Quercetin has multiple potential to control various cell function keeping our body condition healthy. In this review article, we describe the molecular mechanism on how
quercetin exerts its action on blood pressure, neurite elongation and epithelial ion transport based from a viewpoint of cytosolic Cl- environments, which is recently recognized as an important signaling factor in various types of cells. Recent studies show various roles of cytosolic Cl- in regulation of blood pressure and neurite elongation, and prevention from bacterial and
viral infection. We have found the stimulatory action of
quercetin on Cl- transporter, Na+-K+-2Cl- cotransporter 1 (NKCC1; an
isoform of NKCC), which has been recognized as one of the most interesting, fundamental actions of
quercetin. In this review article, based on this stimulatory action of
quercetin on NKCC1, we introduce the molecular mechanism of
quercetin on: 1) blood pressure, 2) neurite elongation, and 3) epithelial Cl- secretion including tight junction forming in epithelial tissues. 1)
Quercetin induces elevation of the cytosolic Cl- concentration via activation of NKCC1, leading to
anti-hypertensive action by diminishing expression of epithelial Na+ channel (ENaC), a key
ion channel involved in renal Na+ reabsorption, while
quercetin has no effects on the blood pressure with normal
salt intake. 2)
Quercetin also has stimulatory effects on neurite elongation by elevating the cytosolic Cl- concentration via activation of NKCC1 due to
tubulin polymerization facilitated through Cl--induced inhibition of
GTPase. 3) Further, in lung airway epithelia
quercetin stimulates Cl- secretion by increasing the driving force for Cl- secretion via elevation of the cytosolic Cl- concentration: this leads to water secretion, participating in prevention of our body from bacterial and
viral infection. In addition to transcellular ion transport,
quercetin regulates tight junction function via enhancement of tight junction integrity by modulating expression and assembling tight junction-forming
proteins. Based on these observations, it is concluded that
quercetin is a useful medicinal compound keeping our body to be in healthy condition.