Kim S H, Kang K W, Kim K W, Kim N D
College of Pharmacy, Seoul National University, Korea.
Life Sci. 2000;67(2):121-31. doi: 10.1016/s0024-3205(00)00608-1.
The extract of Crataegus, a mixture of flavonoids and procyanidins extracted from hawthorn, Crataegus oxyacantha, L. and C. monogyna Jacq., relaxed vascular tone or increased production of cyclic GMP in the rat aorta, but flavonoid components of Crataegus extract, hyperoside, rutin and vitexin, did not affect the vascular tone. The aim of the present study was to characterize the endothelium-dependent relaxation elicited by procyanidins fractionated from Crataegus extract in isolated rat aorta. Procyanidins caused endothelium-dependent relaxation which was associated with the production of cyclic GMP. Both responses to these procyanidins were inhibited by methylene blue or N(G)-nitro-L-arginine, but not by indomethacin. Relaxation in response to procyanidins was not affected by atropine, diphenhydramine, [D-Pro2,D-Trp7,9]substance P, propranolol, nifedipine, verapamil and glibenclamide, but were markedly reduced by tetraethylammonium. These findings showed that procyanidins in Crataegus extract may be responsible for the endothelium-dependent nitric oxide-mediated relaxation in isolated rat aorta, possibly via activation of tetraethylammonium-sensitive K+ channels.
山楂提取物是从山楂（山楂属植物山楂和山里红）中提取的黄酮类化合物和原花青素的混合物，可使大鼠主动脉血管张力松弛或增加环鸟苷酸（cGMP）的生成，但山楂提取物中的黄酮类成分，如金丝桃苷、芦丁和牡荆素，对血管张力没有影响。本研究的目的是对从山楂提取物中分离出的原花青素在离体大鼠主动脉中引起的内皮依赖性舒张进行表征。原花青素引起内皮依赖性舒张，这与环鸟苷酸的生成有关。对这些原花青素的两种反应均被亚甲蓝或N（G）-硝基-L-精氨酸抑制，但不受吲哚美辛抑制。对原花青素的舒张反应不受阿托品、苯海拉明、[D-脯氨酸2，D-色氨酸7，9]P物质、普萘洛尔、硝苯地平、维拉帕米和格列本脲的影响，但被四乙铵显著降低。这些发现表明，山楂提取物中的原花青素可能是离体大鼠主动脉中内皮依赖性一氧化氮介导舒张的原因，可能是通过激活四乙铵敏感的钾通道。
