Hesperidin produces cardioprotective activity via PPAR-γ pathway in ischemic heart disease model in diabetic rats

Beetroot juice alleviates isoproterenol-induced myocardial damage by reducing oxidative stress, inflammation, and apoptosis in rats

Beetroot (Beta vulgaris L.) juice (BRJ) is a good source of betalain (betacyanins and betaxanthin) pigments and exhibits antioxidant, anti-inflammatory, and chemo-preventive activities in vitro and in vivo. The current study was performed to determine the cardioprotective effect of BRJ on lipid peroxidation, antioxidant defense, functional impairment, and histopathology in rats with isoproterenol (ISP)-induced myocardial injury. Myocardial ischemia was induced by ISP (85 mg/kg) s.c. injection at 24 h intervals, followed by oral administration of BRJ for 28 days at doses of 150 and 300 mg/kg. ISP-induced myocardial damage was confirmed by an increase in heart weight to body weight ratio, % infarction size, serum cardiac indices (AST, ALT, GGT, ALP, LDH and CK-MB), and histological alterations in the myocardium. Pretreatment with BRJ (150 and 300 mg/kg) followed by ISP induction reduced oxidative/nitrosative stress and restored the cardiac endogenous antioxidants in rats. ISP augmented cardiac inflammatory cytokines (TNF-α, IL-6 and IL-10), myeloperoxidase activity, NF-κB DNA binding and protein expression of NF-κB (p65), and the hyperlipidemia level was significantly reduced by the BRJ pretreatment. Furthermore, the BRJ pretreatment significantly reduced caspase-3, Bax, and MMP-9 protein expression, enhanced the Bcl-2 antiapoptotic protein expression, alleviated the extent of histological damage, myonecrosis, and edema, and maintained the architecture of cardiomyocytes. These findings suggest that BRJ pretreatment mitigates cardiac dysfunction and structural damages by decreasing oxidative stress, inflammation, and apoptosis in cardiac tissues. These results further support the use of BRJ in traditional medicine against cardiovascular diseases.

Beneficial Effects of Citrus Flavonoids on Cardiovascular and Metabolic Health

The prevalence of cardiovascular disease (CVD) is increasing over time. CVD is a comorbidity in diabetes and contributes to premature death. Citrus flavonoids possess several biological activities and have emerged as efficient therapeutics for the treatment of CVD. Citrus flavonoids scavenge free radicals, improve glucose tolerance and insulin sensitivity, modulate lipid metabolism and adipocyte differentiation, suppress inflammation and apoptosis, and improve endothelial dysfunction. The intake of citrus flavonoids has been associated with improved cardiovascular outcomes. Although citrus flavonoids exerted multiple beneficial effects, their mechanisms of action are not completely established. In this review, we summarized recent findings and advances in understanding the mechanisms underlying the protective effects of citrus flavonoids against oxidative stress, inflammation, diabetes, dyslipidemia, endothelial dysfunction, and atherosclerosis. Further studies and clinical trials to assess the efficacy and to explore the underlying mechanism(s) of action of citrus flavonoids are recommended.

Potential Role of Flavonoids in Treating Chronic Inflammatory Diseases with a Special Focus on the Anti-Inflammatory Activity of Apigenin

Inflammation has been reported to be intimately linked to the development or worsening of several non-infectious diseases. A number of chronic conditions such as cancer, diabetes, cardiovascular disorders, autoimmune diseases, and neurodegenerative disorders emerge as a result of tissue injury and genomic changes induced by constant low-grade inflammation in and around the affected tissue or organ. The existing therapies for most of these chronic conditions sometimes leave more debilitating effects than the disease itself, warranting the advent of safer, less toxic, and more cost-effective therapeutic alternatives for the patients. For centuries, flavonoids and their preparations have been used to treat various human illnesses, and their continual use has persevered throughout the ages. This review focuses on the anti-inflammatory actions of flavonoids against chronic illnesses such as cancer, diabetes, cardiovascular diseases, and neuroinflammation with a special focus on apigenin, a relatively less toxic and non-mutagenic flavonoid with remarkable pharmacodynamics. Additionally, inflammation in the central nervous system (CNS) due to diseases such as multiple sclerosis (MS) gives ready access to circulating lymphocytes, monocytes/macrophages, and dendritic cells (DCs), causing edema, further inflammation, and demyelination. As the dearth of safe anti-inflammatory therapies is dire in the case of CNS-related disorders, we reviewed the neuroprotective actions of apigenin and other flavonoids. Existing epidemiological and pre-clinical studies present considerable evidence in favor of developing apigenin as a natural alternative therapy against chronic inflammatory conditions.

PIAS1 protects against myocardial ischemia-reperfusion injury by stimulating PPARγ SUMOylation

Background

Myocardial ischemia-reperfusion injury (IRI) has become one of the most serious complications after reperfusion therapy in patients with acute myocardial infarction. Small ubiquitin-like modification (SUMOylation) is a reversible process, including SUMO E1-, E2-, and E3-mediated SUMOylation and SUMO-specific protease-mediated deSUMOylation, with the latter having been shown to play a vital role in myocardial IRI previously. However, little is known about the function and regulation of SUMO E3 ligases in myocardial IRI.

Results

In this study, we found dramatically decreased expression of PIAS1 after ischemia/reperfusion (I/R) in mouse myocardium and H9C2 cells. PIAS1 deficiency aggravated apoptosis and inflammation of cardiomyocytes via activating the NF-κB pathway after I/R. Mechanistically, we identified PIAS1 as a specific E3 ligase for PPARγ SUMOylation. Moreover, H9C2 cells treated with hypoxia/reoxygenation (H/R) displayed reduced PPARγ SUMOylation as a result of down-regulated PIAS1, and act an anti-apoptotic and anti-inflammatory function through repressing NF-κB activity. Finally, overexpression of PIAS1 in H9C2 cells could remarkably ameliorate I/R injury.

Conclusions

Collectively, our findings demonstrate the crucial role of PIAS1-mediated PPARγ SUMOylation in protecting against myocardial IRI.

Electronic supplementary material

The online version of this article (10.1186/s12860-018-0176-x) contains supplementary material, which is available to authorized users.

Eplerenone attenuates myocardial infarction in diabetic rats via modulation of the PI3K-Akt pathway and phosphorylation of GSK-3β

We investigated the effect of eplerenone on myocardial infarcted diabetic rats via modulation of the PI3K/Akt pathway and its downstream target GSK-3β. Diabetes was induced by administration of a single dose of streptozotocin (55 mg/kg IP). Diabetic rats received either eplerenone or PI3k/Akt antagonist (wortmannin) or in combination for 14 days with concurrent administration of isoproterenol (100 mg/kg s.c) on 13^th and 14^th day. Isoproterenol prompted cardiotoxicity and was demonstrated by a decrease in the maximal positive rate of developed left ventricular pressure, the maximal negative rate of developed left ventricular pressure and an increase in left ventricular end-diastolic pressure along with oxidative stress. Myocardial infarcted diabetic rats exhibited increased myonecrosis, edema, and apoptotic cell death. Treatment with eplerenone significantly improved the redox status of the myocardium. Eplerenone markedly inhibited Bax expression, TUNEL-positive cells, and myonecrosis. On the other hand, the administration of eplerenone and wortmanin did not draw out the same effects, when administered concomitantly or individually. Moreover, the rats treated with eplerenone showed increased expression of PI3K/Akt and decreased its downstream target GSK-3β. The present study confirms the protective effects of eplerenone on myocardial infarction in diabetic rats via modulation of PI3K/Akt pathway and its downstream regulator GSK-3β.

PPAR-gamma activation is associated with reduced liver ischemia-reperfusion injury and altered tissue-resident macrophages polarization in a mouse model

BACKGROUND

PPAR-gamma (γ) is highly expressed in macrophages and its activation affects their polarization. The effect of PPAR-γ activation on Kupffer cells (KCs) and liver ischemia-reperfusion injury (IRI) has not yet been evaluated. We investigated the effect of PPAR-γ activation on KC-polarization and IRI.

MATERIALS AND METHODS

Seventy percent (70%) liver ischemia was induced for 60mins. PPAR-γ-agonist or vehicle was administrated before reperfusion. PPAR-γ-antagonist was used to block PPAR-γ activation. Liver injury, necrosis, and apoptosis were assessed post-reperfusion. Flow-cytometry determined KC-phenotypes (pro-inflammatory Nitric Oxide +, anti-inflammatory CD206+ and anti-inflammatory IL-10+).

RESULTS

Liver injury assessed by serum AST was significantly decreased in PPAR-γ-agonist versus control group at all time points post reperfusion (1hr: 3092±105 vs 4469±551; p = 0.042; 6hr: 7041±1160 vs 12193±1143; p = 0.015; 12hr: 5746±328 vs 8608±1259; p = 0.049). Furthermore, liver apoptosis measured by TUNEL-staining was significantly reduced in PPAR-γ-agonist versus control group post reperfusion (1hr:2.46±0.49 vs 6.90±0.85%;p = 0.001; 6hr:26.40±2.93 vs 50.13±8.29%; p = 0.048). H&E staining demonstrated less necrosis in PPAR-γ-agonist versus control group (24hr:26.66±4.78 vs 45.62±4.57%; p = 0.032). The percentage of pro-inflammatory NO+ KCs was significantly lower at all post reperfusion time points in the PPAR-γ-agonist versus control group (1hr:28.49±4.99 vs 53.54±9.15%; p = 0.040; 6hr:5.51±0.54 vs 31.12±9.58%; p = 0.009; 24hr:4.15±1.50 vs 17.10±4.77%; p = 0.043). In contrast, percentage of anti-inflammatory CD206+ KCs was significantly higher in PPAR-γ-agonist versus control group prior to IRI (8.62±0.96 vs 4.88 ±0.50%; p = 0.04). Administration of PPAR-γ-antagonist reversed the beneficial effects on AST, apoptosis, and pro-inflammatory NO+ KCs.

CONCLUSION

PPAR-γ activation reduces IRI and decreases the pro-inflammatory NO+ Kupffer cells. PPAR-γ activation can become an important tool to improve outcomes in liver surgery through decreasing the pro-inflammatory phenotype of KCs and IRI.

Orange juice affects acylcarnitine metabolism in healthy volunteers as revealed by a mass-spectrometry based metabolomics approach

Citrus juices, especially orange juice, constitute rich sources of bioactive compounds with a wide range of health-promoting activities. Data from epidemiological and in vitro studies suggest that orange juice (OJ) may have a positive impact on lipid metabolism. However, the effect of orange juice intake on blood lipid profile is still poorly understood. We have used two different blood samples, Dried Blood Spots (DBS) and plasma, to assess the effect of two-week orange juice consumption in healthy volunteers by a mass-spectrometry based metabolomics approach. DBS were analysed by liquid chromatography mass spectrometry (LC-MS) and plasma samples were analysed by the gas chromatography mass spectrometry (GC-MS). One hundred sixty-nine lipids including acylcarnitines (AC), lysophosphatidylcholines (LysoPC), (diacyl- and acyl-alkyl-) phosphatidylcholines (PC aa and PC ae) and sphingomyelins (SM) were identified and quantified in DBS. Eighteen fatty acids were identified and quantified in plasma. Multivariate analysis allowed to identify an increase in C3:1, C5-DC(C6-OH), C5-M-DC, C5:1-DC, C8, C12-DC, lysoPC18:3, myristic acid, pentadecanoic acid, palmitoleic and palmitic acid and a decrease in nervonic acid, C0, C2, C10, C10:1, C16:1, C16-OH, C16:1-OH, C18-OH, PC aa C40:4, PC ae C38:4, PC ae C42:3, PC ae C42:4 and cholesterol levels after orange juice intake. A two-week period of orange juice intake could affect fatty acids β-oxidation through mitochondrial and peroxisomal pathways, leading to an increase of short-chain acylcarnitines and a decrease of medium and long-chain acylcarnitines. This is the first report analyzing the effect of orange juice intake in healthy volunteers using a dried blood spot-based metabolomics approach.

Emodin, A Chinese Herbal Medicine, Inhibits Reoxygenation-Induced Injury in Cultured Human Aortic Endothelial Cells by Regulating the Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ) and Endothelial Nitric Oxide Synthase (eNOS) Signaling Pathway

Background

Ischemia-reperfusion injury is associated with vascular dysfunction. The aim of this study was to investigate the role of emodin, a Chinese herbal medicine, in hypoxia-reoxygenation injury in cultured human aortic endothelial cells (HAECs) and its effects on the expression of the peroxisome proliferator-activated receptor-γ (PPAR-γ) and endothelial nitric oxide synthase (eNOS) signaling pathway.

Material/Methods

An in vitro hypoxia-reoxygenation model used cultured human aortic endothelial cells (HAECs). A colorimetric method evaluated the activity of peroxisome proliferator-activated receptor-γ (PPAR-γ). Phosphorylation of PPAR-γ and endothelial nitric oxide synthase (eNOS) were measured by Western blotting. Expression of inflammatory cytokines, tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-8 were evaluated by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Nitric oxide (NO) production was detected by diaminofluorescein-FM diacetate (DAF-FM DA) fluorescence. Immunoprecipitation was used to evaluate the molecular coupling of heat shock protein (HSP)90 and eNOS.

Results

Hypoxia-reoxygenation injury of HAECs reduced the activity and phosphorylation of PPAR-γ, and eNOS, NO production, and HSP90/eNOS molecular coupling in a time-dependent manner. Hypoxia-reoxygenation increased the levels of inflammatory cytokines TNF-α, IL-6, and IL-8 in a time-dependent manner. Emodin treatment recovered PPAR-γ activity and phosphorylation, eNOS phosphorylation, and HSP90/eNOS coupling in HAECS in a concentration-dependent manner, which was reversed by the PPAR-γ inhibitor GW9662, and the eNOS inhibitor, L-NAME. The recovery of HSP90/eNOS coupling by emodin was impaired by GW9662 treatment.

Conclusions

An in vitro hypoxia-reoxygenation (ischemia-reperfusion injury) model of induction of endothelial cell inflammatory mediators showed that emodin recovered the PPAR-γ and eNOS pathway activity.

Eplerenone pretreatment protects the myocardium against ischaemia/reperfusion injury through the phosphatidylinositol 3-kinase/Akt-dependent pathway in diabetic rats

We investigated the eplerenone-induced, PI3K/Akt- and GSK-3β-mediated cardioprotection against ischemia/reperfusion (I/R) injury in diabetic rats. The study groups comprising diabetic rats were treated for 14 days with 150 mg/kg/day eplerenone orally and 1 mg/kg wortmannin (PI3K/Akt antagonist) intraperitoneally with eplerenone. On the 15th day, the rats were exposed to I/R injury by 20-min occlusion of the left anterior descending coronary artery followed by 30 min of reperfusion. The hearts were processed for biochemical, molecular, and histological investigations. The I/R injury in diabetic rats inflicted a significant rise in the oxidative stress and apoptosis along with a decrease in the arterial and ventricular function and the expressions of PI3K/Akt and GSK-3β proteins. Eplerenone pretreatment reduced the arterial pressure, cardiac inotropy, and lusitropy. It significantly reduced apoptosis and cardiac injury markers. The histology revealed cardioprotection in eplerenone-treated rats. Eplerenone up-regulated the PI3K/Akt and reduced the GSK-3β expression. The group receiving wortmannin with eplerenone was deprived eplerenone-induced cardioprotection. Our results reveal the eplerenone-induced cardioprotection against I/R injury in diabetic rats and substantiate the involvement of PI3K/Akt and GSK-3β pathways in its efficacy.

The protective role of low-concentration alcohol in high-fructose induced adverse cardiovascular events in mice

Cardiovascular disease remains a worldwide public health issue. As fructose consumption is dramatically increasing, it has been demonstrated that a fructose-rich intake would increase the risk of cardiovascular disease. In addition, emerging evidences suggest that low concentration alcohol intake may exert a protective effect on cardiovascular system. This study aimed to investigate whether low-concentration alcohol consumption would prevent the adverse effects on cardiovascular events induced by high fructose in mice. From the results of hematoxylin-eosin staining, echocardiography, heart weight/body weight ratio and the expression of hypertrophic marker ANP, we found high-fructose result in myocardial hypertrophy and the low-concentration alcohol consumption would prevent the cardiomyocyte hypertrophy from happening. In addition, we observed low-concentration alcohol consumption could inhibit mitochondria swollen induced by high-fructose. The elevated levels of glucose, triglyceride, total cholesterol in high-fructose group were reduced by low concentration alcohol. Low expression levels of SIRT1 and PPAR-γ induced by high-fructose were significantly elevated when fed with low-concentration alcohol. The histone lysine 9 acetylation (acH3K9) level was decreased in PPAR-γ promoter in high-fructose group but elevated when intake with low concentration alcohol. The binding levels of histone deacetylase SIRT1 were increased in the same region in high-fructose group, while the low concentration alcohol can prevent the increased binding levels. Overall, our study indicates that low-concentration alcohol consumption could inhibit high-fructose related myocardial hypertrophy, cardiac mitochondria damaged and disorders of glucose-lipid metabolism. Furthermore, these findings also provide new insights into histone acetylation-deacetylation mechanisms of low-concentration alcohol treatment that may contribute to the prevention of cardiovascular disease induced by high-fructose intake.

Febuxostat Modulates MAPK/NF-κBp65/TNF-α Signaling in Cardiac Ischemia-Reperfusion Injury

Xanthine oxidase and xanthine dehydrogenase have been implicated in producing myocardial damage following reperfusion of an occluded coronary artery. We investigated and compared the effect of febuxostat and allopurinol in an experimental model of ischemia-reperfusion (IR) injury with a focus on the signaling pathways involved. Male Wistar rats were orally administered vehicle (CMC) once daily (sham and IR + control), febuxostat (10 mg/kg/day; FEB10 + IR), or allopurinol (100 mg/kg/day; ALL100 + IR) for 14 days. On the 15th day, the IR-control and treatment groups were subjected to one-stage left anterior descending (LAD) coronary artery ligation for 45 minutes followed by a 60-minute reperfusion. Febuxostat and allopurinol pretreatment significantly improved cardiac function and maintained morphological alterations. They also attenuated oxidative stress and apoptosis by suppressing the expression of proapoptotic proteins (Bax and caspase-3), reducing TUNEL-positive cells, and increasing the level of antiapoptotic proteins (Bcl-2). The MAPK-based molecular mechanism revealed suppression of active JNK and p38 proteins concomitant with the rise in ERK1/ERK2, a prosurvival kinase. Additionally, a reduction in the level of inflammatory markers (TNF-α, IL-6, and NF-κB) was also observed. The changes observed with febuxostat were remarkable in comparison with those observed with allopurinol. Febuxostat protects relatively better against IR injury than allopurinol by suppressing inflammation and apoptosis mediating the MAPK/NF-κBp65/TNF-α pathway.

Flavanones: Citrus phytochemical with health-promoting properties

Citrus fruit and juices represent one of the main sources of compounds with a high potential for health promoting properties. Among these compounds, flavanones (such as hesperetin, naringenin, eriodictyol, isosakuranetin, and their respective glycosides), which occur in quantities ranging from ∼180 to 740 mg/L (depending on the Citrus species and cultivar) are responsible for many biological activities. These compounds support and enhance the body's defenses against oxidative stress and help the organism in the prevention of cardiovascular diseases, atherosclerosis, and cancer. Moreover, among other properties, they also show anti-inflammatory, antiviral, and antimicrobial activities. This review analyzes the biochemistry, pharmacology, and biology of Citrus flavanones, emphasizing the occurrence in Citrus fruits and juices and their bioavailability, structure-function correlations and ability to modulate signal cascades both in vitro and in vivo. © 2017 BioFactors, 43(4):495-506, 2017.

Dual character of flavonoids in attenuating and aggravating ischemia-reperfusion-induced myocardial injury

The concept that flavonoids exert cardioprotection against myocardial ischemia-reperfusion (I/R) injury has been acknowledged by a large body of evidence. However, recent studies reported cardiotoxic effects of certain flavonoids, while the underlying mechanisms have remained largely elusive. Flavonoids have been demonstrated to activate aryl hydrocarbon receptor (Ahr), which is implicated in an array of cell signaling processes. The present study examined the cardioprotective roles of quercetin (Qu) and β-naphthoflavone (β-NF) against I/R injury and explored whether the underlying mechanism proceeds via molecular signaling downstream of Ahr. An oxygen glucose deprivation/reoxygenation (OGD/R) model of I/R was established in myocardial H9c2 cells in the absence or presence of Qu or β-NF. Qu as well as β-NF reversed OGD/R-induced overproduction of reactive oxygen species by increasing the anti-oxidative capacity of the cells and protected them from lethal injury, as demonstrated by a decreased cell death rate, lactate hydrogenase leakage and caspase-3 activity as determined by flow cytometry, colorimetric assay and western blot analysis, respectively. Immunocytochemistry, co-immunoprecipitation and western blot assays collectively revealed that Qu and β-NF engendered the translocation of Ahr from the cytoplasm into the cell nucleus, where binding of Ahr with the Ahr nuclear translocator (ARNT) blocked its binding to hypoxia-inducible factor (HIF)-1α, which inhibited the cardioprotection of HIF-1α, including the induction of nitric oxide (NO) and inhibition of vascular endothelial growth factor (VEGF) production. Ahr knockdown recovered the binding of ARNT to HIF-1α and the generation of NO and VEGF. The results of the present study suggested a dual character of Qu and β-NF in the process of myocardial I/R.

Effects of Polyphenols on Oxidative Stress-Mediated Injury in Cardiomyocytes

Cardiovascular diseases are the main cause of mortality and morbidity in the world. Hypertension, ischemia/reperfusion, diabetes and anti-cancer drugs contribute to heart failure through oxidative and nitrosative stresses which cause cardiomyocytes nuclear and mitochondrial DNA damage, denaturation of intracellular proteins, lipid peroxidation and inflammation. Oxidative or nitrosative stress-mediated injury lead to cardiomyocytes apoptosis or necrosis. The reactive oxygen (ROS) and nitrogen species (RNS) concentration is dependent on their production and on the expression and activity of anti-oxidant enzymes. Polyphenols are a large group of natural compounds ubiquitously expressed in plants, and epidemiological studies have shown associations between a diet rich in polyphenols and the prevention of various ROS-mediated human diseases. Polyphenols reduce cardiomyocytes damage, necrosis, apoptosis, infarct size and improve cardiac function by decreasing oxidative stress-induced production of ROS or RNS. These effects are achieved by the ability of polyphenols to modulate the expression and activity of anti-oxidant enzymes and several signaling pathways involved in cells survival. This report reviews current knowledge on the potential anti-oxidative effects of polyphenols to control the cardiotoxicity induced by ROS and RNS stress.

Momordica charantia polysaccharides ameliorate oxidative stress, hyperlipidemia, inflammation, and apoptosis during myocardial infarction by inhibiting the NF-κB signaling pathway

The polysaccharide extract of Momordica charantia has various biological activities; however, its effect on endothelial dysfunction in myocardial infarction remains unclear. To elucidate this, myocardial infarction was induced in rats using isoproterenol (ISP). Pretreatment with M. charantia polysaccharides (MCP; 150 or 300mg/kg) for 25days significantly inhibited increases in heart weight, the heart-weight-to-body-weight ratio, and infarction size, and ameliorated the increased serum levels of aspartate transaminase, creatine kinase, lactate dehydrogenase, total cholesterol, triglycerides, very-low-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. In addition, MCP enhanced the activity of superoxide dismutase, catalase, and non-protein sulfhydryls, and decreased the level of lipid peroxidation. Moreover, MCP pretreatment downregulated the expression of proinflammatory cytokines (tumor necrosis factor alpha, interleukin (IL)-6, and IL-10), inflammatory markers (nitric oxide, myeloperoxidase, and inducible nitric oxide synthase), and apoptotic markers (caspase-3 and BAX), and upregulated Bcl-2 expression. Pretreatment with MCP reduced myonecrosis, edema, and inflammatory cell infiltration, and restored cardiomyocytes architecture. This myocardial protective effect could be related to the enhancement of the antioxidant defense system through the nuclear factor kappa B (NF-kB) pathways, and to anti-apoptosis through regulation of Bax, caspase-3, and Bcl-2.

Peroxisome proliferator-activated receptor γ (PPARγ) mediates the protective effect of quercetin against myocardial ischemia-reperfusion injury via suppressing the NF-κB pathway

Quercetin plays an important role in myocardial ischemia and reperfusion injury (IRI). However, the underlying mechanism for the protective effect of quercetin is largely unclear. In this study, we explored the protected effects of quercetin against myocardial IRI and its molecular mechanisms. Quercetin, GW9962 (PPARγ antagonist) or PPARγ-siRNA was administered alone or in combination prior to myocardial IRI in mice or to hypoxia and reoxygenation (H/R) treatment in H9C2 cells. Infarct size was evaluated by TTC staining after reperfusion. Myocardial injury was assessed by the serum levels of AST, CK-MB, cardiac troponin T (cTnT) and LDH. Cardiac function was measured by echocardiography. Oxidative stress injury was evaluated by analyses of inducible nitric oxide synthase (iNOS), MDA, SOD and glutathione peroxidase (GSH-PX) levels and by reactive oxygen species (ROS) detection. Myocardium apoptosis was evaluated by TUNEL staining, cleaved caspase-3 and Annexin V/PI detection. Moreover, activation of the NF-κB pathway was reflected by phosphorylation of IκB (p-IκB) and nuclear translocation of NF-κB p65. We reported that pretreatment of quercetin significantly improved cardiac function, diminished myocardial injury and reduced the infarct size. Myocardium oxidative damage and apoptosis were remarkably improved by quercetin treatment in vivo and in vitro. Quercetin also suppressed the activation of the NF-κB pathway induced by myocardial IRI. GW9662 or PPARγ knockdown partially attenuated these cardioprotective effects of quercetin during myocardial IRI. In conclusion, our findings suggest that quercetin ameliorated IRI-induced heart damage via PPARγ activation and the underlying mechanism might involve the inhibition of NF-κB pathway by PPARγ activation.

New Insights on the Use of Dietary Polyphenols or Probiotics for the Management of Arterial Hypertension

Arterial hypertension (AH) is one of the most prevalent risk factors for cardiovascular diseases (CD) and is the main cause of deaths worldwide. Current research establish that dietary polyphenols may help to lower blood pressure (BP), thus contributing to the reduction of cardiovascular complications. In addition, the health benefits of probiotics on BP have also attracted increased attention, as probiotics administration modulates the microbiota, which, by interacting with ingested polyphenols, controls their bioavalability. The aim of the present mini-review is to summarize and clarify the effects of dietary polyphenols and probiotics administration on BP using combined evidence from clinical and experimental studies, as well as to discuss the current debate in the literature about the usefulness of this nutritional approach to manage BP. Clinical trials and experimental studies have demonstrated that consuming dietary polyphenols or probiotics in adequate amounts may improve BP, ranging from modest to greater effects. However, the mechanisms linking probiotic intake and reduced BP levels need to be further elucidated as a definitive consensus on the link between intake of polyphenols or probiotics and improvement of AH has not been reached yet.

Antioxidative and Antidiabetic Effects of Natural Polyphenols and Isoflavones

Many polyphenols that contain more than two phenolic hydroxyl groups are natural antioxidants and can provide health benefits to humans. These polyphenols include, for example, oleuropein, hydroxytyrosol, catechin, chlorogenic acids, hesperidin, nobiletin, and isoflavones. These have been studied widely because of their strong radical-scavenging and antioxidative effects. These effects may contribute to the prevention of diseases, such as diabetes. Insulin secretion, insulin resistance, and homeostasis are important factors in the onset of diabetes, a disease that is associated with dysfunction of pancreatic β-cells. Oxidative stress is thought to contribute to this dysfunction and the effects of antioxidants on the pathogenesis of diabetes have, therefore, been investigated. Here, we summarize the antioxidative effects of polyphenols from the perspective of their radical-scavenging activities as well as their effects on signal transduction pathways. We also describe the preventative effects of polyphenols on diabetes by referring to recent studies including those reported by us. Appropriate analytical approaches for evaluating antioxidants in studies on the prevention of diabetes are comprehensively reviewed.

The Possible Role of Flavonoids in the Prevention of Diabetic Complications

Type 2 diabetes mellitus is a disease that affects many metabolic pathways. It is associated with insulin resistance, impaired insulin signaling, β-cell dysfunction, abnormal glucose levels, altered lipid metabolism, sub-clinical inflammation and increased oxidative stress. These and other unknown mechanisms lead to micro- and macro-complications, such as neuropathy, retinopathy, nephropathy and cardiovascular disease. Based on several in vitro animal models and some human studies, flavonoids appear to play a role in many of the metabolic processes involved in type 2 diabetes mellitus. In this review, we seek to highlight the most recent papers focusing on the relationship between flavonoids and main diabetic complications.

Molecular Mechanisms of the Anti-Obesity and Anti-Diabetic Properties of Flavonoids

Obesity and diabetes are the most prevailing health concerns worldwide and their incidence is increasing at a high rate, resulting in enormous social costs. Obesity is a complex disease commonly accompanied by insulin resistance and increases in oxidative stress and inflammatory marker expression, leading to augmented fat mass in the body. Diabetes mellitus (DM) is a metabolic disorder characterized by the destruction of pancreatic β cells or diminished insulin secretion and action insulin. Obesity causes the development of metabolic disorders such as DM, hypertension, cardiovascular diseases, and inflammation-based pathologies. Flavonoids are the secondary metabolites of plants and have 15-carbon skeleton structures containing two phenyl rings and a heterocyclic ring. More than 5000 naturally occurring flavonoids have been reported from various plants and have been found to possess many beneficial effects with advantages over chemical treatments. A number of studies have demonstrated the potential health benefits of natural flavonoids in treating obesity and DM, and show increased bioavailability and action on multiple molecular targets. This review summarizes the current progress in our understanding of the anti-obesity and anti-diabetic potential of natural flavonoids and their molecular mechanisms for preventing and/or treating obesity and diabetes.

Antidiabetic properties of dietary flavonoids: a cellular mechanism review

Background

Natural food products have been used for combating human diseases for thousands of years. Naturally occurring flavonoids including flavones, flavonols, flavanones, flavonols, isoflavones and anthocyanidins have been proposed as effective supplements for management and prevention of diabetes and its long-term complications based on in vitro and animal models.

Aim

To summarize the roles of dietary flavonoids in diabetes management and their molecular mechanisms.

Findings

Tremendous studies have found that flavonoids originated from foods could improve glucose metabolism, lipid profile, regulating the hormones and enzymes in human body, further protecting human being from diseases like obesity, diabetes and their complications.

Conclusion

In the current review, we summarize recent progress in understanding the biological action, mechanism and therapeutic potential of the dietary flavonoids and its subsequent clinical outcomes in the field of drug discovery in management of diabetes mellitus.

Thymoquinone Protects against Myocardial Ischemic Injury by Mitigating Oxidative Stress and Inflammation

The present study was aimed at investigating the cardioprotective activity of thymoquinone (TMQ), an active principle of the herb, Nigella sativa, which is used for the management of various diseases. The present study examined the cardioprotective effect of TMQ in isoproterenol- (ISP-) induced myocardial infarction in rats. Myocardial infarction was induced by two subcutaneous injections of ISP (85 mg/kg) at an interval of 24 hr. TMQ (20 mg/kg) was administered orally for 21 days. ISP-treated rats showed depletion of antioxidants and marker enzymes from myocardium along with lipid peroxidation and enhanced levels of proinflammatory cytokines. ISP also induced histopathological alterations in myocardium. Treatment with TMQ prevented the depletion of endogenous antioxidants and myocyte injury marker enzymes and inhibited lipid peroxidation as well as reducing the levels of proinflammatory cytokines. TMQ pretreatment also reduced myonecrosis, edema, and infiltration of inflammatory cells and showed preservation of cardiomyocytes histoarchitecture. The present study results demonstrate that TMQ exerts cardioprotective effect by mitigating oxidative stress, augmenting endogenous antioxidants, and maintaining structural integrity. The results of the present study indicate that TMQ may serve as an excellent agent alone or as adjuvant to prevent the onset and progression of myocardial injury.