A flavonoid-rich diet increases nitric oxide production in rat aorta

Vasorelaxant Activity of (2S)-Sakuranetin and Other Flavonoids Isolated from the Green Propolis of the Caatinga Mimosa tenuiflora

Some in vitro and in vivo evidence is consistent with the cardiovascular beneficial activity of propolis. As the single actors responsible for this effect have never been identified, an in-depth investigation of flavonoids isolated from the green propolis of the Caatinga Mimosa tenuiflora was performed and their mechanism of action was described. A comprehensive electrophysiology, functional, and molecular docking approach was applied. Most flavanones and flavones were effective CaV1.2 channel blockers with a potency order of (2S)-sakuranetin > eriodictyol-7,3'-methyl ether > quercetin 3-methyl ether > 5,4'-dihydroxy-6,7-dimethoxyflavanone > santin > axillarin > penduletin > kumatakenin, ermanin and viscosine being weak or modest stimulators. Except for eriodictyol 5-O-methyl ether, all the flavonoids were also effective spasmolytic agents of vascular rings, kumatakenin and viscosine also showing an endothelium-dependent activity. (2S)-Sakuranetin also stimulated KCa1.1 channels both in single myocytes and vascular rings. In silico analysis provided interesting insights into the mode of action of (2S)-sakuranetin within both CaV1.2 and KCa1.1 channels. The green propolis of the Caatinga Mimosa tenuiflora is a valuable source of multi-target vasoactive flavonoids: this evidence reinforces its nutraceutical value in the cardiovascular disease prevention arena.

Pleiotropic Functions of Nitric Oxide Produced by Ascorbate for the Prevention and Mitigation of COVID-19: A Revaluation of Pauling's Vitamin C Therapy

Linus Pauling, who was awarded the Nobel Prize in Chemistry, suggested that a high dose of vitamin C (l-ascorbic acid) might work as a prevention or treatment for the common cold. Vitamin C therapy was tested in clinical trials, but clear evidence was not found at that time. Although Pauling's proposal has been strongly criticized for a long time, vitamin C therapy has continued to be tested as a treatment for a variety of diseases, including coronavirus infectious disease 2019 (COVID-19). The pathogen of COVID-19, SARS-CoV-2, belongs to the β-coronavirus lineage, which includes human coronavirus, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). This review intends to shed new light on vitamin C antiviral activity that may prevent SARS-CoV-2 infection through the chemical production of nitric oxide (NO). NO is a gaseous free radical that is largely produced by the enzyme NO synthase (NOS) in cells. NO produced by upper epidermal cells contributes to the inactivation of viruses and bacteria contained in air or aerosols. In addition to enzymatic production, NO can be generated by the chemical reduction of inorganic nitrite (NO2-), an alternative mechanism for NO production in living organisms. Dietary vitamin C, largely contained in fruits and vegetables, can reduce the nitrite in saliva to produce NO in the oral cavity when chewing foods. In the stomach, salivary nitrite can also be reduced to NO by vitamin C secreted from the epidermal cells of the stomach. The strong acidic pH of gastric juice facilitates the chemical reduction of salivary nitrite to produce NO. Vitamin C contributes in multiple ways to the host innate immune system as a first-line defense mechanism against pathogens. Highlighting chemical NO production by vitamin C, we suggest that controversies on the therapeutic effects of vitamin C in previous clinical trials may partly be due to less appreciation of the pleiotropic functions of vitamin C as a universal bioreductant.

Antioxidant Cardioprotection against Reperfusion Injury: Potential Therapeutic Roles of Resveratrol and Quercetin

Ischemia-reperfusion myocardial damage is a paradoxical tissue injury occurring during percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI) patients. Although this damage could account for up to 50% of the final infarct size, there has been no available pharmacological treatment until now. Oxidative stress contributes to the underlying production mechanism, exerting the most marked injury during the early onset of reperfusion. So far, antioxidants have been shown to protect the AMI patients undergoing PCI to mitigate these detrimental effects; however, no clinical trials to date have shown any significant infarct size reduction. Therefore, it is worthwhile to consider multitarget antioxidant therapies targeting multifactorial AMI. Indeed, this clinical setting involves injurious effects derived from oxygen deprivation, intracellular pH changes and increased concentration of cytosolic Ca²⁺ and reactive oxygen species, among others. Thus, we will review a brief overview of the pathological cascades involved in ischemia-reperfusion injury and the potential therapeutic effects based on preclinical studies involving a combination of antioxidants, with particular reference to resveratrol and quercetin, which could contribute to cardioprotection against ischemia-reperfusion injury in myocardial tissue. We will also highlight the upcoming perspectives of these antioxidants for designing future studies.

The Potential of Dietary Bioactive Compounds against SARS-CoV-2 and COVID-19-Induced Endothelial Dysfunction

COVID-19 is an endothelial disease. All the major comorbidities that increase the risk for severe SARS-CoV-2 infection and severe COVID-19 including old age, obesity, diabetes, hypertension, respiratory disease, compromised immune system, coronary artery disease or heart failure are associated with dysfunctional endothelium. Genetics and environmental factors (epigenetics) are major risk factors for endothelial dysfunction. Individuals with metabolic syndrome are at increased risk for severe SARS-CoV-2 infection and poor COVID-19 outcomes and higher risk of mortality. Old age is a non-modifiable risk factor. All other risk factors are modifiable. This review also identifies dietary risk factors for endothelial dysfunction. Potential dietary preventions that address endothelial dysfunction and its sequelae may have an important role in preventing SARS-CoV-2 infection severity and are key factors for future research to address. This review presents some dietary bioactives with demonstrated efficacy against dysfunctional endothelial cells. This review also covers dietary bioactives with efficacy against SARS-CoV-2 infection. Dietary bioactive compounds that prevent endothelial dysfunction and its sequelae, especially in the gastrointestinal tract, will result in more effective prevention of SARS-CoV-2 variant infection severity and are key factors for future food research to address.

Effect of Calamintha officinalis on Vascular Contractility and Angiotensinconverting Enzyme-2

AIMS

The study aimed to assess the antihypertensive activity of Calamintha officinalis.

BACKGROUND

Calamintha officinalis (CO) is a medicinal and aromatic herb as well as an antihypertensive plant that is widely used for its medicinal properties in several regions.

OBJECTIVE

This study aimed to evaluate the effect of the aqueous extract of Calamintha officinalis (AECO) on vasorelaxant activity and arterial blood pressure under normal and hypertensive states in rats. Additionally, the effect of AECO on vascular angiotensin-converting enzyme 2 (ACE-2) was assessed.

METHODS

In the current study, AECO (100 mg/Kg) was prepared, and its antihypertensive ability was assessed in L-N^G-Nitro arginine methyl ester (L-NAME)-induced hypertensive rats. Blood pressure and heart rate were recorded for 6 h for the acute experiment and during seven days for the subchronic treatment.

RESULTS

The results indicated that AECO reduced the systolic, diastolic, and mean arterial blood pressure in hypertensive rats. In addition, the study showed that AECO exerts a vasorelaxant ability through the sGC-cGMP induction pathway, vascular cyclooxygenase pathway, and the opening of K+ channels. However, AECO had no inhibitory effect on aortic ACE-2.

CONCLUSION

The study illustrates the beneficial action of AECO as an antihypertensive and vasorelaxant agent.

Quercetin and resveratrol ameliorate nickel-mediated hypercontraction in isolated Wistar rat aorta

PURPOSE

The ameliorative potential of quercetin and resveratrol on isolated endothelium-intact aortic rings incubated with nickel was examined.

METHOD

The effect of varying concentrations of quercetin and resveratrol was investigated on isolated Wistar rat aortic rings using an organ bath system over vasoconstrictor phenylephrine (PE) at 1 µM. To delineate the mechanism of action, isolated aortic rings were pre-incubated with pharmacological modulators, such as verapamil 1 µM, apocynin 100 µM, indomethacin 100 µM or N-G-nitro-L-arginine methyl ester (L-NAME) 100 µM, separately, before incubation with 100 µM quercetin and 30 µM resveratrol. To assess the ameliorative and prophylactic potentials of quercetin and resveratrol, aortic rings were also incubated with quercetin or resveratrol for 40 min, followed by incubation with nickel for 40 min.

RESULTS

At 100 µM, quercetin caused 29% inhibition of contraction, while resveratrol at 30 µM caused 55% inhibition of contraction in aortic rings compared with control. Aortic rings incubated with contractile modulators, such as verapamil, apocynin, indomethacin or N-G-nitro-L-arginine methyl ester (L-NAME), along with quercetin or resveratrol at their concentrations producing maximum relaxant effect, showed that both of these natural compounds exert their relaxant effect by inhibiting the generation of reactive oxygen species (ROS) from endothelial and smooth muscle cells, blocking voltage-gated calcium channels, and increasing the release of nitric oxide (NO). The mediation of hypercontraction by nickel is due to the increased ROS and the influx of calcium through voltage-dependent calcium channels. These natural compounds are shown to counter the nickel-induced effects, appearing as effective ameliorators.

CONCLUSION

In this study, we found that quercetin and resveratrol act as ameliorators of nickel-mediated hypercontraction by decreasing ROS and enhancing NO release from endothelial cells.

Harnessing polyphenol power by targeting eNOS for vascular diseases

Vascular diseases arise due to vascular endothelium dysfunction in response to several pro-inflammatory stimuli and invading pathogens. Thickening of the vessel wall, formation of atherosclerotic plaques consisting of proliferating smooth muscle cells, macrophages and lymphocytes are the major consequences of impaired endothelium resulting in atherosclerosis, hypercholesterolemia, hypertension, type 2 diabetes mellitus, chronic renal failure and many others. Decreased nitric oxide (NO) bioavailability was found to be associated with anomalous endothelial function because of either its reduced production level by endothelial NO synthase (eNOS) which synthesize this potent endogenous vasodilator from L-arginine or its enhanced breakdown due to severe oxidative stress and eNOS uncoupling. Polyphenols are a group of bioactive compounds having more than 7000 chemical entities present in different cereals, fruits and vegetables. These natural compounds possess many OH groups which are largely responsible for their strong antioxidative, anti-inflammatory antithrombotic and anti-hypersensitive properties. Several flavonoid-derived polyphenols like flavones, isoflavones, flavanones, flavonols and anthocyanidins and non-flavonoid polyphenols like tannins, curcumins and resveratrol have attracted scientific interest for their beneficial effects in preventing endothelial dysfunction. This article will focus on in vitro as well as in vivo and clinical studies evidences of the polyphenols with eNOS modulating activity against vascular disease condition while their molecular mechanism will also be discussed.

Transcriptional Regulation of Structural and Functional Adaptations in a Developing Adulthood Myocardium

The development of the heart follows a synergic action of several signaling pathways during gestational, pre- & postnatal stages. The current study aimed to investigate whether the myocardium experiences transcriptional changes during the transition from post-natal to adult hood stages. Herein, we used C57/B16/J mice at 4 (28- days; post-natal/PN) and 20 weeks (adulthood/AH) of ages and employed the next generation RNAseq (NGS) to profile the transcriptome and echocardiography analysis to monitor the structural/functional changes in the heart. NGS-based RNA-seq revealed that 1215 genes were significantly upregulated and 2549 were down regulated in the AH versus PN hearts, indicating a significant transcriptional change during this transition.

A synchronized cardiac transcriptional regulation through cell cycle, growth hormones, redox homeostasis and metabolic pathways was noticed in both PN and AH hearts. Echocardiography reveals significant structural and functional (i.e. systolic/diastolic) changes during the transition of PN to adult stage. Particularly, a progressive decline in ejection fraction and cardiac output was observed in AH hearts. These structural adaptations are in line with critical signaling pathways that drive the maturation of heart during AH. Overall, we have presented a comprehensive transcriptomic analysis along with structural-functional relationship during the myocardial development in adult mice.

Protective Mechanisms of Quercetin Against Myocardial Ischemia Reperfusion Injury

Quercetin has attracted more attention in recent years due to its protective role against ischemia/reperfusion injury. Quercetin can alleviate oxidative stress injury through the inhibition of NADPH oxidase and xanthine oxidase, blockage of the Fenton reaction, and scavenging of reactive oxygen species. Quercetin can also exert anti-inflammatory and anti-apoptotic effects by reducing the response to inflammatory factors and inhibiting cell apoptosis. Moreover, it can induce vasodilation effects through the inhibition of endothelin-1 receptors, the enhancement of NO stimulation and the activation of the large-conductance calcium-activated potassium channels. Finally, Quercetin can also antagonize the calcium overload. These multifaceted activities of Quercetin make it a potential therapeutic alternative for the treatment of ischemia/reperfusion injury.

Opposite Modulatory Effects of Crataegus aronia Aqueous Extract on Platelet Aggregation in Rats

OBJECTIVES

To reveal the mechanisms behind the dual effects of Crataegus aronia (C. aronia) aqueous extract on platelet aggregation by focusing on function, regulation, expression, and signaling of platelets P₂Y₁₂ receptors.

METHODS

Adult male Wistar rats (120 ± 10 g) were classified as control received the vehicle, C. aronia (200 mg/kg), and C. aronia (2,000 mg/kg)-treated rats. After treatments for consecutive 7 days, hematological and molecular experiments were conducted to detect alterations in platelet aggregation, thromboxane B2 (THXB2) and intracellular reactive oxygen species (ROS) content; protein levels of P₂Y₁₂, p-Akt, cyclic adenosine monophosphate (cAMP), phosphorylated vasodilator-stimulated-phosphoprotein (p-VASP), nuclear factor κB (NF-κB), P-selectin, and etc. in platelets were determined by Western blot; mRNA expressions of P₂Y₁₂ and some inflammatory markers were determined by real-time polymerase chain reaction.

RESULTS

At a concentration of 200 mg/kg, C. aronia inhibited platelet aggregation through multiple interconnected mechanisms including downregulation P₂Y₁₂ synthesis and expression, stimulating intracellular cAMP levels and protein levels of p-VASP, inhibiting platelets THXB2 release and protein levels of P-selectin. Also, it inhibited platelets level of ROS and of NF-κB, a major signaling pathway that stimulates the expression of P₂Y₁₂ and THXA2 synthesis. Opposite findings were seen in platelets of rats received C. aronia at a concentration of 2,000 mg/kg. Interestingly, co-administration of N-acetylcysteine prevented all hematological and molecular alterations exerted by the high dose of the extract and inhibited platelet aggregation.

CONCLUSION

Oral administration of C. aronia at low dose inhibits platelet aggregation by reducing THXB2 release, expression of P-selectin and activating cAMP and Akt signaling through two major mechanisms including downregulation of P₂Y₁₂ and inhibition of ROS-induced activation of NF-κB, an effect that is observed to be in the opposite direction with its high dose.

Impact of polyphenols in phagocyte functions

Polyphenols are a broad group of substances with potential health benefits found in plant species. Several of these compounds are capable of influencing the activation of intracellular signaling pathways, such as NF-kB, MAPK and JAK-STAT, responsible for the production of various inflammatory mediators such as tumor necrosis factor α (TNF-α) and interleukin 1 beta (IL-1β) and 12 (IL-12), enzymes involved in the production of reactive species such as inducible nitric oxide synthase (iNOS) and superoxide dehydrogenase (SOD), as well as enzymes involved in the production of eicosanoids, such as cyclooxygenase (COX) and lipoxygenase (LO). There is increased interest in the use of polyphenol-rich foods because of their immunomodulatory effect; however, the mechanisms used during macrophage responses are extremely complex and little is known about the effects of polyphenols on these cells. As such, this review summarizes the current view of polyphenol influences on macrophages.

Acute consumption of flavanol-rich cocoa beverage improves attenuated cutaneous microvascular function in healthy young African Americans

Flavanols have beneficial effects on vascular health and we have recently demonstrated that cerebral vasodilatory capacity in healthy young African Americans (AA) is improved with acute flavanol intake relative to aged-matched Caucasian Americans (CA). However, whether the positive benefits of acute flavanol consumption would also be present in the cutaneous microvascular circulation of AA remains unknown. Thus, we hypothesized that acute consumption of flavanol-rich cocoa (FC) would improve the previously reported reduced cutaneous microvascular responses to local heating in young AA. Seven AA and seven CA participated in this double-blind crossover study. Data were collected on two different days, separated by a minimum of one week. Two intradermal microdialysis membranes were inserted in the forearm and each site was randomly assigned to receive lactated Ringer's solution or NO synthase (NOS) inhibitor. Participants were randomly assigned to consume either a non-flavanol containing (NF) beverage or FC beverage. Cutaneous vascular conductance (CVC) was calculated as cutaneous blood flux/mean arterial pressure and normalized as % maximal CVC (%CVCmax). The difference in %CVCmax between the Ringer's site and NOS inhibited site was calculated to assess NO contribution (Δ %CVCmax). In the Ringer's site, acute consumption of FC beverage improved %CVCmax during 39 °C heating when compared to NF beverage in AA (NF: 36 ± 6 vs. FC: 47 ± 5%CVCmax; P < .01) while there was similar %CVCmax during 39 °C heating between beverages in CA (NF: 55 ± 4 vs. FC: 59 ± 5%CVCmax; P = .40). During 39 °C heating, NO contribution was significantly higher with FC beverage than NF beverage in AA (NF: 27 ± 5 vs. FC: 35 ± 4 Δ %CVCmax; P = .03) while there was similar NO contribution between beverages in CA (NF: 42 ± 4 vs. FC: 45 ± 4 Δ %CVCmax; P = .36). This data suggests that acute consumption of FC could be a therapeutic solution to improve an attenuated microvascular function in young AA.

Potential mechanisms underlying cardiovascular protection by polyphenols: Role of the endothelium

Epidemiological studies have indicated that regular intake of polyphenol-rich diets such as red wine and tea, are associated with a reduced risk of cardiovascular diseases. The beneficial effect of polyphenol-rich products has been attributable, at least in part, to their direct action on the endothelial function. Indeed, polyphenols from tea, grapes, cacao, berries, and plants have been shown to activate endothelial cells to increase the formation of potent vasoprotective factors including nitric oxide (NO) and to delay endothelial ageing. Moreover, intake of such polyphenol-rich products has been associated with the prevention and/or the improvement of an established endothelial dysfunction in several experimental models of cardiovascular diseases and in Humans with cardiovascular diseases. This review will discuss both experimental and clinical evidences indicating that polyphenols are able to promote endothelial and vascular health, as well as the underlying mechanisms.

Antihypertensive Effect of Ethanolic Extract from Acanthopanax sessiliflorus Fruits and Quality Control of Active Compounds

Acanthopanax sessiliflorus (Rupr. & Maxim.) Seem., which belongs to the Araliaceae family, mainly inhabits Korea, China, and Japan. Traditionally, Acanthopanax species have been used as treatment for several diseases such as diabetes, tumors, and rheumatoid arthritis. Especially, its fruits have many biological functions including antitumor, immunostimulating, antithrombosis, and antiplatelet activities. Recently, the extract of A. sessiliflorus fruit has been reported to have antithrombotic and antiplatelet activities related to the alleviation of hypertension. Therefore, we investigated the antihypertensive effect of ethanolic extract from A. sessiliflorus fruits (DHP1501) through in vivo, ex vivo, and in vitro studies. In this study, DHP1501 demonstrated free radical scavenging capacity, enhanced endothelial nitric oxide (NO) production, and inhibited angiotensin-converting enzyme (ACE) activity in spontaneously hypertensive rats (SHRs), resulting in the improvement of vascular relaxation and decrease in blood pressure in the hypertensive animal model. These results suggest that A. sessiliflorus fruit extract may be a promising functional material for the prevention and treatment of hypertension. Furthermore, this study demonstrated the utility of MS-based active compounds for the quality control of DHP1501.

An Acute Dose of Specific Grape and Apple Polyphenols Improves Endurance Performance: A Randomized, Crossover, Double-Blind versus Placebo Controlled Study

Polyphenols are thought to be an interesting ergogenic aid for exercise and recovery. However, most studies regarding the effects of polyphenols investigated several days of supplementations. The present work aimed to study the effects of an acute intake of grape and apple polyphenols on the capacity to maintain intense exercise, here named endurance performance. Forty-eight physically active men (31 ± 6 years) were included in this study. During the two testing sessions, volunteers completed an endurance test at a high percentage of their maximal aerobic power and time to exhaustion was measured. Respiratory and pain parameters were also monitored. The preceding evening and 1 h before testing, volunteers had to absorb either 500 mg of polyphenols or placebo according to randomization. In comparison with the placebo, the mean duration of the maximal endurance test was significantly increased with polyphenols (+9.7% ± 6.0%, p < 0.05). The maximal perceived exertion was reached later with polyphenols (+12.8% ± 6.8%, p < 0.05). Practically, the present study showed the beneficial effects of grape and apple polyphenols for athletes looking for endurance performance improvements. The specifically designed profile of polyphenols appeared to enhance the capacity to maintain intensive efforts and delay perceived exertion.

Catechins as Potential Mediators of Cardiovascular Health

The impact of diet on cardiovascular disease has become an increasingly relevant topic as ongoing epidemiological evidence continues to demonstrate clear associations with disease burden and mortality. Certain diets, such as those high in sodium and saturated fat, are associated with cardiovascular disease states, while other diets can be cardioprotective. However, there is limited knowledge on how the micro- and macronutrients within such cardioprotective diets afford their benefits. One such micronutrient is the catechin class, which are naturally occurring compounds in plant foods, such as teas, cocoa, wine, pears, and apples. Recent evidence reveals that catechins may be a key mediator in cardiovascular health via mechanisms of blood pressure reduction, flow-mediated vasodilation, and atherosclerosis attenuation. This review evaluates the current literature on the interplay between catechins and cardiovascular disease, which may have important implications for nutrition counseling and pharmaceutical drug development.

Evaluation of anti-hypertensive activity of Ulmus wallichiana extract and fraction in SHR, DOCA-salt- and L-NAME-induced hypertensive rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ulmus wallichiana Planchon (Himalayan Elm), a traditional medicinal plant, used in fracture healing in folk tradition of Uttarakhand, Himalaya, India. It is also used as diuretic. U. rhynchophylla, native to China, known as Gou Teng in Chinese medicine, is used for hypertension (WHO). U. macrocarpa has antihypertensive and vasorelaxant activity. However, no detailed studies related to hypertension have been reported previously, so we have explored the antihypertensive activity of U. wallichiana.

AIM OF THE STUDY

To investigate the pharmacological effect of ethanolic extract (EE) and butanolic fraction (BF) of U. wallichiana in hypertensive rats.

MATERIALS AND METHODS

SHR, DOCA-salt- and L-NAME-induced hypertension models were used. Treatment was performed by oral administration of EE and BF of U. wallichiana (500mg/kg/day and 50mg/kg/day) for 14 days. Then blood pressure was measured by non-invasive blood pressure (NIBP) measurement technique. Invasive blood pressure (IBP) was also reported to support the NIBP data. Concentrations of plasma renin, angiotensin II (Ang II), nitrate/nitrite (NO), cGMP were estimated. Angiotensin-converting enzyme (ACE) activity and ROS activity were also estimated.

RESULTS

Blood pressure was significantly higher in SHR as compared to normotensive wistar group (170.59±0.83mmHg vs 121.54±1.24mmHg, respectively). SBP was increased in DOCA-salt induced group compared to their control (132.77±3.90mmHg vs 107.85±5.95mmHg, respectively) and L-NAME-induced group compared to their control (168.55±5.07mmHg vs 113.03±4.13mmHg, respectively). The treatment of extract and fraction of U. wallichiana significantly decreased the blood pressure in SHR+EE (151.26±1.85mmHg, p<0.001), SHR+BF (140.44±1.16mmHg, p<0.001); DOCA+EE (113.43±5.44mmHg, p<0.05), DOCA+BF (105.09±5.12mmHg, p<0.05) and L-NAME+EE (119.76±4.39mmHg, p<0.001), L-NAME+BF (117.50±7.27mmHg, p<0.001) compared to their respective diseased control groups. The plasma renin, Ang II and ACE activity were also significantly decreased and augmented the NO and cGMP levels. It also down regulated the expression of Renin, ACE, NOS3 and TGF-β1 at mRNA levels.

CONCLUSIONS

The EE and BF probably reducing the BP via Renin-angiotensin-aldosterone system and NO/cGMP signaling pathway. The decrease in blood pressure may be due to presence of quercetin analogue flavonoids (2S,3S)-(+)-3',4',5,7-tetrahydroxydihydroflavonol-6-C-β-D-glucopyranoside; 6-Glucopyranosyl-3,3',4',5,7-pentahydroxyflavone; 6-Glucopyranosyl-4',5,7-trihydroxyflavanone and (2S,3S)-(+)-4',5,7-trihydroxydihydroflavonol-6-C-β-D-glucopyranoside, may be due to its antioxidant activity. Thus EE and BF of U. wallichiana found to have the potential ability to be used as herbal medicament to treat hypertension.

Targeting Nitric Oxide with Natural Derived Compounds as a Therapeutic Strategy in Vascular Diseases

Within the family of endogenous gasotransmitters, nitric oxide (NO) is the smallest gaseous intercellular messenger involved in the modulation of several processes, such as blood flow and platelet aggregation control, essential to maintain vascular homeostasis. NO is produced by nitric oxide synthases (NOS) and its effects are mediated by cGMP-dependent or cGMP-independent mechanisms. Growing evidence suggests a crosstalk between the NO signaling and the occurrence of oxidative stress in the onset and progression of vascular diseases, such as hypertension, heart failure, ischemia, and stroke. For these reasons, NO is considered as an emerging molecular target for developing therapeutic strategies for cardio- and cerebrovascular pathologies. Several natural derived compounds, such as polyphenols, are now proposed as modulators of NO-mediated pathways. The aim of this review is to highlight the experimental evidence on the involvement of nitric oxide in vascular homeostasis focusing on the therapeutic potential of targeting NO with some natural compounds in patients with vascular diseases.

Molecular Properties of Red Wine Compounds and Cardiometabolic Benefits

Wine has been used since the dawn of human civilization. Despite many health benefits, there is still a lot of discussion about the real properties of its components and its actions on cells and molecular interactions. A large part of these issues permeate the fine line between the amount of alcohol that causes problems to organic systems and the amount that could be beneficial for the health. However, even after the process of fermentation, wine conserves different organic compounds from grapes, such as polysaccharides, acids, and phenolic compounds, such as flavonoids and nonflavonoids. These substances have known anti-inflammatory and antioxidant capacities, and are considered as regulatory agents in cardiometabolic process. In this study, the main chemical components present in the wine, its interaction with molecules and biological mechanisms, and their interference with intra- and extracellular signaling are reviewed. Finally, the properties of wine that may benefit cardiovascular system are also revised.

Vasculoprotective Effects of Dietary Cocoa Flavanols in Patients on Hemodialysis: A Double-Blind, Randomized, Placebo-Controlled Trial

BACKGROUND AND OBJECTIVES

Hemodialysis (HD) per se entails vascular dysfunction in patients with ESRD. Endothelial dysfunction is a key step in atherosclerosis and is characterized by impaired flow-mediated dilation (FMD). Interventional studies have shown that cocoa flavanol (CF)-rich supplements improve vascular function. Aim of this study was to investigate the effect of flavanol-rich bioactive food ingredients on acute and chronic HD-induced vascular dysfunction in ESRD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a randomized, double-blind, placebo-controlled trial from 2012 to 2013. Fifty-seven participants were enrolled, ingested CF-rich beverages (900 mg CF per study day), and were compared with those ingesting CF-free placebo. This included (1) a baseline cross-over acute study to determine safety and efficacy of CF and (2) a subsequent chronic parallel group study with a 30-day follow-up period to study effects of CF on HD-mediated vascular dysfunction entailing (3) an acute substudy during HD in flavanol-naive patients and (4) an acute on chronic study during HD. Primary and secondary outcome measures included changes in FMD and hemodynamics.

RESULTS

CF ingestion was well tolerated. Acute ingestion improved FMD by 53% (3.2±0.6% to 4.8±0.9% versus placebo, 3.2±0.7% to 3.3±0.8%; P<0.001), with no effects on BP or heart rate. A 30-day ingestion of CF led to an increase in baseline FMD by 18% (3.4±0.9% to 3.9±0.8% versus placebo, 3.5±0.7% to 3.5±0.7%; P<0.001), with reduced diastolic BP (73±12 to 69±11 mmHg versus placebo, 70±11 to 73±13 mmHg; P=0.03) and increased heart rate (70±12 to 74±13 bpm versus placebo, 75±15 to 74±13 bpm; P=0.01). No effects were observed for placebo. Acute ingestion of CF during HD alleviated HD-induced vascular dysfunction (3.4±0.9% to 2.7±0.6% versus placebo, 3.5±0.7% to 2.0±0.6%; P<0.001). This effect was sustained throughout the study (acute on chronic, 3.9±0.9% to 3.0±0.7% versus placebo, 3.5±0.7% to 2.2±0.6; P=0.01).

CONCLUSIONS

Dietary CF ingestion mitigates acute HD-induced and chronic endothelial dysfunction in patients with ESRD and thus, improves vascular function in this high-risk population. Larger clinical trials are warranted to test whether this translates into an improved cardiovascular prognosis in patients with ESRD.

NADPH Oxidase Activity in Cerebral Arterioles Is a Key Mediator of Cerebral Small Vessel Disease-Implications for Prevention

Cerebral small vessel disease (SVD), a common feature of brain aging, is characterized by lacunar infarcts, microbleeds, leukoaraiosis, and a leaky blood-brain barrier. Functionally, it is associated with cognitive decline, dementia, depression, gait abnormalities, and increased risk for stroke. Cerebral arterioles in this syndrome tend to hypertrophy and lose their capacity for adaptive vasodilation. Rodent studies strongly suggest that activation of Nox2-dependent NADPH oxidase activity is a crucial driver of these structural and functional derangements of cerebral arterioles, in part owing to impairment of endothelial nitric oxide synthase (eNOS) activity. This oxidative stress may also contribute to the breakdown of the blood-brain barrier seen in SVD. Hypertension, aging, metabolic syndrome, smoking, hyperglycemia, and elevated homocysteine may promote activation of NADPH oxidase in cerebral arterioles. Inhibition of NADPH oxidase with phycocyanobilin from spirulina, as well as high-dose statin therapy, may have potential for prevention and control of SVD, and high-potassium diets merit study in this regard. Measures which support effective eNOS activity in other ways-exercise training, supplemental citrulline, certain dietary flavonoids (as in cocoa and green tea), and capsaicin, may also improve the function of cerebral arterioles. Asian epidemiology suggests that increased protein intakes may decrease risk for SVD; conceivably, arginine and/or cysteine-which boosts tissue glutathione synthesis, and can be administered as N-acetylcysteine-mediate this benefit. Ameliorating the risk factors for SVD-including hypertension, metabolic syndrome, hyperglycemia, smoking, and elevated homocysteine-also may help to prevent and control this syndrome, although few clinical trials have addressed this issue to date.

Gallic acid isolated from Spirogyra sp. improves cardiovascular disease through a vasorelaxant and antihypertensive effect

In this study, we investigated the vasorelaxant and antihypertensive effects of gallic acid (GA), a polyphenol isolated from the green alga Spirogyra sp., to assess its suitability as a therapeutic for cardiovascular diseases (CVDs). We examined the effect of GA on endothelium-dependent vasorelaxation in human umbilical vein endothelial cells (HUVECs). GA increased nitric oxide (NO) levels by increasing phosphorylation of endothelial nitric oxide synthase (eNOS), and its effect on NO production was attenuated by pretreatment with the eNOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). We also investigated its antihypertensive effect by examining GA-mediated inhibition of angiotensin-I converting enzyme (ACE). GA inhibited ACE with a half-maximal inhibitory concentration (IC50) value of 37.38 ± 0.39 μg/ml. In silico simulations revealed that GA binds to the active site of ACE (PDB: 1O86) with a binding energy of -270.487 kcal/mol. Furthermore, GA clearly reduced blood pressure in spontaneously hypertensive rats (SHR) to an extent comparable to captopril. These results suggest that GA isolated from Spirogyra sp. exerts multiple therapeutic effects and has potential as a CVD treatment.

Fruit extract from a Sechium edule hybrid induce apoptosis in leukaemic cell lines but not in normal cells

The antiproliferative potential of a crude extract from the chayote hybrid H-837-07-GISeM® and its potential for apoptosis induction were assessed in leukaemic cell lines and normal mouse bone marrow mononuclear cells (BM-MNCs). The extract strongly inhibited the proliferation of the P388, J774, and WEHI-3 cell lines (with an IC50 below 1.3 μg·mL(-1)), reduced cell viability, and induced apoptotic body production, phosphatidylserine translocation, and DNA fragmentation. However, the extract had no effect on BM-MNCs. We postulate that these properties make the extract a good candidate for an anti-tumour agent for clinical use.

Daily blueberry consumption improves blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension: a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Postmenopausal women have a high prevalence of hypertension and often develop arterial stiffness thereby increasing cardiovascular disease risk. Although antihypertensive drug therapies exist, increasing numbers of people prefer natural therapies. In vivo studies and a limited number of clinical studies have demonstrated the antihypertensive and vascular-protective effects of blueberries.

OBJECTIVE

To examine the effects of daily blueberry consumption for 8 weeks on blood pressure and arterial stiffness in postmenopausal women with pre- and stage 1-hypertension.

DESIGN

This was an 8-week, randomized, double-blind, placebo-controlled clinical trial.

PARTICIPANTS/SETTING

Forty-eight postmenopausal women with pre- and stage 1-hypertension recruited from the greater Tallahassee, FL, area participated.

INTERVENTION

Participants were randomly assigned to receive either 22 g freeze-dried blueberry powder or 22 g control powder.

MAIN OUTCOME MEASURES

Resting brachial systolic and diastolic blood pressures were evaluated and arterial stiffness was assessed using carotid-femoral pulse wave velocity and brachial-ankle pulse wave velocity. C-reactive protein, nitric oxide, and superoxide dismutase were measured at baseline, 4 weeks, and 8 weeks.

STATISTICAL ANALYSES PERFORMED

Statistical analysis was performed using a split plot model of repeated measures analysis of variance.

RESULTS

After 8 weeks, systolic blood pressure and diastolic blood pressure (131±17 mm Hg [P<0.05] and 75±9 mm Hg [P<0.01], respectively) and brachial-ankle pulse wave velocity (1,401±122 cm/second; P<0.01) were significantly lower than baseline levels (138±14 mm Hg, 80±7 mm Hg, and 1,498±179 cm/second, respectively), with significant (P<0.05) group×time interactions in the blueberry powder group, whereas there were no changes in the group receiving the control powder. Nitric oxide levels were greater (15.35±11.16 μmol/L; P<0.01) in the blueberry powder group at 8 weeks compared with baseline values (9.11±7.95 μmol/L), whereas there were no changes in the control group.

CONCLUSIONS

Daily blueberry consumption may reduce blood pressure and arterial stiffness, which may be due, in part, to increased nitric oxide production.

Vasorelaxing and antihypertensive effects of 7,8-dihydroxyflavone

BACKGROUND

Although 7,8-dihydroxyflavone (7,8-DHF) has been demonstrated to be potently neuroprotective, its effect on vascular function remains unknown.

METHODS

The effect of 7,8-DHF on phenylephrine (PE)-induced preconstriction was examined with aortic rings isolated from normal rats. Its effective mechanisms were studied with blockers, Western blotting, and primarily cultured vascular smooth myocytes. The blood pressure (BP) of rats was measured with a tail cuff method.

RESULTS

7,8-DHF dose-dependently dilated the PE-preconstricted, endothelia-intact aortic rings with concentration for 50% of maximal effect (EC50) of approximately 24 µM. Both Nω-nitro-L-arginine methyl ester hydrochloride, a nitric oxide synthase inhibitor, and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a soluble guanylyl cyclase blocker, significantly reduced the vasorelaxing effect of 7,8-DHF. Western blotting showed that 7,8-DHF increased the aortic endothelial nitric oxide synthase protein expression and phosphorylation. With endothelia removed, 7,8-DHF also dilated the PE-preconstricted rings but with EC50 of approximately 104 µM. Ca(2+) imaging experiments detected that 7,8-DHF probably blocked both intracellular Ca(2+) release and extracellular Ca(2+) influx. Therefore, the mechanisms of 7,8-DHF dilating effect might be stimulating the nitric oxide/cGMP production and blocking the Ca(2+) signaling pathway instead of tropomyosin receptor kinase B receptors because ANA-12, its specific antagonist, did not show any effect against 7,8-DHF. When administered intravenously, 7,8-DHF significantly reduced the BP of the spontaneously hypertensive rats. However, when used orally, there was only a slight but significant reduction in the diastolic pressure.

CONCLUSIONS

The results suggest that neuro-protective 7,8-DHF is also a vasorelaxing and antihypertensive substance in rats.

Gallic acid tailoring surface functionalities of plasma-polymerized allylamine-coated 316L SS to selectively direct vascular endothelial and smooth muscle cell fate for enhanced endothelialization

The creation of a platform for enhanced vascular endothelia cell (VEC) growth while suppressing vascular smooth muscle cell (VSMC) proliferation offers possibility for advanced coatings of vascular stents. Gallic acid (GA), a chemically unique phenolic acid with important biological functions, presents benefits to the cardiovascular disease therapy because of its superior antioxidant effect and a selectivity to support the growth of ECs more than SMCs. In this study, GA was explored to tailor such a multifunctional stent surface combined with plasma polymerization technique. On the basis of the chemical coupling reaction, GA was bound to an amine-group-rich plasma-polymerized allylamine (PPAam) coating. The GA-functionalized PPAam (GA-PPAam) surface created a favorable microenvironment to obtain high ECs and SMCs selectivity. The GA-PPAam coating showed remarkable enhancement in the adhesion, viability, proliferation, migration, and release of nitric oxide (NO) of human umbilical vein endothelial cells (HUVECs). The GA-PPAam coating also resulted in remarkable inhibition effect on human umbilical artery smooth muscle cell (HUASMC) adhesion and proliferation. These striking findings may provide a guide for designing the new generation of multifunctional vascular devices.

Vasorelaxant and antihypertensive effects of methanolic extracts from Hymenocardia acida Tul

ETHNOPHARMACOLOGICAL RELEVANCE

In Congolese traditional medicine, decoctions of Hymenocardia acida root bark (HaRB) and trunk bark (HaTrB) are used for the treatment of conditions assumed to be hypertension. In this work, we propose to study the vasorelaxant effect of HaRB and HaTrB methanolic extracts on isolated rat thoracic aorta, to characterize the group of molecules responsible for the observed vasorelaxant activity, to evaluate the in vitro antioxidant activity of these extracts and to determine the antihypertensive activity of the HaRB extract on spontaneously hypertensive rats (SHR).

MATERIALS AND METHODS

The vasorelaxant effect of the HaRB and HaTrB methanolic extracts was studied on endothelium-intact aortic rings pre-contracted with phenylephrine (PE, 1μM). The mechanism of this vasorelaxant effect was investigated on endothelium-denuded vessels and on endothelium-intact aortic rings in the presence of three inhibitors: l-N(G)-nitroarginine methyl ester (100μM), indomethacin (10μM) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (10μM). To determine the nature of the compounds responsible for the vasorelaxant activity, we carried out a fractionation of the extracts and a thiolysis of the most active fraction followed by a liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) analysis. The extracts antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetric assay. In vivo anti-hypertensive activity of the HaRB extract was conducted on SHR.

RESULTS

HaRB and HaTrB methanolic extracts produced a concentration-dependent vasorelaxation on intact aortic rings pre-contracted with PE (1μM). The vasorelaxant responses obtained were 95.3±1.5% (5μg/ml) and 100.6±3.0% (1μg/ml), respectively. The effect was markedly attenuated by removal of endothelium or pretreatment of aortic rings with all inhibitors except indomethacin. The LC/ESI-MS analysis of the thiolysis products indicated that the fraction which caused the most important vasorelaxation (97.9±2.5% at 3μg/ml) was a mixture of procyanidins and prodelphinidins, with a predominance of procyanidins. Both extracts and all fractions from HaRB extract showed a DPPH scavenging activity, ranging from 0.4 to 0.8 quercetin-equivalents. The HaRB methanolic extract reduced the systolic blood pressure in SHR (from 214±3mmHg to 194±4mmHg) after a 5-week treatment.

CONCLUSIONS

The methanolic extracts of Hymenocardia acida root and trunk bark have vasorelaxant activity. The vasorelaxant effect observed is endothelium-dependent and seems mainly mediated through the NO-cGMP pathway. The COX pathway is not involved. The vasorelaxant activity appears to be due to polymeric procyanidins and prodelphinidins. These extracts also have an antioxidant effect. The extract of Hymenocardia acida root bark shows a significant but weak antihypertensive activity in SHR.

Beneficial effects of polyphenols on cardiovascular disease

In recent years, numerous studies have demonstrated the health benefits of polyphenols, and special attention has been paid to their beneficial effects against cardiovascular disease, the leading cause of death in the world today. Polyphenols present vasodilator effects and are able to improve lipid profiles and attenuate the oxidation of low density lipoproteins. In addition, they present clear anti-inflammatory effects and can modulate apoptotic processes in the vascular endothelium. It has been suggested that most of these effects are a consequence of the antioxidant properties of polyphenols, but this idea is not completely accepted, and many other mechanisms have been proposed recently to explain the health effects of these compounds. In fact, different signaling pathways have been linked to polyphenols. This review brings together some recent studies which establish the beneficial properties of polyphenols for cardiovascular disease and analyzes the mechanisms involved in these properties.

Is it merely a myth that alcoholic beverages such as red wine can be cardioprotective?

It has been suggested that although the negative impact of alcohol consumption varies from person to person, on a global level the adverse effect of alcohol on cardiovascular disease outweighs any protective effect by between two- and three-fold. This is inaccurate. There is a proven positive relationship between alcohol consumption and cardiovascular disease that is acknowledged by the World Health Organization. For example, moderate alcohol consumption reduces the risk of cardiovascular disease by approximately 25%, such that alcohol consumption per se accounts for -4.7% of the total cardiovascular disease burden in Australia. Correspondingly, cardiovascular disease accounted for 34% of the total number of deaths in Australia in 2008, and 18% of the overall burden of disease in Australia in 2003, with coronary heart disease and stroke contributing over 80% of this burden. Australia is not substantially different from other developed countries having similar demographics to, and the same leading causes of burden as, other high-income developed countries. This article examines the suggestions and evidence surrounding the relationship between light-to-moderate alcohol consumption and benefits to human health.

Vascular effects and antioxidant activity of two Combretum species from Democratic Republic of Congo

ETHNOPHARMACOLOGICAL RELEVANCE

Combretum racemosum P. Beauv (Combretaceae) leaves (CrLv) and root bark (CrRB) and Combretum celastroides subsp. laxiflorum Welw (Combretaceae) leaves (ClLv) are used in Congolese traditional medicine for several therapeutic purposes, notably for the treatment of conditions consistent with hypertension. The present study aims to investigate the vasorelaxant and in vitro antioxidant activities of these plants polar extracts and to examine the in vivo antihypertensive effect of the extract which displays the most potent vasorelaxant effect.

MATERIAL AND METHODS

The vasorelaxant effect of CrLv, CrRB and ClLv methanolic extracts was studied on rat aorta rings pre-contracted with phenylephrine (PE, 1 μM) in the presence or absence of the endothelium. In some experiments, prior to the addition of the extract, rings were incubated for 30 min with either L-N(G)-nitroarginine methyl ester (L-NAME; 100 μM), a nitric oxide synthase (NOS) inhibitor, indomethacin (10 μM), a cyclooxygenase inhibitor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM), a guanylate cyclase inhibitor. The antioxidant activity was determined by the measurement of the scavenging ability of extracts towards the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Blood pressure was measured on normotensive Wistar rats and spontaneously hypertensive rats (SHR) treated orally with a daily dose (40 mg/kg) of the CILv extract for 5 weeks. Tested extracts have been characterised by TLC profiles targeted at flavonoids.

RESULTS

All tested extracts showed an important DPPH scavenging activity, ranging from 0.6 to 1.1 quercetin-equivalents. They caused a concentration-dependent vasorelaxation on intact aortic rings pre-contracted with PE (1 μM). The responses to CrRB and CrLv methanolic extracts reached 74.0±5.1% and 62.2±8.6% at a cumulative concentration of 50 μg/ml, respectively. The ClLv (10 μg/ml) extract was more active and, in the same conditions, relaxed aortic rings by 90.3±5.8%. The vasorelaxant activity of all extracts disappeared or was significantly attenuated by removal of the endothelium or after pretreatment with L-NAME or ODQ. Indomethacin only inhibited the activity of CrLv and CrRB extracts. The ClLv extract was able to lower the systolic blood pressure in SHR rats by 7% after a 5-week treatment.

CONCLUSIONS

The present study shows that methanolic extracts from ClLv, CrRB and CrLv have an antioxidant activity and an endothelium-dependent vasorelaxant effect. ClLv induces the vasorelaxant effect through the NO-cGMP pathway while CrLv and CrRB extracts also act via a prostanoid pathway. ClLv extract demonstrated a modest but significant antihypertensive activity in SHR rats.

Extract of Scutellaria baicalensis Georgi root exerts protection against myocardial ischemia-reperfusion injury in rats

Ischemic heart disease is a major cause of death in the world. Common therapies, such as primary coronary angioplasty and thrombolysis, are applied to restore blood supply to the heart, limit infarct size and reduce mortality. However, the restoration of blood supply would generate reactive oxygen species in damaged sites of the myocardium, intensifying the damage to the cardiac tissues. Radix Scutellariae baicalensis (Huangqin) is a well-known herb in traditional Chinese medicine with high antioxidant power. In this study, extract of the dry root of Scutellaria baicalensis Georgi (Sb) was confirmed to have a high content of flavonoids and phenolic compounds. The cardioprotective effects of the Sb extracts (3, 30 and 300 mg/kg) were evaluated in myocardial ischemia-reperfusion injuried rats. The results showed that animals that had received five-day pretreatment of the Sb extract (30 mg/kg) had a significant reduction in myocardial infarct size and a marked increase in the activity of catalase in the liver. The Sb extract could additionally enhance acetylcholine-induced vasorelaxation. It was proposed that the Sb extract exerted its cardioprotection by stimulating the catalase activity and improving vascular elasticity.

Vasorelaxant and hypotensive effects of the extract and the isolated flavonoid rutin obtained from Polygala paniculata L

Objectives

This study aimed to investigate the in-vitro and in-vivo cardiovascular effects of the crude hydroalcoholic extract from Polygala paniculata (HEPP) in rats.

Methods

The procedures were performed on aortic rings and on normotensive anaesthetized rats.

Key findings

When tested in endothelium-intact aorta rings, HEPP (30–1000 µg/ml) produced a significant non-concentration-dependent relaxing effect (∼40%), which was completely prevented by incubation with L-NAME (nitric oxide synthase inhibitor), ODQ (soluble guanylate cyclase inhibitor) and partially inhibited by tetraethylammonium (TEA; a non-selective potassium channel blocker) and charybdotoxin (a large- and intermediate-conductance calcium-activated potassium channel blocker). In contrast, atropine (a muscarinic receptor antagonist) or pyrilamine(a histamine H1 receptor antagonist) had no effect. Furthermore, oral administration of HEPP (30–300 mg/kg) in anaesthetized rats caused a dose-dependent and sustained hypotensive action. This effect was unchanged by atropine or TEA, but was strongly reduced in rats continuously infused with L-NAME or methylene blue. Moreover, rutin (1–3 mg/kg) administered by an intravenous route also caused a dose-dependent hypotensive effect in rats.

Conclusions

Our results demonstrated that the extract obtained from P. paniculata induces potent hypotensive and vasorelaxant effects that are dependent on the nitric oxide/guanylate cyclase pathway. These effects could be related, at least in part, to the rutin contents in this extract.

Flavanols and cardiovascular disease prevention

Diet is a major lifestyle factor in the primary and secondary prevention of numerous chronic diseases, including myocardial infarction, stroke, and diabetes. Epidemiological studies suggest that the beneficial cardiovascular health effects of diets rich in fruits and vegetables are in part mediated by their flavonoid content, with particular benefits provided by one member of this family, the flavanols. This concept is supported by findings from small-scale intervention studies with surrogate endpoints including endothelium-dependent vasodilation, blood pressure, platelet function, and glucose tolerance. Mechanistically, short-term effects on endothelium-dependent vasodilation following the consumption of flavanol-rich foods, as well as purified flavanols, have been linked to an increased nitric oxide bioactivity in healthy humans, and those with increased cardiovascular risk. The critical biological target(s) for flavanols have yet to be identified and the extent to which these acute results are important in the context of long-term human health is unknown. While flavanols represent a promising class of food components with respect to their ability to lower cardiovascular risk the flavanol-rich foods used in many trials have been poorly defined with respect to their flavanol content and flavanol-isomer profile; several studies have lacked appropriate controls, and the long-term randomized controlled intervention trials with flavanol-rich foods are missing. Thus, while the literature regarding flavanols and vascular health is encouraging, more in-depth and well-controlled clinical and experimental studies are needed to better define the potential protective vascular effects of these nutrients and their therapeutic value in cardiovascular medicine.

Flavonols and cardiovascular disease

Flavonols, and specially quercetin, are widely distributed in plants and are present in considerable amounts in fruits and vegetables. In addition to their anti-oxidant effect, flavonols interfere with a large number of biochemical signaling pathways and, therefore, physiological and pathological processes. There is solid evidence that, in vitro, quercetin and related flavonols exert endothelium-independent vasodilator effects, protective effect on nitric oxide and endothelial function under conditions of oxidative stress, platelet antiaggregant effects, inhibition of LDL oxidation, reduction of adhesion molecules and other inflammatory markers and prevention of neuronal oxidative and inflammatory damage. The metabolites of quercetin show partial protective effects on endothelial function and LDL oxidation. Quercetin produces undisputed antihypertensive and antiatherogenic effects, prevents endothelial dysfunction and protects the myocardium from ischemic damage. It has no clear effects on serum lipid profile and on insulin resistance. Human intervention trials with isolated flavonols demonstrate an antihypertensive effect. The meta-analysis of epidemiological studies show an inverse association between flavonol (together with flavone) intake and coronary heart disease and stroke. Therefore, although there is no solid proof yet, a substantial body of evidence suggests that quercetin may prevent the most common forms of cardiovascular disease contributing to the protective effects afforded by fruits and vegetables.

Effects of resveratrol and flavonols on cardiovascular function: Physiological mechanisms

Resveratrol and flavonols are commonly found together in fruits and vegetables and, therefore, consumed in the diet. These two polyphenols share both vasorelaxant and antioxidant activity and may act together to improve cardiovascular function. This review examines the mechanisms by which resveratrol and flavonols influence cardiovascular function and perhaps offer a new approach for the development of therapeutic agents for the prevention and/or treatment of coronary artery disease.