Quercetin: A Treatment for Hypertension?—A Review of Efficacy and Mechanisms

Abstract

Quercetin is a polyphenolic flavonoid. Common sources in the diet are apples, onions, berries, and red wine. Epidemiological studies have found an inverse relationship between dietary quercetin intake and cardiovascular disease. This has led to in vitro, in vivo, and clinical research to determine the mechanism by which quercetin exerts cardio-protective effects. Recent studies have found a reduction in blood pressure when hypertensive (>140 mm Hg systolic and >90 mm Hg diastolic) animals and humans are supplemented with quercetin. Proposed mechanisms for the antihypertensive effect of quercetin include decreased oxidative stress, inhibition of angiotensin converting enzyme activity, improved endothelial function, direct action on the vascular smooth muscle, and/or modulation in cell signaling and gene expression. Although in vitro and in vivo evidence exists to support and refute each possibility, it is likely that quercetin influences multiple targets via a combination of known and as yet undiscovered mechanisms. The purpose of this review is to examine the mechanisms whereby quercetin might reduce blood pressure in hypertensive individuals.

The Effect of ethanol Psidium Guava leaf extract on KCl Induced Contracted Aortic tissues of Guinea Pigs

“…Different factors such as gender, age, genetic factors, alcohol consumption, dyslipidemia, smoking increases its severity [5], [10]. It can be classified into primary resulted from sedentary lifestyle and diet (accounts for 90-95%) and secondary resulted from chronic kidney disease which accounts for 5-10% [21], [22]. Although mechanisms of primary hypertension are not well known, secondary hypertension can be resulted from defect in arterial subendothelial cells; renin-angiotensin-aldosterone system; central nervous system dysfunction, leading to elevated sympathetic activity [13].…”

“…Its effects may be due to the presence of many different phytochemical compounds such as vitamin C, vitamin A, iron, calcium, manganese, phosphoric, oxalic and malic acids, saponin combined with oleanolic and others [16], [34]. Quercetin, α-pinene, β-pinene, limonene, menthol are compounds from its leaves; polyphenols and resin exist in its bark; gallic acid and tannin are found in its roots; and phenolics and flavonoids are found in its seed and wings [22], [38]. Therefore, this study was designed to examine the effect ethanol P. guava leaf extract on relaxation of aortic muscles in guinea pigs.…”

The qualitative analysis of the green tea extract using ESI-MS method

“…Also, the polyphenols of green tea reduce the level of lipids, triglycerides and cholesterol in the blood, thereby reducing the risk of circulatory system diseases and atherosclerosis [21]. Tea contains around 5-7 % minerals, mainly potassium, copper, iron and manganese which have an important role in the human body.…”

Reduction in Nitrogen Prior to Harvest Increases Phenolic Content of Baby Red Lettuce Leaves

“…The major flavonols contributing to antioxidant activity found in lettuce are quercetin and kaempferol derivatives [5]. Quercetin has been extensively studied in vitro and is known to be a potent free-radical scavenger and anti-oxidant [6] [7]. The closely related compound, kaempferol, has also been shown to possess antioxidant activity in its own right, albeit lower than quercetin [8].…”