Programa de Pós-graduação em Ciências Farmacêuticas, Núcleo de Investigações Químico-Farmacêuticas (NIQFAR), Universidade do Vale do Itajaí - UNIVALI, Itajaí, Santa Catarina, Brazil.
Programa de Pós-graduação em Química, Universidade Federal de Santa Catarina (UFSC), Florianópolis-SC, Brazil.
J Ethnopharmacol. 2019 Oct 28;243:112118. doi: 10.1016/j.jep.2019.112118. Epub 2019 Jul 24.
Bauhinia forficata Link, commonly known as "cow's paw", is a native plant from South America. Its leaves are widely used in Brazilian folk medicine to treat diabetes and cardiovascular disorders. Although this species' biological potential has been extensively proven as an antidiabetic, anti-inflammatory and antioxidant agent, there is a lack of studies to evidence its action on the cardiovascular system.
This study was designed to investigate the vascular effects of B. forficata leaves preparations and its majority compound kaempferitrin, as well as its aglycone form kaempferol, in rat aortic rings of normotensive (NTR) and hypertensive (SHR) rats.
Aorta rings from NTR and SHR precontracted with phenylephrine were exposed to cumulative concentrations of B. forficata extract, fractions (1-50 μg/mL) and compounds (0.001-0.3 μg/mL). The mechanisms involved in the vasorelaxant effect of ethyl-acetate plus butanol fraction (EAButF) were also evaluated.
Although kaempferitrin is the most abundant compound found in both methanolic extract and EAButF, 24 minor phenolic compounds were identified in B. forficata leaves, including kaempferol. EAButF was the only with endothelium-dependent and independent vasorelaxant properties in both NTR and SHR. The incubation with L-NAME or ODQ completely blocked EAButF-induced vasorelaxation. On the other hand, the incubation with propranolol, atropine, indomethacin, glibenclamide or barium chloride did not change the vasorelaxant activity of EAButF (50 μg/mL). Nevertheless, the incubation with tetraethylammonium and 4-aminopyridine significantly influenced the EAButF activity. It was also shown that Ca influx or efflux is not related to EAButF vasorelaxation potential. Kaempferitrin and kaempferol were also able to relax the rat aortic rings in 34.70% and 40.54%, respectively.
This study shows, for the first time, the vasorelaxant effect of EAButF from B. forficata leaves, an effect that may be attributed to the modulation of vascular tone through nitric oxide/soluble guanylate cyclase pathway, and potassium channels. The bioactive kaempferitrin and kaempferol seem to be important for the effects observed with the fraction. Finally, preparations obtained from the leaves of B. forficata may be interesting candidates for new or complementary strategies regarding cardiovascular diseases.
凤凰木（Bauhinia forficata Link），俗称“牛蹄”，是一种原产于南美洲的植物。其叶子在巴西民间医学中被广泛用于治疗糖尿病和心血管疾病。尽管该物种的生物潜力已被广泛证明是一种抗糖尿病、抗炎和抗氧化剂，但缺乏其对心血管系统作用的研究证据。
本研究旨在研究凤凰木叶制剂及其主要化合物山柰酚-3-O-芸香糖苷（kaempferitrin）及其苷元形式山柰酚（kaempferol）对正常血压大鼠（NTR）和高血压大鼠（SHR）主动脉环的血管作用。
用苯肾上腺素预收缩 NTR 和 SHR 的主动脉环，然后暴露于凤凰木叶提取物、馏分（1-50μg/mL）和化合物（0.001-0.3μg/mL）的累积浓度下。还评估了乙酸乙酯-正丁醇部分（EAButF）舒张血管作用的机制。
尽管山柰酚-3-O-芸香糖苷是甲醇提取物和 EAButF 中含量最丰富的化合物，但在凤凰木叶中还鉴定出 24 种酚类化合物，包括山柰酚。EAButF 是唯一在 NTR 和 SHR 中具有内皮依赖性和非依赖性舒张血管作用的化合物。用 L-NAME 或 ODQ 孵育完全阻断了 EAButF 诱导的血管舒张。另一方面，用心得安、阿托品、吲哚美辛、格列本脲或氯化钡孵育不会改变 EAButF 的舒张血管活性（50μg/mL）。然而，用四乙铵和 4-氨基吡啶孵育显著影响 EAButF 的活性。还表明，Ca 内流或外流与 EAButF 的舒张血管潜力无关。山柰酚-3-O-芸香糖苷和山柰酚分别能使大鼠主动脉环舒张 34.70%和 40.54%。
本研究首次表明，凤凰木叶的 EAButF 具有舒张血管作用，这种作用可能归因于通过一氧化氮/可溶性鸟苷酸环化酶途径和钾通道调节血管张力。生物活性的山柰酚-3-O-芸香糖苷和山柰酚似乎对该馏分观察到的作用很重要。最后，从凤凰木叶中获得的制剂可能是针对心血管疾病的新策略或补充策略的有前途的候选物。
