Green and Black Tea May Prevent Hypertension

Research shows that our blood vessels get relaxed when ion channel proteins in the blood vessel wall get activated by compounds present in green and black tea. One-third of the world's adult population has hypertension, and this condition is considered the number one modifiable risk factor for global cardiovascular disease and premature mortality.

Kaitlyn Redford was the first author of this study conducted in Geoffrey Abbott’s lab.

Findings showed that KCNQ5, a specific type of ion protein channel, gets activated by two catechin-type flavonoid compounds (epicatechin gallate and epigallocatechin-3-gallate) present in tea. This results in the diffusion of potassium ions out of cells to reduce cellular excitability.

Since KCNQ5 is found in the smooth muscle that lines blood vessels, its activation by tea catechins was also predicted to relax blood vessels.

Abbott explained that using computer modeling and mutagenesis studies showed that specific catechins bind to the foot of the voltage sensor, which is the part of KCNQ5 that allows the channel to open in response to cellular excitation. This binding allows the channel to open much more easily and earlier in the cellular excitation process.

KCNQ5 also regulates the electrical activity and signaling between neurons in various parts of the brain. Additionally, pathogenic KCNQ5 gene variants impair its channel function and result in epileptic encephalopathy (a developmental disorder that is severely debilitating and causes frequent seizures).

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Results also revealed that the addition of milk to black tea prevents the beneficial KCNQ5-activating effects of tea.

However, Abbott adds, "We don't believe this means one needs to avoid milk when drinking tea to take advantage of the beneficial properties of tea. We are confident that the environment in the human stomach will separate the catechins from the proteins and other molecules in milk that would otherwise block catechins' beneficial effects."

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Other studies have shown the antihypertensive benefits of tea regardless of milk co-consumption.

Using mass spectrometry, the research team found that heating green tea to 35 degrees celsius alters its chemical composition in a way that makes it more effective at activating KCNQ5.

"Regardless of whether tea is consumed iced or hot, this temperature is achieved after tea is drunk, as human body temperature is about 37 degrees Celsius," explained Abbott. "Thus, simply by drinking tea, we activate its beneficial, antihypertensive properties."

Identification of KCNQ5 as a novel target for tea catechins' hypertensive properties may facilitate medicinal chemistry optimization for improved potency or efficacy. The discovery helps explain the antihypertensive properties of tea and could lead to the design of new blood pressure-lowering medications.



Source-Eurekalert