A new flavonoid glycoside (APG) isolated from Clematis tangutica attenuates myocardial ischemia/reperfusion injury via activating PKCε signaling

Rapidly screening of pancreatic lipase inhibitors from Clematis tangutica using affinity ultrafiltration-HPLC-QTOFMS technique combined with targeted separation, in vitro validation, and molecular docking

INTRODUCTION

Screening of novel pancreatic lipase inhibitors from complex natural products is a meaningful task.

OBJECTIVES

Through accurately screening and separating pancreatic lipase inhibitors from Clematis tangutica (C. tangutica), to discover new leading compounds for slimming and accelerate the development and utilization of Tibetan medicine resources.

METHODS

An integrated strategy that combines affinity ultrafiltration and high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (AU-HPLC-QTOFMS), targeted separation, in vitro validation, and molecular docking was developed to screen pancreatic lipase inhibitors from C. tangutica. The AU-HPLC-QTOFMS technique was performed to fish for the potential active substances. Macroporous resin, preparative liquid chromatography, and high-speed countercurrent chromatography were implemented for the accurate and targeted separation of active compounds. The inhibitory activities of target compounds to pancreatic lipase were detected by the inhibition experiments in vitro. The binding affinities and binding sites were analyzed using molecular docking.

RESULTS

A total of eleven kinds of pancreatic lipase inhibitory substances were screened from C. tangutica. Seven triterpenoid saponins were screened for the first time as lipase inhibitors and successfully prepared with purities higher than 97%. Tanguticoside B, clematangoticoside J, hederoside H1, and rutin showed stronger inhibitory effects with IC50 values of 1.539 ± 0.048, 1.661 ± 0.092, 1.793 ± 0.069, and 1.792 ± 0.094 mmol/l. Moreover, they have the lowest ΔG values of -10.84, -9.97, -10.87, and -9.39 kcal/mol to pancreatic lipase.

CONCLUSION

The integrated strategy using AU-HPLC-QTOFMS, targeted separation, in vitro validation, and molecular docking was feasible for rapidly screening and directionally isolating pancreatic lipase inhibitors from C. tangutica.

Roles of flavonoids in ischemic heart disease: Cardioprotective effects and mechanisms against myocardial ischemia and reperfusion injury

BACKGROUND

Flavonoids are extensively present in fruits, vegetables, grains, and medicinal plants. Myocardial ischemia and reperfusion (MI/R) comprise a sequence of detrimental incidents following myocardial ischemia. Research indicates that flavonoids have the potential to act as cardioprotective agents against MI/R injuries. Several specific flavonoids, e.g., luteolin, hesperidin, quercetin, kaempferol, and puerarin, have demonstrated cardioprotective activities in animal models.

PURPOSE

The objective of this review is to identify the cardioprotective flavonoids, investigate their mechanisms of action, and explore their application in myocardial ischemia.

METHODS

A search of PubMed database and Google Scholar was conducted using keywords "myocardial ischemia" and "flavonoids". Studies published within the last 10 years reporting on the cardioprotective effects of natural flavonoids on animal models were analyzed.

RESULTS

A total of 55 natural flavonoids were identified and discussed within this review. It can be summarized that flavonoids regulate the following main strategies: antioxidation, anti-inflammation, calcium modulation, mitochondrial protection, ER stress inhibition, anti-apoptosis, ferroptosis inhibition, autophagy modulation, and inhibition of adverse cardiac remodeling. Additionally, the number and position of OH, 3'4'-catechol, C2=C3, and C4=O may play a significant role in the cardioprotective activity of flavonoids.

CONCLUSION

This review serves as a reference for designing a daily diet to prevent or reduce damages following ischemia and screening of flavonoids for clinical application.

Effect and possible mechanisms of saponins in Chinese herbal medicine exerts for the treatment of myocardial ischemia-reperfusion injury in experimental animal: a systematic review and meta-analysis

Introduction

Preventing ischemia-reperfusion injury is the main direction of myocardial infarction treatment in the convalescent stage. Some studies have suggested that saponins in Traditional Chinese medicine (TCM) preparations can protect the myocardium by various mechanisms. Our meta-analysis aims to evaluate the efficacy of TCM saponins in treating myocardial ischemia-reperfusion injury (MIRI) and to summarize the potential molecular mechanisms further.

Methods

We conducted a literature search in six electronic databases [Web of Science, PubMed, Embase, Cochrane Library, Sinomed, China National Knowledge Infrastructure (CNKI)] until October 2022.

Results

Seventeen eligible studies included 386 animals (254 received saponins and 132 received vehicles). The random effect model is used to calculate the combined effect. The effect size is expressed as the weighted average difference (WMD) and 95% confidence interval (CI). Compared with placebo, saponins preconditioning reduced infarct size after MIRI significantly (WMD: -3.60,95% CI: -4.45 to -2.74, P < 0.01, I2: 84.7%, P < 0.001), and significantly increased EF (WMD: 3.119, 95% CI: 2.165 to 4.082, P < 0.01, I2: 82.9%, P < 0.0 L) and FS (WMD: 3.157, 95% CI: 2.218 to 4.097, P < 0.001, I2: 81.3%, P < 0.001).

Discussion

The results show that the pre-administration of saponins from TCM has a significant protective effect on MIRI in preclinical studies, which provides an application prospect for developing anti-MIRI drugs with high efficiency and low toxicity.

Pharmacological and Molecular Insight on the Cardioprotective Role of Apigenin

Apigenin is a naturally occurring dietary flavonoid found abundantly in fruits and vegetables. It possesses a wide range of biological properties that exert antioxidant, anti-inflammatory, anticancer, and antibacterial effects. These effects have been reported to be beneficial in the treatment of atherosclerosis, stroke, hypertension, ischemia/reperfusion-induced myocardial injury, and diabetic cardiomyopathy, and provide protection against drug-induced cardiotoxicity. These potential therapeutic effects advocate the exploration of the cardioprotective actions of apigenin. This review focuses on apigenin, and the possible pharmacological mechanisms involved in the protection against cardiovascular diseases. We further discuss its therapeutic uses and highlight its potential applications in the treatment of various cardiovascular disorders. Apigenin displays encouraging results, which may have implications in the development of novel strategies for the treatment of cardiovascular diseases. With the commercial availability of apigenin as a dietary supplement, the outcomes of preclinical studies may provide the investigational basis for future translational strategies evaluating the potential of apigenin in the treatment of cardiovascular disorders. Further preclinical and clinical investigations are required to characterize the safety and efficacy of apigenin and establish it as a nutraceutical as well as a therapeutic agent to be used alone or as an adjuvant with current drugs.

GAS6/Axl is associated with AMPK activation and attenuates H2O2-induced oxidative stress

Oxidative stress plays a key part in cardiovascular event. Growth arrest-specific gene 6 (GAS6) is a vitamin K-dependent ligand which has been shown to exert important effects in heart. The effects of GAS6 were evaluated against hydrogen peroxide (H₂O₂) ‑induced oxidative stress injury in HL-1 cardiomyocytes. A series of experimental methods were used to analyze the effects of GAS6 on cell viability, apoptosis, oxidative stress, mitochondrial function and AMPK/ACC signaling in H₂O₂‑injured HL-1 cells. In this study, we found that H₂O₂ reduced cell viability, increased apoptotic rate and intracellular reactive oxygen species (ROS). Meanwhile, H₂O₂ decreased the protein levels of GAS6, and increased the protein level of p-AMPK/AMPK, p-ACC/ACC. Then, we observed that overexpression of GAS6 significantly reduced cell death, manifested as increased cell viability, improved oxidative stress, apoptosis and upregulated the levels of GAS6, p-Axl/Axl, Nrf2, NQO1, HO-1, Bcl-2/Bax, PGC-1α, NRF1, TFAM, p-AMPK/AMPK, and p-ACC/ACC-related protein expression in HL-1 cells and H₂O₂‑injured cardiomyocytes. To further verify the results, we successfully constructed GAS6 lentiviral vectors, and found GAS6 shRNA partially reversed the above results. These data suggest that AMPK/ACC may be a downstream effector molecule in the antioxidant action of GAS6. In summary, our findings indicate that activation GAS6/Axl-AMPK signaling protects H₂O₂‑induced oxidative stress which is accompanied by the amelioration of oxidative stress, apoptosis, and mitochondrial function.

Characterization of a novel polysaccharide from red ginseng and its ameliorative effect on oxidative stress injury in myocardial ischemia

BACKGROUND

Red ginseng (RG) was widely used as traditional Chinese medicine (TCM) or dietary supplement. However, few researches had been reported on the red ginseng polysaccharide (RGP).

METHODS

In this study, a novel heteropolysaccharide named RGP1-1 was fractionated sequentially by DEAE-52 column and Sephadex G-100 gel column. The primary structure of RGP1-1, including glycosyl linkages, molecular weight, monosaccharide composition, morphology and physicochemical property were conducted by nuclear magnetic resonance (NMR), gas chromatography-mass spectrometer (GC-MS), atomic force microscope (AFM), scanning electron microscope (SEM), differential scanning calorimetry-thermogravimetric analysis (DSC-TG) and so on. The effect of RGP1-1 in preventing and treating myocardial ischemia was evaluated by an animal model isoprenaline (ISO) induced mice.

RESULTS

RGP1-1, with a homogeneous molecular weight of 5655 Da, was composed of Glc and Gal in the ratio of 94.26:4.92. The methylation and NMR analysis indicated the backbone was composed of → 1)-Glcp-(4 → and → 1)-Galp-(4 →, branched partially at O-4 with α-D-Glcp-(1 → residue. Morphology and physicochemical property analysis revealed a triple-helical conformation, flaky and irregular spherical structure with molecule aggregations and stable thermal properties of RGP1-1. And it contained 6.82 mV zeta potential, 117.4 nm partical size and polymerization phenomenon. Furthermore, RGP1-1 possessed strong antioxidant activity in vitro and in vivo, RGP1-1 could decrease cardiomyocyte apoptosis and myocardium fibrosis of mice in histopathology and it could decrease significantly the serum levels of cardiac troponin (cTnI), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), malondialdehyde (MDA). Western blot analysis showed that RGP1-1 can increase the expression of main protein Nuclear factor E2-related factor 2(Nrf2), NAD(P)H:quinone oxidoreductase 1 (NQO1), heme oxygenase-1(HO-1) and kelch-like ECH-associated protein1(keap1) in oxidative stress injure progress, and therefore regulate the pathway of Nrf2/HO-1.

CONCLUSION

The above findings indicated that RGP1-1 had an improving effect on ISO-induced myocardial ischemia injury in mice, as novel natural antioxidant and heart-protecting drugs.

Puerarin activates adaptive autophagy and protects the myocardium against doxorubicin-induced cardiotoxicity via the 14–3-3γ/PKCε pathway

Doxorubicin (Dox)-induced cardiotoxicity (DIC) seriously threatens the health of related patients. Studies have confirmed that 14-3-3γ and protein kinase C epsilon (PKCε) are the endogenous protective proteins. Puerarin (Pue) is a bioactive ingredient isolated from the root of Pueraria lobata. It possesses many pharmacological properties, which have been widely used in treating and adjuvant therapy of cardiovascular diseases. In the study, we intended to explore the effects and mechanism of Pue pretreatment to protect the myocardium against DIC injury. Adult mice and H9c2 cells were pretreated with Pue, and the injury model was made with Dox. Results showed that Pue pretreatment alleviated DIC injury, as revealed by increased cell viability, decreased LDH activity and apoptosis, inhibited excess oxidative stress, maintained mitochondrial function and energy metabolism, and improved myocardial function. Furthermore, Pue pretreatment upregulated 14-3-3γ expression, interacted with PKCε, phosphorylated and impelled migration to mitochondria, activated adaptive autophagy, and protected the myocardium. However, pAD/14-3-3γ-shRNA or εV1-2 (a PKCε activity inhibitor) or 3-methyladenine (an autophagy inhibitor) could weaken the above effects of Pue pretreatment. Together, Pue pretreatment could activate adaptive autophagy by the 14-3-3γ/PKCε pathway and protect the myocardium against DIC injury.

Beta-Boswellic Acid Protects Against Cerebral Ischemia/Reperfusion Injury via the Protein Kinase C Epsilon/Nuclear Factor Erythroid 2-like 2/Heme Oxygenase-1 Pathway

Ischemic strokes are associated with a high rate of disability and death globally. Cerebral ischemia/reperfusion (I/R) injury is a type of brain damage associated with oxidative stress after an ischemic stroke. Beta-boswellic acid (β-BA) reportedly exerts antioxidant and neuroprotective effects, but its role in cerebral I/R injury is unclear. The aim of this research was to investigate the neuroprotective effects, as well as the mechanisms of β-BA in cerebral I/R injury. In vivo experiments were conducted using a rat middle cerebral artery occlusion and reperfusion (MCAO/R) model, and in vitro experiments were performed using a rat neuronal oxygen-glucose deprivation and reoxygenation (OGD/R) model. Triphenyltetrazolium chloride staining, neurological function scores, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, hematoxylin and eosin staining, and antioxidant levels in the brain were used to assess the effects of β-BA. Flow cytometry was used to detect reactive oxygen species and apoptotic cells. Western blotting and immunofluorescence staining were used to measure protein levels. The results showed that β-BA markedly improved neurological deficits and decreased infarct volume and necrotic neurons in rats. The in vitro results showed that β-BA protected neurons against OGD/R-induced injury. Additionally, β-BA significantly increased the phosphorylation of protein kinase C epsilon (PRKCE) at S729, the translocation of nuclear factor erythroid 2-like 2 (NFE2L2), and expression of heme oxygenase-1 (HMOX1). This study demonstrates that β-BA exerts neuroprotective effects against cerebral I/R via the activation of the PRKCE/NFE2L2/HMOX1 pathway and is a potential therapeutic candidate for ischemic stroke.

Old targets, new strategy: Apigenin-7-O-β-d-(-6″-p-coumaroyl)-glucopyranoside prevents endothelial ferroptosis and alleviates intestinal ischemia-reperfusion injury through HO-1 and MAO-B inhibition

With the increasing morbidity and mortality, intestinal ischemia/reperfusion injury (IIRI) has attracted more and more attention, but there is no efficient therapeutics at present. Apigenin-7-O-β-D-(-6″-p-coumaroyl)-glucopyranoside (APG) is a new flavonoid glycoside isolated from Clematis tangutica that has strong antioxidant abilities in previous studies. However, the pharmacodynamic function and mechanism of APG on IIRI remain unknown. This study aimed to investigate the effects of APG on IIRI both in vivo and in vitro and identify the potential molecular mechanism. We found that APG could significantly improve intestinal edema and increase Chiu's score. MST analysis suggested that APG could specifically bind to heme oxygenase 1 (HO-1) and monoamine oxidase b (MAO-B). Simultaneously, APG could attenuate ROS generation and Fe²⁺ accumulation, maintain mitochondria function thus inhibit ferroptosis with a dose-dependent manner. Moreover, we used siRNA silencing technology to confirm that knocking down both HO-1 and MAO-B had a positive effect on intestine. In addition, we found the HO-1 and MAO-B inhibitors also could reduce endothelial cell loss and protect vascular endothelial after reperfusion. We demonstrate that APG plays a protective role on decreasing activation of HO-1 and MAO-B, attenuating IIRI-induced ROS generation and Fe²⁺ accumulation, maintaining mitochondria function thus inhibiting ferroptosis.

Dietary Flavonoids: Cardioprotective Potential with Antioxidant Effects and Their Pharmacokinetic, Toxicological and Therapeutic Concerns

Flavonoids comprise a large group of structurally diverse polyphenolic compounds of plant origin and are abundantly found in human diet such as fruits, vegetables, grains, tea, dairy products, red wine, etc. Major classes of flavonoids include flavonols, flavones, flavanones, flavanols, anthocyanidins, isoflavones, and chalcones. Owing to their potential health benefits and medicinal significance, flavonoids are now considered as an indispensable component in a variety of medicinal, pharmaceutical, nutraceutical, and cosmetic preparations. Moreover, flavonoids play a significant role in preventing cardiovascular diseases (CVDs), which could be mainly due to their antioxidant, antiatherogenic, and antithrombotic effects. Epidemiological and in vitro/in vivo evidence of antioxidant effects supports the cardioprotective function of dietary flavonoids. Further, the inhibition of LDL oxidation and platelet aggregation following regular consumption of food containing flavonoids and moderate consumption of red wine might protect against atherosclerosis and thrombosis. One study suggests that daily intake of 100 mg of flavonoids through the diet may reduce the risk of developing morbidity and mortality due to coronary heart disease (CHD) by approximately 10%. This review summarizes dietary flavonoids with their sources and potential health implications in CVDs including various redox-active cardioprotective (molecular) mechanisms with antioxidant effects. Pharmacokinetic (oral bioavailability, drug metabolism), toxicological, and therapeutic aspects of dietary flavonoids are also addressed herein with future directions for the discovery and development of useful drug candidates/therapeutic molecules.

The roles of PKC-δ and PKC-ε in myocardial ischemia/reperfusion injury

Ischemia and reperfusion (I/R) cause a reduction in arterial blood supply to tissues, followed by the restoration of perfusion and consequent reoxygenation. The reestablishment of blood flow triggers further damage to ischemic tissue through reactive oxygen species (ROS) accumulation, interference with cellular ion homeostasis, opening of mitochondrial permeability transition pores (mPTPs) and promotion of cell death (apoptosis or necrosis). PKC-δ and PKC-ε, belonging to a family of serine/threonine kinases, have been demonstrated to play important roles during I/R injury in cardiovascular diseases. However, the cardioprotective mechanisms of PKC-δ and PKC-ε in I/R injury have not been elaborated until now. This article discusses the roles of PKC-δ and PKC-ε during myocardial I/R in redox regulation (redox signaling and oxidative stress), cell death (apoptosis and necrosis), Ca²⁺ overload, and mitochondrial dysfunction.

A review on herbal Nrf2 activators with preclinical evidence in cardiovascular diseases

Cardiovascular diseases (CVDs) are an ever-growing problem and are the most common cause of death worldwide. The uncontrolled production of reactive oxygen species (ROS) and the activation of ROS associated with various cell signaling pathways with oxidative cellular damage are the most common pathological conditions connected with CVDs including endothelial dysfunction, hypercontractility of vascular smooth muscle, cardiac hypertrophy and heart failure. The nuclear factor E2-related factor 2 (Nrf2) is a basic leucine zipper redox transcription factor, together with its negative regulator, kelch-like ECH-associated protein 1 (Keap1), which serves as a key regulator of cellular defense mechanisms to combat oxidative stress and associated diseases. Multiple lines of evidence described here support the cardiac protective property of Nrf2 in various experimental models of cardiac related disease conditions. In this review, we emphasized the molecular mechanisms of Nrf2 and described the detailed outline of current findings on the therapeutic possibilities of the Nrf2 activators specifically from herbal origin in various CVDs. Based on evidence from various preclinical experimental models, we have highlighted the activation of Nrf2 pathway as a budding therapeutic option for the prevention and treatment of CVDs, which needs further investigation and validation in the clinical settings.

Cardioprotective Effects of Natural Products via the Nrf2 Signaling Pathway

Due to its poor regenerative capacity, the heart is specifically vulnerable to xenobiotic- induced cardiotoxicity, myocardial ischaemia/reperfusion injury and other pathologies. Nuclear factor erythroid-2-related factor 2 (Nrf2) is considered as an essential factor in protecting cardiomyocytes against oxidative stress resulting from free radicals and reactive oxygen species. It also serves as a key regulator of antioxidant enzyme expression via the antioxidant response element, a cis-regulatory element, which is found in the promoter region of several genes encoding detoxification enzymes and cytoprotective proteins. It has been reported that a variety of natural products are capable of activating Nrf2 expression, and in this way, increase the antioxidant potential of cardiomyocytes. In the present review, we consider the cardioprotective activities of natural products and their possible therapeutic potential.

The Protective Effects of Melatonin Against LPS-Induced Septic Myocardial Injury: A Potential Role of AMPK-Mediated Autophagy

Aim: Melatonin is an indolamine secreted by the pineal gland, as well as most of the organs and tissues. In addition to regulating circadian biology, studies have confirmed the multiple pharmacological effects of melatonin. Melatonin provides a strong defense against septic myocardial injury. However, the underlying mechanism has not been fully described. In this study, we investigated the protective effects of melatonin against lipopolysaccharide (LPS)-induced myocardial injury as well as the mechanisms involved. Methods: Mice were intraperitoneally injected with LPS to induce a septic myocardial injury model or an LPS shock model, depending on the dose of LPS. Melatonin was given (20 mg/kg/day, via intraperitoneal injection) for a week prior to LPS insult. 6 h after LPS injection, echocardiographic analysis, TUNEL staining, transmission electron microscopy (TEM), western blot, quantitative real-time PCR and ELISA were used to investigate the protective effects of melatonin against LPS induced myocardial injury. AMPK inhibitor, autophagy activator and inhibitor, siRNAs were used for further validation. Results: Survival test showed that melatonin significantly increased the survival rate after LPS-induced shock. In the sepsis model, melatonin markedly ameliorated myocardial dysfunction, decreased the release of inflammatory cytokines, activated AMP-activated protein kinase (AMPK), improved mitochondrial function, and activated autophagy. To confirm whether the protection of melatonin was mediated by AMPK and autophagy, Compound C, an AMPK inhibitor; 3-MA, an autophagy inhibitor; and Rapamycin (Rapa), an autophagy activator, were used in this study. AMPK inhibition down-regulated autophagy, abolished protection of melatonin, as indicated by significantly decreased cardiac function, increased inflammation and damaged mitochondrial function. Furthermore, autophagy inhibition by 3-MA significantly impaired the protective effects of melatonin, whereas autophagy activation by Rapa reversed LPS + Compound C induced myocardial injury. In addition, in vitro studies further confirmed the protection of melatonin against LPS-induced myocardial injury and the mechanisms involving AMPK-mediated autophagy signaling. Conclusions: In summary, our results demonstrated that melatonin protects against LPS-induced septic myocardial injury by activating AMPK mediated autophagy pathway.

Growth Hormone Receptor Gene is Essential for Chicken Mitochondrial Function In Vivo and In Vitro

The growth hormone receptor (GHR) gene is correlated with many phenotypic and physiological alternations in chicken, such as shorter shanks, lower body weight and muscle mass loss. However, the role of the GHR gene in mitochondrial function remains unknown in poultry. In this study, we assessed the function of mitochondria in sex-linked dwarf (SLD) chicken skeletal muscle and interfered with the expression of GHR in DF-1 cells to investigate the role of the GHR gene in chicken mitochondrial function both in vivo and in vitro. We found that the expression of key regulators of mitochondrial biogenesis and mitochondrial DNA (mtDNA)-encoded oxidative phosphorylation (OXPHOS) genes were downregulated and accompanied by reduced enzymatic activity of OXPHOS complexes in SLD chicken skeletal muscle and GHR knockdown cells. Then, we assessed mitochondrial function by measuring mitochondrial membrane potential (ΔΨm), mitochondrial swelling, reactive oxygen species (ROS) production, malondialdehyde (MDA) levels, ATP levels and the mitochondrial respiratory control ratio (RCR), and found that mitochondrial function was impaired in SLD chicken skeletal muscle and GHR knockdown cells. In addition, we also studied the morphology and structure of mitochondria in GHR knockdown cells by transmission electron microscopy (TEM) and MitoTracker staining. We found that knockdown of GHR could reduce mitochondrial number and alter mitochondrial structure in DF-1 cells. Above all, we demonstrated for the first time that the GHR gene is essential for chicken mitochondrial function in vivo and in vitro.

Targeting NLRP3 (Nucleotide-Binding Domain, Leucine-Rich–Containing Family, Pyrin Domain–Containing-3) Inflammasome in Cardiovascular Disorders

Inflammation is an important innate immune response to infection or tissue damage. Inflammasomes are involved in the onset and development of inflammation. The NLRP3 (nucleotide-binding domain, leucine-rich–containing family, pyrin domain–containing-3) inflammasome is the best-characterized inflammasome. Recent evidence has indicated the importance of the NLRP3 inflammasome in the pathophysiology of cardiovascular disorders. To further understand the roles of the NLRP3 inflammasome in the cardiovascular system, we provide a comprehensive overview and discuss the remaining questions. First, a summary of NLRP3 inflammasome in the cardiovascular system is introduced. Then, the associations between NLRP3 inflammasome and cardiovascular disorders are presented. Finally, we discuss existing problems and potential directions with this issue. The information compiled here summarizes recent progress, thus potentially aiding in the understanding of the NLRP3 inflammasome in cardiovascular disorders, designing experimental and clinical research about the NLRP3 inflammasome, and promoting therapeutics for cardiovascular disorders.

Pretreatment with Total Flavonoid Extract from Dracocephalum Moldavica L. Attenuates Ischemia Reperfusion-induced Apoptosis

We previously demonstrated the cardio-protection mediated by the total flavonoid extracted from Dracocephalum moldavica L. (TFDM) following myocardial ischemia reperfusion injury (MIRI). The present study assessed the presence and mechanism of TFDM-related cardio-protection on MIRI-induced apoptosis in vivo. Male Sprague-Dawley rats experienced 45-min ischemia with 12 h of reperfusion. Rats pretreated with TFDM (3, 10 or 30 mg/kg/day) were compared with Sham (no MIRI and no TFDM), MIRI (no TFDM), and Positive (trapidil tablets, 13.5 mg/kg/day) groups. In MIRI-treated rats, high dose-TFDM (H-TFDM) pre-treatment with apparently reduced release of LDH, CK-MB and MDA, enhanced the concentration of SOD in plasma, and greatly reduced the infarct size, apoptotic index and mitochondrial injury. H-TFDM pretreatment markedly promoted the phosphorylation of PI3K, Akt, GSK-3β and ERK1/2 in comparison with the MIRI model group. Western blot analysis after reperfusion also showed that H-TFDM decreased release of Bax, cleaved caspase-3, caspase-7 and caspase-9, and increased expression of Bcl-2 as evident by the higher Bcl-2/Bax ratio. TFDM cardio-protection was influenced by LY294002 (PI3K inhibitor) and PD98059 (ERK1/2 inhibitor). Taken together, these results provide convincing evidence of the benefit of TFDM pretreatment due to inhibited myocardial apoptosis as mediated by the PI3K/Akt/GSK-3β and ERK1/2 signaling pathways.

Food Bioactive HDAC Inhibitors in the Epigenetic Regulation of Heart Failure

Approximately 5.7 million U.S. adults have been diagnosed with heart failure (HF). More concerning is that one in nine U.S. deaths included HF as a contributing cause. Current HF drugs (e.g., β-blockers, ACEi) target intracellular signaling cascades downstream of cell surface receptors to prevent cardiac pump dysfunction. However, these drugs fail to target other redundant intracellular signaling pathways and, therefore, limit drug efficacy. As such, it has been postulated that compounds designed to target shared downstream mediators of these signaling pathways would be more efficacious for the treatment of HF. Histone deacetylation has been linked as a key pathogenetic element for the development of HF. Lysine residues undergo diverse and reversible post-translational modifications that include acetylation and have historically been studied as epigenetic modifiers of histone tails within chromatin that provide an important mechanism for regulating gene expression. Of recent, bioactive compounds within our diet have been linked to the regulation of gene expression, in part, through regulation of the epi-genome. It has been reported that food bioactives regulate histone acetylation via direct regulation of writer (histone acetyl transferases, HATs) and eraser (histone deacetylases, HDACs) proteins. Therefore, bioactive food compounds offer unique therapeutic strategies as epigenetic modifiers of heart failure. This review will highlight food bio-actives as modifiers of histone deacetylase activity in the heart.

Apigenin-7-O-β-d-(-6″-p-coumaroyl)-glucopyranoside pretreatment attenuates myocardial ischemia/reperfusion injury via activating AMPK signaling

AIMS

Apigenin-7-O-β-d-(-6″-p-coumaroyl)-glucopyranoside (APG) was considered as the major active compound derived from Clematis tangutica. Though we have demonstrated that APG exerts cardioprotective effects, the mechanism of APG-mediated cardioprotection remains largely unknown. Numerous studies indicate that endoplasmic reticulum stress (ERS) is a vital injury factor in myocardial ischemia reperfusion (MI/R). In this study, we mainly investigated whether modulation of the ERS and AMPK were involved in the cardioprotective action of APG during MI/R injury.

MAIN METHODS

The perfused isolated rat heart or primary neonatal rat cardiomyocytes which exposed to APG with or else without the AMPK inhibitor Compound C was then subject to MI/R. After reperfusion, the degree of myocardial injury was assessed by using lactate dehydrogenase (LDH) release, creatine kinase (CK) release, histological examination, and TTC staining. The protein expressions of p-AMPK, AMPK, p-PERK, PERK, p-eIF2α, eIF2α, CHOP, Bax, Bcl2 and Cleaved Caspase 3 were analyzed by western blot. The cell viability was assessed by CCK-8 kit while apoptosis assessed by using TUNEL assay.

KEY FINDINGS

Pretreatment of APG significantly improved cardiac function and suppressed ERS through activating the AMPK signaling pathway, which could simultaneously improve cardiac function, alleviate myocardial injury, increase the cell viability and decrease apoptosis.

SIGNIFICANCE

To conclude, APG ameliorates MI/R injury by activating the AMPK signaling pathway and relieving endoplasmic reticulum stress. APG may be a natural product with pharmacological preconditioning activity, which could do us a favor to develop more novel therapy methods to against MI/R injury in the future.