Qianyang yuyin granule ameliorates mitochondrial dysfunction of hypertensive myocardial remodeling

ETHNOPHARMACOLOGICAL RELEVANCE

Clinical studies have found that Qianyang Yuyin granule (QYYYG), a kind of oral Chinese patent medicine, had definite clinical effect for hypertensive myocardial remodeling. However, the potential mechanism is not entirely clear.

AIM OF THE STUDY

The purpose of this research was to explore the underlying mechanism QYYYG on the treatment of hypertensive myocardial remodeling.

MATERIALS AND METHODS

Analysis the transcriptome data from the NCBI public platform GEO database and our study to explore the key pathological change of myocardial tissues in hypertensive mice and the main pathway of QYYYG in treating hypertensive myocardial remodeling. Network pharmacological analysis was used to predict the potential target of QYYYG. The molecular docking and molecular dynamics simulation was used for molecular binding analysis of specific compounds and target proteins. In the experiment in vivo, the effect of QYYYG on hypertensive myocardial remodeling and myocardial mitochondrial dysfunction in hypertensive mice caused by Ang Ⅱ was estimated. In the experiment in vitro, the Ang Ⅱ-induced myocardial remodeling model in H9c2 cells was constructed, and the effect of QYYYG on ameliorating myocardial remodeling and mitochondrial dysfunction was evaluated.

RESULTS

Transcriptome analysis suggested that mitochondrial dysfunction was a key pathological change of myocardial tissues in hypertensive mice, and QYYYG could improve hypertensive myocardial remodeling through enhancing mitochondrial biogenesis to repair myocardial mitochondrial dysfunction. Network pharmacological analysis predicted that SIRT1 was an important potential target of QYYYG in treating hypertensive myocardial remodeling, and basically all the active components, especially quercetin, had a great binding affinity with SIRT1. Experiments in vivo proved that QYYYG had great efficacy hypertensive myocardial remodeling in Ang Ⅱ-treated mice. It was found that QYYYG improved the quality and quantity of mitochondria, and increased SIRT1 levels in myocardial tissue of Ang Ⅱ-treated mice. In Ang Ⅱ-treated H9c2 cells, with intervention of QYYYG, myocardial remodeling and myocardial mitochondrial dysfunction was ameliorated. In addition, QYYYG up-regulated SIRT1 expression and enhanced mitochondrial biogenesis in Ang Ⅱ-treated H9c2 cells.

CONCLUSION

This study suggested that mitochondrial dysfunction was an important pathological change of myocardial tissues in hypertensive mice. QYYYG might ameliorate the mitochondrial dysfunction of hypertensive myocardial remodeling through up-regulating SIRT1 expression to enhance the mitochondrial biogenesis.

Elucidation of the Molecular Mechanism of Compound Danshen Dripping Pills against Angina Pectoris based on Network Pharmacology and Molecular Docking

BACKGROUND

Compound Danshen dripping pills (CDDP), a traditional Chinese medicine, has had an extensive application in the treatment of angina pectoris (AP) in China. However, research on the bioactive ingredients and underlying mechanisms of CDDP in AP remains unclear.

OBJECTIVE

In the present study, we explored the major chemical components and potential molecular mechanisms linked to the anti-angina effects of CDDP through the application of network pharmacology and molecular docking.

METHODS

The potential targets of active ingredients in CDDP were sourced from the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and the Swiss Target Prediction Database (STPD). Additionally, targets related to angina pectoris (AP) were retrieved from various databases, including Gene Cards, DisGeNET, Dis Genet, the Drug Bank database (DBD), and the Therapeutic Target Database (TDD). Protein- protein interaction networks were also established, and core targets were identified based on their topological significance. GO enrichment analysis and KEGG pathway analysis were conducted using the R software. Interactions between active ingredients and potential targets selected through the above process were investigated through molecular docking.

RESULTS

Seventy-six active ingredients were selected with the following criteria: OB ≥ 30%, DL ≥ 0.18. 383 targets of CDDP and 1488 targets on AP were gathered, respectively. Afterwards, 194 common targets of CDDP and anti-AP targets were defined, of which 12 were core targets. GO enrichment analysis indicated that CDDP acted on AP by response to lipopolysaccharide, regulating the reactive oxygen species and metal ion metabolism, and epithelial cell proliferation. In addition, KEGG enrichment analysis indicated that the signaling pathways were notably enriched in lipid and atherosclerosis, fluid shear stress and atherosclerosis, IL-17 signaling pathway, EGFR tyrosine kinase inhibitor resistance, PI3K-Akt signaling pathway, and TNF signaling pathway. Moreover, the molecular docking manifested excellent binding capacity between the active ingredients and targets on AP.

CONCLUSION

This study comprehensively illustrated the bioactive, potential targets, and molecular mechanisms of CDDP against AP, offering fresh perspectives into the molecular mechanisms of CDDP in preventing and treating AP.

Research progress of quercetin in cardiovascular disease

Quercetin is one of the most common flavonoids. More and more studies have found that quercetin has great potential utilization value in cardiovascular diseases (CVD), such as antioxidant, antiplatelet aggregation, antibacterial, cholesterol lowering, endothelial cell protection, etc. However, the medicinal value of quercetin is mostly limited to animal models and preclinical studies. Due to the complexity of the human body and functional structure compared to animals, more research is needed to explore whether quercetin has the same mechanism of action and pharmacological value as animal experiments. In order to systematically understand the clinical application value of quercetin, this article reviews the research progress of quercetin in CVD, including preclinical and clinical studies. We will focus on the relationship between quercetin and common CVD, such as atherosclerosis, myocardial infarction, ischemia reperfusion injury, heart failure, hypertension and arrhythmia, etc. By elaborating on the pathophysiological mechanism and clinical application research progress of quercetin's protective effect on CVD, data support is provided for the transformation of quercetin from laboratory to clinical application.

Resveratrol and beyond: The Effect of Natural Polyphenols on the Cardiovascular System: A Narrative Review

Cardiovascular diseases (CVDs) are among the leading causes of morbidity and mortality worldwide. Unhealthy dietary habits have clearly been shown to contribute to the development of CVDs. Beyond the primary nutrients, a healthy diet is also rich in plant-derived compounds. Natural polyphenols, found in fruits, vegetables, and red wine, have a clear role in improving cardiovascular health. In this review, we strive to summarize the results of the relevant pre-clinical and clinical trials that focused on some of the most important natural polyphenols, such as resveratrol and relevant flavonoids. In addition, we aim to identify their common sources, biosynthesis, and describe their mechanism of action including their regulatory effect on signal transduction pathways. Finally, we provide scientific evidence regarding the cardiovascular benefits of moderate, long-term red wine consumption.

Impact of polyphenols on heart failure and cardiac hypertrophy: clinical effects and molecular mechanisms

Polyphenols are abundant in regular diets and possess antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and cardioprotective effects. Regarding the inadequacy of the current treatments in preventing cardiac remodeling following cardiovascular diseases, attention has been focused on improving cardiac function with potential alternatives such as polyphenols. The following online databases were searched for relevant orginial published from 2000 to 2023: EMBASE, MEDLINE, and Web of Science databases. The search strategy aimed to assess the effects of polyphenols on heart failure and keywords were "heart failure" and "polyphenols" and "cardiac hypertrophy" and "molecular mechanisms". Our results indicated polyphenols are repeatedly indicated to regulate various heart failure-related vital molecules and signaling pathways, such as inactivating fibrotic and hypertrophic factors, preventing mitochondrial dysfunction and free radical production, the underlying causes of apoptosis, and also improving lipid profile and cellular metabolism. In the current study, we aimed to review the most recent literature and investigations on the underlying mechanism of actions of different polyphenols subclasses in cardiac hypertrophy and heart failure to provide deep insight into novel mechanistic treatments and direct future studies in this context. Moreover, due to polyphenols' low bioavailability from conventional oral and intravenous administration routes, in this study, we have also investigated the currently accessible nano-drug delivery methods to optimize the treatment outcomes by providing sufficient drug delivery, targeted therapy, and less off-target effects, as desired by precision medicine standards.

Do Rutin and Quercetin Retain Their Structure and Radical Scavenging Activity after Exposure to Radiation?

The influence of ionizing radiation on the physicochemical properties of quercetin and rutin in the solid state was studied. Quercetin and rutin were irradiated with the standard recommended radiation dose (25 kGy) according to EN 522 standard. The samples were irradiated by electron beam radiation. EPR studies indicate the formation of a small number of free radicals due to irradiation. Moreover, some radicals recombined with the mean lifetime of 1200 and 93 h, and a stable radical concentration reached only 0.29 and 0.90 ppm for quercetin and rutin, respectively. The performed spectroscopic study (FT-IR) confirmed the radiostability of the flavonoids tested. Chromatographic tests (HPLC, HPLC-MS) showed that irradiation of quercetin and rutin with a 25 kGy dose did not change the physicochemical properties of the tested compounds. Degradation products were not observed. The antioxidant activities were determined by the 2,2-diphenyl-1-pycrylhydrazyl (DPPH) free radical scavenging activity assay, ABTS Radical Scavenging Assay (ABTS), Ferric Reducing Antioxidant Power Assay (FRAP), Cupric Ion Reducing Antioxidant Capacity Assay (CUPRAC). The conducted research confirmed that exposure to ionizing radiation does not change the chemical structure of tested flavonoids and their antioxidant properties.

Modulation of integrin receptor by polyphenols: Downstream Nrf2-Keap1/ARE and associated cross-talk mediators in cardiovascular diseases

As a group of heterodimeric and transmembrane glycoproteins, integrin receptors are widely expressed in various cell types overall the body. During cardiovascular dysfunction, integrin receptors apply inhibitory effects on the antioxidative pathways, including nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch like ECH Associated Protein 1 (Keap1)/antioxidant response element (ARE) and interconnected mediators. As such, dysregulation in integrin signaling pathways influences several aspects of cardiovascular diseases (CVDs) such as heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. So, modulation of integrin pathway could trigger the downstream antioxidant pathways toward cardioprotection. Regarding the involvement of multiple aforementioned mediators in the pathogenesis of CVDs, as well as the side effects of conventional drugs, seeking for novel alternative drugs is of great importance. Accordingly, the plant kingdom could pave the road in the treatment of CVDs. Of natural entities, polyphenols are multi-target and accessible phytochemicals with promising potency and low levels of toxicity. The present study aims at providing the cardioprotective roles of integrin receptors and downstream antioxidant pathways in heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. The potential role of polyphenols has been also revealed in targeting the aforementioned dysregulated signaling mediators in those CVDs.

Application of network pharmacology and molecular docking approach to explore active compounds and potential pharmacological mechanisms of Aconiti Lateralis Radix Praeparata and Lepidii Semen Descurainiae Semen for treatment of heart failure

BACKGROUND

Heart failure (HF) is the end stage of the development of heart disease, whose prognosis is poor. The previous research of our team indicated that the formulae containing Aconiti Lateralis Radix Praeparata and Lepidii Semen Descurainiae Semen (ALRP-LSDS) could inhibit myocardial hypertrophy, inhibit cardiomyocyte apoptosis, delay myocardial remodeling (REM), and improve the prognosis of patients with HF effectively. In order to explore the mechanism of ALRP-LSDS for the treatment of HF, a combined approach of network pharmacology and molecular docking was conducted.

METHODS

Public database TCMSP was used to screen the active compounds of ALRP-LSDS. The targets of screened active compounds were obtained from the TCMSP database and predicted using the online analysis tool PharmMapper. The targets of HF were obtained from 6 databases including GeneCards, OMIM, DrugBank, TTD, PharmGKB, and DisGeNET. Protein-protein interaction and enrichment analysis were performed, respectively, by STRING and Metascape online tools after merging the targets of active compounds and HF. Cytoscape software was used to conduct networks. Finally, molecular docking was performed by Vina to verify the correlation between key targets and active compounds.

RESULTS

Final results indicated that the active compounds including β-sitosterol, isorhamnetin, quercetin, kaempferol, and (R)-norcoclaurine, the targets including AKT1, CASP3, and MAPK1 might be the main active compounds and key targets of ALRP-LSDS for the treatment of HF separately. The binding ability of AKT1 to the main active compounds was better compared with the other 2 key targets, which means it might be more critical. The pathways including AGE-RAGE signaling pathway in diabetic complications, Pathways in cancer, and Fluid shear stress and atherosclerosis might play important roles in the treatment of HF with ALRP-LSDS. In general, ALRP-LSDS could inhibit cardiomyocyte apoptosis, delay REM, and improve cardiac function through multicompound, multitarget, and multipathway, which contributes to the treatment of HF.

CONCLUSIONS

Based on the combined approach of network pharmacology and molecular docking, this study screened out the main active compounds, key targets, and main pathways of ALRP-LSDS for the treatment of HF, and revealed its potential mechanisms, providing a theoretical basis for further research.

Health Benefits of Cereal Grain- and Pulse-Derived Proteins

Pulses and whole grains are considered staple foods that provide a significant amount of calories, fibre and protein, making them key food sources in a nutritionally balanced diet. Additionally, pulses and whole grains contain many bioactive compounds such as dietary fibre, resistant starch, phenolic compounds and mono- and polyunsaturated fatty acids that are known to combat chronic disease. Notably, recent research has demonstrated that protein derived from pulse and whole grain sources contains bioactive peptides that also possess disease-fighting properties. Mechanisms of action include inhibition or alteration of enzyme activities, vasodilatation, modulation of lipid metabolism and gut microbiome and oxidative stress reduction. Consumer demand for plant-based proteins has skyrocketed primarily based on the perceived health benefits and lower carbon footprint of consuming foods from plant sources versus animal. Therefore, more research should be invested in discovering the health-promoting effects that pulse and whole grain proteins have to offer.

A Systematic Review on the Role of SIRT1 in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a muscular disease characterized by progressive muscle degeneration. Life expectancy is between 30 and 50 years, and death is correlated with cardiac or respiratory complications. Currently, there is no cure, so there is a great interest in new pharmacological targets. Sirtuin1 (SIRT1) seems to be a potential target for DMD. In muscle tissue, SIRT1 exerts anti-inflammatory and antioxidant effects. The aim of this study is to summarize all the findings of in vivo and in vitro literature studies about the potential role of SIRT1 in DMD. A systematic literature search was performed according to PRISMA guidelines. Twenty-three articles satisfied the eligibility criteria. It emerged that SIRT1 inhibition led to muscle fragility, while conversely its activation improved muscle function. Additionally, resveratrol, a SIRT1 activator, has brought beneficial effects to the skeletal, cardiac and respiratory muscles by exerting anti-inflammatory activity that leads to reduced myofiber wasting.

Quercetin treatment increases H2O2 removal by restoration of endogenous antioxidant activity and blocks isoproterenol-induced cardiac hypertrophy

Oxidative stress, characterized by the accumulation of reactive oxygen species (ROS), is implicated in the pathogenesis of several diseases, including cardiac hypertrophy. The flavonoid quercetin is a potent ROS scavenger, with several beneficial effects for the cardiovascular system, including antihypertrophic effects. Oxidative imbalance has been implicated in cardiac hypertrophy and heart failure. In this work, we tested whether quercetin could attenuate cardiac hypertrophy by improving redox balance and mitochondrial homeostasis. To test this hypothesis, we treated a group of mice with isoproterenol (30 mg/kg/day) for 4 or 8 consecutive days. Another group received quercetin (10 mg/kg/day) from day 5th of isoproterenol treatment. We carried out the following assays in cardiac tissue: measurement of cardiac hypertrophy, protein sulfhydryl, catalase, Cu/Zn and Mn-superoxide dismutase (SOD) activity, detection of H₂O₂, and opening of the mitochondrial permeability transition pore. The animals treated with isoproterenol for the initial 4 days showed increased cardiac weight/tibia length ratio, decreased protein sulfhydryl content, compromised SOD and catalase activity, and high H₂O₂ levels. Quercetin was able to attenuate cardiac hypertrophy, restore protein sulfhydryl, and antioxidant activity, in addition to efficiently blocking the H₂O₂. We also observed that isoproterenol decreases mitochondrial SOD activity, while quercetin reverses it. Strikingly, quercetin also protects mitochondria against the opening of mitochondrial permeability transition pore. Taken together, these results suggest that quercetin is capable of reversing established isoproterenol-induced cardiac hypertrophy through the restoration of cellular redox balance and protecting mitochondria.

Quercetin Dihydrate inhibition of cardiac fibrosis induced by angiotensin II in vivo and in vitro

Cardiac fibroblasts play a key role in the process of myocardial remodeling and myocardial fibrosis, which will eventually lead to heart failure. Quercetin Dihydrate has been studied in cardiovascular disease, but its effect on myocardial fibrosis is not clear. Here, cardiac remodeling was induced by infusion of Ang II (1000 ng/kg/min) for 2 weeks in mice. Quercetin Dihydrate was injected intraperitoneally for 25 mM/kg body weight (BW) once two days. We found that Quercetin Dihydrate significantly reduced cardiac contractile function, fibrosis, inflammation and myocardial hypertrophy induced by Ang II. Quercetin Dihydrate could inhibit the expression of Collagen I and Collagen III, which are the markers of fibroblast differentiation. We also verified the inhibitory effect of Quercetin Dihydrate on the proliferation and differentiation of fibroblasts induced by angiotensin II in vitro. Our results show that quercetin dihydrate plays a key role in the progression of myocardial fibrosis and suggests that Quercetin Dihydrate may be a promising drug for the treatment of myocardial fibrosis.

Cardioprotective Effects of Dietary Phytochemicals on Oxidative Stress in Heart Failure by a Sex-Gender-Oriented Point of View

Dietary phytochemicals are considered an innovative strategy that helps to reduce cardiovascular risk factors. Some phytochemicals have been shown to play a beneficial role in lipid metabolism, to improve endothelial function and to modify oxidative stress pathways in experimental and clinical models of cardiovascular impairment. Importantly, investigation on phytochemical effect on cardiac remodeling appears to be promising. Nowadays, drug therapy and implantation of devices have demonstrated to ameliorate survival. Of interest, sex-gender seems to influence the response to HF canonical therapies. In fact, starting by the evidence of the feminization of world population and the scarce efficacy and safety of the traditional drugs in women, the search of alternative therapeutic tools has become mandatory. The aim of this review is to summarize the possible role of dietary phytochemicals in HF therapy and the evidence of a different sex-gender-oriented response.

Quercetin protects against atherosclerosis by regulating the expression of PCSK9, CD36, PPARγ, LXRα and ABCA1

The aim of this study was to investigate the mechanisms through which quercetin protects against atherosclerosis (AS) in apoE‑/‑ mice by regulating the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9), cluster of differentiation 36 (CD36), peroxisome proliferator‑activated receptor γ (PPARγ), liver X receptor α (LXRα) and ATP binding cassette transporter A1 (ABCA1). We established an animal model of high‑fat diet induced AS using apoE‑/‑ mice. H&E, Oil Red O and Masson's trichrome staining were performed on aortic sinus and liver tissue sections to evaluate the histopathology, lipid accumulation and collagen deposition, respectively. Filipin staining was performed to detect free cholesterol (FC) in the aortic sinus. ELISA was performed to measure the serum levels of lipids including total cholesterol (TC), triglyceride (TG), high‑density lipoprotein‑cholesterol (HDL‑C), low‑density lipoprotein‑cholesterol (LDL‑C) and oxidized low‑density lipoprotein (oxLDL), as well as the levels of inflammatory cytokines, including tumor necrosis factor (TNF)‑α, interleukin (IL)‑6 and IL‑10. Western blot analysis was performed to analyze the protein expression levels of PCSK9, CD36, PPARγ, LXRα and ABCA1 in both the aorta and liver tissue. H&E staining revealed the presence of atherosclerotic plaques in the aortic sinus. Oil Red O staining revealed the existence of massive red‑stained lipids in the aortic sinus and Masson's trichrome staining revealed decreased collagen fibers and increased plaque instability. Filipin staining revealed that free cholesterol levels in the aorta sinus were increased. In addition, H&E staining suggested hepatocyte structural disorder in the model group, and Oil Red O staining revealed a cytoplasm filled with lipid droplets, which contained a large amount of red‑stained lipids. Masson's trichrome staining revealed that the liver tissue of the model group had fewer collagen fibers compared with that of the control group. Moreover, the mice in the model group had higher serum TC, LDL‑C, oxLDL, TNF‑α and IL‑6 levels, and lower IL‑10 levels. The protein expression levels of PCSK9 and CD36 were increased, while those of PPARγ, LXRα and ABCA1 were decreased in the aortas and livers of the model group mice. However, treatment with quercetin attenuated all these effects. On the whole, these results demonstrate that quercetin prevents the development of AS in apoE‑/‑ mice by regulating the expression of PCSK9, CD36, PPARγ, LXRα and ABCA1.

Quercetin and Epigallocatechin Gallate in the Prevention and Treatment of Obesity: From Molecular to Clinical Studies

Obesity is a worldwide epidemic, which is characterized by the excess accumulation of adipose tissue and to an extent that impairs both the physical and psychosocial health and well-being. There are several weight-loss strategies available, including dietary modification, pharmacotherapy, and bariatric surgery, but many are ineffective or not a long-term solution. Bioactive compounds present in medicinal plants and plant extracts, like polyphenols, constitute the oldest and most extensive form of alternative treatments for the prevention and management of obesity. Their consumption is currently increasing in the population due to the high cost, potential adverse effects, and limited benefits of the currently available pharmaceutical drugs. A great number of studies has explored how dietary polyphenols can interfere with the different mechanisms associated with obesity development. They suggest that these compounds can decrease energy and food intake, lipogenesis, and preadipocyte differentiation and proliferation, while increasing energy expenditure, lipolysis, and fat oxidation. Both quercetin, one of the most common dietary flavonols in the western diet, and epigallocatechin gallate (EGCG), the most abundant polyphenol in green tea, exhibit antiobesity effects in adipocyte cultures and animal models. However, the extrapolation of these potential benefits to obese humans remains unclear. Although quercetin supplementation does not seem to exert any beneficial effects on body weight, this polyphenol could prevent the obesity-associated mortality by reducing cardiovascular disease risk. An important consideration for the design of further trials is the occurrence of gene polymorphisms in key enzymes involved in flavanol metabolism, which determines a subject's sensitivity to catechins and seems, therefore, crucial for the success of the antiobesity intervention. Although the evidence supporting antiobesity effects is more consistent in EGCG than with quercetin studies, they could still be beneficial by reducing the cardiovascular risk of obese subjects, rather than inducing body weight loss.

Quercetin Prevents In Vivo and In Vitro Myocardial Hypertrophy Through the Proteasome-GSK-3 Pathway

PURPOSE

Quercetin, a flavonoid, has been reported to ameliorate cardiovascular diseases, such as cardiac hypertrophy. However, the mechanism is not completely understood. In this study, a mechanism related to proteasome-glycogen synthesis kinase 3 (GSK-3) was elucidated in rats and primary neonatal cardiomyocytes.

METHODS

Rats were subjected to sham or constriction of abdominal aorta surgery groups and treated with or without quercetin for 8 weeks. Angiotensin II (Ang II)-induced primary cardiomyocytes were cultured with quercetin treatment or not for 48 h. Echocardiography, real-time RT-PCR, histology, immunofluorescence, and Western blotting were conducted. Proteasome activities were also detected using a fluorescent peptide substrate.

RESULTS

Echocardiography showed that quercetin prevented constriction of abdominal aorta-induced cardiac hypertrophy and improved the cardiac diastolic function. In addition, quercetin also significantly reduced the Ang II-induced hypertrophic surface area and atrial natriuretic factor (ANF) mRNA level in primary cardiomyocytes. Proteasome activities were obviously inhibited in the quercetin-treated group both in vivo and in vitro. Quercetin also decreased the levels of proteasome subunit beta type (PSMB) 1, PSMB2, and PSMB5 of the 20S proteasome as well as the levels of proteasome regulatory particle (Rpt) 1 and Rpt4 of the 19S proteasome. In particular, the PSMB5 level in the nucleus was reduced after quercetin treatment. Furthermore, phosphorylated GSK-3α/β (inactivation of GSK-3) was decreased, which means that GSK-3 activity was increased. The phosphorylation levels of upstream AKT (PKB (protein kinase B)) and liver kinase B1/AMP activated protein kinase (LKB1/AMPKα) and those of downstream extracellular signal-regulated kinase (ERK), histone H3, β-catenin, and GATA binding protein 4 (GATA4) were reduced after quercetin treatment, while hypertrophy was reversed after treatment with the GSK-3 inhibitor.

CONCLUSION

In summary, quercetin prevents cardiac hypertrophy, which is related to proteasome inhibition and activation of GSK-3α/β. Upstream (AKT, LKB1/AMPKα) and downstream hypertrophic factors, such as ERK, histone H3, β-catenin, and GATA4, may also be involved.

Therapeutic potential of quercetin as a cardiovascular agent

Flavonoids are integral components of various vegetation and in foods; consequently, they represent an inevitable part of the diet. Historical and epidemiological proof recommend that diet plans consisting of flavonoids such as quercetin have positive health benefits, especially on the heart. Flavonoids have been proven to be active against hypertension, inflammation, diabetes and vascular diseases. Quercetin exhibits significant heart related benefits as inhibition of LDL oxidation, endothelium-independent vasodilator effects, reduction of adhesion molecules and other inflammatory markers, the protective effect on nitric oxide and endothelial function under conditions of oxidative stress, prevention of neuronal oxidative and inflammatory damage and platelet antiaggregant effects. Searching for experimental evidence to validate the cardioprotective effects of quercetin, we review here the recent detailed in vivo studies. Quercetin and its derivatives lead to an enhancement in heart features, indicating the prospective for quercetin to be used therapeutically in the treatment of cardiac diseases. Several evidence-based studies suggest mechanisms to observe cardiovascular diseases such as aging effects, hypertension, angiotensin-converting enzyme activity and endothelial-dependent and independent functions. Different animal models including human are also used to elucidate the in vivo role of quercetin in cardiovascular diseases. The role of quercetin and its derivatives may go beyond their existence in food and has potential as a lead molecule in drug development programs.

Chronic Administration of Quercetin Induces Biomechanical and Pharmacological Remodeling in the Rat Coronary Arteries

Acute dilation brought about by the dietary flavonoid quercetin in coronary arterioles has been described earlier, but no information is available on its chronic effects. Male Wistar rats (body weight about 190 g) were divided to two groups: the quercetin-treated group (n=22) had quercetin supplementation of approximately 30 mg/kg/day, whereas the control group (n=20) had none. After eight weeks of treatment, intramural coronary arterioles with identical passive diameters (178±14 µm and 171±9 µm) were prepared and their biomechanics and pharmacological reactivities were tested using pressure arteriography ex vivo. The spontaneous tone of quercetin-treated arteries was higher (16.5±1.9 % vs. 12.9±0.9 %), which resulted in a reduced lumen size (144±9 μm vs. 167±12 μm), thicker vascular wall (22.6±1.8 μm vs. 17.4±1.6 μm) and decreased tangential wall stress (16.8±1.1 kPa vs. 20.5±1.6 kPa) in supplemented animals (in spontaneous tone at 50 mm Hg, p<0.01 in all these comparisons). Elevated basal NO release resulted in increased endothelial dilation in quercetin-treated animals, especially at higher intraluminal pressures (10.8±2.5 % vs. 5.7±1.3 % at 70 mm Hg, p<0.01). We found remodeling of the geometry of coronary arterioles to ensure higher dilatory reserve and nitrogen monoxide production, as well as lowered elastic stress of the vessel wall.

Pterostilbene reduces oxidative stress, prevents hypertrophy and preserves systolic function of right ventricle in cor pulmonale model

BACKGROUND AND PURPOSE

In cor pulmonale, the increased afterload imposed on the right ventricle (RV) generates a maladaptive response, impairing the contractile cardiac function. Oxidative mechanisms play an important role in the pathophysiology and progression of this disease. The administration of pterostilbene (PTS), a phytophenol with antioxidant potential, may represent a therapeutic option. In the present study, we evaluated the effect of PTS complexed with hydroxypropyl-β-cyclodextrin (HPβCD) on hypertrophy, contractile function and oxidative parameters in the RV of rats with pulmonary hypertension, induced by the administration of monocrotaline (MCT).

EXPERIMENTAL APPROACH

The rats received daily doses of the PTS : HPβCD complex at 25, 50 or 100 mg·kg^-1 , p.o., for 14 days. The diastolic function, E/A ratio, and systolic function, shortening fraction, fractional area change (FAC) and tricuspid annular plane systolic excursion (TAPSE) of the RV were determined by echocardiography.

KEY RESULTS

The PTS : HPβCD complex reduced the production of NADPH oxidase-dependent superoxide anions and oxidative stress in the RV of MCT-treated rats in a dose-dependent manner. At higher doses it prevented the reduction in FAC and TAPSE in MCT-treated animals.

CONCLUSIONS AND IMPLICATIONS

The PTS : HPβCD complex prevented the maladaptative remodelling and protected systolic function in the RV of rats with pulmonary hypertension. These cardioprotective mechanisms may be related, in part, to the antioxidant potential of PTS, favoured by the increased p.o. bioavailability promoted by the presence of HPβCD in the complex.

Natural products with anti-inflammatory and immunomodulatory activities against autoimmune myocarditis

Myocarditis is an inflammatory disease of the myocardium associated with immune dysfunction which may frequently lead to the development of dilated cardiomyopathy. Experimental autoimmune myocarditis is an animal model which mimics myocarditis in order to allow assessment of the therapeutic effects of different molecules on this disease. We aimed to review the inflammatory and immunological mechanisms involved in the pathogenesis of the myocarditis and finding natural products and phytochemicals with anti-myocarditis activities based on studies of cardiac myosin-induced experimental autoimmune myocarditis in rodents. A number of natural molecules (e.g. apigenin, berberine and quercetin) along with some plant extracts were found to be effective in alleviating experimental autoimmune myocarditis. Upregulation of Th1-type cytokines and elevation of the Th2-type cytokines (IL-4 and IL-10), mitigation of oxidative stress, modulation of mitogen-activated protein kinase signaling pathways and increasing Sarco-endoplasmic reticulum Ca²⁺-ATPase levels are among the most important anti-myocarditis mechanisms for the retrieved molecules and extracts. Interestingly, there are structural similarities between the anti-EAM compounds, suggesting the presence of similar pharmacophore and enzymatic targets for these molecules. Naturally occurring molecules discussed in the present article are potential anti-myocarditis drugs and future additional animal studies and clinical trials would shed more light on their effectiveness in the treatment of myocarditis and prevention of dilated cardiomyopathy.

Long-term dietary quercetin enrichment as a cardioprotective countermeasure in mdx mice

NEW FINDINGS

What is the central question of this study? The central question of this study is to understand whether dietary quercetin enrichment attenuates physiologic, histological, and biochemical indices of cardiac pathology. What is the main finding and its importance? Novel findings from this investigation, in comparison to prior published studies, suggest that mouse strain-dependent cardiac outcomes in performance and remodelling exist. Unlike Mdx/Utrn^-/+ mice, mdx mice receiving lifelong quercetin treatment did not exhibit improvements cardiac function. Similar to prior work in Mdx/Utrn^-/+ mice, histological evidence of remodelling suggests that quercetin consumption may have benefited hearts of mdx mice. Positive outcomes may be related to indirect markers that suggest improved mitochondrial wellbeing and to selected indices of inflammation that were lower in hearts from quercetin-fed mice. Duchenne muscular dystrophy causes a decline in cardiac health, resulting in premature mortality. As a potential countermeasure, quercetin is a polyphenol possessing inherent anti-inflammatory and antioxidant effects that activate proliferator-activated γ coactivator 1α (PGC-1α), increasing the abundance of mitochondrial biogenesis proteins. We investigated the extent to which lifelong 0.2% dietary quercetin enrichment attenuates dystrophic cardiopathology in mdx mice. Dystrophic animals were fed a quercetin-enriched or control diet for 12 months, while control C57 mice were fed a control diet. Cardiac function was assessed via 7 T magnetic resonance imaging at 2, 10 and 14 months. At 14 months, hearts were harvested for histology and Western blotting. The results indicated an mdx strain-dependent decline in cardiac performance at 14 months and that dietary quercetin enrichment did not attenuate functional losses. In contrast, histological analyses provided evidence that quercetin feeding was associated with decreased fibronectin and indirect damage indices (Haematoxylin and Eosin) compared with untreated mdx mice. Dietary quercetin enrichment increased cardiac protein abundance of PGC-1α, cytochrome c, electron transport chain complexes I-V, citrate synthase, superoxide dismutase 2 and glutathione peroxidase (GPX) versus untreated mdx mice. The protein abundance of the inflammatory markers nuclear factor-κB, phosphorylated nuclear factor kappa beta (P-NFκB) and phosphorylated nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (P-IKBα) was decreased by quercetin compared with untreated mdx mice, while preserving nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha( IKBα) compared with mdx mice. Furthermore, quercetin decreased transforming growth factor-β1, cyclooxygenase-2 (COX2) and macrophage-restricted F4/80 protein (F4/80) versus untreated mdx mice. The data suggest that long-term quercetin enrichment does not impact physiological parameters of cardiac function but improves indices of mitochondrial biogenesis and antioxidant enzymes, facilitates dystrophin-associated glycoprotein complex (DGC) assembly and decreases inflammation in dystrophic hearts.

Dissection of the Effects of Quercetin on Mouse Myocardium

Quercetin is a plant flavonoid with several biological activities. This study aimed to describe quercetin effects on contractile and electrophysiological properties of the cardiac muscle as well as on calcium handling. Quercetin elicited positive inotropism that was significantly reduced by propranolol indicating an involvement of the sympathetic nervous system. In cardiomyocytes, 30 μM quercetin increased I_Ca,L at 0 mV from -0.95 ± 0.01 A/F to -1.21 ± 0.08 A/F. The membrane potential at which 50% of the channels are activated (V_0.5 ) shifted towards more negative potentials from -13.06 ± 1.52 mV to -19.26 ± 1.72 mV and did not alter the slope factor. Furthermore, quercetin increased [Ca²⁺ ]_i transient by 28% when compared to control. Quercetin accelerated [Ca²⁺ ]_i transient decay time, which could be attributed to SERCA activation. In resting cardiomyocytes, quercetin did not change amplitude or frequency of Ca²⁺ sparks. In isolated heart, quercetin increased heart rate and decreased PRi, QTc and duration of the QRS complex. Thus, we showed that quercetin activates β-adrenoceptors, leading to increased L-type Ca²⁺ current and cell-wide intracellular Ca²⁺ transient without visible changes in Ca²⁺ sparks.

microRNA-10a Targets T-box 5 to Inhibit the Development of Cardiac Hypertrophy

The mechanism of cardiac hypertrophy involving microRNAs (miRNAs) is attracting increasing attention. Our study aimed to investigate the role of miR-10a in cardiac hypertrophy development and the underlying regulatory mechanism.Transverse abdominal aortic constriction (TAAC) surgery was performed to establish a cardiac hypertrophy rat model, and angiotensin II (AngII) was used to induce cardiac hypertrophy in cultured neonatal rat cardiomyocytes. Expression of T-box 5 (TBX5) and miR-10a was altered by cell transfection of siRNA or miRNA mimic/inhibitor. Leucine incorporation assay, histological and cytological examination, quantitative real-time PCR (qRT-PCR), and Western blot were performed to detect the effects of miR-10a and TBX5 on cardiac hypertrophy. Dual-luciferase reporter assay was conducted to verify the regulation of TBX5 by miR-10a.miR-10a was down-regulated, and TBX5 was up-regulated in the rat model and AngII-stimulated cardiomyocytes. miR-10a inhibited TBX5 expression by directly targeting the binding site in Tbx5 3'UTR. Overexpression of miR-10a in AngII-treated cardiomyocytes decreased relative cell area, and significantly reduced the mRNA levels of natriuretic peptide A (Nppa), myosin heavy chain 7 cardiac muscle beta (Myh7), and leucine incorporation (P < 0.01 or P < 0.001). Knockdown of Tbx5 had similar effects on AngII-induced cardiomyocytes.Our findings indicate that miR-10a may inhibit cardiac hypertrophy via targeting Tbx5. Thus, miR-10a provides promising therapeutic strategies for the treatment of cardiac hypertrophy.

Lifelong quercetin enrichment and cardioprotection in Mdx/Utrn+/− mice

Duchenne Muscular Dystrophy (DMD) is associated with progressive cardiac pathology; however, the SIRT1/PGC1-α activator quercetin may cardioprotect dystrophic hearts. We tested the extent to which long-term 0.2% dietary quercetin enrichment attenuates dystrophic cardiopathology in Mdx/Utrn+/− mice. At 2 mo, Mdx/Utrn+/− mice were fed quercetin-enriched (Mdx/Utrn+/−-Q) or control diet (Mdx/Utrn+/−) for 8 mo. Control C57BL/10 (C57) animals were fed a control diet for 10 mo. Cardiac function was quantified by MRI at 2 and 10 mo. Spontaneous physical activity was quantified during the last week of treatment. At 10 mo hearts were excised for histological and biochemical analysis. Quercetin feeding improved various physiological indexes of cardiac function in diseased animals. Mdx/Utrn+/−-Q also engaged in more high-intensity physical activity than controls. Histological analyses of heart tissues revealed higher expression and colocalization of utrophin and α-sarcoglycan. Lower abundance of fibronectin, cardiac damage (Hematoxylin Eosin-Y), and MMP9 were observed in quercetin-fed vs. control Mdx/Utrn+/− mice. Quercetin evoked higher protein abundance of PGC-1α, cytochrome c, ETC complexes I–V, citrate synthase, SOD2, and GPX compared with control-fed Mdx/Utrn+/−. Quercetin decreased abundance of inflammatory markers including NFκB, TGF-β1, and F4/80 compared with Mdx/Utrn+/−; however, P-NFκB, P-IKBα, IKBα, CD64, and COX2 were similar between groups. Dietary quercetin enrichment improves cardiac function in aged Mdx/Utrn+/− mice and increases mitochondrial protein content and dystrophin glycoprotein complex formation. Histological analyses indicate a marked attenuation in pathological cardiac remodeling and indicate that long-term quercetin consumption benefits the dystrophic heart.

NEW & NOTEWORTHY The current investigation provides first-time evidence that quercetin provides physiological cardioprotection against dystrophic pathology and is associated with improved spontaneous physical activity. Secondary findings suggest that quercetin-dependent outcomes are in part due to PGC-1α pathway activation.

Cardioprotective Effect of Ulmus wallichiana Planchon in β-Adrenergic Agonist Induced Cardiac Hypertrophy

Ulmus wallichiana Planchon (Family: Ulmaceae), a traditional medicinal plant, was used in fracture healing in the folk tradition of Uttarakhand, Himalaya, India. The present study investigated the cardioprotective effect of ethanolic extract (EE) and butanolic fraction (BF) of U. wallichiana in isoprenaline (ISO) induced cardiac hypertrophy in Wistar rats. Cardiac hypertrophy was induced by ISO (5 mg/kg/day, subcutaneously) in rats. Treatment was performed by oral administration of EE and BF of U. wallichiana (500 and 50 mg/kg/day). The blood pressure (BP) and heart rate (HR) were measured by non-invasive blood pressure measurement technique. Plasma renin, Ang II, NO, and cGMP level were estimated using an ELISA kit. Angiotensin converting enzyme activity was estimated. BP and HR were significantly increased in ISO group (130.33 ± 1.67 mmHg vs. 111.78 ± 1.62 mmHg, p < 0.001 and 450.51 ± 4.90 beats/min vs. 347.82 ± 6.91 beats/min, respectively, p < 0.001). The BP and HR were significantly reduced (EE: 117.53 ± 2.27 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001, BF: 119.74 ± 3.32 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001); HR: (EE: 390.22 ± 8.24 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001, BF: 345.38 ± 6.79 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001) after the treatment of EE and BF of U. wallichiana, respectively. Plasma renin, Ang II, ACE activity was decreased and NO, cGMP level were increased. The EE and BF of U. wallichiana down regulated the expression of ANP, BNP, TNF-α, IL-6, MMP9, β1-AR, TGFβ1 and up regulated NOS3, ACE2 and Mas expression level, respectively. Thus, this study demonstrated that U. wallichiana has cardioprotective effect against ISO induced cardiac hypertrophy.

Selective inhibition of HDAC2 by magnesium valproate attenuates cardiac hypertrophy

The regulatory paradigm in cardiac hypertrophy involves alterations in gene expression that is mediated by chromatin remodeling. Various data suggest that class I and class II histone deacetylases (HDACs) play opposing roles in the regulation of hypertrophic pathways. To address this, we tested the effect of magnesium valproate (MgV), an HDAC inhibitor with 5 times more potency on class I HDACs. Cardiac hypertrophy was induced by partial abdominal aortic constriction in Wistar rats, and at the end of 6 weeks, we evaluated hypertrophic, hemodynamic, and oxidative stress parameters, and mitochondrial DNA concentration. Treatment with MgV prevented cardiac hypertrophy, improved hemodynamic functions, prevented oxidative stress, and increased mitochondrial DNA concentration. MgV treatment also increased the survival rate of the animals as depicted by the Kaplan-Meier curve. Improvement in hypertrophy due to HDAC inhibition was further confirmed by HDAC mRNA expression studies, which revealed that MgV decreases expression of pro-hypertrophic HDAC (i.e., HDAC2) without altering the expression of anti-hypertrophic HDAC5. Selective class I HDAC inhibition is required for controlling cardiac hypertrophy. Newer HDAC inhibitors that are class I inhibitors and class II promoters can be designed to obtain "pan" or "dual" natural HDAC "regulators".

MicroRNA-101 inhibits rat cardiac hypertrophy by targeting Rab1a

Cardiac hypertrophy is a primary pathological change associated with cardiovascular diseases. Dysregulated microRNAs are frequent in cardiovascular diseases and contribute to cardiac hypertrophy by regulating a series of targeted genes. In this study, a rat model of cardiac hypertrophy was created by transverse abdominal aortic constriction, and cardiomyocyte hypertrophy in cultured neonatal rat cardiomyocytes was induced using angiotensin II (AngII) to investigate the role of miR-101 in myocardial hypertrophy. We demonstrated that miR-101 was downregulated in both the transverse abdominal aortic constriction rat model and hypertrophic cardiac myocytes. The overexpression of miR-101 in neonatal rat cardiomyocytes, which was accompanied by a reduced Rab1a level, inhibits 3 cardinal features of cardiomyocyte hypertrophy: fetal gene expression, protein synthesis, and cell enlargement. Conversely, the downregulation of miR-101 reverses these effects. Furthermore, the luciferase reporter system demonstrated that Rab1a is a target gene of miR-101, and the ectopic expression of Rab1a can reverse the cardiomyocyte hypertrophy inhibitory activity of miR-101. Taken together, our findings identify miR-101 as an important regulator in cardiac hypertrophy and implicate the potential application of miR-101 in the therapy of cardiac hypertrophy.

Antioxidants in Cardiovascular Therapy: Panacea or False Hope?

Oxidative stress is a key feature of the atherothrombotic process involved in the etiology of heart attacks, ischemic strokes, and peripheral arterial disease. It stands to reason that antioxidants represent a credible therapeutic option to prevent disease progression and thereby improve outcome, but despite positive findings from in vitro studies, clinical trials have failed to consistently show benefit. The aim of this review is to re-appraise the concept of antioxidants in the prevention and management of cardiovascular disease. In particular, the review will explore the reasons behind failed antioxidant strategies with vitamin supplements and will evaluate how flavonoids might improve cardiovascular function despite bioavailability that is not sufficiently high to directly influence antioxidant capacity. As well as reaching conclusions relating to those antioxidant strategies that might hold merit, the major myths, limitations, and pitfalls associated with this research field are explored.

Pycnogenol® and its fractions influence the function of isolated heart in rats with experimental diabetes mellitus

The aim of this study was to test the effect of Pycnogenol(®) (PYC) mixture and its three fractions (buthanolic, water, ethyl acetate) on heart function in rats with experimental diabetes mellitus (DM) and compare their effects to the diabetic group. Their antioxidant activity "in vitro" was also determined. DM rats (streptozotocin over 3 consecutive days at a dose of 25 mg/kg of body weight) had increased systolic blood pressure, thicker left ventriculi wall (LV) and weaker myocardial contraction, prolonged QT interval in comparison to controls rats. In comparison to the diabetic group, PYC (20 mg/kg b.w./day) suppressed the influence of DM on the LV, improved contraction, increased coronary flow and displayed negative effect on electrical activity of hearts. The most effective of PYC's fractions was the water fraction. It improved biometric parameters and hemodynamic function of the DM hearts, enhanced shortening the QT interval, reduced the amount of dysrhythmias of the DM hearts and had the strongest antioxidant activity. In conclusion, DM damaged isolated rat heart function. Only the water fraction improved the function of the diabetic heart. The different results of three fractions and PYC on myocardial function may be caused by a various lipo- and hydro-philic action of the PYC components.

Histological and biochemical outcomes of cardiac pathology in mdx mice with dietary quercetin enrichment

NEW FINDINGS

What is the central question of this study? Does dietary quercetin enrichment improve biochemical and histological outcomes in hearts from mdx mice? What is the main finding and what is its importance? Biochemical and histological findings suggest that chronic quercetin feeding of mdx mice may improve mitochondrial function and attenuate tissue pathology. Patients with Duchenne muscular dystrophy suffer from cardiac pathology, which causes up to 40% of all deaths because of fibrosis and cardiac complications. Quercetin is a flavonol with anti-inflammatory and antioxidant effects and is also an activator of peroxisome proliferator-activated receptor γ coactivator 1α capable of antioxidant upregulation, mitochondrial biogenesis and prevention of cardiac complications. We sought to determine the extent to which dietary quercetin enrichment prevents (experiment 1) and rescues cardiac pathology (experiment 2) in mdx mice. In experiment 1, 3-week-old mdx mice were fed control chow (C3w6m, n = 10) or chow containing 0.2% quercetin for 6 months (Q3w6m, n = 10). In experiment 2, 3-month-old mdx mice were fed control chow (C3m6m, n = 10) or 0.2% chow containing 0.2% quercetin for 6 months (Q3m6m, n = 10). Hearts were excised for histological and biochemical analyses. In experiment 1, Western blot targets for mitochondrial biogenesis (cytochrome c, P = 0.007) and antioxidant expression (superoxide dismutase 2, P = 0.014) increased in Q3w6m mice compared with C3w6m. Histology revealed increased utrophin (P = 0.025) and decreased matrix metalloproteinase 9 abundance (P = 0.040) in Q3w6m mice compared with C3w6m. In experiment 2, relative (P = 0.023) and absolute heart weights (P = 0.020) decreased in Q3m6m mice compared with C3m6m. Indications of damage (Haematoxylin- and Eosin-stained sections, P = 0.007) and Western blot analysis of transforming growth factor β1 (P = 0.009) were decreased in Q3m6m mice. Six months of quercetin feeding increased a mitochondrial biomarker, antioxidant protein and utrophin and decreased matrix metalloproteinase 9 in young mice. Given that these adaptations are associated with attenuated cardiac pathology and damage, the present findings may indicate that dietary quercetin enrichment attenuates dystrophic cardiac pathology, but physiological confirmation is needed.

Quercetin-rich onion peel extract suppresses adipogenesis by down-regulating adipogenic transcription factors and gene expression in 3T3-L1 adipocytes

BACKGROUND

Onion peel contains a high amount of quercetin, which has been reported to have anti-cholesterol, antithrombotic and insulin-sensitizing properties. This study aimed to elucidate the anti-adipogenic effects of quercetin-rich onion peel extract (OPE) and to compare it with commercially available quercetin using 3T3-L1 preadipocytes.

RESULTS

Without affecting cell viability, both OPE and quercetin averted adipogenesis, as characterized by dose-dependent decreases in intracellular triglyceride content and glycerol 3-phosphate dehydrogenase activity, but the effect was more pronounced with OPE than with quercetin. The mRNA expression levels of key adipogenic genes such as PPARγ, C/EBPα, FABP4, aP2 and LPL were decreased in a dose-dependent manner by both OPE and quercetin.

CONCLUSION

The results indicate that OPE treatment significantly prevents intracellular lipid accumulation via hyperactivation of genes regulating lipolysis as compared with quercetin alone.

MicroRNA-26 was decreased in rat cardiac hypertrophy model and may be a promising therapeutic target

MicroRNA (miR)-26 was found to be downregulated in cardiac diseases. In this study, the critical role of miR-26 in myocardial hypertrophy in both in vivo and in vitro was investigated. Sixteen male Wistar rats that underwent sham or transverse abdominal aortic constriction (TAAC) surgery were divided into control or TAAC group. Cardiomyocytes were isolated from neonatal Sprague-Dawley rats. Our study demonstrated that miR-26a/b was downregulated in both TAAC rat model and cardiomyocytes. The results of luciferase assays also suggested that glycogen synthase kinase 3β (GSK3β) may be a direct target of miR-26. The overexpression of miR-26 attenuated GSK3β expression and inhibited myocardial hypertrophy. The downregulation of miR-26 reversed these effects. Furthermore, silence of GSK3β gene phenocopied the anti-hypertrophy effects of miR-26, whereas overexpression of this protein attenuated the effects of miR-26. Taken together, these data suggest that miR-26 regulates pathological structural changes in the rat heart, which may be associated with suppression of the GSK3β signaling pathway, and implicate the potential application of miR-26 in diagnosis and therapy of cardiac hypertrophy.

miR-34a modulates angiotensin II-induced myocardial hypertrophy by direct inhibition of ATG9A expression and autophagic activity

Cardiac hypertrophy is characterized by thickening myocardium and decreasing in heart chamber volume in response to mechanical or pathological stress, but the underlying molecular mechanisms remain to be defined. This study investigated altered miRNA expression and autophagic activity in pathogenesis of cardiac hypertrophy. A rat model of myocardial hypertrophy was used and confirmed by heart morphology, induction of cardiomyocyte autophagy, altered expression of autophagy-related ATG9A, LC3 II/I and p62 proteins, and decrease in miR-34a expression. The in vitro data showed that in hypertrophic cardiomyocytes induced by Ang II, miR-34a expression was downregulated, whereas ATG9A expression was up-regulated. Moreover, miR-34a was able to bind to ATG9A 3'-UTR, but not to the mutated 3'-UTR and inhibited ATG9A protein expression and autophagic activity. The latter was evaluated by autophagy-related LC3 II/I and p62 levels, TEM, and flow cytometry in rat cardiomyocytes. In addition, ATG9A expression induced either by treatment of rat cardiomyocytes with Ang II or ATG9A cDNA transfection upregulated autophagic activity and cardiomyocyte hypertrophy in both morphology and expression of hypertrophy-related genes (i.e., ANP and β-MHC), whereas knockdown of ATG9A expression downregulated autophagic activity and cardiomyocyte hypertrophy. However, miR-34a antagonized Ang II-stimulated myocardial hypertrophy, whereas inhibition of miR-34a expression aggravated Ang II-stimulated myocardial hypertrophy (such as cardiomyocyte hypertrophy-related ANP and β-MHC expression and cardiomyocyte morphology). This study indicates that miR-34a plays a role in regulation of Ang II-induced cardiomyocyte hypertrophy by inhibition of ATG9A expression and autophagic activity.

Piceatannol attenuates cardiac hypertrophy in an animal model through regulation of the expression and binding of the transcription factor GATA binding factor 6

Piceatannol is found in grapes, passion fruit, and Japanese knotweed. Piceatannol pretreatment suppresses cardiac hypertrophy induced by isoproterenol as assessed by heart weight/body weight ratio, cross-sectional area, and expression of hypertrophic markers. The anti-hypertrophic effect of piceatannol in rat neonatal cardiomyocytes is the same as that in vivo. Piceatannol inhibits lentiviral-GATA6-induced cardiomyocyte hypertrophy. Furthermore, piceatannol reduces the interaction between GATA4 and GATA6 as well as the DNA-binding activity of endogenous GATA6 in the ANP promoter. Our results suggest that piceatannol may be a novel therapeutic agent for the prevention of cardiac hypertrophy.

Quercetin can reduce insulin resistance without decreasing adipose tissue and skeletal muscle fat accumulation

Quercetin exhibits a wide range of biological functions. The first aim of the present work was to analyze the effects of quercetin on fat accumulation in adipose tissue and glycemic control in rats. Any potential involvement of muscle fatty acid oxidation in its effect on glycemic control was also assessed. Animals were fed a high-fat high-sucrose diet either supplemented with quercetin (30 mg/kg body weight/day), or not supplemented, for 6 weeks. One week before killing, a glucose tolerance test was carried out. Muscle triacylglycerol content, serum glucose, insulin, fructosamine and free fatty acids were measured, and homeostatic model assessment for insulin resistance (HOMA-IR) was calculated. The activities of lipogenic enzymes and lipoprotein lipase in adipose tissue, carnitine palmitoyl transferase-1b (CPT-1b) and citrate synthase in skeletal muscle, and the expression of several genes, ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP3, TFAM and COX-2 in skeletal muscle were analyzed. Quercetin caused no significant reduction in body weight or adipose tissue sizes. However, fructosamine, basal glucose and insulin, and consequently HOMA-IR, were significantly reduced by quercetin. No changes were observed in the activity of lipogenic enzymes and lipoprotein lipase. Muscle triacylglycerol content was similar in both experimental groups. The expression of ACO, CD36, CPT-1b, PPAR-α, PGC-1α, UCP3, TFAM and COX-2 remained unchanged. It can be concluded that quercetin is more effective as an anti-diabetic than as an anti-obesity biomolecule. The improvement in insulin resistance induced by this flavonoid is not mediated by a delipidating effect in skeletal muscle.

Quercetin inhibits left ventricular hypertrophy in spontaneously hypertensive rats and inhibits angiotensin II-induced H9C2 cells hypertrophy by enhancing PPAR-γ expression and suppressing AP-1 activity

BACKGROUND

Quercetin is the most abundant flavonoid in fruit and vegetables and is believed to attenuate cardiovascular disease. We hypothesized that quercetin inhibits cardiac hypertrophy by blocking AP-1 (c-fos, c-jun) and activating PPAR-γ signaling pathways.

METHODOLOGY/PRINCIPAL FINDINGS

The aim of this study was to identify the mechanism underlying quercetin-mediated attenuation of cardiac hypertrophy. Quercetin therapy reduced blood pressure and markedly reduced the ratio of left ventricular to body weight (LVW/BW) (P<0.05, vs. spontaneously hypertensive rats (SHRs)). In vitro, quercetin also significantly attenuated Ang II-induced H9C2 cells hypertrophy, as indicated by its concentration dependent inhibitory effects on [³H]leucine incorporation into H9C2 cells (64% reduction) and by the reduced hypertrophic surface area in H9C2 cells compared with the Ang II group (P<0.01, vs. Ang II group). Concurrently, we found that PPAR-γ activity was significantly increased in the quercetin-treated group both in vivo and in vitro when analyzed using immunofluorescent or immunohistochemical assays (P<0.05, vs. SHRs or P<0.01, vs. the Ang II group). Conversely, in vivo, AP-1 (c-fos, s-jun) activation was suppressed in the quercetin-treated group, as was the downstream hypertrophy gene, including mRNA levels of ANP and BNP (P<0.05, vs. SHRs). Additionally, both western blotting and real time-PCR demonstrated that PPAR-γ protein and mRNA were increased in the myocardium and AP-1 protein and mRNA were significantly decreased in the quercetin-treated group (P<0.05, vs. SHRs). Furthermore, western blotting and real time-PCR analyses also showed that transfection with PPAR-γ siRNA significantly increased AP-1 signaling and reversed the effects of quercetin inhibition on mRNA expression levels of genes such as ANP and BNP in hypertrophic H9C2 cells.

CONCLUSIONS

Our data indicate that quercetin may inhibit cardiac hypertrophy by enhancing PPAR-γ expression and by suppressing the AP-1 signaling pathway.

Role of quercetin in vascular physiology

A recent paper in the Canadian Journal of Physiology and Pharmacology has shown that quercetin has a vascular protective effect associated with eNOS up-regulation, blood GSH redox ratio, and reduction of oxidative stress. Recent reports have recommended the consumption of quercetin, as it may contribute to a reduction in the risk of cardiovascular disease. However, the mechanisms by which quercetin exerts its action have not been fully elucidated. The majority of these mechanisms have been identified with models using animals treated with quercetin, and relatively few have been corroborated in human studies, which indicates the need for further investigation.

Quercetin reduces high-fat diet-induced fat accumulation in the liver by regulating lipid metabolism genes

To understand the molecular mechanisms underlying the influence of quercetin on the physiological effects of hyperlipidemia, we investigated its role in the prevention of high-fat diet (HFD)-induced obesity and found that it regulated hepatic gene expression related to lipid metabolism. Quercetin supplementation in mice significantly reduced the HFD-induced gains in body weight, liver weight, and white adipose tissue weight compared with the mice fed only with HFD. It also significantly reduced HFD-induced increases in serum lipids, including cholesterol, triglyceride, and thiobarbituric acid-reactive substance (TBARS). Consistent with the reduced liver weight and white adipose tissue weight, hepatic lipid accumulation and the size of lipid droplets in the epididymal fat pads were also reduced by quercetin supplementation. To further investigate how quercetin may reduce obesity, we analyzed lipid metabolism-related genes in the liver. Quercetin supplementation altered expression profiles of several lipid metabolism-related genes, including Fnta, Pon1, Pparg, Aldh1b1, Apoa4, Abcg5, Gpam, Acaca, Cd36, Fdft1, and Fasn, relative to those in HFD control mice. The expression patterns of these genes observed by quantitative reverse transcriptase-polymerase chain reaction were confirmed by immunoblot assays. Collectively, our results indicate that quercetin prevents HFD-induced obesity in C57B1/6 mice, and its anti-obesity effects may be related to the regulation of lipogenesis at the level of transcription.

Effects of quercetin on the apoptosis of the human gastric carcinoma cells

Quercetin, a natural constituent abundantly present in grapes, red wine, and other food products, is known to possess potent antiproliferative effects against various malignant cells. The present study aims to investigate the effect of quercetin on the apoptosis and morphology of gastric carcinoma BGC-823 cells, as well as the probable mechanism, in an effort to identify an effective drug as a potential candidate for gastric cancer. Gastric carcinoma BGC-823 cells were treated with quercetin, and cell morphology was determined by light microscopy and transmission electron microscopy. Apoptosis and cell cycle were measured by flow cytometry, using propidium iodide staining. The apoptotic protein expression of caspase-3, Bcl-2 and Bax was detected by Western blot. Quercetin induced apoptosis in BGC-823 cell. Some morphologic features of apoptosis were found, such as cell shrinkage or even apoptosis body. Quercetin changed the apoptotic protein expression. These results indicate that quercetin can induce apoptosis of the BGC-823 cells. A decrease in Bcl-2/Bax ratio with the increased expression of caspase-3 provides evidence that quercetin-induced apoptosis may be mediated via the mitochondrial pathway.

Chemical constituents of the Mexican mistletoe (Psittacanthus calyculatus)

A phytochemical study of the methanol-soluble fraction of an aqueous extract of a sample of Psittacanthus calyculatus collected from the host plant Prosopsis laevigata (Smooth Mesquite) using several techniques, including co-chromatography coupled with UV detection, chromatographic purifications and IR, NMR and MS studies, resulted in the identification of gallic acid, two flavonol-3-biosides and the nonprotein amino acid N-methyl-trans-4-hydroxy-L-proline.