A workforce of researchers from the College of California, Irvine and the College of Copenhagen has discovered that two polyphenol compounds present in inexperienced and black teas, epicatechin gallate and epigallocatechin-3-gallate, selectively activate KCNQ5, a voltage-gated potassium channel expressed in vascular clean muscle that regulates vascular tone.
Since its preliminary use in China over 4,000 years in the past, tea — produced from the evergreen Camellia sinensis — has change into one of the crucial generally consumed drinks worldwide, second solely to water.
Tea leaves include polyphenols belonging to the catechin household — particularly epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin-3-gallate (EGCG).
The fermentation technique of the leaves that leads to the totally different tea varieties (inexperienced, oolong, and black) causes the oxidization of catechins, leading to inexperienced tea containing the next focus of those compounds.
Tea catechins are identified for his or her antioxidant properties and are thought to convey the therapeutic advantages of tea, with some research displaying anticancer and cardiovascular well being advantages.
In new analysis, College of California, Irvine’s Professor Geoffrey Abbott and colleagues discovered that two catechin compounds, ECG and EGCG, every activate a selected kind of ion channel protein named KCNQ5, which permits potassium ions to diffuse out of cells to scale back mobile excitability.
As KCNQ5 is discovered within the clean muscle that traces blood vessels, its activation by tea catechins was additionally predicted to loosen up blood vessels.
“We discovered by utilizing pc modeling and mutagenesis research that particular catechins bind to the foot of the voltage sensor, which is the a part of KCNQ5 that enables the channel to open in response to mobile excitation,” Professor Abbott mentioned.
“This binding permits the channel to open rather more simply and earlier within the mobile excitation course of.”
Along with its function in controlling vascular tone, KCNQ5 is expressed in varied elements of the mind, the place it regulates electrical exercise and signaling between neurons.
Pathogenic KCNQ5 gene variants exist that impair its channel perform and in doing so trigger epileptic encephalopathy, a developmental dysfunction that’s severely debilitating and causes frequent seizures.
As a result of catechins can cross the blood-brain barrier, discovery of their capacity to activate KCNQ5 might recommend a future mechanism to repair damaged KCNQ5 channels to ameliorate mind excitability issues stemming from their dysfunction.
The scientists discovered that when black tea was instantly utilized to cells containing the KCNQ5 channel, the addition of milk prevented the useful KCNQ5-activating results of tea.
“Nevertheless, we don’t consider this implies one must keep away from milk when consuming tea to reap the benefits of the useful properties of tea,” Professor Abbott mentioned.
“We’re assured that the setting within the human abdomen will separate the catechins from the proteins and different molecules in milk that might in any other case block catechins’ useful results.”
The authors additionally discovered that warming inexperienced tea to 35 levels Celsius alters its chemical composition in a means that renders it more practical at activating KCNQ5.
“No matter whether or not tea is consumed iced or sizzling, this temperature is achieved after tea is drunk, as human physique temperature is about 37 levels Celsius,” Professor Abbott mentioned.
“Thus, just by consuming tea we activate its useful, antihypertensive properties.”
The findings have been printed within the journal Mobile Physiology and Biochemistry.
Kaitlyn E. Redford et al. 2021. KCNQ5 Potassium Channel Activation Underlies Vasodilation by Tea. Cell Physiol Biochem 55 (S3): 46-64; doi: 10.33594/000000337