然的黄酮类化合物。
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