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Tea flavanols inhibit angiotensin-converting enzyme activity and increase nitric oxide production in human endothelial cells
Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Pharmacology.
Linköping University, Department of Medicine and Care. Linköping University, Faculty of Health Sciences.
Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Pharmacology.
Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Pharmacology.
2006 (English)In: Journal of Pharmacy and Pharmacology (JPP), ISSN 0022-3573, E-ISSN 2042-7158, Vol. 58, no 8, 1139-1144 p.Article in journal (Refereed) Published
Abstract [en]

A diversity of pharmacological effects on the cardiovascular system have been reported for Camellia sinensis: antioxidative, antiproliferative and anti-angiogenic activity, and nitric oxide synthase activation. The purpose of this study was to investigate if the connection between tea and angiotensin-converting enzyme (ACE) and nitric oxide (NO) might be an explanation of the pharmacological effects of tea on the cardiovascular system. Cultured endothelial cells from human umbilical veins (HUVEC) were incubated with extracts of Japanese Sencha (green tea), Indian Assam Broken Orange Pekoe (black tea) and Rooibos tea, respectively. The main flavanols and purine alkaloids in green and black tea were examined for their effects on ACE and NO. After incubation with green tea, black tea and Rooibos tea for 10 min, a significant and dose-dependent inhibition of ACE activity in HUVEC was seen with the green tea and the black tea. No significant effect on ACE was seen with the Rooibos tea. After 10-min incubation with (-)-epicatechin, (-)- epigallocatechin, (-)-epicatechingallate and (-)-epigallocatechingallate, a dose-dependent inhibition of ACE activity in HUVEC was seen for all four tea catechins. After 24-h incubation, a significantly increased dose-dependent effect on NO production in HUVEC was seen for the green tea, the black tea and the Rooibos tea. After 24-h incubation with (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechingallate and (-)-epigallocatechingallate, a dose-dependent increased NO production in HUVEC was seen. In conclusion, tea extracts from C. sinensis may have the potential to prevent and protect against cardiovascular disease. © 2006 The Authors.

Place, publisher, year, edition, pages
2006. Vol. 58, no 8, 1139-1144 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-34910DOI: 10.1211/jpp.58.8.0016Local ID: 24032OAI: oai:DiVA.org:liu-34910DiVA: diva2:255758
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Plant-Derived Substances and Cardiovascular Diseases: Effects of Flavonoids, Terpenes and Sterols on Angiotensin-Converting Enzyme and Nitric Oxide
Open this publication in new window or tab >>Plant-Derived Substances and Cardiovascular Diseases: Effects of Flavonoids, Terpenes and Sterols on Angiotensin-Converting Enzyme and Nitric Oxide
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Diet has for many years been known to play a key role in the development of chronic diseases. There are clear associations between consumption of vegetables, fruits and berries, and risk of cardiovascular diseases, the number one cause of death in the world. To maintain homeostasis of the vascular wall the balance between angiotensin II, nitric oxide and reactive oxygen species is of great importance in order to affect the development of cardiovascular diseases. Angiotensin II, a potent vasoconstrictor causing cell growth and nitric oxide, a signalling molecule influencing the vascular system as a vasodilatator, inhibiting cell proliferation and reactive oxygen species, are linked together in the renin-angiotensin aldosteron system. Angiotensin-converting enzyme will as a key enzyme in the reninangiotensin aldosteron system convert angiotensin I to form angiotensin II and nitric oxide is known to inhibit angiotensin-converting enzyme and act as a scavenger of reactive oxygen species. Plant-derived substances as flavonoids, tocopherols and carotenoids are shown to have beneficial effects on the cardiovascular system due to their antioxidative effects. The aims of this study were to investigate beverages, dietary products, herbal medicinal plants, α-tocopherol, β-carotene, sterols and lipidowering drugs on angiotensin-converting enzyme activity and nitric oxide concentrations. This was done to investigate if the sole mechanism of plant-derived substances is their antioxidative properties and to investigate if there is any connection between effect and biosynthesis/structure of plant substances. The tested infusions and extracts containing high amounts of flavonoids, the flavonoids and β-carotene significantly inhibited angiotensin-converting enzyme activity in vitro. The other substances tested did not affect, or in some cases significantly increased, angiotensin-converting enzyme activity. The infusions and extracts containing high amounts of flavonoids, the flavonoids andβ-carotene showed an increase on nitric oxide concentrations in vitro. Oral intake of a single dose of Rooibos tea significantly inhibited angiotensin-converting enzyme activity. A significant inhibition of angiotensin-converting enzyme activity was seen with the green tea for the angiotensin-converting enzyme genotypes II and ID. A significant inhibition of angiotensin-converting enzyme activity was also seen with the Rooibos tea for the angiotensin-converting enzyme genotype II.

Conclusion; flavonoids and β-carotene interact with the cardiovascular system in severalways, by reducing reactive oxygen species (as shown in several studies), increasing nitricoxide concentrations (as shown here and by others) and also by inhibiting angiotensinconvertingenzyme activity (as shown here). Infusions and extracts as tea containing highamounts of flavonoids function as angiotensin-converting enzyme inhibitors. Angiotensinconvertingenzyme contains two zink-dependent catalytic domains and angiotensinconvertingenzyme inhibitors are designed to bind to the Zn2+ at the active site. If theinhibitory mechanism of flavonoids on angiotensin-converting enzyme activity is due to theirability to bind to Zn2+ ions then it would be possible for the flavonoids to also inhibit otherzinc metallopeptidases, i.e. endothelin-converting enzyme, matrix metallopeptidases, neutralendopeptidase and maybe insulin-degrading enzyme, thereby exerting several additionalpositive effects on the cardiovascular system.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 127 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1097
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-45338 (URN)81632 (Local ID)978-91-7393-706-1 (ISBN)81632 (Archive number)81632 (OAI)
Public defence
2009-02-05, Linden, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 09:00 (Swedish)
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Note
2009Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2009-10-16Bibliographically approved

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Persson, IngridJosefsson, MartinPersson, KarinAndersson, Rolf

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