Department of Medical and Health Sciences, Division of Drug Research/Pharmacology, Faculty of Health Sciences, Linköping University, Sweden.
Phytother Res. 2012 Apr;26(4):517-21. doi: 10.1002/ptr.3588. Epub 2011 Sep 8.
Green tea (Camellia sinensis L.) and Rooibos (Aspalathus linearis Dahlg.) inhibit angiotensin-converting enzyme (ACE) in vitro and in vivo. The ACE inhibitor enalaprilat has been described previously as a competitive inhibitor and sometimes as a non-competitive inhibitor. The aim of this study was to investigate the pharmacological mechanism of ACE inhibition of green tea and Rooibos by enzyme kinetics, and to compare this with enalaprilat. A Michaelis-Menten kinetics and Lineweaver-Burk graph showed mean values of V(max) = 3.73 µM and K(m) = 0.71 µM for green tea, of V(max) = 6.76 µM and K(m) = 0.78 µM for Rooibos, of V(max) = 12.54 µM and K(m) = 2.77 µM for enalaprilat, and of V(max) = 51.33 µM and K(m) = 9.22 µM for the PBS control. Incubating serum with green tea or Rooibos saturated with zinc chloride did not change the inhibitory effect. Enalaprilat preincubated with zinc chloride showed a decrease in the inhibitory effect. In conclusion, green tea, Rooibos and enalaprilat seem to inhibit ACE activity using a mixed inhibitor mechanism.
绿茶（Camellia sinensis L.）和路易波士茶（Aspalathus linearis Dahlg.）在体外和体内均能抑制血管紧张素转换酶（ACE）。先前已有文献报道，依那普利拉是一种竞争性抑制剂，有时也被认为是非竞争性抑制剂。本研究旨在通过酶动力学研究绿茶和路易波士茶抑制 ACE 的药理机制，并与依那普利拉进行比较。米氏动力学和 Lineweaver-Burk 图显示，绿茶的 Vmax 值为 3.73 μM，Km 值为 0.71 μM；路易波士茶的 Vmax 值为 6.76 μM，Km 值为 0.78 μM；依那普利拉的 Vmax 值为 12.54 μM，Km 值为 2.77 μM；PBS 对照组的 Vmax 值为 51.33 μM，Km 值为 9.22 μM。用氯化锌饱和处理的血清孵育绿茶或路易波士茶不会改变抑制作用。用氯化锌预孵育的依那普利拉显示出抑制作用的降低。综上所述，绿茶、路易波士茶和依那普利拉似乎通过混合抑制剂机制抑制 ACE 活性。
