Concentration Dependent Effect of (−)‐Epicatechin on Na⁺/K⁺‐ATPase and Ca²⁺‐ATPase Inhibition Induced by Free Radicals in Hypertensive Patients: Comparison with L‐ascorbic Acid

Abstract

Although the antioxidant properties of flavonoids are well documented, it is still unclear whether these effects are dependent on radical scavenging or iron chelating activities. Oxidative stress, a state of excessive reactive oxygen species (ROS) activity, is associated with vascular disease conditions such as hypertension. Both the anti- and pro-oxidant effects of tea catechins have been implicated in the alterations of cellular functions that determine their chemoprotective and therapeutic potentials in health and diseases. The present study examined the concentration dependent (10(-7) to 10(-4) m) effects of (-)-epicatechin and L-ascorbic acid on Na(+) /K(+) -ATPase and Ca(2+) -ATPase activity in hypertensive patients and normal subjects. L-ascorbic acid has been used as a positive control to compare the effect of (-)-epicatechin. A significant (p < 0.0001) decrease in the activities of Na(+) /K(+) -ATPase and Ca(2+) -ATPase was observed in hypertensive patients compared with normal subjects. We report that (-)-epicatechin shows a significant (p < 0.001) dose-dependent protective effect against oxidative stress induced by tert-butyl hydroperoxide (t-BHP), which is manisfested as a decrease in the activity of erythrocyte Na(+) /K(+) -ATPase and Ca(2+) -ATPase, in hypertensive patients as well as normal subjects. The effect of L-ascorbic acid was also significant (p < 0.001) and was comparable with that of (-)-epicatechin.

(−)‐Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats

“…One possible mechanism is a reduction in noradrenergic neurotransmission, which is elevated in SHR and associated with high blood pressure and locomotor hyperactivity [62, 72]. In Epi-treated SHR rats, noradrenergic hyperfunction may be diminished by presynaptic α 2 -autoreceptor-mediated feedback [62, 73], the improvement of calcium signaling [62, 74], and/or increases in bioavailability of NO [75]. These effects may prevent hypertension development and decrease locomotion in young SHR.…”

Moderation of doxorubicin-induced nephrotoxicity in Wistar rats by aqueous leaf-extracts of Chromolaena odorata and Tridax procumbens

“…The extracts’ ability to increase ATPase activities may be due to the presence of any one or both of ascorbic acid and epicatechin, earlier reported in them. According to Kumar et al 94 ascorbic acid or epicatechin prevents oxidative stress-induced lowering of Ca 2+ -ATPase and Na + ,K + -ATPase activities.…”

Novel Insights into the Pharmacology of Flavonoids

“…epicatechin, avicularin and quercitrin) from Lindera erythrocarpa have been shown to protect H9c2 cardiomyocytes against oxidative stressinduced cell death ; (ii) Kraussianone-2, a pyrano-isoflavone isolated from the roots of Eriosema kraussianum, improved fetal outcomes and decreased antiangiogenic factors in pregnant rats (Ramesar et al, 2012); (iii) hesperidin, glucosyl hesperidin, a water-soluble derivative of hesperidin, and naringin, mixed on diet, suppressed the age-related increase in blood pressure, decreased thrombotic tendency and increased the production of NO metabolites in stroke-prone spontaneously hypertensive rats (Ikemura et al, 2012); (iv) polyphenol-rich extracts from berries of Aronia melanocarpa or seeds of Vitis vinifera inhibited proteolytic activity of thrombin (Bijak et al, 2013). Finally, a study in hypertensive patients showed that (À)-epicatechin exerted protective effects against oxidative stress induced by tert-butyl hydroperoxide on isolated erythrocytes (Kumar et al, 2012).…”