Epicatechin's cardiovascular protective effects are mediated via opioid receptors and nitric oxide

Nailfold Capillaroscopy: A Comprehensive Review on Its Usefulness in Both Clinical Diagnosis and Improving Unhealthy Dietary Lifestyles

Since the 1970s, the utility of nailfold capillaroscopy (NFC) in diagnosing rheumatological disorders such as systemic sclerosis has been well established. Further studies have also shown that NFC can detect non-rheumatic diseases such as diabetes, glaucoma, dermatitis, and Alzheimer disease. In the past decade, nailfold capillary morphological changes have also been reported as symptoms of unhealthy lifestyle habits such as poor diet, smoking, sleep deprivation, and even psychological stress, all of which contribute to slow blood flow. Therefore, studying the relationships between the morphology of nailfold capillaries and lifestyle habits has a high potential to indicate unhealthy states or even pre-disease conditions. Simple, inexpensive, and non-invasive methods such as NFC are important and useful for routine medical examinations. The present study began with a systematic literature search of the PubMed database followed by a summary of studies reporting the assessment of morphological changes detected by NFC, and a comprehensive review of NFC's utility in clinical diagnosis and improving unhealthy dietary lifestyles. It culminates in a summary of dietary and lifestyle health promotion strategy, assessed based on NFC and other related measurements that indicate healthy microvascular blood flow and endothelial function.

Effects of epicatechin on cardiovascular function in middle-aged diet-induced obese rat models of metabolic syndrome

The current study aimed to investigate the cardiovascular effects of epicatechin, a flavonoid found in green tea and cocoa, in attenuating complications associated with metabolic syndrome in diet-induced obese rats. Male Wistar-Kyoto (WKY) rats aged 16 weeks were fed either standard rat chow or given a high-fat-high-carbohydrate (HFHC) diet for 20 weeks. Epicatechin treatment (5 mg/kg/d) was administered to a subset of WKY rats commencing at week 8 of the 20 week HFHC feeding period. Body weights, food, water and energy intakes, blood pressure, heart rate and glucose tolerance were measured throughout the treatment period. Oxidative stress and inflammatory markers, lipid levels, cardiac collagen deposition, cardiac electrical function, aortic and mesenteric vessel reactivity were examined after the treatment. Twenty weeks of HFHC feeding in WKY rats resulted in the development of metabolic syndrome indicated by the presence of abdominal obesity, dyslipidaemia, glucose intolerance and increased blood pressure. Epicatechin treatment was found to enhance the oxidative stress status in HFHC groups through an increase in serum nitric oxide levels and a decrease in 8-isoprostane concentrations. Furthermore, WKY-HFHC rats displayed a decrease in IL-6 levels. The lipid profiles in HFHC groups showed improvement, with a decrease in LDL-cholesterol and TAG and an increase in HDL-cholesterol levels observed in WKY-HFHC rats. However, epicatechin was not effective in preventing weight gain, glucose intolerance or hypertension in HFHC fed rats. Overall, the results of this study suggest that epicatechin has the potential to improve the underlying mechanisms associated with metabolic syndrome in obese rats.

Small ubiquitin-related modifier (SUMO)ylation of SIRT1 mediates (-)-epicatechin inhibited- differentiation of cardiac fibroblasts into myofibroblasts

CONTEXT

(-)-Epicatechin (EPI) is a crucial substance involved in the protective effects of flavanol-rich foods. Previous studies have indicated EPI has a cardioprotective effect, but the molecular mechanisms in inhibition of cardiac fibrosis are unclear.

OBJECTIVE

We evaluated the effect of EPI in preventing cardiac fibrosis and the underlying molecular mechanism related to the SIRT1-SUMO1/AKT/GSK3β pathway.

MATERIALS AND METHODS

Cardiac fibrosis mice model was established with transaortic constriction (TAC). Male C57BL/6 mice were randomly separated into 4 groups. Mice received 1 mg/kg/day of EPI or vehicle orally for 4 weeks. The acutely isolated cardiac fibroblasts were induced to myofibroblasts with 1 µM angiotensin II (Ang II). The cardiac function was measured with the ultrasonic instrument. Histological analysis of mice's hearts was determined with H&E or Masson method. The protein level of fibrosis markers, SUMOylation of SIRT1, and AKT/GSK3β pathway were quantified by immunofluorescence and western blot.

RESULTS

EPI treatment (1 mg/kg/day) could reverse the TAC-induced decline in LVEF (TAC, 61.28% ± 1.33% vs. TAC + EPI, 74.00% ± 1.64%), LVFS (TAC, 28.16% ± 0.89% vs. TAC + EPI, 37.18% ± 1.29%). Meantime, we found that 10 µM EPI blocks Ang II-induced transformation of cardiac fibroblasts into myofibroblasts. The underlying mechanism of EPI-inhibited myofibroblasts transformation involves activation of SUMOylation of SIRT1 through SP1. Furthermore, SUMOylation of SIRT1 inhibited Ang II-induced fibrogenic effect via the AKT/GSK3β pathway.

CONCLUSION

EPI plays a protective effect on cardiac fibrosis by regulating the SUMO1-dependent modulation of SIRT1, which provides a theoretical basis for use in clinical therapies.

A κ-OR Agonist Protects the Endothelial Function Impaired by Hyperuricemia Through Regulating the Akt/eNOS Signal Pathway

To investigate the effects of κ-OR agonist on hyperuricemia rats and injured endothelial function, as well as the underlying mechanism. A hyperuricemia model was established on rats. The endothelial protective effects of U50,488H were evaluated and compared to the controlled groups. The protein levels of eNOS, p-eNOS, Akt, and p-Akt were determined using western blot analysis. ELISA was employed to measure the expression of soluble ET-1, ICAM-1, TNF-α, and NO in cell supernatants and rat serum samples. Cell migration and the artery tension were determined by in vitro functional assays. The suppressed production of ET-1, ICAM-1, and NO in the hyperuricemia rats was promoted by the treatment of U50,488H, which was reversed by the co-administration of nor-BNI. P-eNOS/eNOS and p-Akt/Akt were up-regulated by the incubation of serum from hyperuricemia rats, which was down-regulated by the introduction of U50,488H. The vascular tension of vessels incubated with U50,488H was higher than the baseline in the presence of ACh, which was lower than baseline in the presence of SNAP. U50,488H significantly promoted the release of ET-1, ICAM-1, and NO, and inhibited the release of TNF-α from endothelial cells and the migration ability of neutrophils in the presence of hyperuricemia rat serum, which were reversed by the co-incubation with nor-BNI, Akt inhibitor or L-NAME. U50,488H protected the endothelial function impaired by hyperuricemia through regulating the Akt/eNOS signal pathway.

( -)-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.

(-)-Epicatechin ameliorates cigarette smoke-induced lung inflammation via inhibiting ROS/NLRP3 inflammasome pathway in rats with COPD

Chronic obstructive pulmonary disease (COPD) with increased morbidity and mortality is a worldwide healthcare challenge closely associated with cigarette smoking (CS). Currently, there is no effective therapeutic strategy to control inflammation in COPD patients. The present study tested the protective effects of (-)-Epicatechin (EC), a type of flavonoid, on CS-induced COPD and the underlying mechanism. Also, EC repressed the production of reactive oxygen species (ROS) and improved human bronchial epithelial cell viability after cigarette smoke extract (CSE) treatment. Further studies demonstrated that EC promotes ubiquitin-mediated Keap1 degradation by upregulating tripartite motif-containing protein 25 (TRIM25) expression and enhances the nuclear localization of Nrf2 protein. Also, EC dramatically inhibits the activation of NLRP3 inflammasome and reduces the CSE-induced pyroptosis, as indicated by decreasing lactate dehydrogenase release and the number of caspase-1-positive cells. Importantly, Nrf2 knockdown reversed the protective effect of EC on human bronchial epithelial cells, at least partially. Consistent with the results in vitro, EC inhibits the activation of NLRP3 inflammasome and relieves the CS-induced lung inflammation, as evident from decreased interleukin (IL)-1β and IL-18 secretion in a COPD rat model. In conclusion, this study revealed the protective effect of EC on experimental COPD rats and elucidated the mechanism of EC promoting Nrf2 activity, which might provide a novel therapeutic strategy for COPD.

κ Opioid Receptor Agonist Inhibits Myocardial Injury in Heart Failure Rats through Activating Nrf2/HO-1 Pathway and Regulating Ca2+-SERCA2a

OBJECTIVES

We aimed to observe the protective effect of κ opioid receptor (κ-OR) agonist on myocardial injury in heart failure (HF) rats and its effect on Ca2+-SERCA2a and to explore the regulatory mechanism with the Nrf2/HO-1 signaling pathway.

METHODS

50 Sprague-Dawley rats were randomly divided into the following groups: the sham operation group (sham group), HF model group (HF group), HF+κ-OR agonist U50488 group (HU group), HF+U50488H+novel calmodulin-dependent protein kinase II (CaMKII) agonist (oleic acid) (HUO group), and HF+U50488H+Nrf2 inhibitor (HUM group). The HF rat's model was established through surgical ligation of the left anterior descending coronary artery and the exhausting swimming exercise. After that, rat's cardiac function was monitored by echocardiography. HE and MASSON staining was used to detect the myocardial injury, and TUNEL staining was used to detect the myocardial apoptosis. ELISA was performed to detect the biomarkers of oxidative stress. Moreover, the distribution of reactive oxygen species (ROS) and Nrf2 was detected under immunofluorescence. The expression of sarco/endoplasmic reticulum calcium (Ca2+) ATPase (SERCA) 2a, calmodulin, endoplasmic reticulum stress- (ERS-) related proteins, and Nrf2/HO-1 signaling pathway-related proteins were detected by Western Blotting.

RESULTS

κ-OR agonist U50488H can significantly enhance rat's cardiac function, reduce the injury and apoptosis of myocardial cells, and alleviate endoplasmic reticulum stress injury in HF rats via upregulating the SERCA2a expression and inhibiting the Ca2+ influx. Furthermore, U50488H could also inhibit the phosphorylation of CaMKII and cAMP-response element binding protein (CREB). Additionally, administration of CaMKII-specific agonist could partially block the therapeutic effect of κ-OR agonist on the myocardium of HF rats. Interestingly, the antagonist of Nrf2 could also significantly reverse the therapeutic effect of κ-OR agonist. Therefore, these results suggested that the effect of U50488H on HF rats is dependent on regulating CaMKII phosphorylation and activating the Nrf2/HO-1 pathway.

CONCLUSION

κ-OR agonists U50488H can improve ERS in cardiomyocytes and relieve myocardial injury in HF rats through activating the Nrf2/HO-1 pathway and regulating Ca2+-SERCA2a to inhibit Ca2+ influx.

Mechanisms Modified by (-)-Epicatechin and Taxifolin Relevant for the Treatment of Hypertension and Viral Infection: Knowledge from Preclinical Studies

Various studies have shown that certain flavonoids, flavonoid-containing plant extracts, and foods can improve human health. Experimental studies showed that flavonoids have the capacity to alter physiological processes as well as cellular and molecular mechanisms associated with their antioxidant properties. An important function of flavonoids was determined in the cardiovascular system, namely their capacity to lower blood pressure and to improve endothelial function. (-)-Epicatechin and taxifolin are two flavonoids with notable antihypertensive effects and multiple beneficial actions in the cardiovascular system, but they also possess antiviral effects, which may be of particular importance in the ongoing pandemic situation. Thus, this review is focused on the current knowledge of (-)-epicatechin as well as (+)-taxifolin and/or (-)-taxifolin-modified biological action and underlining molecular mechanisms determined in preclinical studies, which are relevant not only to the treatment of hypertension per se but may provide additional antiviral benefits that could be relevant to the treatment of hypertensive subjects with SARS-CoV-2 infection.

Promising Medicinal Plants with Diuretic Potential Used in Brazil: State of the Art, Challenges, and Prospects

Medicinal plants are used in traditional medicine to treat a wide range of ailments. The knowledge of them is handed down from generation to generation and is described in several pharmacopoeia and in the general literature. The immense biodiversity of the Brazilian flora, covering about 25% of all plant species worldwide, makes Brazil a huge potential source of medicinal plants. Indeed, many of these plant species are already used in the Brazilian ethnopharmacology for their probable effect to induce diuresis, to reduce fluid retention, and to treat cardiovascular and renal disorders. This review article describes and discusses the main native Brazilian medicinal plants (including some of their isolated compounds) used as diuretics. It also gives a comprehensive analysis of the most relevant scientific studies presented to date, as well as addressing a special topic with future prospects for plant species that have not yet been scientifically studied. In brief, several plants can be indicated for more detailed study, with a view to obtain scientific subsidies for a new and effective diuretic medicine in the future. These include Bauhinia forficata, Leandra dasytricha, and Tropaeolum majus. Other species have reputed medicinal properties but lack experimental assays to demonstrate their pharmacological effects (e.g., Mikania hirsutissima, Phyllanthus niruri, and Tagetes minuta). Several active principles are indicated as responsible for the diuretic effects of the plants studied, with emphasis on phenolic compounds as flavonoids, phenolic acids, and xanthones. These results should encourage more detailed preclinical, clinical, and phytochemical investigations on Brazilian plants in the future.

Docking Characterization and in vitro Inhibitory Activity of Flavan-3-ols and Dimeric Proanthocyanidins Against the Main Protease Activity of SARS-Cov-2

We report to use the main protease (M^pro) of SARS-Cov-2 to screen plant flavan-3-ols and proanthocyanidins. Twelve compounds, (-)-afzelechin (AF), (-)-epiafzelechin (EAF), (+)-catechin (CA), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin-3-O-gallate (CAG), (-)-epicatechin-3-O-gallate (ECG), (-)-gallocatechin-3-O-gallate (GCG), (-)-epigallocatechin-3-O-gallate (EGCG), procyanidin A2 (PA2), and procyanidin B2 (PB2), were selected for docking simulation. The resulting data predicted that all 12 metabolites could bind to M^pro. The affinity scores of PA2 and PB2 were predicted to be -9.2, followed by ECG, GCG, EGCG, and CAG, -8.3 to -8.7, and then six flavan-3-ol aglycones, -7.0 to -7.7. Docking characterization predicted that these compounds bound to three or four subsites (S1, S1', S2, and S4) in the binding pocket of M^pro via different spatial ways and various formation of one to four hydrogen bonds. In vitro analysis with 10 available compounds showed that CAG, ECG, GCG, EGCG, and PB2 inhibited the M^pro activity with an IC₅₀ value, 2.98 ± 0.21, 5.21 ± 0.5, 6.38 ± 0.5, 7.51 ± 0.21, and 75.3 ± 1.29 μM, respectively, while CA, EC, EGC, GC, and PA2 did not have inhibitory activities. To further substantiate the inhibitory activities, extracts prepared from green tea (GT), two muscadine grapes (MG), cacao, and dark chocolate (DC), which are rich in CAG, ECG, GAG, EGCG, or/and PB2, were used for inhibitory assay. The resulting data showed that GT, two MG, cacao, and DC extracts inhibited the M^pro activity with an IC₅₀ value, 2.84 ± 0.25, 29.54 ± 0.41, 29.93 ± 0.83, 153.3 ± 47.3, and 256.39 ± 66.3 μg/ml, respectively. These findings indicate that on the one hand, the structural features of flavan-3-ols are closely associated with the affinity scores; on the other hand, the galloylation and oligomeric types of flavan-3-ols are critical in creating the inhibitory activity against the M^pro activity.

Ethanol Extract of Chinese Hawthorn (Crataegus pinnatifida) Fruit Reduces Inflammation and Oxidative Stress in Rats with Doxorubicin-Induced Chronic Heart Failure

Background

Chinese hawthorn (Crataegus pinnatifida) fruit is a traditional Chinese medicine for treatment of digestive system and cardiovascular diseases. The fruit contains polyphenol compounds, such as epicatechin, that have anti-inflammatory activity. This study aimed to investigate the effects of an alcohol extract of hawthorn fruit (HAE) on inflammation and oxidative stress in rats with doxorubicin-induced chronic heart failure (CHF).

Material/Methods

Rats were intraperitoneally injected with doxorubicin to induce CHF and subsequently treated with HAE intragastrically once daily for 6 weeks. At the end of the experiment, echocardiographic and hemodynamic parameters were assessed, and enzyme-linked immunoassays were used to detect the levels of cardiac injury markers (brain natriuretic peptide, creatine kinase-MB, aspartate aminotransferase, lactate dehydrogenase, copeptin, and adrenomedullin), oxidative stress markers (glutathione peroxidase and malondialdehyde), and inflammatory cytokines (interleukin [IL]-6, IL-8, IL-1β, and tumor necrosis factor-α). The IL-1β, IL-6, glutathione peroxidase-1, and catalase mRNA levels were also measured by quantitative real-time polymerase chain reaction.

Results

Our findings indicated that HAE exerts a cardioprotective effect, as shown by improved echocardiographic and hemodynamic parameters, decreased activity of serum myocardial enzymes, reduced serum levels of CHF markers, and inhibited inflammatory response in cardiac tissue. In addition, HAE treatment downregulated the mRNA expression of IL-1β and tumor necrosis factor-α and upregulated the mRNA expression of glutathione peroxidase-1 and catalase compared with untreated doxorubicin-induced CHF rats.

Conclusions

HAE shows promise for the prevention and treatment of CHF. The cardioprotective effect of HAE appears to be related to inhibition of both the inflammatory response and oxidative stress in vivo.

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.

Current state and future perspective of cardiovascular medicines derived from natural products

The contribution of natural products (NPs) to cardiovascular medicine has been extensively documented, and many have been used for centuries. Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Over the past 40 years, approximately 50% of newly developed cardiovascular drugs were based on NPs, suggesting that NPs provide essential skeletal structures for the discovery of novel medicines. After a period of lower productivity since the 1990s, NPs have recently regained scientific and commercial attention, leveraging the wealth of knowledge provided by multi-omics, combinatorial biosynthesis, synthetic biology, integrative pharmacology, analytical and computational technologies. In addition, as a crucial part of complementary and alternative medicine, Traditional Chinese Medicine has increasingly drawn attention as an important source of NPs for cardiovascular drug discovery. Given their structural diversity and biological activity NPs are one of the most valuable sources of drugs and drug leads. In this review, we briefly described the characteristics and classification of NPs in CVDs. Then, we provide an up to date summary on the therapeutic potential and the underlying mechanisms of action of NPs in CVDs, and the current view and future prospect of developing safer and more effective cardiovascular drugs based on NPs.

(-)-Epicatechin Reduces Blood Pressure and Improves Left Ventricular Function and Compliance in Deoxycorticosterone Acetate-Salt Hypertensive Rats

(−)-Epicatechin (E) is a flavanol found in green tea and cocoa and has been shown to attenuate tumour necrosis factor alpha (TNF-α)-mediated inflammation, improve nitric oxide levels, promote endothelial nitric oxide synthase (eNOS) activation and inhibit NADPH oxidase. This study investigated the effect of 28 days of low epicatechin dosing (1 mg/kg/day) on the cardiovascular function of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Wistar rats (n = 120, 8 weeks of age) underwent uninephrectomy and were randomised into four groups (uninephrectomy (UNX), UNX + E, DOCA, DOCA + E). DOCA and DOCA + E rats received 1% NaCl drinking water along with subcutaneous injections of 25 mg deoxycorticosterone-acetate (in 0.4 mL of dimethylformamide) every fourth day. UNX + E and DOCA + E rats received 1 mg/kg/day of epicatechin by oral gavage. Single-cell micro-electrode electrophysiology, Langendorff isolated-heart assessment and isolated aorta and mesenteric organ baths were used to assess cardiovascular parameters. Serum malondialdehyde concentration was used as a marker of oxidative stress. Myocardial stiffness was increased and left ventricular compliance significantly diminished in the DOCA control group, and these changes were attenuated by epicatechin treatment (p < 0.05). Additionally, the DOCA + E rats showed significantly reduced blood pressure and malondialdehyde concentrations; however, there was no improvement in left ventricular hypertrophy, electrophysiology or vascular function. This study demonstrates the ability of epicatechin to reduce blood pressure, prevent myocardial stiffening and preserve cardiac compliance in hypertrophied DOCA-salt rat hearts.