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Effects of green tea, black tea and rooibos on angiotensin-converting enzyme activity in healthy volunteers
Linköpings universitet, Institutionen för medicin och hälsa, Farmakologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Institutionen för medicin och hälsa, Farmakologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Institutionen för medicin och hälsa, Klinisk farmakologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Institutionen för medicin och hälsa, Farmakologi. Linköpings universitet, Hälsouniversitetet.
2009 (Engelska)Ingår i: in Planta Medica(ISSN 0032-0943), 2009, Vol. 75, nr 9, s. 1030-1030Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Tea has been reported to reduce cardiovascular mortality, but the mechanisms behind are largely unknown. The aim of this project was to investigate the effect of green tea (Japanese Sencha), black tea (Indian Assam B.O.P.) and Rooibos on angiotensin-converting enzyme and nitric oxide. Seventeen healthy volunteers received a single oral dose of either 400 ml green tea, black tea or Rooibos tea in a randomized three-phase cross over study. ACE activity and NO concentration were measured (at 0, 30, 60 and 180 minutes) in all phases. ACE activity was analysed with a commercial radioenzymatic assay. Nitrite was analysed as a marker of NO concentration. In addition ACE genotype was determined using a PCR method. Oral intake of a single dose of Rooibos significantly inhibited ACE activity, p<0.01 after 30 min and p<0.05 after 60 min. A significant inhibition of ACE activity was seen with green tea for the ACE genotype II (p<0.05), 30 minutes after intake of the tea and for the ACE genotype ID (p<0.05), 60 minutes after intake. A significant inhibition of ACE activity was also seen with Rooibos for the ACE genotype II (p<0.05), 60 minutes after intake. No significant effect on NO concentration was seen.

Ort, förlag, år, upplaga, sidor
2009. Vol. 75, nr 9, s. 1030-1030
Nyckelord [en]
Tea, angiotensin-converting enzyme, nitric oxide
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
URN: urn:nbn:se:liu:diva-20327OAI: oai:DiVA.org:liu-20327DiVA, id: diva2:234027
Anmärkning
On the day of the defence date the status of this article was Submitted.Tillgänglig från: 2009-09-04 Skapad: 2009-09-04 Senast uppdaterad: 2011-03-31Bibliografiskt granskad
Ingår i avhandling
1. Plant-Derived Substances and Cardiovascular Diseases: Effects of Flavonoids, Terpenes and Sterols on Angiotensin-Converting Enzyme and Nitric Oxide
Öppna denna publikation i ny flik eller fönster >>Plant-Derived Substances and Cardiovascular Diseases: Effects of Flavonoids, Terpenes and Sterols on Angiotensin-Converting Enzyme and Nitric Oxide
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2009. s. 127
Serie
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1097
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
urn:nbn:se:liu:diva-45338 (URN)81632 (Lokalt ID)978-91-7393-706-1 (ISBN)81632 (Arkivnummer)81632 (OAI)
Disputation
2009-02-05, Linden, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 09:00 (Svenska)
Opponent
Handledare
Anmärkning
2009Tillgänglig från: 2009-10-10 Skapad: 2009-10-10 Senast uppdaterad: 2009-10-16Bibliografiskt granskad

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Persson, IngridPersson, KarinHägg, StaffanAndersson, Rolf

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