Therapeutic Effect of Alpha Lipoic Acid in a Rat Preclinical Model of Preeclampsia: Focus on Maternal Signs, Fetal Growth and Placental Function.

Chronic hypertension is a major risk factor for preeclampsia (PE), associated with significant maternal and neonatal morbidity. We previously demonstrated that pregnant stroke-prone spontaneously hypertensive rats (SHRSP) display a spontaneous PE-like phenotype with distinct placental, fetal, and maternal features. Here, we hypothesized that supplementation with alpha lipoic acid (ALA), a potent antioxidant, during early pregnancy could ameliorate the PE phenotype in this model. To test this hypothesis, timed pregnancies were established using 10 to 12-week-old SHRSP females (n = 19-16/group), which were assigned to two treatment groups: ALA (injected intraperitoneally with 25 mg/kg body weight ALA on gestation day (GD1, GD8, and GD12) or control, receiving saline following the same protocol. Our analysis of maternal signs showed that ALA prevented the pregnancy-dependent maternal blood pressure rise (GD14 blood pressure control 169.3 ± 19.4 mmHg vs. 146.1 ± 13.4 mmHg, p = 0.0001) and ameliorated renal function, as noted by the increased creatinine clearance and improved glomerular histology in treated dams. Treatment also improved the fetal growth restriction (FGR) phenotype, leading to increased fetal weights (ALA 2.19 ± 0.5 g vs. control 1.98 ± 0.3 g, p = 0.0074) and decreased cephalization indexes, indicating a more symmetric fetal growth pattern. This was associated with improved placental efficiency, decreased oxidative stress marker expression on GD14, and serum soluble fms-like tyrosine kinase 1 (sFlt1) levels on GD20. In conclusion, ALA supplementation mitigated maternal signs and improved placental function and fetal growth in SHRSP pregnancies, emerging as a promising therapy in pregnancies at high risk for PE.

Natural Products and Diabetes: (-)-Epicatechin and Mechanisms Involved in the Regulation of Insulin Sensitivity.

Type 2 diabetes (T2D) is a disease that occurs when cells do not respond normally to insulin, a condition called insulin resistance, which leads to high blood glucose levels. Although it can be treated pharmacologically, dietary habits beyond carbohydrate restriction can be highly relevant in the management of T2D. Emerging evidence supports the possibility that natural products (NPs) could contribute to managing blood glucose or counteract the undesirable effects of hyperglycemia and insulin resistance. This chapter summarizes the relevant preclinical evidence involving the flavonoid (-)-epicatechin (EC) in the optimization of glucose homeostasis, reducing insulin resistance and/or diabetes-associated disorders. Major effects of EC are observed on (i) intestinal functions, including digestive enzymes, glucose transporters, microbiota, and intestinal permeability, and (ii) redox homeostasis, including oxidative stress and inflammation. There is still a need for further clinical studies to confirm the in vitro and rodent data, allowing recommendations for EC, particularly in prediabetic and T2D patients. The collection of similar data and the lack of clinical evidence for EC is also applicable to other NPs.

(Poly)phenols and the regulation of NADPH oxidases.

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are enzymes that generate superoxide anion (O2•-) and hydrogen peroxide (H2O2), and that are widely distributed in mammalian tissues. Many bioactives, especially plant (poly)phenols are being studied for their capacity to regulate NOXs. The modulation of these enzymes are of central relevance to maintain redox homeostasis and regulate cell signaling. In in vitro and ex vivo assays, and in experimental animal models, different (poly)phenols are able to modulate NOX-dependent generation of O2•- and H2O2. Mechanistically, most of the known effects of (poly)phenols and of their metabolites on NOX1, NOX2, and NOX4, include the modulation of: i) the expression of the different constituent subunits, and/or ii) posttranslational modifications involved in the assembly and translocation of the protein complexes. Very limited evidence is available on a direct action of (poly)phenols on NOX active site (electron-transferring protein). Moreover, it is suggested that the regulation by (poly)phenols of systemic events, e.g. inflammation, is frequently associated with their capacity to regulate NOX activation. Although of physiological significance, more studies are needed to understand the specific targets/mechanisms of NOX regulation by (poly)phenols, and the (poly)phenol chemical structures and moieties directly involved in the observed effects. It should be kept in mind the difficulties of NOX's studies associated with the complexity of NOXs biochemistry and the methodological limitations of O2•- and H2O2 the determinations. Studies relating human ingestion of specific (poly)phenols, with NOX activity and disease conditions, are guaranteed to better understand the health importance of (poly)phenol consumption and the involvement of NOXs as biological targets.

(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 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.

Placental Glycoredox Dysregulation Associated with Disease Progression in an Animal Model of Superimposed Preeclampsia.

Pregnancies carried by women with chronic hypertension are at increased risk of superimposed preeclampsia, but the placental pathways involved in disease progression remain poorly understood. In this study, we used the stroke-prone spontaneously hypertensive rat (SHRSP) model to investigate the placental mechanisms promoting superimposed preeclampsia, with focus on cellular stress and its influence on galectin-glycan circuits. Our analysis revealed that SHRSP placentas are characterized by a sustained activation of the cellular stress response, displaying significantly increased levels of markers of lipid peroxidation (i.e., thiobarbituric acid reactive substances (TBARS)) and protein nitration and defective antioxidant enzyme expression as early as gestation day 14 (which marks disease onset). Further, lectin profiling showed that such redox imbalance was associated with marked alterations of the placental glycocode, including a prominent decrease of core 1 O-glycan expression in trophoblasts and increased decidual levels of sialylation in SHRSP placentas. We also observed significant changes in the expression of galectins 1, 3 and 9 with pregnancy progression, highlighting the important role of the galectin signature as dynamic interpreters of placental microenvironmental challenges. Collectively, our findings uncover a new role for the glycoredox balance in the pathogenesis of superimposed preeclampsia representing a promising target for interventions in hypertensive disorders of pregnancy.

Hacia el esclarecimiento del rol del anión cloruro en la hipertensión arterial: / Towards the Elucidation of the Role of the Chloride Anion in Arterial Hypertension:

RESUMEN Introducción: Se desconoce el papel del anión cloruro en los efectos deletéreos del consumo excesivo de sal (NaCl) y si sus efectos son independientes de la presencia del sodio. Objetivo: Demostrar que tanto una sobrecarga de cloruro como una sobrecarga de sodio en la dieta producen efectos deletéreos, en forma independiente, sobre la presión arterial sistólica (PAS), la función renal y los marcadores de estrés oxidativo en el riñón. Materiales y métodos: Ratas Wistar macho fueron divididas en cuatro grupos (n = 8/grupo) y fueron alimentadas con diferentes dietas durante tres semanas: C: control (dieta estándar), NaCl: hipersódica-hiperclórica, Na: hipersódica sin cloruro, Cl: hiperclórica sin sodio. Se determinaron la presión arterial sistólica (PAS) y la función renal y en la corteza renal, se evaluó la producción de especies reactivas del ácido tiobarbitúrico (en inglés: TBARS) y la actividad y la expresión de las enzimas superóxido dismutasa (SOD), catalasa (CAT) y glutatión peroxidasa (GPx). Resultados: Al cabo de tres semanas, la PAS aumentó (*) en los dos grupos alimentados con cloruro. La excreción fraccional de sodio y de cloruro aumentó (*) en los grupos NaCl y Na. La diuresis y los TBARS en la corteza renal aumentaron (*) con las tres dietas, sin cambios en la actividad y en la expresión de SOD y CAT. La actividad de la GPx aumentó (*) en los dos grupos que recibieron cloruro; (*p < 0,05 vs C). Conclusión: Tanto la sobrecarga de sodio como la de cloruro se asocian a mayor estado oxidativo caracterizado por un incremento en la peroxidación lipídica en la corteza renal. Sin embargo, solo el exceso de cloruro se asocia a mayor actividad de la GPx y de la hipertensión, sin cambios en la excreción urinaria de cloruros, sugiriendo un mayor estado prooxidante renal en comparación con el grupo Na.

ABSTRACT Introduction: The role of the chloride anion on the deleterious effects of excessive consumption of salt (NaCl) and whether its effects are independent each other of the presence of sodium remains to date, unknown and unclear. Objective: To demonstrate that both a chloride overload and a sodium overload in the diet produce deleterious effects, by different mechanisms, on systolic blood pressure (SBP), renal function and markers of oxidative stress in the kidney. Materials and Methods: Male Wistar rats were divided into four groups (n = 8 / group) and fed with different diets for three weeks: C: control (standard diet), and diets: NaCl: hypersodic-hyperchloric; Na: hypersodic without chloride and Cl: hyperchloric without sodium. Systolic blood pressure (SBP) and renal function were determined, and the production of thiobarbituric acid reactive species (TBARS) and the activity and expression of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzymes were evaluated in renal cortex tissue. Results: SBP increased (*) in the two groups fed with chloride. The fractional excretion of sodium and chloride increased (*) in the NaCl and Na groups. increased (*) in the renal cortex with the three diets. No changes were observed in the activity and expression of SOD and CAT. GPx activity increased (*) in the two groups that received chloride; (* p <0.05 vs C). Conclusion: Both sodium and chloride overload are associated with a higher oxidative state characterized by an increase in lipid peroxidation in the renal cortex. However, compared with Na group, only chloride overload is associated with higher GPx activity and hypertension without any changes in urinary chloride excretion, suggesting a higher renal pro-oxidant state in this experimental group.

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.

(-)-Epicatechin protects thoracic aortic perivascular adipose tissue from whitening in high-fat fed mice.

High adipose tissue (AT) accumulation in the body increases the risk for many metabolic and chronic diseases. This work investigated the capacity of the flavonoid (-)-epicatechin to prevent undesirable modifications of AT in mice fed a high-fat diet. Studies were focused on thoracic aorta perivascular AT (taPVAT), which is involved in the control of blood vessel tone, among other functions. Male C57BL/6J mice were fed for 15 weeks a high-fat diet with or without added (-)-epicatechin (20 mg per kg body weight per d). In high-fat diet fed mice, (-)-epicatechin supplementation: (i) prevented the expansion of taPVAT, (ii) attenuated the whitening of taPVAT (according to the adipocyte morphology, diameter, and uncoupling-protein 1 (UCP-1) levels) and (iii) blunted the increase in plasma glucose and cholesterol. The observed taPVAT modifications were not associated with alterations in the aorta wall thickness, aorta tumor necrosis factor-alpha (TNF-α) and NADPH-oxidase 2 (NOX2) expression, and endothelial nitric oxide synthase (eNOS) phosphorylation levels. In summary, our results indicate (-)-epicatechin as a relevant bioactive protecting from the slow and silent development of metabolic and chronic diseases as they are associated with excessive fat intake.

(-)-Epicatechin administration protects kidneys against modifications induced by short-term l-NAME treatment in rats.

The aim of this work was to evaluate the protective effects of (-)-epicatechin on the kidneys of NO-deprived rats. Male Sprague Dawley rats were divided into three groups: control (C), receiving water and standard diet; l-NAME (L), receiving a solution of N(ω)-nitro-l-arginine methyl ester (l-NAME) (360 mg l-1 in water) as a beverage and standard diet; and l-NAME-(-)-epicatechin (LE), receiving l-NAME solution as a beverage and standard diet supplemented with (-)-epicatechin (4 g kg-1 diet). The L-group showed altered kidney function parameters, evaluated based on plasma urea and creatinine. In parallel, kidney oxidative stress markers, i.e. superoxide anion production, malondialdehyde content, and 3-nitrotyrosine protein adducts, were significantly increased in the L group. In addition, l-NAME treatment induced modifications in kidney NO bioavailability determinants: increased expression of NOX subunits (p47phox, gp91phox, NOXO1, and NOX4) and lowered NOS activity. (-)-Epicatechin administration restored kidney function parameters, oxidative stress markers, expression of p47phox, gp91phox, and NOX4 and NOS activity to control values. These results indicate that (-)-epicatechin can mitigate NO-mediated impairment of kidney function, in part due to its capacity to modulate NOXs, NOSs, and consequently oxidative stress, and NO bioavailability.

Dietary (-)-epicatechin affects NF-κB activation and NADPH oxidases in the kidney cortex of high-fructose-fed rats.

Inflammation involves the activation of redox-sensitive transcription factors, e.g., nuclear factor κB (NF-κB). Administration of (-)-epicatechin to high-fructose-fed rats prevented NF-κB activation and up-regulation of the NADPH oxidase 4 (NOX4) in the kidney cortex. These results add mechanistic insights into the action of (-)-epicatechin diminishing inflammatory responses.

Effects of quercetin on heart nitric oxide metabolism in l-NAME treated rats.

This study investigated the effects of a quercetin-supplemented diet on the biochemical changes installed in the heart of NO-deficient rats in terms of oxidants production and NO bioavailability determinants. Sprague-Dawley rats were subjected to Nω-nitro-l-arginine methyl ester (l-NAME) treatment (360 mg/L l-NAME in the drinking water, 4 d) with or without supplementation with quercetin (4 g/kg diet). l-NAME administration led to increased blood pressure (BP) (30%), decreased nitric oxide synthase (NOS) activity (50%), and increases in NADPH oxidase (NOX)-dependent superoxide anion production (60%) and p47phox protein level (65%). The co-administration of quercetin prevented the increase in BP and the activation of NOX but did not modify the decrease in NOS activity caused by l-NAME. In addition, quercetin affected oxidative stress parameters as glutathione oxidation, and the activities of oxidant detoxifying enzymes superoxide dismutase, glutathione peroxidase, and catalase. Thus, quercetin administration counteracts l-NAME effects on NO bioavailability determinants in vivo, essentially through controlling NOX-mediated superoxide anion production.

Plant bioactives and redox signaling: (-)-Epicatechin as a paradigm.

Polyphenols are bioactives claimed to be responsible for some of the health benefits provided by fruit and vegetables. It is currently accepted that the bioactivities of polyphenols can be mostly ascribed to their interactions with proteins and lipids. Such interactions can affect cell oxidant production and cell signaling, and explain in part the ability of polyphenols to promote health. EC can modulate redox sensitive signaling by: i) defining the extent of oxidant levels that can modify cell signaling, function, and fate, e.g. regulating enzymes that generate superoxide, hydrogen peroxide and nitric oxide; or ii) regulating the activation of transcription factors sensible to oxidants. The latter includes the regulation of the nuclear factor E2-related factor 2 (Nfr2) pathway, which in turn can promote the synthesis of antioxidant defenses, and of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) pathway, which mediates the expression of oxidants generating enzymes, as well as proteins not involved in redox reactions. In summary, a significant amount of data vindicates the participation of EC in redox regulated signaling pathways. Progress in the understanding of the molecular mechanisms involved in EC biological actions will help to define recommendations in terms of which fruit and vegetables are healthier and the amounts necessary to provide health effects.

Fructose increases corticosterone production in association with NADPH metabolism alterations in rat epididymal white adipose tissue.

Metabolic syndrome is an array of closely metabolic disorders that includes glucose intolerance/insulin resistance, central obesity, dyslipidemia, and hypertension. Fructose, a highly lipogenic sugar, has profound metabolic effects in adipose tissue, and has been associated with the etiopathology of many components of the metabolic syndrome. In adipocytes, the enzyme 11 ß-HSD1 amplifies local glucocorticoid production, being a key player in the pathogenesis of central obesity and metabolic syndrome. 11 ß-HSD1 reductase activity is dependent on NADPH, a cofactor generated by H6PD inside the endoplasmic reticulum. Our focus was to explore the effect of fructose overload on epididymal white adipose tissue (EWAT) machinery involved in glucocorticoid production and NADPH and oxidants metabolism. Male Sprague-Dawley rats fed with a fructose solution (10% (w/v) in tap water) during 9 weeks developed some characteristic features of metabolic syndrome, such as hypertriglyceridemia, and hypertension. In addition, high levels of plasma and EWAT corticosterone were detected. Activities and expressions of H6PD and 11 ß-HSD1, NAPDH content, superoxide anion production, expression of NADPH oxidase 2 subunits, and indicators of oxidative metabolism were measured. Fructose overloaded rats showed an increased potential in oxidant production respect to control rats. In parallel, in EWAT from fructose overloaded rats we found higher expression/activity of H6PD and 11 ß-HSD1, and NADPH/NADP+ ratio. Our in vivo results support that fructose overload installs in EWAT conditions favoring glucocorticoid production through higher H6PD expression/activity supplying NADPH for enhanced 11 ß-HSD1 expression/activity, becoming this tissue a potential extra-adrenal source of corticosterone under these experimental conditions.

LPS-induced renal inflammation is prevented by (-)-epicatechin in rats.

This work investigated the capacity of (-)-epicatechin to prevent the renal damage induced by LPS administration in rats. Male Sprague Dawley rats were fed for 4 days a diet without or with supplementation with (-)-epicatechin (80mg/kg BW/d), and subsequently i.p. injected with lipopolysaccharide (LPS). Six hours after injection, LPS-treated rats exhibited increased plasma creatinine and urea levels as indicators of impaired renal function. The renal cortex of the LPS-treated rats showed: i) increased expression of inflammatory molecules (TNF-α, iNOS and IL-6); ii) activation of several steps of NF-κB pathway; iii) overexpression of TLR4, and iv) higher superoxide anion production and lipid peroxidation index in association with increased levels of gp91phox and p47phox (NOX2) and NOX4. Pretreatment with dietary (-)-epicatechin prevented the adverse effects of LPS challenge essentially by inhibiting TLR4 upregulation and NOX activation and the consequent downstream events, e.g. NF-kB activation.

Modifications in nitric oxide and superoxide anion metabolism induced by fructose overload in rat heart are prevented by (-)-epicatechin.

Fructose overload promotes functional and metabolic derangements in humans and in animal experimental models. Evidence suggests that dietary flavonoids have the ability to prevent/attenuate the development of metabolic diseases. In this work we investigated the effects of (-)-epicatechin on the modifications induced by fructose overload in the rat heart in terms of nitric oxide and superoxide metabolism. Male Sprague Dawley rats received 10% (w/v) fructose in the drinking water for 8 weeks, with or without (-)-epicatechin (20 mg per kg body weight per day) in the rat chow diet. These conditions of fructose overload did not lead to overt manifestations of heart hypertrophy or tissue remodeling. However, biochemical and molecular changes were observed and could represent the onset of functional alterations. (-)-Epicatechin prevented a compromised NO bioavailability and the development of oxidative stress produced by fructose overload essentially acting on superoxide anion metabolism. In this line, the increase in superoxide anion production, the overexpression of NOX2 subunit p47phox and of NOX4, the decrease in superoxide dismutase activity, and the higher oxidized/reduced glutathione ratio installed by fructose overload were absent in the rats receiving (-)-epicatechin. These results support the hypothesis that diets rich in (-)-epicatechin could prevent the onset and progression of heart dysfunctions associated with metabolic alterations.

Dietary (-)-epicatechin mitigates oxidative stress, NO metabolism alterations, and inflammation in renal cortex from fructose-fed rats.

High fructose consumption has been associated to deleterious metabolic conditions. In the kidney, high fructose causes renal alterations that contribute to the development of chronic kidney disease. Evidence suggests that dietary flavonoids have the ability to prevent/attenuate risk factors of chronic diseases. This work investigated the capacity of (-)-epicatechin to prevent the renal damage induced by high fructose consumption in rats. Male Sprague Dawley rats received 10% (w/v) fructose in the drinking water for 8 weeks, with or without supplementation with (-)-epicatechin (20mg/kg body weight/d) in the rat chow diet. Results showed that, in the presence of mild proteinuria, the renal cortex from fructose-fed rats exhibited fibrosis and decreases in nephrin, synaptopodin, and WT1, all indicators of podocyte function in association with: (i) increased markers of oxidative stress; (ii) modifications in the determinants of NO bioavailability, i.e., NO synthase (NOS) activity and expression; and (iii) development of a pro-inflammatory condition, manifested as NF-κB activation, and associated with high expression of TNFα, iNOS, and IL-6. Dietary supplementation with (-)-epicatechin prevented or ameliorated the adverse effects of high fructose consumption. These results suggest that (-)-epicatechin ingestion would benefit when renal alterations occur associated with inflammation or metabolic diseases.

(-)-Epicatechin reduces blood pressure increase in high-fructose-fed rats: effects on the determinants of nitric oxide bioavailability.

This work investigated the blood pressure (BP)-lowering effect of the flavanol (-)-epicatechin in a model of metabolic syndrome. Rats were fed a regular chow diet without (Control) or with 10% (w/v) fructose in the drinking water (high fructose, HF) for 8 weeks. A subgroup of the HF-fed rats was supplemented with (-)-epicatechin 20 mg/kg body weight (HF-EC). Dietary (-)-epicatechin reverted the increase in BP caused by the fructose treatment. In aorta, superoxide anion production and the expression of the NADPH oxidase (NOX) subunits p47(phox) and p22(phox) were enhanced in the HF-fed rats. The increase was prevented by (-)-epicatechin. Similar profile was observed for NOX4 expression. The activity of aorta nitric oxide synthase (NOS) was increased in the HF group and was even higher in the HF-EC rats. These effects were paralleled by increased endothelial NOS phosphorylation at the activation site Ser1177. Among the more relevant mitogen-activated protein kinase pathways in vascular tissue, c-Jun-N-terminal kinase was shown to be activated in the aorta of the HF-fed rats, and (-)-epicatechin supplementation mitigated this activation. Thus, the results suggest that dietary (-)-epicatechin supplementation prevented hypertension in HF-fed rats, decreasing superoxide anion production and elevating NOS activity, favoring an increase in NO bioavailability.

Amaranth peptides from simulated gastrointestinal digestion: antioxidant activity against reactive species.

We evaluated the capacity of simulated gastrointestinal digests or alcalase hydrolysates of protein isolates from amaranth to scavenge diverse physiologically relevant reactive species. The more active hydrolysate was obtained with the former method. Moreover, a prior alcalase treatment of the isolate followed by the same simulated gastrointestinal digestion did not improve the antioxidant capacity in any of the assays performed and even produced a negative effect under some conditions. Gastrointestinal digestion produced a strong increment in the scavenging capacity against peroxyl radicals (ORAC assay), hydroxyl radicals (ESR-OH assay), and peroxynitrites; thus decreasing the IC50 values to approximately 20, 25, and 20%, respectively, of the levels attained with the nonhydrolyzed proteins. Metal chelation (HORAC assay) also enhanced respect to isolate levels, but to a lesser extent (decreasing IC50 values to only 50%). The nitric-oxide- and superoxide-scavenging capacities of the digests were not relevant with respect to the methodologies used. The gastrointestinal digests from amaranth proteins acted against reactive species by different mechanisms, thus indicating the protein isolate to be a potential polyfunctional antioxidant ingredient.

(-)-Epicatechin prevents alterations in the metabolism of superoxide anion and nitric oxide in the hearts of L-NAME-treated rats.

The aim of this work was to evaluate the effects of (-)-epicatechin administration in the heart of a rat model with reduced NO production that follows a short-term treatment with L-NAME. Sprague-Dawley rats were treated for 4 d with L-NAME in the absence or presence of (-)-epicatechin in the diet. The redox status in cardiac tissue was improved by (-)-epicatechin administration. L-NAME treatment induced a decrease in NO synthase activity (-62%, p<0.05) and an increase in NADPH-dependent superoxide anion production (+300%, p<0.05) that were totally prevented by (-)-epicatechin administration. These effects of (-)-epicatechin were associated with a higher endothelial NO synthase phosphorylation at an activation site and a reduced expression of the regulatory subunit, p47(phox), suggesting the involvement of posttranslational mechanisms in (-)-epicatechin action. Thus, the (-)-epicatechin treatment would restore NO steady state levels in vivo through effects on both, its synthesis and degradation via the reaction with superoxide anion. The fact that (-)-epicatechin is commonly present in human diet makes this compound a reasonable explanation for the positive cardiovascular effects of a high consumption of fruits and vegetables.