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Global Translational Medicine Impact of flavonoids on vascular health

bond. Flavones have a ketone at position 4 of the closed cardioprotective impact, and have been shown to reduce
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pyran ring and a double bond between positions 2 and 3. both diastolic and systolic BP. 36
These compounds are present in various foods, including Another type of catechin, epigallocatechin-3-gallate,
celery, mint, red peppers, garlic, parsley, and chamomile is highly prevalent in green tea, serving as an ester of
flowers. Such sources of flavones are abundant in apigenin, gallic acid and epigallocatechin. This compound exerts
luteolin, and tangeritin. In addition, the peel of citrus diverse effects on various physiological and pathological
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fruits contains flavones (polymethoxylated flavones), such processes in humans, demonstrating bioactivities such as
as nobiletin, tangeretin, and sinensetin. Luteolin has been anti-atherogenic action, antioxidant properties, and anti-
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shown to decrease BP in hypertensive rats by reducing the inflammatory effects. Epicatechin, another flavan-3-ol
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proliferation of angiotensin I-induced vascular smooth
muscle cells (VSMCs), enhancing vasodilation in the aorta, flavonoid, is recognized for its antihypertensive action.
and inhibiting cAMP-specific phosphodiesterase, leading The consumption of an epicatechin-supplemented diet has
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to the accumulation of cAMP. Luteolin activates cAMP, been linked to reductions in both systolic and diastolic BP,
along with a decrease in myocardial tissue rigidity in rats
subsequently triggering protein kinase A. Moreover, nitric 36,37
oxide (NO) synthase becomes activated, elevating NO with hypertrophic cardiomyopathy.
levels in endothelial cells. The accumulated NO promotes 2.4. Flavanones
vascular relaxation through potassium (K ) and calcium
+
(Ca ) channels. 27 Flavanones, alternatively known as dihydroflavones,
2+
exhibit a distinctive structural feature—a saturated
2.2. Flavonols closed pyran ring. Key flavanones in this class include
Flavonols stand out among all flavonoids due to the naringenin and hesperetin, prominently found in citrus
presence of the ketone group, acting as precursors of fruit peels. Renowned for their antioxidant properties,
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proanthocyanins. These compounds feature a hydroxyl these compounds, as reviewed in Barreca et al.,
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group at position 3 of the closed pyran ring, which can effectively block the activity of free radicals. Hesperetin,
undergo glycosylation. The most commonly encountered a dietary flavanone, is notably abundant in lemons and
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flavonols include quercetin, kaempferol, fisetin, and sweet oranges. Rapid absorption from the intestine
myricetin, abundant in foods such as broccoli, beans, kale, facilitates the generation of metabolites that demonstrate
onion, lettuce, tea, tomatoes, apples, berries, strawberries, an antihypertensive effect. The mechanism involves
grapes, and wine. 29 G-hesperidin under hypertension, leading to lowered
BP. In addition, the antioxidant nature of hesperetin
Quercetin, a prominent flavonol, is recognized for contributes to increased nitric acid content and reduced
its antihypertensive effects. On consumption, quercetin Ca levels, promoting the relaxation of vascular smooth
2+
enhances endothelial function and regulates the renin- muscles. 39
angiotensin-aldosterone system (RAAS). It induces
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vasodilation in the kidneys and lowers BP levels in Naringenin, found in grapefruit and certain herbs,
diabetic patients. Studies have demonstrated its efficacy has been subject to numerous studies investigating its
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in addressing hypertension, hyperinsulinemia, and beneficial effects. A naringin-supplemented diet has
dyslipidemia, as well as inducing anti-inflammatory effects shown promise in the treatment of hypertension, diabetes,
in vascular adipose tissue, leading to reduced body weight antiviral and antibacterial activities, anti-inflammatory
in obese Wistar rats. Quercetin also provides relief from responses, antiadipogenic effects, and the management of
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oxidative stress in organs such as the heart and kidneys. the metabolic syndrome. Notably, naringenin is recognized
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Its antihypertensive properties are attributed to the release for its ability to reduce BP, protect against endothelial
of NO in endothelial cells. 33 dysfunction, and modulate NO levels. 41
2.3. Flavan-3-ols 2.5. Anthocyanidins
In flavan-3-ols, the hydroxyl group at position 3 of Anthocyanidins, characterized by their water-soluble
the closed pyran ring is bonded, and the double bond nature, stand as pigments unique among flavonoids,
is absent at positions 2 and 3. This category includes predominantly contributing to the vibrant hues in
catechin, epicatechin, gallocatechin, and oligomers. plants, especially fruits, flowers, and vegetables. Notably,
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Catechins, found in various plants such as apples, apricots, they are recognized for imparting shades of blue, red,
cocoa, pears, and tea in the aglycone form, represent or purple to fruits, exemplified in berries and black
the monomeric form of flavanols. Catechins exhibit currants. The coloration of anthocyanins, glycosides
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positive effects on vascular functions, contributing to a derived from anthocyanidins, is subject to pH levels and
Volume 3 Issue 2 (2024) 3 doi: 10.36922/gtm.2458