Antihypertensive and antioxidant effects of the Graptopetalum paraguayense E. Walther extract in spontaneously hypertensive rats

BACKGROUND: Our previous in vitro study showed that 50% ethanolic extract of Graptopetalum paraguayense E. Walther (GE50) exhibited an inhibitory effect on angiotensin I converting enzyme (ACE). This study was aimed at evaluating the antihypertensive and antioxidant effects of GE50 extract on spontaneously hypertensive rats (SHR). RESULTS: Daily oral administration of GE50 extract (2.5 g kg⁻¹ body weight) for 4 weeks exhibited a significant decrease in blood pressure as well as ACE activity of tested tissues in SHR rats, while no significant change was found in normotensive Wistar Kyoto rats (WKY). For SHR, GE50 extract increased the total antioxidant status in the plasma and decreased malondialdehyde levels in all tested tissues. Furthermore, GE50 extract increased α‐tocopherol and glutathione levels in brain tissue, glutathione peroxidase and catalase activities in heart, as well as catalase activity in liver tissue. In WKY rats, GE50 extract only increased ascorbic acid level in liver tissue. CONCLUSION: The present study demonstrated that GE50 might serve as an antioxidant and an ACE inhibitor in convalescence from hypertension in rats. Copyright © 2009 Society of Chemical Industry     

芹菜汁降压和舒张血管作用的研究

目的:观察芹菜汁对肾血管性高血压大鼠(RHR)血压的影响,对离体血管环张力的影响及其机制。方法:①建立RHR模型,实验组分别给予芹菜约60.3±18.1g/kgbw和123.5±28.1g/kgbw,共6w,每周测量血压、心率和体重一次。②在离体血管环标本,观察芹菜汁对血管张力的影响及其对CaCl2、KCl和NE(去甲肾上腺素)量效曲线的影响。③观察在不同温度(37、70、100℃)处理后的芹菜汁对血管张力的影响。结果:①芹菜高、低剂量组血压下降与阴性对照组相比均有统计学意义(p<0.05)。②芹菜汁可引起NE(3.0×10-7mol/L)预收缩血管张力下降。芹菜汁可使CaCl2引起的血管张力下降,量效曲线明显下移(p<0.05)。同时芹菜汁使NE引起的血管张力下降,量效曲线明显下移(p<0.05),而对KCl引起的血管张力没有显著影响(p>0.05)。③芹菜汁经70℃、20min处理后与37℃下相比较舒张血管程度没有显著差异(p>0.05),而芹菜汁经100℃、3min处理后与37℃下相比较舒张血管程度明显减弱(p<0.05)。结论:芹菜汁可降低RHR大鼠的血压,同时也能有效舒张血管,其舒张血管机制可能是通过抑制血管平滑肌的受体依赖性钙通道实现的。芹菜中的降压成分有一定耐热性,70℃、20min不影响其舒张血管活性,100℃、3min其舒张血管活性明显减弱。     

ACE-inhibitory and antihypertensive properties of a bovine casein hydrolysate

The aim of this study was to investigate the potential angiotensin converting enzyme (ACE)-inhibitory activity and the antihypertensive effect, after a single oral administration, of a pepsin hydrolysed bovine casein (HBC) and a fraction with molecular mass lower than 3000 Da (HBC < 3000). ACE-inhibitory activity was measured by spectrophotometric assay. These products were orally administered by gastric intubation. The systolic (SBP) and the diastolic blood pressure (DBP) were measured in spontaneously hypertensive rats by the tail cuff method before administration and also 2, 4, 6, 8, and 24 h post-administration. HBC showed a potent ACE-inhibitory activity. This activity was 10 times higher in HBC < 3000. HBC and HBC < 3000 decreased the arterial blood pressure of the rats. The decrease in the SBP observed for HBC (400 mg/kg) or HBC < 3000 (200 mg/kg) was less pronounced than that caused by 50 mg/kg of captopril (antihypertensive positive control). However, the maximal decreases in DBP caused by HBC or HBC < 3000 were as high as the maximum decrease observed for captopril. The antihypertensive effect of these products was transient and reverted 24 h after the administration. HBC and HBC < 3000 exert antihypertensive effect caused by small peptides with ACE-inhibitory activity.