Cocoa flavanols lower vascular arginase activity in human endothelial cells in vitro and in erythrocytes in vivo

Short-term cocoa bioflavanol supplementation does not improve cold-induced vasodilation in young healthy adults

PURPOSE

Cold-induced vasodilation (CIVD) is an oscillatory rise in blood flow to glabrous skin that occurs in cold-exposed extremities. Dietary flavanols increase bioavailable nitric oxide, a proposed mediator of CIVD through active vasodilation and/or withdrawal of sympathetic vascular smooth muscle tone. However, no studies have examined the effects of flavanol intake on extremity skin perfusion during cold exposure. We tested the hypothesis that acute and 8-day flavanol supplementation would augment CIVD during single-digit cold water immersion (CWI).

METHODS

Eleven healthy adults (24 ± 6 years; 10 M/1F) ingested cocoa flavanols (900 mg/day) or caffeine- and theobromine-matched placebo for 8 days in a double-blind, randomized, crossover design. On Days 1 and 8, CIVD was assessed 2 h post-treatment. Subjects immersed their 3rd finger in warm water (42 °C) for 15 min before CWI (4 °C) for 30 min, during which nail bed and finger pad skin temperature were measured.

RESULTS

Flavanol ingestion had no effect on CIVD frequency (Day 1, Flavanol: 3 ± 2 vs. Placebo: 3 ± 2; Day 8, Flavanol: 3 ± 2 vs. Placebo: 3 ± 1) or amplitude (Day 1, Flavanol: 4.3 ± 1.7 vs. Placebo: 4.9 ± 2.6 °C; Day 8, Flavanol: 3.9 ± 1.9 vs. Placebo: 3.9 ± 2.0 °C) in the finger pad following acute or 8-day supplementation (P > 0.05). Furthermore, average, nadir, and apex finger pad temperatures during CWI were not different between treatments on Days 1 or 8 of supplementation (P > 0.05). Similarly, no differences in CIVD parameters were observed in the nail bed following supplementation (P > 0.05).

CONCLUSION

These data suggest that cocoa flavanol ingestion does not alter finger CIVD. Clinical Trial Registration Clinicaltrials.gov Identifier: NCT04359082. April 24, 2020.

(Poly)phenols and nitrolipids: Relevant participants in nitric oxide metabolism

Nitric oxide (^•NO) is an essential molecule able to control and regulate many biological functions. Additionally, ^•NO bears a potential toxicity or damaging effects under conditions of uncontrolled production, and because of its participation in redox-sensitive pathways and oxidizing reactions. Several plant (poly)phenols present in the diet are able to regulate the enzymes producing ^•NO (NOSs). In addition, (poly)phenols are implicated in defining ^•NO bioavailability, especially by regulating NADPH oxidases (NOXs), and the subsequent generation of superoxide and ^•NO depletion. Nitrolipids are compounds that are present in animal tissues because of dietary consumption, e.g. of olive oil, and/or as result of endogenous production. This endogenous production of nitrolipids is dependent on the nitrate/nitrite presence in the diet. Select nitrolipids, e.g. the nitroalkenes, are able to exert ^•NO-like signaling actions, and act as ^•NO reservoirs, becoming relevant for systemic ^•NO bioavailability. Furthermore, the presence of (poly)phenols in the stomach reduces dietary nitrite to ^•NO favoring nitrolipids formation. In this review we focus on the capacity of molecules representing these two groups of bioactives, i.e. (poly)phenols and nitrolipids, as relevant participants in ^•NO metabolism and bioavailability. This participation acquires especial relevance when human homeostasis is lost, for example under inflammatory conditions, in which the protective actions of (poly)phenols and/or nitrolipids have been associated with local and systemic ^•NO bioavailability.

(-)-Epicatechin Alters Reactive Oxygen and Nitrogen Species Production Independent of Mitochondrial Respiration in Human Vascular Endothelial Cells

Introduction

Vascular endothelial dysfunction is characterised by lowered nitric oxide (NO) bioavailability, which may be explained by increased production of reactive oxygen species (ROS), mitochondrial dysfunction, and altered cell signalling. (-)-Epicatechin (EPI) has proven effective in the context of vascular endothelial dysfunction, but the underlying mechanisms associated with EPI's effects remain unclear. Objective(s). Our aim was to investigate whether EPI impacts reactive oxygen and nitrogen species (RONS) production and mitochondrial function of human vascular endothelial cells (HUVECs). We hypothesised that EPI would attenuate ROS production, increase NO bioavailability, and enhance indices of mitochondrial function.

Methods

HUVECs were treated with EPI (0-20 μM) for up to 48 h. Mitochondrial and cellular ROS were measured in the absence and presence of antimycin A (AA), an inhibitor of the mitochondrial electron transport protein complex III, favouring ROS production. Genes associated with mitochondrial remodelling and the antioxidant response were quantified by RT-qPCR. Mitochondrial bioenergetics were assessed by respirometry and signalling responses determined by western blotting.

Results

Mitochondrial superoxide production without AA was increased 32% and decreased 53% after 5 and 10 μM EPI treatment vs. CTRL (P < 0.001). With AA, only 10 μM EPI increased mitochondrial superoxide production vs. CTRL (25%, P < 0.001). NO bioavailability was increased by 45% with 10 μM EPI vs. CTRL (P = 0.010). However, EPI did not impact mitochondrial respiration. NRF2 mRNA expression was increased 1.5- and 1.6-fold with 5 and 10 μM EPI over 48 h vs. CTRL (P = 0.015 and P = 0.001, respectively). Finally, EPI transiently enhanced ERK1/2 phosphorylation (2.9 and 3.2-fold over 15 min and 1 h vs. 0 h, respectively; P = 0.035 and P = 0.011). Conclusion(s). EPI dose-dependently alters RONS production of HUVECs but does not impact mitochondrial respiration. The induction of NRF2 mRNA expression with EPI might relate to enhanced ERK1/2 signalling, rather than RONS production. In humans, EPI may improve vascular endothelial dysfunction via alteration of RONS and activation of cell signalling.

An Update on Arginase Inhibitors and Inhibitory Assays

Arginase, which converts arginine into ornithine and urea, is a promising therapeutic target. Arginase is involved in cardiovascular diseases, parasitic infections and, through a critical role in immunity, in some cancers. There is a need to develop effective arginase inhibitors and therefore efforts to identify and optimize new inhibitors are increasing. Several methods of evaluating arginase activity are available, but few directly measure the product. Radiometric assays need to separate urea and dying reactions require acidic conditions and sometimes heating. Hence, there are a variety of different approaches available, and each approach has its own limits and benefits. In this review, we provide an update on arginase inhibitors, followed by a discussion on available arginase assays and alternative methods, with a focus on the intrinsic biases and parameters that are likely to impact results.

( -)-Epicatechin and cardiometabolic risk factors: a focus on potential mechanisms of action

This review summarizes experimental evidence on the beneficial effects of ( -)-epicatechin (EC) attenuating major cardiometabolic risk factors, i.e., dyslipidemias, obesity (adipose tissue dysfunction), hyperglycemia (insulin resistance), and hypertension (endothelial dysfunction). Studies in humans are revised and complemented with experiments in animal models, and cultured cells, aiming to understand the molecular mechanisms involved in EC-mediated effects. Firstly, an assessment of EC metabolism gives relevance to both conjugated-EC metabolites product of host metabolism and microbiota-derived species. Integration and analysis of results stress the maintenance of redox homeostasis and mitigation of inflammation as relevant processes associated with cardiometabolic diseases. In these processes, EC appears having significant effects regulating NADPH oxidase (NOX)-dependent oxidant production, nitric oxide (NO) production, and energy homeostasis (mitochondrial biogenesis and function). The potential participation of cell membranes and membrane-bound receptors is also discussed in terms of direct molecular action of EC and EC metabolites reaching cells and tissues.

Dietary Cocoa Flavanols Enhance Mitochondrial Function in Skeletal Muscle and Modify Whole-Body Metabolism in Healthy Mice

Mitochondrial dysfunction is widely reported in various diseases and contributes to their pathogenesis. We assessed the effect of cocoa flavanols supplementation on mitochondrial function and whole metabolism, and we explored whether the mitochondrial deacetylase sirtuin-3 (Sirt3) is involved or not. We explored the effects of 15 days of CF supplementation in wild type and Sirt3^-/- mice. Whole-body metabolism was assessed by indirect calorimetry, and an oral glucose tolerance test was performed to assess glucose metabolism. Mitochondrial respiratory function was assessed in permeabilised fibres and the pyridine nucleotides content (NAD⁺ and NADH) were quantified. In the wild type, CF supplementation significantly modified whole-body metabolism by promoting carbohydrate use and improved glucose tolerance. CF supplementation induced a significant increase of mitochondrial mass, while significant qualitative adaptation occurred to maintain H₂O₂ production and cellular oxidative stress. CF supplementation induced a significant increase in NAD⁺ and NADH content. All the effects mentioned above were blunted in Sirt3^-/- mice. Collectively, CF supplementation boosted the NAD metabolism that stimulates sirtuins metabolism and improved mitochondrial function, which likely contributed to the observed whole-body metabolism adaptation, with a greater ability to use carbohydrates, at least partially through Sirt3.

Systematic bioinformatic analysis of nutrigenomic data of flavanols in cell models of cardiometabolic disease

Flavanol intake positively influences several cardiometabolic risk factors in humans. However, the specific molecular mechanisms of action of flavanols, in terms of gene regulation, in the cell types relevant to cardiometabolic disease have never been systematically addressed. On this basis, we conducted a systematic literature review and a comprehensive bioinformatic analysis of genes whose expression is affected by flavanols in cells defining cardiometabolic health: hepatocytes, adipocytes, endothelial cells, smooth muscle cells and immune cells. A systematic literature search was performed using the following pre-defined criteria: treatment with pure compounds and metabolites (no extracts) at low concentrations that are close to their plasma concentrations. Differentially expressed genes were analyzed using bioinformatics tools to identify gene ontologies, networks, cellular pathways and interactions, as well as transcriptional and post-transcriptional regulators. The systematic literature search identified 54 differentially expressed genes at the mRNA level in in vitro models of cardiometabolic disease exposed to flavanols and their metabolites. Global bioinformatic analysis revealed that these genes are predominantly involved in inflammation, leukocyte adhesion and transendothelial migration, and lipid metabolism. We observed that, although the investigated cells responded differentially to flavanol exposure, the involvement of anti-inflammatory responses is a common mechanism of flavanol action. We also identified potential transcriptional regulators of gene expression: transcriptional factors, such as GATA2, NFKB1, FOXC1 or PPARG, and post-transcriptional regulators: miRNAs, such as mir-335-5p, let-7b-5p, mir-26b-5p or mir-16-5p. In parallel, we analyzed the nutrigenomic effects of flavanols in intestinal cells and demonstrated their predominant involvement in the metabolism of circulating lipoproteins. In conclusion, the results of this systematic analysis of the nutrigenomic effects of flavanols provide a more comprehensive picture of their molecular mechanisms of action and will support the future setup of genetic studies to pave the way for individualized dietary recommendations.

Effects of (-)-epicatechin on mitochondria

Mitochondrial dysfunction is observed in a broad range of human diseases, including rare genetic disorders and complex acquired pathologies. For this reason, there is increasing interest in identifying safe and effective strategies to mitigate mitochondrial impairments. Natural compounds are widely used for multiple indications, and their broad healing properties suggest that several may improve mitochondrial function. This review focuses on (-)-epicatechin, a monomeric flavanol, and its effects on mitochondria. The review summarizes the available data on the effects of acute and chronic (-)-epicatechin supplementation on mitochondrial function, outlines the potential mechanisms involved in mitochondrial biogenesis induced by (-)-epicatechin supplementation and discusses some future therapeutic applications.

Linking biomarkers of oxidative stress and disease with flavonoid consumption: From experimental models to humans

Identification of the links among flavonoid consumption, mitigation of oxidative stress and improvement of disease in humans has significantly advanced in the last decades. This review used (−)-epicatechin (EC) as an example of dietary flavonoids, and inflammation, endothelial dysfunction/hypertension and insulin resistance/diabetes as paradigms of human disease. In these pathologies, oxidative stress is part of their development and/or their perpetuation. Evidence from both, rodent studies and characterization of mechanisms in cell cultures are encouraging and mostly support indirect antioxidant actions of EC and EC metabolites in endothelial dysfunction and insulin resistance. Human studies also show beneficial effects of EC on these pathologies based on biomarkers of disease. However, there is limited available information on oxidative stress biomarkers and flavonoid consumption to allow establishing conclusive associations. The evolving discovery of metabolites that could serve as reliable markers of intake of specific flavonoids constitutes a powerful tool to link flavonoid consumption to disease and prevention of oxidative stress in human populations.

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Flavonoid’s metabolism and concentration determine their antioxidant mechanisms.

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Except for the GI tract, flavonoids are relevant indirect antioxidants in organs and tissues.

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Flavonoid's health effects are not always linked to biomarkers of oxidative stress.

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(‒)-Epicatechin mitigates the redox deregulation involved in hypertension/T2D pathogenesis.

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More human studies will strength links among flavonoids, oxidative stress, and disease.

Arginase inhibition by (-)-Epicatechin reverses endothelial cell aging

Endothelial dysfunction (EnD) occurs with aging and endothelial nitric oxide (NO) production by NO synthase (NOS) can be impaired. Low NO levels have been linked to increased arginase (Ar) activity as Ar competes with NOS for L-arginine. The inhibition of Ar activity can reverse EnD and (-)-epicatechin (Epi) inhibits myocardial Ar activity. In this study, through in silico modeling we demonstrate that Epi interacts with Ar similarly to its inhibitor Norvaline (Norv). Using in vitro and in vivo models of aging, we examined Epi and Norv-inhibition of Ar activity and its endothelium-protective effects. Bovine coronary artery endothelial cells (BCAEC) were treated with Norv (10 μM), Epi (1 μM) or the combination (Epi + Norv) for 48 h. Ar activity increased in aged BCAEC, with decreased NO generation. Treatment decreased Ar activity to levels seen in young cells. Epi and Epi + Norv decreased nitrosylated Ar levels by ~25% in aged cells with lower oxidative stress (~25%) (dihydroethidium) levels. In aged cells, Epi and Epi + Norv restored the eNOS monomer/dimer ratio, protein expression levels and NO production to those of young cells. Furthermore, using 18 month old rats 15 days of treatment with either Epi (1 mg/kg), Norv (10 mg/kg) or combo, decreased hypertension and improved aorta vasorelaxation to acetylcholine, blood NO levels and tetra/dihydribiopterin ratios in cultured rat aortic endothelial cells. In conclusion, results provide evidence that inhibiting Ar with Epi reverses aged-related loss of eNOS function and improves vascular function through the modulation of Ar and eNOS protein levels and activity.

The Effects of Flavonoids in Cardiovascular Diseases

Flavonoids are metabolites of plants and fungus. Flavonoid research has been paid special attention to in recent times after the observation of their beneficial effects on the cardiovascular system. These favorable effects are exerted by flavonoids mainly due to their antioxidant properties, which result from the ability to decrease the oxidation of low-density lipoproteins, thus improving the lipid profiles. The other positive effect exerted on the cardiovascular system is the ability of flavonoids to produce vasodilation and regulate the apoptotic processes in the endothelium. Researchers suggested that these effects, including their anti-inflammatory function, are consequences of flavonoids' potent antioxidant properties, but recent studies have shown multiple signaling pathways linked to them, thus suggesting that there are more mechanisms involved in the beneficial effect of the flavonoids on the human body. This review aims to present the latest data on the classification of these substances, their main mechanisms of action in the human body, and the beneficial effects on the physiological and pathological status of the cardiovascular system.

Antunes I, Dömling A, H. Elsinga P. Arginase as a Potential Biomarker of Disease Progression: A Molecular Imaging Perspective

Arginase is a widely known enzyme of the urea cycle that catalyzes the hydrolysis of L-arginine to L-ornithine and urea. The action of arginase goes beyond the boundaries of hepatic ureogenic function, being widespread through most tissues. Two arginase isoforms coexist, the type I (Arg1) predominantly expressed in the liver and the type II (Arg2) expressed throughout extrahepatic tissues. By producing L-ornithine while competing with nitric oxide synthase (NOS) for the same substrate (L-arginine), arginase can influence the endogenous levels of polyamines, proline, and NO•. Several pathophysiological processes may deregulate arginase/NOS balance, disturbing the homeostasis and functionality of the organism. Upregulated arginase expression is associated with several pathological processes that can range from cardiovascular, immune-mediated, and tumorigenic conditions to neurodegenerative disorders. Thus, arginase is a potential biomarker of disease progression and severity and has recently been the subject of research studies regarding the therapeutic efficacy of arginase inhibitors. This review gives a comprehensive overview of the pathophysiological role of arginase and the current state of development of arginase inhibitors, discussing the potential of arginase as a molecular imaging biomarker and stimulating the development of novel specific and high-affinity arginase imaging probes.

The sweet side of dark chocolate for chronic kidney disease patients

Chocolate is a widely appreciated foodstuff with historical appreciation as a food from the gods. In addition to its highly palatable taste, it is a rich source of (poly)phenolics, which have several proposed salutogenic effects, including neuroprotective anti-inflammatory, anti-oxidant and cardioprotective capabilities. Despite the known benefits of this ancient foodstuff, there is a paucity of information on the effects of chocolate in the context of chronic kidney disease (CKD). This review focusses on the potential salutogenic contribution of chocolate intake, to mitigate inflammatory and oxidative burden in CKD, its potential, for cardiovascular protection and on the maintenance of diversity in gut microbiota, as well as clinical perspectives, on regular chocolate intake by CKD patients.

The influence of different concentrations of flavanol chocolate bars under acute supplement conditions on exercise and performance

OBJECTIVE

The purpose of this study was to assess the effects and acute dosage of different flavanol concentrations in a dark chocolate bar on physiological parameters during steady state (SS) and incremental exercise.

METHODS

In a double-blind, randomised, crossover study, 15 healthy participants with a mean ± SD age of 30 ± 7 years; stature 176.8 ± 8.6 cm and body mass 80.3 ± 8.4 kg supplemented with high flavanol (HF) (1060 mg), moderate flavanol (MF) (746 mg), low flavanol (LF) (406 mg), or a control (CON) (88 mg) chocolate bar (~ 34 g), 2 h prior to 40 min of SS cycling (80% gas-exchange threshold) followed by an incremental test to volitional fatigue. During the SS cycle oxygen consumption ([Formula: see text]), respiratory exchange ratio (RER) and heart rate (HR) were continuously monitored. Plasma samples were collected prior to commencing exercise to determine nitrate (NO₃^-) and nitrite (NO₂^-) levels under each condition.

RESULTS

There was no observed effect between flavanol concentrations on [Formula: see text], RER, and HR during SS cycling (P > 0.05). [Formula: see text], peak power, HR peak, and RER peak also did not significantly differ between conditions (P > 0.05). There was a small trend for higher plasma NO₂^- levels following higher flavanol concentration; however, this did not reach statistical significance (P > 0.05).

CONCLUSION

Acute supplementation with cocoa of differing flavanol concentrations does not appear to have any effect on exercise and performance. It is plausible that longer flavanol supplementation periods might have greater accumulative effects and thus may potentially elicit a larger effect.

Diet, Lifestyle and Cardiovascular Diseases: Linking Pathophysiology to Cardioprotective Effects of Natural Bioactive Compounds

Heart and blood vessels disorders comprise one of the main causes of death worldwide. Pharmacologically active natural compounds have been used as a complementary therapy in cardiovascular disease around the world in a traditional way. Dietary, natural bioactive compounds, as well as healthy lifestyles, are considered to prevent coronary artery diseases. Pre-clinical and clinical studies reported that consumption of plant-food bioactive derivatives including polyphenolic compounds, peptides, oligosaccharides, vitamins, unsaturated fatty acids possess protective effects on cardiovascular diseases. This review aims to summarize the cardiovascular risk factors, pre-clinical studies and clinical trials related to cardioprotective properties of the plant-food-derived bioactive compounds. Molecular mechanisms by the natural bioactive compounds exert their cardiovascular protective properties have also been highlighted.

Chronic and acute effects of cocoa products intake on arterial stiffness and platelet count and function: A systematic review and dose-response Meta-analysis of randomized clinical trials

The findings of trials investigating the effect of cocoa products consumption on vascular stiffness and platelet are controversial. The aim of this study is to summarize the findings on the acute and chronic effects of different forms of cocoa on the risk factors of cardiovascular disease. We searched SCOPUS, Pub Med and Web of Science from inception to Jan 2020. Finally, the random-effect model was used to report the pooled effect sizes. Results are expressed as weighted mean difference (WMD) with 95% confidence intervals (CI).Overall, 41 trials were included, of which only 14 studies met the eligibility criteria for analysis, including 11 long-term RCTs (more than a week was considered as a chronic phase) and 7 short-term RCTs (less than a week was considered as an acute phase). According to the result of 11 long-term RCTs, cocoa products had a negative significant effect on pulse wave velocity; PWV (WMD: -0.33 m/s, P < 0.0001), Augmentation index; AIx (WMD: -4.50%, P = 0.001) but had no significant effect on platelet count (WMD: -10.41 10⁹/L, P = 0.053). Also, according to the results of 7 short-term RCTs, cocoa products had a negative significant effect on PWV (WMD: -0.27 m/s, P = 0.019), AIx (WMD: -4.47%, P = 0.003).Current study indicated the beneficial effect of acute and chronic consumption of cocoa-based products ingestion on platelet function and arterial stiffness in healthy adult regardless of age especially in male and for consumption (≤4 weeks) in the chronic intake and (≤120 minutes) in acute intake, but did not affect on platelet count. However, further studies are required to shed light on this issue.

Flavonoids and Reduction of Cardiovascular Disease (CVD) in Chronic Obstructive Pulmonary Disease (COPD)

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) and Cardiovascular Diseases (CV) Often Coexist. COPD and CVD are complex diseases characterized by a strict interaction between environment and genetic. The mechanisms linking these two diseases are complex, multifactorial and not entirely understood, influencing the therapeutic approach. COPD is characterized by several comorbidities, it hypothesized the treatment of cardiovascular co-morbidities that may reduce morbidity and mortality. Flavonoids are an important class of plant low molecular weight Secondary Metabolites (SMs). Convincing data from laboratory, epidemiological, and human clinical studies point the important effects on CVD risk prevention.

OBJECTIVE

This review aims to provide up-to-date information on the ability of Flavonoids to reduce the CVD risk.

CONCLUSION

Current studies support the potential of Flavonoids to prevent the risk of CVD. Well-designed clinical studies are suggested to evaluate advantages and limits of Flavonoids for managing CVD comorbidity in COPD.

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.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

The purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk.

Long term treatment with quercetin in contrast to the sulfate and glucuronide conjugates affects HIF1α stability and Nrf2 signaling in endothelial cells and leads to changes in glucose metabolism

Endothelial functionality profoundly contributes to cardiovascular health. The effects of flavonoids shown to improve endothelial performance include regulating blood pressure by modulating endothelial nitric oxide synthase and NADPH oxidases, but their impact on glucose uptake and metabolism has not been explored. We treated human umbilical vein endothelial cells (HUVEC) with the flavonoid quercetin and its circulating metabolites acutely and chronically, then assessed glucose uptake, glucose metabolism, gene transcription and protein expression. Acute treatment had no effect on glucose uptake, ruling out any direct interaction with sugar transporters. Long term treatment with quercetin, but not quercetin 3-O-glucuronide or 3'-O-sulfate, significantly increased glucose uptake. Heme oxygenase-1 (HO-1) was induced by quercetin but not its conjugates, but was not implicated in the glucose uptake stimulation since hemin, a classical inducer of HO-1, did not affect glucose metabolism. Quercetin increased stability of the transcription factor hypoxia induced factor 1α (HIF1α), a powerful stimulant of glucose metabolism, which was also paralleled by treatment with a prolyl-4-hydroxylase inhibitor dimethyloxalylglycine (DMOG). 6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), which regulates the rate of glycolysis, was upregulated by both quercetin and DMOG. Pyruvate dehydrogenase kinase (PDK) isoforms regulate pyruvate dehydrogenase; PDK2 and PDK4 were down-regulated by both effectors, but only DMOG also upregulated PDK1 and PDK3. Quercetin, but not DMOG, increased glucose-6-phosphate dehydrogenase. Chronic quercetin treatment also stimulated glucose transport across the HUVEC monolyer in a 3D culture model. Gene expression of several flavonoid transporters was repressed by quercetin, but this was either abolished (Organic anion transporter polypeptide 4C1) or reversed (Multidrug resistance gene 1) by both conjugates. We conclude that quercetin and its circulating metabolites differentially modulate glucose uptake/metabolism in endothelial cells, through effects on HIF1α and transcriptional regulation of energy metabolism.

Cocoa Flavanols: Natural Agents with Attenuating Effects on Metabolic Syndrome Risk Factors

The interest in cacao flavanols is still growing, as bioactive compounds with potential benefits in the prevention of chronic diseases associated with inflammation, oxidative stress and metabolic disorders. Several analytical methodologies support that the flavanols in cacao-derived products can be absorbed, have bioactive properties, and thus can be responsible for their beneficial effects on human health. However, it must be considered that their biological actions and underlying molecular mechanisms will depend on the concentrations achieved in their target tissues. Based on the antioxidant properties of cacao flavanols, this review focuses on recent advances in research regarding their potential to improve metabolic syndrome risk factors. Additionally, it has included other secondary plant metabolites that have been investigated for their protective effects against metabolic syndrome. Studies using laboratory animals or human subjects represent strong available evidence for biological effects of cacao flavanols. Nevertheless, in vitro studies are also included to provide an overview of these phytochemical mechanisms of action. Further studies are needed to determine if the main cacao flavanols or their metabolites are responsible for the observed health benefits and which are their precise molecular mechanisms.

Cardioprotective Mechanisms of Cocoa

Cardiovascular diseases are the main cause of deaths in highly developed countries. Dietetic interventions that involve recommendations for consumption of products with a confirmed health-improving action are an important aspect of prevention of cardiovascular diseases. Cocoa is an alimentary product with significant cardioprotective potential due to its high content of bioactive compounds. The aim of the present study was to review the most recent literature concerning the effectiveness and mechanisms of action of compounds contained in cocoa with regard to selected cardiovascular risk factors and cardiometabolic markers. Study results indicate that cocoa consumption, especially in the form of dark chocolate with high flavonoid content, may be a good strategy to diminish cardiovascular risk due to its beneficial effect on platelet aggregation, decreasing blood pressure, diminishing dyslipidemia, and decreasing blood plasma glucose concentration. Many studies have shown that cocoa-derived flavonoids have antioxidant and anti-inflammatory activity and also play a significant role in preventing insulin resistance. However, in order to completely confirm the potential cardiovascular benefits, it is necessary to conduct larger and longer studies, also with regard to potential dangers associated with long-term consumption of large amounts of flavonoids and determination of a safe and effective dose. Key teaching points Cocoa consumption may be a good strategy in diminishing cardiovascular risk. Beneficial effects on platelet aggregation, blood pressure, dyslipidemia, glycemia, as well as antioxidant and anti-inflammatory activity are observed. There is a need to conduct larger and longer studies to determine a safe and effective dose of cocoa flavonoids.

Cardiovascular Effects of Flavonoids

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Cardiovascular Disease (CVD) is the major cause of death worldwide, especially in Western society. Flavonoids are a large group of polyphenolic compounds widely distributed in plants, present in a considerable amount in fruit and vegetable. Several epidemiological studies found an inverse association between flavonoids intake and mortality by CVD. The antioxidant effect of flavonoids was considered the main mechanism of action of flavonoids and other polyphenols. In recent years, the role of modulation of signaling pathways by direct interaction of flavonoids with multiple protein targets, namely kinases, has been increasingly recognized and involved in their cardiovascular protective effect. There are strong evidence, in in vitro and animal experimental models, that some flavonoids induce vasodilator effects, improve endothelial dysfunction and insulin resistance, exert platelet antiaggregant and atheroprotective effects, and reduce blood pressure. Despite interacting with multiple targets, flavonoids are surprisingly safe. This article reviews the recent evidence about cardiovascular effects that support a beneficial role of flavonoids on CVD and the potential molecular targets involved.

The cardioprotective effects of (-)-Epicatechin are mediated through arginase activity inhibition in a murine model of ischemia/reperfusion

The production of nitric oxide (NO) by nitric oxide synthases (NOS) depends on the bioavailability of L-arginine as NOS competes with arginase for this common substrate. As arginase activity increases, less NO is produced and adverse cardiovascular consequences can emerge. (-)-Epicatechin (EPI), the most abundant flavonoid in cacao, has been reported to stimulate endothelial and neuronal NOS expression and function leading to enhanced vascular function and cardioprotective effects. However, little is known about the effects of EPI on myocardial arginase activity. The aim of the present study was to determine if EPI is able to interact and modulate myocardial arginase and NOS expression and activity. For this purpose, in silico modeling, in vitro activity assays and a rat model of ischemia/reperfusion injury were used. In silico and in vitro results demonstrate that EPI can interact with arginase and significantly decrease its activity. In vivo, 10 days of EPI pretreatment reduces ischemic myocardium arginase expression while increasing NOS expression and phosphorylation levels. Altogether, these results may partially account for the cardioprotective effects of EPI.

Acute cocoa Flavanols intake has minimal effects on exercise-induced oxidative stress and nitric oxide production in healthy cyclists: a randomized controlled trial

BACKGROUND

Cocoa flavanols (CF) can stimulate vasodilation by improved nitric oxide (NO) synthesis and have antioxidant and anti-inflammatory capacities. This study aimed to examine whether acute CF intake can affect exercise-induced changes in antioxidant capacity, oxidative stress, inflammation and NO production, as well as exercise performance and recovery in well-trained cyclists.

METHODS

Twelve well-trained male cyclists (mean ± SD age, VO2max: 30 ± 3 years, 63.0 ± 3.5 ml/kg/min) participated in this randomized, double-blind, cross over study. On 2 separate occasions, subjects performed two 30-min time trials 1.5 (TT1) and 3 (TT2) hours after CF (900 mg CF) or placebo (PL, 13 mg CF) intake, interposed by passive rest. Lactate, glucose, heartrate, rating of perceived exertion (RPE) and power output were measured during the TTs. Blood was drawn at baseline, before and after each TT and analyzed for epicatechin serum concentrations, trolox equivalent antioxidative capacity (TEAC), uric acid (UA), malonaldehyde (MDA), L-arginine/ADMA, citrulline, interleukin (IL)-1, IL-6 and tumor necrosis factor (TNF)-α plasma concentrations. Relative changes in blood markers and pacing strategy during TT were analysed by repeated measured ANOVA. TT performance was compared between PL and CF by paired t-test.

RESULTS

Epicatechin concentrations were increased by CF intake. Exercise-induced increase in TEAC/UA was improved by CF intake (F(1) = 5.57; p = .038) (post-TT1: PL: 113.34 ± 3.9%, CF: 117.64 ± 3.96%, post-TT2: PL: 108.59 ± 3.95%, CF: 123.72 ± 7.4% to baseline), while exercise-induced increases in MDA, IL-1 and IL-6 were not affected by CF intake. TNF-α was unaltered by exercise and by CF. Exercise-induced decreases in L-arginine/ADMA and increases in citrulline were not affected by CF intake. TT1 and TT2 performance and exercise-induced physiological changes were unaffected by CF intake.

CONCLUSION

Acute CF intake increased total antioxidant capacity in rest and during exercise, but did not affect exercise-induced lipid peroxidation, inflammation, nor NO production in healthy athletes. Acute CF intake did not improve TT performance and recovery.

TRIAL REGISTRATION

ISRCTN32875, 21-11-2016, retrospectively registered.

Therapeutic uses of epicatechin in diabetes and cancer

Epicatechin is a natural flavonoid found in green tea. It has been reported to possess an immense antioxidant effect which contributes to its therapeutic effect against a handful of ailments. In this review, we discuss its therapeutic role in the management of two of the most important human diseases; diabetes and cancer. The consumption of epicatechin has been shown to reduce blood glucose levels in diabetic patients, while is anticancer effect was attributed to its antioxidant properties, antiangiogenic and direct cytotoxicity to cancer cells. Although the exact mechanism of action of epicatechin is still being explored, there is no doubt that it is a promising candidate as an alternative. The significance of this review is to highlight the importance of the usage of natural products (in this case, epicatechin) as an alternative for the treatment of two potentially fatal diseases which is diabetes and cancer. The aim of this review is to educate the scientific community on the role of epicatechin in ameliorating the effects of diabetes and cancers on human while understanding the potential mechanisms of these aforementioned effects.

Cocoa, Blood Pressure, and Vascular Function

Cardiovascular disease (CVD) represents the most common cause of death worldwide. The consumption of natural polyphenol-rich foods, and cocoa in particular, has been related to a reduced risk of CVD, including coronary heart disease and stroke. Intervention studies strongly suggest that cocoa exerts a beneficial impact on cardiovascular health, through the reduction of blood pressure (BP), improvement of vascular function, modulation of lipid and glucose metabolism, and reduction of platelet aggregation. These potentially beneficial effects have been shown in healthy subjects as well as in patients with risk factors (arterial hypertension, diabetes, and smoking) or established CVD (coronary heart disease or heart failure). Several potential mechanisms are supposed to be responsible for the positive effect of cocoa; among them activation of nitric oxide (NO) synthase, increased bioavailability of NO as well as antioxidant, and anti-inflammatory properties. It is the aim of this review to summarize the findings of cocoa and chocolate on BP and vascular function.

Dietary polyphenol intake and risk of hypertension in the Polish arm of the HAPIEE study

Purpose

Dietary polyphenols have been studied for their potential effects on metabolic disorders, but studies on risk of hypertension are scarce. This study aimed to test the association between total and individual classes of dietary polyphenols and incidence of hypertension in the Polish arm of the Health, Alcohol and Psychosocial factors In Eastern Europe (HAPIEE) study.

Methods

A total of 2725 participants free of hypertension at baseline were tested for blood pressure or taking hypertensive medication within the last 2 weeks at 2–4-year follow-up visit. A 148-item food frequency questionnaire and the Phenol-Explorer database were used to estimate dietary polyphenol intake. Odds ratios (ORs) and 95% confidence intervals (CIs) of hypertension comparing the various categories of exposure (total and individual classes of polyphenol intake) with the lowest one (reference category) were calculated by performing age- and energy-adjusted and multivariate-adjusted logistic regression models.

Results

During follow-up, 1735 incident cases of hypertension occurred. The highest quartile of total polyphenol intake was associated with 31% decreased risk of hypertension compared with the lowest intake (OR 0.69, 95% CI 0.48, 0.98) in women. There was no significant association in men. Among main classes of polyphenols, flavonoids and phenolic acids were independent contributors to this association. The analysis of individual subclasses of polyphenol revealed that, among phenolic acids, hydroxycynnamic acids were independently associated to lower odds of hypertension (OR 0.66, 95% CI 0.47, 0.93), while among flavonoids, most of the association was driven by flavanols (OR 0.56, 95% CI 0.36, 0.87).

Conclusion

Certain classes of dietary polyphenols were associated with lower risk of hypertension, but potential differences between men and women should be further investigated.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-017-1438-7) contains supplementary material, which is available to authorized users.

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

This study investigated the effects of subchronic (−)-epicatechin (Epi) treatment on locomotor activity and hypertension development in young spontaneously hypertensive rats (SHR). Epi was administered in drinking water (100 mg/kg/day) for 2 weeks. Epi significantly prevented the development of hypertension (138 ± 2 versus 169 ± 5 mmHg, p < 0.001) and reduced total distance traveled in the open-field test (22 ± 2 versus 35 ± 4 m, p < 0.01). In blood, Epi significantly enhanced erythrocyte deformability, increased total antioxidant capacity, and decreased nitrotyrosine concentration. In the aorta, Epi significantly increased nitric oxide (NO) synthase (NOS) activity and elevated the NO-dependent vasorelaxation. In the left heart ventricle, Epi increased NOS activity without altering gene expressions of nNOS, iNOS, and eNOS. Moreover, Epi reduced superoxide production in the left heart ventricle and the aorta. In the brain, Epi increased nNOS gene expression (in the brainstem and cerebellum) and eNOS expression (in the cerebellum) but had no effect on overall NOS activity. In conclusion, Epi prevented the development of hypertension and reduced locomotor hyperactivity in young SHR. These effects resulted from improved cardiovascular NO bioavailability concurrently with increased erythrocyte deformability, without changes in NO production in the brain.

Chitosan treatment abrogates hypercholesterolemia-induced erythrocyte's arginase activation

This study aimed to evaluate the protective effect of chitosan (CS) against hypercholesterolemia (HC) induced arginase activation and disruption of nitric oxide (NO) biosynthesis using erythrocytes as cellular model. Human erythrocytes were isolated and classified into eight groups. Next, cells were treated with l-arginine (l-ARG), N^ω-nitro-l-arginine methyl ester (l-NAME), CS or CS + l-ARG in the presence of normal plasma or cholesterol enriches plasma. Then, erythrocytes were incubated at 37 °C for 24 h. The present results revealed that, HC induced significant increase of cholesterol inclusion into erythrocytes membrane compared to control. Moreover, HC caused significant decrease in nitric oxide synthase (NOS) activity similar to l-NAME; however, arginase activity and arginase/NOS ratio significantly increased compared to control. On contrast, treatment of HC with, l-arginine, CS or CS plus l-arginine prevents HC induced cholesterol loading into erythrocytes membrane, NOS inhibition and arginase activation. This study suggested that CS could be protective agent against HC induced disruption of erythrocyte’s oxidative status and arginase activation.

At the interface of antioxidant signalling and cellular function: Key polyphenol effects

The hypothesis that dietary (poly)phenols promote well‐being by improving chronic disease‐risk biomarkers, such as endothelial dysfunction, chronic inflammation and plasma uric acid, is the subject of intense current research, involving human interventions studies, animal models and in vitro mechanistic work. The original claim that benefits were due to the direct antioxidant properties of (poly)phenols has been mostly superseded by detailed mechanistic studies on specific molecular targets. Nevertheless, many proposed mechanisms in vivo and in vitro are due to modulation of oxidative processes, often involving binding to specific proteins and effects on cell signalling. We review the molecular mechanisms for 3 actions of (poly)phenols on oxidative processes where there is evidence in vivo from human intervention or animal studies. (1) Effects of (poly) phenols on pathways of chronic inflammation leading to prevention of some of the damaging effects associated with the metabolic syndrome. (2) Interaction of (poly)phenols with endothelial cells and smooth muscle cells, leading to effects on blood pressure and endothelial dysfunction, and consequent reduction in cardiovascular disease risk. (3) The inhibition of xanthine oxidoreductase leading to modulation of intracellular superoxide and plasma uric acid, a risk factor for developing type 2 diabetes.

Dark chocolate supplementation reduces the oxygen cost of moderate intensity cycling

Background

Dark chocolate (DC) is abundant in flavanols which have been reported to increase the bioavailability and bioactivity of nitric oxide (NO). Increasing NO bioavailability has often demonstrated reduced oxygen cost and performance enhancement during submaximal exercise.

Methods

Nine moderately-trained male participants volunteered to undertake baseline (BL) measurements that comprised a cycle \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overset{.}{V}{O}_{2 max} $$\end{document}V.O2max test followed by cycling at 80 % of their established gas exchange threshold (GET) for 20-min and then immediately followed by a two-minute time-trial (TT). Using a randomised crossover design participants performed two further trials, two weeks apart, with either 40 g of DC or white chocolate (WC) being consumed daily. Oxygen consumption, RER, heart rate and blood lactate (BLa) were measured during each trial.

Results

DC consumption increased GET and TT performance compared to both BL and WC (P < 0.05). DC consumption increased \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overset{.}{V}{O}_{2 max} $$\end{document}V.O2max by 6 % compared to BL (P < 0.05), but did not reach statistical significance compared to WC. There were no differences in the moderate-intensity cycling for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overset{.}{V}{O}_2 $$\end{document}V.O2_, RER, BLa and heart rate between conditions, although, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \overset{.}{V}{O}_2 $$\end{document}V.O2 and RER exhibited consistently lower trends following DC consumption compared to BL and WC, these did not reach statistical significance.

Conclusion

Chronic supplementation with DC resulted in a higher GET and enhanced TT performance. Consequently, ingestion of DC reduced the oxygen cost of moderate intensity exercise and may be an effective ergogenic aid for short-duration moderate intensity exercise.

The red blood cell: a new key player in cardiovascular homoeostasis? Focus on the nitric oxide pathway

RBCs (red blood cells) have a fundamental role in the regulation of vascular homoeostasis thanks to the ability of these cells to carry O2 (oxygen) between respiratory surfaces and metabolizing tissues and to release vasodilator compounds, such as ATP and NO (nitric oxide), in response to tissue oxygenation. More recently it has been shown that RBCs are also able to produce NO endogenously as they express a functional NOS (nitric oxide synthase), similar to the endothelial isoform. In addition, RBCs carry important enzymes and molecules involved in L-arginine metabolism, such as arginase, NO synthesis inhibitors and the cationic amino acid transporters. Altogether these findings strongly support the role of these cells as producers, vehicles and scavengers of NO, therefore affecting several physiological processes such as blood rheology and cell adhesion. Consequently, the importance of alterations in the L-arginine/NO metabolic pathway induced by specific conditions, e.g. oxidative stress, in different pathological settings have been investigated. In the present review we discuss the role of RBCs in vascular homoeostasis, focusing our attention on the importance of the NO pathway alterations in cardiovascular diseases and their relationship to major risk factors.

Oxidative stress as common trait of endothelial dysfunction in chorionic arteries from fetuses with IUGR and LGA

INTRODUCTION

Fetal macrosomia and intrauterine growth restriction (IUGR) associate with increased morbidity in the neonate. Placental vascular relaxation is impaired in fetal macrosomia, as well as in IUGR, and this could result from increased oxidative stress present in both conditions. We determined the role of pro- and anti-oxidants on NOS dependent relaxation in placental chorionic arteries from pregnancies with LGA babies from overweight and/or obese mothers (LOOM) and IUGR fetuses from normal BMI women.

METHODS

Chorionic arteries were mounted in a wire-myograph, where responses to the NOS-dependent agent CGRP in presence or absence of the antioxidant N-acetyl cysteine (NAC), the pro-oxidant SIN-1, the SOD inhibitor DDC, and the GPx inhibitor MS were determined. Additionally the presence of pro- and antioxidant enzymes (NOX-4, SOD-1, SOD-2 and GPx-1) and eNOS in chorionic and umbilical vessels were addressed by immunohistochemistry.

RESULTS

Maximal CGRP-induced relaxation was comparable to controls but presented a reduced potency in chorionic arteries from LOOM placentae, whilst in IUGR vessels both maximal response and potency were reduced. NAC increased maximal relaxation in controls, IUGR and LOOM arteries, whilst SIN-1 completely abolished the CGRP-induced relaxation only in IUGR and LOOM samples, the later effect was paralleled by SOD or GPx inhibition. These responses associated with the presence of NOX-4, SOD-1 and GPx-1 in the endothelium and vascular wall of chorionic and umbilical arteries in the different groups studied.

DISCUSSION

These data suggest that NOS dependent relaxation in placental vessels from IUGR and LOOM pregnancies present a higher sensitivity to oxidative stress.

Modulation of nitric oxide by flavonoids

One of the main mechanisms by which dietary flavonoids are thought to influence cardiovascular disease is via protection of the bioactivity of the endothelium-derived nitric oxide (NO). Additionally, flavonoids may also interfere with the signalling cascades of inflammation and prevent overproduction of NO and its deleterious consequences in shock and ischemia-reperfusion injury. In the present paper we review the evidence of the effects of flavonoids on NO. Flavonoids exert complex actions on the synthesis and bioavailability of NO which may result both in enhanced or decreased NO levels: (1) in cell free systems, several flavonoids may scavenge NO via its pro-oxidant properties by increasing superoxide. However, under conditions of oxidative stress, flavonoids may also protect NO from superoxide-driven inactivation. (2) In intact healthy tissues, some flavonoids increase eNOS activity in endothelial cells. Paradoxically this effect involves a pro-oxidant effect which results in Ca(2+)-dependent activation of eNOS. As inhibitors of PI3K, flavonoids may potentially inhibit the PI3K/Akt-dependent activation of eNOS. (3) Under conditions of inflammation and oxidative stress, flavonoids may prevent the inflammatory signalling cascades via inhibition of NFκB and thereby downregulate iNOS. On the other hand, they also prevent the overexpression of ROS generating enzymes, reducing superoxide and peroxynitrite levels, and hence preventing superoxide-induced NO inactivation and eNOS uncoupling. Therefore, the final effect of flavonoids on NO levels will depend on the flavonoid structure and the concentrations used, on the cell type under study and particularly on the presence of inflammatory/oxidative conditions.

Dietary flavonoids and nitrate: effects on nitric oxide and vascular function

Emerging evidence highlights dietary flavonoids and nitrate as candidates that may explain at least part of the cardioprotective effect of a fruit and vegetable diet. Nitric oxide plays a pivotal role in cardiovascular health. Components of a fruit and vegetable diet that are cardioprotective, in part through effects on nitric oxide status, could substantially reduce the cardiovascular risk profile of the general population with increased intake of such a diet. Epidemiological evidence suggests that dietary flavonoids and nitrate have a cardioprotective effect. Clinical trials with flavonoid- and nitrate-rich foods have shown benefits on measures of vascular health. While the molecular mechanisms by which flavonoids and nitrate are cardioprotective are not completely understood, recent evidence suggests both nonspecific and specific effects through nitric oxide pathways. This review presents an overview of nitric oxide and its key role in cardiovascular health and discusses the possible vascular benefits of flavonoids and nitrate, individually and in combination, through effects on nitric oxide status.

Cecropia pachystachya extract attenuated the renal lesion in 5/6 nephrectomized rats by reducing inflammation and renal arginase activity

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Cecropia pachystachya Trécul has been used in Brazilian folk medicine to treat hypertension, bladder and kidney inflammation and renal diseases. The aim of this study was to evaluate the potential of the aqueous fraction from the ethanolic extract of Cecropia pachystachya (FCP) in the management of hypertension, inflammation and progressive renal disease in rats submitted to 5/6 nephrectomy.

MATERIALS AND METHODS

Thirty male Wistar rats submitted to 5/6 nephrectomy (5/6 NE) were untreated (NE) or treated (NE+FCP) with the FCP (0.5g/kg/day). The treatment started 15 days after surgery, and the rats were followed for a period of 60 days. Systolic blood pressure (SBP) and albuminuria were evaluated from 15-60 days after the surgical procedure. Function and estructural renal changes, TGF-β (transforming growth factor β), MCP-1 (monocyte chemoattractant protein-1) and nitric oxide (NO) urinary excretion were analyzed. Expression and activity of the renal enzymes arginase (ARG), angiotensin converting enzyme (ACE), and MAP kinase p-JNK expression also were analyzed.

RESULTS

The nephrectomized rats developed progressive albuminuria and increased SBP that was less intense in the treated group. There was a reduction in the glomerular filtration rate (GFR) in the nephrectomized rats, which was attenuated by treatment with FCP extract. The treatment with FCP also attenuated the histological changes, reduced the expression and activity of renal arginase, the number of macrophages (ED-1 positive cells) and the p-JNK expression in the renal cortex of the rats submitted to 5/6 NE. The urinary excretion of TGF-β was less intense in the treated group and was associated with the reduction of the expression and activity of the renal arginase.

CONCLUSIONS

These results suggest that the reduction of renal arginase activity, p-JNK and TGF-β expression can explain the mechanism by which the treatment with C. pachystachya reduced the inflammation and improved renal function. This study presents the potential use of Cecropia pachystachya in the treatment of chronic renal diseases.

Arginase inhibition restores endothelial function in diet-induced obesity

Arginase may play a major role in the regulation of vascular function in various cardiovascular disorders by impairing nitric oxide (NO) production. In the current study, we investigated whether supplementation of the arginase inhibitor N(ω)-hydroxy-nor-l-arginine (nor-NOHA) could restore endothelial function in an animal model of diet-induced obesity. Arginase 1 expression was significantly lower in the aorta of C57BL/6J mice fed a high-fat diet (HFD) supplemented with nor-NOHA (40mgkg(-1)/day) than in mice fed HFD without nor-NOHA. Arginase inhibition led to considerable increases in eNOS expression and NO levels and significant decreases in the levels of circulating ICAM-1. These findings were further confirmed by the results of siRNA-mediated knockdown of Arg in human umbilical vein endothelial cells. In conclusion, arginase inhibition can help restore dysregulated endothelial function by increasing the eNOS-dependent NO production in the endothelium, indicating that arginase could be a therapeutic target for correcting obesity-induced vascular endothelial dysfunction.

Mitigation of lead-induced neurotoxicity by the naringin: erythrocytes as neurons substitute markers

This study aimed to investigate the effect of lead (Pb) on neuronal nitric oxide synthase (nNOS) activity using erythrocytes as neurons surrogate markers. Moreover, the protective effect of naringin (NAR) against lead acetate (PbAc)-induced neurotoxicity was investigated. Human erythrocytes were incubated with L-arginine (L-Arg), Nω-nitro-L-Arginine methyl ester ( L-NAME), NAR, PbAc, PbAc+L-Arg, PbAc+NAR, or PbAc+L-Arg+NAR. The present results revealed that incubation of erythrocytes with PbAc inhibited NOS activity and decreased nitrite levels as an index for nitric oxide (NO) production to values similar that of L-NAME as known NOS inhibitor. Likewise, PbAc induced a significant decrease in activities of ATPases and acetylcholinesterase compared to control cells. Furthermore, PbAc exposure significantly increased protein carbonyl content (PCC) and malondialdehyde (MDA) levels while significantly decrease the levels of reduced glutathione (GSH). On the contrary, incubation of erythrocytes with PbAc in the presence of L-Arg+NAR synergistically ameliorated the investigated parameters compared to erythrocytes incubated with PbAc alone. These data suggest that NAR can restore NO bioavailability in a situation of Pb-induced cellular damage. This attributed to antioxidant activity and restoration NOS activity.