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The pharmacological mechanism of angiotensin-converting enzyme inhibition by green tea, Rooibos and enalaprilat - a study on enzyme kinetics.

Authors
  • Persson, Ingrid A-L
Type
Published Article
Journal
Phytotherapy Research
Publisher
Wiley (John Wiley & Sons)
Publication Date
Apr 01, 2012
Volume
26
Issue
4
Pages
517–521
Identifiers
DOI: 10.1002/ptr.3588
PMID: 22095883
Source
Medline
License
Unknown

Abstract

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.

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