Water-soluble acacetin prodrug confers significant cardioprotection against ischemia/reperfusion injury

Acacetin inhibits inflammation by blocking MAPK/NF-κB pathways and NLRP3 inflammasome activation

Objective: Our preliminary research indicates that acacetin modulates the nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain containing 3 (NLRP3) inflammasome, providing protection against Alzheimer's Disease (AD) and cerebral ischemic reperfusion injury. The mechanisms of acacetin to inhibit the activation of the NLRP3 inflammasome remain fully elucidated. This study aims to investigate the effects and potential mechanisms of acacetin on various agonists induced NLRP3 inflammasome activation. Methods: A model for the NLRP3 inflammasome activation was established in mouse bone marrow-derived macrophages (BMDMs) using Monosodium Urate (MSU), Nigericin, Adenosine Triphosphate (ATP), and Pam3CSK4, separately. Western blot analysis (WB) was employed to detect Pro-caspase-1, Pro-Interleukin-1β (Pro-IL-1β) in cell lysates, and caspase-1, IL-1β in supernatants. Enzyme-Linked Immunosorbent Assay (ELISA) was used to measured the release of IL-1β, IL-18, and Tumor Necrosis Factor-alpha (TNF-α) in cell supernatants to assess the impact of acacetin on NLRP3 inflammasome activation. The lactate dehydrogenase (LDH) release was also assessed. The Nuclear Factor Kappa B (NF-κB) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways related proteins were evaluated by WB, and NF-κB nuclear translocation was observed via laser scanning confocal microscopy (LSCM). Disuccinimidyl Suberate (DSS) cross-linking was employed to detect oligomerization of Apoptosis-associated Speck-like protein containing a Caspase Recruitment Domain (ASC), and LSCM was also used to observe Reactive Oxygen Species (ROS) production. Inductively Coupled Plasma (ICP) and N-(6-methoxyquinolyl) acetoethyl ester (MQAE) assays were utilized to determined the effects of acacetin on the efflux of potassium (K+) and chloride (Cl-) ions. Results: Acacetin inhibited NLRP3 inflammasome activation induced by various agonists, reducing the release of TNF-α, IL-1β, IL-18, and LDH. It suppressed the expression of Lipopolysaccharides (LPS)-activated Phosphorylated ERK (p-ERK), p-JNK, and p-p38, inhibited NF-κB p65 phosphorylation and nuclear translocation. Acacetin also reduced ROS production and inhibited ASC aggregation, thus suppressing NLRP3 inflammasome activation. Notably, acacetin did not affect K+ and Cl-ions efflux during the activation process. Conclusion: Acacetin shows inhibitory effects on both the priming and assembly processes of the NLRP3 inflammasome, positioning it as a promising new candidate for the treatment of NLRP3 inflammasome-related diseases.

Protective Effect of Water-Soluble Acacetin Prodrug on APAP-Induced Acute Liver Injury Is Associated with Upregulation of PPARγ and Alleviation of ER Stress

A water-soluble acacetin prodrug has been synthesized and reported by our group previously. Acetaminophen (APAP) overdose is a leading cause of acute liver injury. We found that subcutaneous injection of acacetin prodrug (5, 10, 20 mg/kg) decreased serum ALT, AST, and ALP, corrected the abnormal MDA and GSH in liver, and improved intrahepatic hemorrhage and destruction of liver structures in APAP (300 mg/kg)-treated mice. Molecular mechanism analysis revealed that the expressions of endoplasmic reticulum (ER) stress markers ATF6, CHOP, and p-PERK, apoptosis-related protein BAX, and cleaved caspase 3 were decreased by acacetin in a dose-dependent manner in vivo and in vitro. Moreover, via the acacetin-upregulated peroxisome-proliferator-activated receptor gamma (PPARγ) of HepG2 cells and liver, the suppressive effect of acacetin on ER stress and apoptosis was abolished by PPARγ inhibitor (GW9662) or PPARγ-siRNA. Molecular docking revealed that acacetin can bind to three active pockets of PPARγ, mainly by hydrogen bond. Our results provide novel evidence that acacetin prodrug exhibits significant protective effect against APAP-induced liver injury by targeting PPARγ, thereby suppressing ER stress and hepatocyte apoptosis. Acacetin prodrug is likely a promising new drug candidate for treating patients with acute liver injury induced by APAP.

Acacetin Alleviates Cardiac Fibrosis via TGF-β1/Smad and AKT/mTOR Signal Pathways in Spontaneous Hypertensive Rats

INTRODUCTION

Attenuating cardiac fibroblasts activation contributes to reducing excessive extracellular matrix deposition and cardiac structural remodeling in hypertensive hearts. Acacetin plays a protective role in doxorubicin-induced cardiomyopathy and ischemia/reperfusion injury. The aim of this study was to investigate the potential molecular mechanisms underlying the protective role of acacetin on hypertension-induced cardiac fibrosis.

METHODS

Echocardiography, histopathological methods, and Western blotting techniques were used to evaluate the anti-fibrosis effects in spontaneous hypertensive rat (SHR) which were daily intragastrically administrated with acacetin (10 mg/kg and 20 mg/kg) for 6 weeks. Angiotensin II (Ang II) was used to induce cellular fibrosis in human cardiac fibroblasts (HCFs) in the absence and presence of acacetin treatment for 48 h.

RESULTS

Acacetin significantly alleviated hypertension-induced increase in left ventricular (LV) posterior wall thickness and LV mass index in SHR. The expressions of collagen-1, collagen-III, and alpha-smooth muscle actin (α-SMA) were remarkedly decreased after treatment with acacetin (n = 6, p < 0.05). In cultured HCFs, acacetin significantly attenuated Ang II-induced migration and proliferation (n = 6, p < 0.05). Moreover, acacetin substantially inhibited Ang II-induced upregulation of collagen-1 and collagen-III (n = 6, p < 0.05) and downregulated the expression of alpha-SMA in HCFs. Additionally, acacetin decreased the expression of TGF-β1, p-Smad3/Smad3, and p-AKT and p-mTOR but increased the expression of Smad7 (n = 6, p < 0.05). Further studies found that acacetin inhibited TGF-β1 agonist SRI and AKT agonist SC79 caused fibrotic effect.

CONCLUSION

Acacetin inhibits the hypertension-associated cardiac fibrotic processes through regulating TGF-β/Smad3, AKT/mTOR signal transduction pathways.

Chinese herbal medicine for the treatment of cardiovascular diseases ─ targeting cardiac ion channels

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality, imposing an increasing global health burden. Cardiac ion channels (voltage-gated Na_V, Ca_V, K_Vs, and others) synergistically shape the cardiac action potential (AP) and control the heartbeat. Dysfunction of these channels, due to genetic mutations, transcriptional or post-translational modifications, may disturb the AP and lead to arrhythmia, a major risk for CVD patients. Although there are five classes of anti-arrhythmic drugs available, they can have varying levels of efficacies and side effects on patients, possibly due to the complex pathogenesis of arrhythmias. As an alternative treatment option, Chinese herbal remedies have shown promise in regulating cardiac ion channels and providing anti-arrhythmic effects. In this review, we first discuss the role of cardiac ion channels in maintaining normal heart function and the pathogenesis of CVD, then summarize the classification of Chinese herbal compounds, and elaborate detailed mechanisms of their efficacy in regulating cardiac ion channels and in alleviating arrhythmia and CVD. We also address current limitations and opportunities for developing new anti-CVD drugs based on Chinese herbal medicines.

Acacetin inhibits myocardial mitochondrial dysfunction by activating PI3K/AKT in SHR rats fed with fructose

To explore the effect of acacetin on myocardial mitochondrial dysfunction in spontaneously hypertensive rats (SHR) with insulin resistance (IR), and the possible mechanism. Rapid IR was first induced in fructose-fed SHR, and they were then treated with acacetin (25, 50 mg/kg). After 7 weeks, the rats were tested for hypertension, IR, cardiac function, and mitochondrial damage status. Potential mechanisms of action were explored in terms of oxidative stress, mitochondrial fission and division, apoptosis, and the insulin signaling pathway. Subsequently, the PI3K gene was silenced, after intervention with acacetin (5 μM) for 24 h, and H2O2 was used to stimulate H9c2 for 4 h, it was evaluated whether silencing PI3K would affect the therapeutic effect of acacetin. In SHR fed with fructose, acacetin can improve hypertension, IR, cardiac function (LVEF, LVFS), and mitochondrial damage (mitochondria number, ATP); inhibit oxidative stress (ROS, SOD, Nrf2, Keap1), mitochondrial fission (MFF, Drp1), and myocardial cell apoptosis (apoptosis rate, Bax, Bcl-2, cytochrome c); promote mitochondrial fusion (Mfn2) and activate insulin signaling pathways (PI3K/AKT). However, silencing PI3K inhibited the abovementioned effects of acacetin. In conclusion, acacetin improved myocardial mitochondrial dysfunction through regulating oxidative stress, mitochondrial fission and fusion, and mitochondrial pathway apoptosis mediated by PI3K/AKT signaling pathway in hypertensive rats with IR.

Acacetin alleviates myocardial ischaemia/reperfusion injury by inhibiting oxidative stress and apoptosis via the Nrf-2/HO-1 pathway

CONTEXT

Acacetin is a natural source of flavonoids with anti-inflammatory and antioxidant effects.

OBJECTIVE

This study determines acacetin's protective effect and mechanism on myocardial ischaemia/reperfusion (I/R) injury.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into sham and I/R injury and treatment with acacetin. Acacetin (10 mg/kg) was subcutaneously injected for 7 days. ECG and echocardiography were conducted to determine arrhythmia and heart function. The pathological characters of the heart were determined with triphenyl tetrazolium chloride staining, Haematoxylin & Eosin staining, and Masson staining. Expression of proteins in infarct tissues was examined with western blots.

RESULTS

Administrated with acacetin in I/R rats significantly reduced the arrhythmia score from 4.90 to 2.50 and the reperfusion arrhythmia score from 3.79 to 1.82 in the vehicle or the acacetin group, respectively. LVEF was improved from 33.5% in the I/R group to 43.7% in the acacetin group, LVFS was increased from 16.4% to 24.5%, LVIDs was decreased from 6.5 to 5.3 mm. The inflammatory cell infiltration, myocardial fibrosis, and collagen 1 and 3 were reduced by acacetin. Acacetin promoted SOD and decreased MDA. In myocardial tissues, the expression level of TLR4 and IL-6 were restrained, and IL-10 was promoted. Apoptotic protein Bax was suppressed, and anti-apoptotic protein Bcl-2 was promoted in the acacetin group. Interestingly, the transcription factor Nrf-2/HO-1 pathway was also reversed by acacetin.

DISCUSSION AND CONCLUSION

Our findings indicated that acacetin has a potential therapeutic effect in clinical application on treating I/R-induced heart injury.

Effects of Lycopene Attenuating Injuries in Ischemia and Reperfusion

Tissue and organ ischemia can lead to cell trauma, tissue necrosis, irreversible damage, and death. While intended to reverse ischemia, reperfusion can further aggravate an ischemic injury (ischemia-reperfusion injury, I/R injury) through a range of pathologic processes. An I/R injury to one organ can also harm other organs, leading to systemic multiorgan failure. A type of carotenoid, lycopene, has been shown to treat and prevent many diseases (e.g., rheumatoid arthritis, cancer, diabetes, osteoporosis, male infertility, neurodegenerative diseases, and cardiovascular disease), making it a hot research topic in health care. Some recent researches have suggested that lycopene can evidently ameliorate ischemic and I/R injuries to many organs, but few clinical studies are available. Therefore, it is essential to review the effects of lycopene on ischemic and I/R injuries to different organs, which may help further research into its potential clinical applications.

Role of Oxidative Stress in the Pathogenesis of Atherothrombotic Diseases

Oxidative stress is generated by the imbalance between reactive oxygen species (ROS) formation and antioxidant scavenger system’s activity. Increased ROS, such as superoxide anion, hydrogen peroxide, hydroxyl radical and peroxynitrite, likely contribute to the development and complications of atherosclerotic cardiovascular diseases (ASCVD). In genetically modified mouse models of atherosclerosis, the overexpression of ROS-generating enzymes and uncontrolled ROS formation appear to be associated with accelerated atherosclerosis. Conversely, the overexpression of ROS scavenger systems reduces or stabilizes atherosclerotic lesions, depending on the genetic background of the mouse model. In humans, higher levels of circulating biomarkers derived from the oxidation of lipids (8-epi-prostaglandin F_2α, and malondialdehyde), as well as proteins (oxidized low-density lipoprotein, nitrotyrosine, protein carbonyls, advanced glycation end-products), are increased in conditions of high cardiovascular risk or overt ASCVD, and some oxidation biomarkers have been reported as independent predictors of ASCVD in large observational cohorts. In animal models, antioxidant supplementation with melatonin, resveratrol, Vitamin E, stevioside, acacetin and n-polyunsaturated fatty acids reduced ROS and attenuated atherosclerotic lesions. However, in humans, evidence from large, placebo-controlled, randomized trials or prospective studies failed to show any athero-protective effect of antioxidant supplementation with different compounds in different CV settings. However, the chronic consumption of diets known to be rich in antioxidant compounds (e.g., Mediterranean and high-fish diet), has shown to reduce ASCVD over decades. Future studies are needed to fill the gap between the data and targets derived from studies in animals and their pathogenetic and therapeutic significance in human ASCVD.

Metabolites Analysis of Anti-Myocardial Ischemia Active Components of Saussurea involucrata Based on Gut Microbiota-Drug Interaction

Saussurea involucrata has been reported to have potential therapeutic effects against myocardial ischemia. The pharmacological effects of oral natural medicines may be influenced by the participation of gut microbiota. In this study, we aimed to investigate the bidirectional regulation of gut microbiota and the main components of Saussurea involucrata. We first established a quantitative method for the four main components (chlorogenic acid, syringin, acanthoside B, rutin) which were chosen by fingerprint using liquid chromatography tandem mass spectrometry (LC-MS/MS), and found that gut microbiota has a strong metabolic effect on them. Meanwhile, we identified five major rat gut microbiota metabolites (M1-M5) using liquid chromatography tandem time-of-flight mass spectrometry (LC/MSⁿ-IT-TOF). The metabolic properties of metabolites in vitro were preliminarily elucidated by LC-MS/MS for the first time. These five metabolites of Saussurea involucrata may all have potential contributions to the treatment of myocardial ischemia. Furthermore, the four main components (10 μg/mL) can significantly stimulate intestinal bacteria to produce short chain fatty acids in vitro, respectively, which can further contribute to the effect in myocardial ischemia. In this study, the therapeutic effect against myocardial ischemia of Saussurea involucrata was first reported to be related to the intestinal flora, which can be useful in understanding the effective substances of Saussurea involucrata.

Acacetin attenuates diabetes-induced cardiomyopathy by inhibiting oxidative stress and energy metabolism via PPAR-α/AMPK pathway

Diabetic cardiomyopathy seriously affects the life quality of diabetic patients and can lead to heart failure and death in severe cases. Acacetin was reported to be an anti-oxidant and anti-inflammatory agent in several cardiovascular diseases. However, the effect of acacetin on diabetic cardiomyopathy was not understood. This study was designed to explore the therapeutic effect of acacetin on diabetic cardiomyopathy and the potential mechanism with in vitro and in vivo experimental techniques. In cultured neonatal rat cardiomyocytes and H9C2 cardiac cells, acacetin (0.3, 1, 3 μM) showed effective protection against high glucose-induced injury in a concentration-dependent manner. Acacetin countered high glucose-induced increase of Bax and decrease of Bcl-2, SOD1, and SOD2. In streptozotocin-induced rat diabetic cardiomyopathy model, treatment with acacetin prodrug (10 mg/kg, s.c., b.i.d.) significantly improved the cardiac function and reduced myocardial injury, and reversed the increase of serum MDA, Ang Ⅱ, and IL-6 levels and myocardial Bax and IL-6, and the decrease of serum SOD, indicating that acacetin plays a cardioprotective effect by inhibiting oxidative stress, inflammation, and apoptosis. In addition, both in vitro and in vivo experimental results showed that acacetin increased the expression of PPAR-α and pAMPK, indicating that PPAR-α and pAMPK are potential targets of acacetin for the protection against diabetic cardiomyopathy. This study demonstrates the new application of acacetin for treating diabetic cardiomyopathy.

Acacetin as a Potential Protective Compound against Cardiovascular Diseases

Acacetin (5,7-dihydroxy-4′-methoxyflavone) is the major bioactive component of the traditional Chinese medicine “Snow lotus”. As a natural flavonoid compound, it has been shown to have good pharmacological effects such as anti-inflammatory, anticancer, and anti-obesity. Among them, its prominent role in cardiovascular diseases (CVD) has received extensive attention from scholars in recent years. In this review, the protective effects of acacetin on a variety of cardiovascular diseases, as well as the existing problems and prospects, are discussed and summarized. This review also highlights the great potential of acacetin, a natural-derived Chinese medicine, as a cardiovascular agent candidate.

Acacetin ameliorates cardiac hypertrophy by activating Sirt1/AMPK/PGC-1α pathway

Cardiac hypertrophy is a major risk factor for developing heart failure. This study investigates the effects of the natural flavone acacetin on myocardial hypertrophy in cellular level and whole animals. In cardiomyocytes from neonatal rat with hypertrophy induced by angiotensin II (Ang II), acacetin at 0.3, 1, and 3 μM reduced the increased myocyte surface area, brain natriuretic peptide (BNP), and ROS production by upregulating anti-oxidative molecules (i.e. Nrf2, SOD1, SOD2, HO-1), anti-apoptotic protein Bcl-2, and downregulating the pro-apoptotic protein Bax and the inflammatory cytokine IL-6 in a concentration-dependent manner. In addition, acacetin rescued Ang II-induced impairment of PGC-1α, PPARα and pAMPK. These beneficial effects of acacetin were mediated by activation of Sirt1, which was confirmed in cardiac hypertrophy induced by abdominal aorta constriction (AAC) in SD rats. Acacetin prodrug (10 mg/kg, s.c., b.i.d.) treatment reduced the elevated artery blood pressure, improved the increased heart size and thickness of left ventricular wall and the ventricular fibrosis associated with inhibiting myocardial fibrosis and BNP, and reversed the impaired protective signal molecules including PGC-1α, Nrf2, PPARα, pAMPK and Sirt1 of left ventricular tissue. Our results demonstrate the novel pharmacological effect that acacetin ameliorates cardiac hypertrophy via Sirt1-mediated activation of AMPK/PGC-1α signal molecules followed by reducing oxidation, inflammation and apoptosis.

DL-3-n-butylphthalide protects H9c2 cardiomyoblasts from ischemia/reperfusion injury by regulating HSP70 expression via PI3K/AKT pathway activation

DL-3-n-butylphthalide (NBP) is commonly used to treat ischemic strokes due to its antioxidative and anti-inflammatory effects. The present study aimed to examine the protective effects of NBP on myocardial ischemia-reperfusion injury (MIRI) by establishing a MIRI model in H9c2 cells. Cell viability assay using Cell Counting Kit-8, lactate dehydrogenase (LDH) cytotoxicity and lipid peroxidation malondialdehyde (MDA) content were assessed to detect cell activity, degree of cell injury and oxidative stress reaction. Reverse transcription-quantitative PCR was used to quantify the expression of inflammatory factors in H9c2 cells. Western blotting and immunofluorescence staining were used to detect the protein expression of PI3K/AKT and heat shock protein 70 (HSP70). The present results indicated that NBP significantly increased cell viability during ischemia-reperfusion. Moreover, NBP inhibited the release of LDH and the production of MDA. NBP treatment also significantly decreased the expression of inflammatory factors at the mRNA level. Additionally, NBP activated the PI3K/AKT pathway and upregulated the expression of HSP70 compared with cells in the MIRI model. LY294002, a PI3K inhibitor, reversed the protective effects of NBP and suppressed the expression of HSP70. The present study demonstrated that NBP protected H9c2 cells from MIRI by regulating HSP70 expression via PI3K/AKT pathway activation.

Acacetin Protects Myocardial Cells against Hypoxia-Reoxygenation Injury through Activation of Autophagy

Ischemic heart disease is a leading cause of mortality and morbidity worldwide. We previously demonstrated that acacetin protects against myocardial ischemia reperfusion injury in rats, although the underlying mechanism remains to be elucidated. In the present study, we investigated the effects of acacetin on autophagy during hypoxia/reoxygenation (H/R) injury by exposing H9c2 myocardial cells to H/R with or without acacetin pretreatment during hypoxia. Our results show that acacetin significantly increased cell viability in a dose-dependent manner, enhanced antioxidant capacity, and suppressed protein apoptosis of rat cardiomyocytes H9c2 cells following H/R injury. In addition, lentiviral infection of H9c2 cardiomyocytes revealed that acacetin pretreatment significantly enhanced the fluorescence intensity of autophagy proteins Beclin 1, LC3-II, and p62. These results indicate that acacetin protected H9c2 cardiomyocytes from H/R damage by enhancing autophagy. Moreover, we found that application of acacetin increased activation of the PI3K/Akt signaling pathway, whereas cotreatment with the PI3K inhibitor LY294002 reversed the inhibition of apoptosis and autophagy induced by acacetin. In conclusion, acacetin mitigated H/R injury by promoting autophagy through activating the PI3K/Akt/mTOR signaling pathway.

Cardiac senescence is alleviated by the natural flavone acacetin via enhancing mitophagy

Cardiac senescence is associated with cardiomyopathy which is a degenerative disease in the aging process of the elderly. The present study investigates using multiple experimental approaches whether the natural flavone acacetin could attenuate myocardial senescence in C57/BL6 mice and H9C2 rat cardiac cells induced by D-galactose. We found that the impaired heart function in D-galactose-induced accelerated aging mice was improved by oral acacetin treatment in a dose-dependent manner. Acacetin significantly countered the increased serum advanced glycation end products, the myocardial telomere length shortening, the increased cellular senescence marker proteins p21 and p53, and the reduced mitophagy signaling proteins PINK1/Parkin and Sirt6 expression in aging mice. In H9C2 rat cardiac cells, acacetin alleviated cell senescence induced by D-galactose in a concentration-dependent manner. Acacetin decreased p21 and p53 expression, up-regulated PINK1/Parkin, LC3II/LC3I ratio, pLKB1, pAMPK and Sirt6, and reversed the depolarized mitochondrial membrane potential in aging cardiac cells. Mitophagy inhibition with 3-methyladenine or silencing Sirt6 abolished the protective effects of acacetin against cardiac senescence. Further analysis revealed that acacetin effect on Sirt6 was mediated by Sirt1 activation and increase of NAD+/NADH ratio. These results demonstrate that acacetin significantly inhibits in vivo and in vitro cardiac senescence induced by D-galactose via Sirt1-mediated activation of Sirt6/AMPK signaling pathway, thereby enhancing mitophagy and preserving mitochondrial function, which suggests that acacetin may be a drug candidate for treating cardiovascular disorders related to aging.

Role of Oxidative Stress in Reperfusion following Myocardial Ischemia and Its Treatments

Myocardial ischemia is a disease with high morbidity and mortality, for which reperfusion is currently the standard intervention. However, the reperfusion may lead to further myocardial damage, known as myocardial ischemia/reperfusion injury (MI/RI). Oxidative stress is one of the most important pathological mechanisms in reperfusion injury, which causes apoptosis, autophagy, inflammation, and some other damage in cardiomyocytes through multiple pathways, thus causing irreversible cardiomyocyte damage and cardiac dysfunction. This article reviews the pathological mechanisms of oxidative stress involved in reperfusion injury and the interventions for different pathways and targets, so as to form systematic treatments for oxidative stress-induced myocardial reperfusion injury and make up for the lack of monotherapy.

Acacetin Protects Against High Glucose-Induced Endothelial Cells Injury by Preserving Mitochondrial Function via Activating Sirt1/Sirt3/AMPK Signals

The strategy of decreasing atherosclerotic cardiovascular disorder is imperative for reducing premature death and improving quality of life in patients with diabetes mellitus. The aim of this study was to investigate whether the natural flavone acacetin could protect against endothelial injury induced by high glucose and attenuate diabetes-accelerated atherosclerosis in streptozotocin-(STZ) induced diabetic ApoE^−/− mice model. It was found that in human umbilical vein endothelial cells (HUVECs) cultured with normal 5.5 mM or high 33 mM glucose, acacetin (0.3–3 μM) exerted strong cytoprotective effects by reversing high glucose-induced viability reduction and reducing apoptosis and excess production of intracellular reactive oxygen species (ROS) and malondialdehyde in a concentration-dependent manner. Acacetin countered high glucose-induced depolarization of mitochondrial membrane potential and reduction of ATP product and mitoBcl-2/mitoBax ratio. Silencing Sirt3 abolished the beneficial effects of acacetin. Further analysis revealed that these effects of acacetin rely on Sirt1 activation by increasing NAD⁺ followed by increasing Sirt3, pAMPK and PGC-1α. In STZ-diabetic mice, acacetin significantly upregulated the decreased signaling molecules (i.e. SOD, Bcl-2, PGC-1α, pAMPK, Sirt3 and Sirt1) in aorta tissue and attenuated atherosclerosis. These results indicate that vascular endothelial protection of acacetin by activating Sirt1/Sirt3/AMPK signals is likely involved in alleviating diabetes-accelerated atherosclerosis by preserving mitochondrial function, which suggests that acacetin may be a drug candidate for treating cardiovascular disorder in patients with diabetes.

Acacetin exerts antioxidant potential against atherosclerosis through Nrf2 pathway in apoE-/- Mice

Oxidative stress has a considerable influence on endothelial cell dysfunction and atherosclerosis. Acacetin, an anti-inflammatory and antiarrhythmic, is frequently used in the treatment of myocarditis, albeit its role in managing atherosclerosis is currently unclear. Thus, we evaluated the regulatory effects of acacetin in maintaining endothelial cell function and further investigated whether the flavonoid could attenuate atherosclerosis in apolipoprotein E deficiency (apoE^-/- ) mice. Different concentrations of acacetin were tested on EA.hy926 cells, either induced or non-induced by human oxidized low-density lipoprotein (oxLDL), to clarify its influence on cell viability, cellular reactive oxidative stress (ROS) level, apoptotic ratios and other regulatory effects. In vivo, apoE^-/- mice were fed either a Western diet or a chow diet. Acacetin pro-drug (15 mg/kg) was injected subcutaneously two times a day for 12 weeks. The effects of acacetin on the atherosclerotic process, plasma inflammatory factors and lipid metabolism were also investigated. Acacetin significantly increased EA.hy926 cell viability by reducing the ratios of apoptotic and necrotic cells at 3 μmol/L. Moreover, 3 μmol/L acacetin clearly decreased ROS levels and enhanced reductase protein expression through MsrA and Nrf2 pathway through phosphorylation of Nrf2 and degradation of Keap1. In vivo, acacetin treatment remarkably attenuated atherosclerosis by increasing reductase levels in circulation and aortic roots, decreasing plasma inflammatory factor levels as well as accelerating lipid metabolism in Western diet-fed apoE^-/- mice. Our findings demonstrate the anti-oxidative and anti-atherosclerotic effects of acacetin, in turn suggesting its potential therapeutic value in atherosclerotic-related cardiovascular diseases (CVD).

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.

Acacetin Suppresses IL-1β-Induced Expression of Matrix Metalloproteinases in Chondrocytes and Protects against Osteoarthritis in a Mouse Model by Inhibiting NF-κB Signaling Pathways

Osteoarthritis (OA) is a very common chronic joint dysfunction, and there is currently a poor understanding of its etiology and pathogenesis. Therefore, there are no active disease-modifying drugs currently available for clinical treatment. Several natural compounds have been shown to play a role in inhibiting OA progression. The present study is aimed at investigating the curative effects of acacetin, a natural flavonoid compound, against OA. Our results demonstrated that MMP-1, MMP-3, and MMP-13 were highly expressed in OA specimens. Acacetin inhibited the interleukin-1β- (IL-1β-) induced expression of MMP-1, MMP-3, and MMP-13in chondrocytes by blocking nuclear factor-κB (NF-κB) signaling pathways. Furthermore, we found that acacetin suppressed OA progression and inhibited the expression of MMP-1, MMP-3, and MMP-13 in ACLT-induced OA mice. Taken together, our study revealed that acacetin may serve as a potential drug for treating OA.

Doxorubicin cardiomyopathy is ameliorated by acacetin via Sirt1-mediated activation of AMPK/Nrf2 signal molecules

Doxorubicin cardiotoxicity is frequently reported in patients undergoing chemotherapy. The present study investigates whether cardiomyopathy induced by doxorubicin can be improved by the natural flavone acacetin in a mouse model and uncovers the potential molecular mechanism using cultured rat cardiomyoblasts. It was found that the cardiac dysfunction and myocardial fibrosis induced by doxorubicin were significantly improved by acacetin in mice with impaired Nrf2/HO‐1 and Sirt1/pAMPK molecules, which is reversed by acacetin treatment. Doxorubicin decreased cell viability and increased ROS production in rat cardiomyoblasts; these effects are significantly countered by acacetin (0.3‐3 μM) in a concentration‐dependent manner via activating Sirt1/pAMPK signals and enhancing antioxidation (Nrf2/HO‐1 and SOD1/SOD2) and anti‐apoptosis. These protective effects were abolished in cells with silencing Sirt1. The results demonstrate for the first time that doxorubicin cardiotoxicity is antagonized by acacetin via Sirt1‐mediated activation of AMPK/Nrf2 signal molecules, indicating that acacetin may be a drug candidate used clinically for protecting against doxorubicin cardiomyopathy.

Carthamin Yellow Protects the Heart Against Ischemia/Reperfusion Injury With Reduced Reactive Oxygen Species Release and Inflammatory Response

Carthamin yellow (CY) is a flavonoid compound isolated from safflower, which is widely used clinically in China. It has various pharmacological effects including promoting blood circulation to remove blood stasis and alleviating pain. Ischemic heart disease is one of the main culprits of illness and death. Here, in this study, ex vivo and in vivo models were used to investigate whether CY reduces ischemia/reperfusion injury. In vitro experiments further verify and explain the potential mechanisms of CY cardioprotective function. Isolated hearts from male rats with or without CY pretreatment before ischemia which underwent 30-minute ischemia followed by 60-minute reperfusion showed that CY pretreatment significantly reduced the infarct size and lactate dehydrogenase release. The in vivo experiments also indicated CY preadministration (i.v.) reduced infarct size and improved the heart function, which was impaired by myocardial ischemia/reperfusion injury. The in vitro model on myocardial cell also showed that CY reduced ischemia/reperfusion injury by reducing the lactate dehydrogenase and reactive oxygen species (ROS) releasing. Eliminating ROS with N-acetylcysteine or preinject CY into rat jugular vein reduces the expression of IL-6, TNF-a, and, especially, IL-1b in an in vivo I/R model. Also, CY pretreatment strongly reduces ischemia/reperfusion-induced NLRP3 up-expression and caspase-1 activation. Our results indicated CY reduced ischemia-reperfusion injury when administered before reperfusion. The reduction in injury is accompanied by a reduced ROS release and decreased inflammatory response.

Acacetin Attenuates Renal Damage-Induced by Ischemia-Reperfusion with Declining Apoptosis and Oxidative Stress in Mice

Background:

Renal ischemia-reperfusion disturbs both the function and the histology of this organ. Acacetin (Aca) is a natural flavonoid that is effective for relief of many diseases. The aim of this study was to determine the impacts of Aca on renal ischemia-reperfusion process in mice.

Methods:

In total, 84 male Balb/cmice divided into 12 groups and were administrated intraperitoneally for 4 days with or without surgery to dimethyl sulfoxide 0.01% or Aca (10, 25, and 50 mg/kg) as Control, control Acas, sham, sham Acas groups. Ischemia-reperfusion without or with Aca (10, 25, and 50 mg/kg) treatments were the other groups. Parameters related to the function and the histology of the kidneys were evaluated and statistically analyzed from kidney and blood serum samples in the respect of the groups.

Results:

In ischemia-reperfusion and ischemia-reperfusion + Aca (10 mg/kg) groups, there were significantly increased in urea, creatinine, malondialdehyde (MDA), and apoptosis rate, whereas total antioxidant capacity decreased compared to the control and sham and ischemia-reperfusion + Aca (25 and 50 mg/kg) (P < 0.05). The histopathology alteration was seen in the ischemia-reperfusion group than the others (P < 0.01). Moreover, there was a significant difference between ischemia-reperfusion + Aca (25 and50 mg/kg) groups than ischemia-reperfusion + Aca (10 mg/kg) one (P < 0.05).

Conclusions:

The recovery effect of Aca was offered on renal ischemia-reperfusion damage in a dose-dependent manner in mice, showing by kidney histopathology and functional criteria improvements. The attributed mechanism for this impression would be the antioxidant property of Aca, decreasing both MDA levels and apoptosis rate in kidney tissue.

Clemastine Fumarate Protects Against Myocardial Ischemia Reperfusion Injury by Activating the TLR4/PI3K/Akt Signaling Pathway

Our pilot studies have shown that clemastine fumarate (CLE) can protect against myocardial ischemia-reperfusion injury (MIRI) through regulation of toll like receptor 4 (TLR4). However, the protective mechanism of CLE and related signaling pathways for MIRI remains unclear. The objective of this study is to determine the mechanism by which CLE relieves MIRI in cardiomyocytes and its relationship with the TLR4/PI3K/Akt signaling pathway. CCK8 analysis was used to test the optimal concentration of TLR4 inhibitor CLI-095 and TLR4 agonist lipopolysaccharide (LPS) on MIRI. The expression of inflammatory factors, oxidative stress response, cell damage, and intracellular calcium redistribution of cardiomyocytes were examined using the ELISA kits, Total Superoxide Dismutase Assay Kit with WST-8 and Lipid Peroxidation MDA Assay Kit, LDH Cytotoxicity Assay Kit, and laser scanning confocal microscope. The expression of TLR4/PI3K/Akt and cleaved caspase-3 were determined by Western blotting and immunofluorescent staining. Our results showed that MIRI aggravated the inflammatory response, oxidative stress, cellular damage of cardiomyocytes, and caused redistribution of intracellular calcium, upregulated the expression of TLR4 protein, cleaved caspase-3 protein, and down-regulated the expression of PI3K/Akt protein. After treatment with CLE, the inflammatory response, oxidative stress, and cellular damage of cardiomyocytes were alleviated, and intracellular calcium ion accumulation decreased. The expression of TLR4 protein, cleaved caspase-3 protein declined, but PI3K/Akt protein expression increased in cardiomyocytes treated with CLE. In addition, after treatment with the TLR4 inhibitor CLI-095, the results were similar to those of CLE treatment. The TLR4 agonist LPS aggravated the reactions caused by MIRI. The role of LPS was reversed after CLE treatment. These results suggested that CLE can attenuate MIRI by activating the TLR4/PI3K/Akt signaling pathway.

Saussureae Involucratae Herba (Snow Lotus): Review of Chemical Compositions and Pharmacological Properties

Saussureae Involucratae Herba is the dried ground part of Saussurea involucrata (Kar. et Kir.) Sch.-Bip, which is also named as “Snow lotus” and being used in traditional Uyghur and/or Chinese medicine. This rare herb can be found at 4,000 m elevation in western part of Tianshan Mountain, Xinjiang China. According to China Pharmacopoeia (2015), the major pharmaceutical values of “Snow lotus” (Xuě liánhuā in Chinese) are alleviating rheumatoid arthritis, accelerating blood circulation and mitigating other “cold” syndromes. Traditionally, the clinical application of “Snow lotus” includes the treatments in inflammation-associated disorder, blood circulation acceleration and heat and dampness elimination. Recent studies suggested that “Snow lotus” possessed therapeutic effects associating with anti-cancer, anti-oxidation, adipogenesis suppression and neuroprotection activities, which were proposed to be related with its bioactive constitutes, i.e. acacetin, hispidulin, and rutin. In the present review, we aim to summarize pharmacological effects and underlying cell signaling pathways of “Snow lotus” in treating various medical problems.

Therapy for myocardial infarction: In vitro and in vivo evaluation of puerarin-prodrug and tanshinone co-loaded lipid nanoparticulate system

Myocardial infarction (MI) is the leading cause of morbidity and mortality worldwide. Nanoparticle systems carrying drugs have already been developed to treat MI. To improve the efficiency of tanshinone (TAN), and to achieve the synergistic effect of TAN and puerarin (PUE), PUE-prodrug and TAN co-loaded solid lipid nanoparticles (SLN) was structured and utilized for MI treatment in the present research. PUE-prodrug was synthesized by an esterification reaction. PUE-prodrug and TAN co-loaded SLN (PUEp/TAN-SLN) were prepared by a single emulsification followed by a solvent evaporation method. The physicochemical properties of SLN were characterized and the in vivo infarct therapy effects were evaluated in MI rats. PUE-prodrug and TAN contained SLN showed a size of 112.6 ± 3.1 nm. The SLN encapsulation reduced the cytotoxicity of drugs and was a safer system. PUEp-SLN exhibited a 1.7-fold increase in comparison to PUE-SLN (21.2 ± 2.1 versus 12.5 ± 1.5 mg/L), in the mean time a 3.4-fold increase compared with free PUE in heart drug concentration (21.2 ± 2.1 versus 6.3 ± 0.9 mg/L). In vivo infarct therapy efficiency of double drugs loaded PUEp/TAN-SLN (17 ± 1.9%) was significantly better than the single drug loaded PUEp-SLN (31 ± 1.6%) and TAN-SLN (40 ± 2.2%). PUE-prodrug contained, double drugs co-loaded SLN can be utilized as promising candidate delivery system for cardioprotective drugs in treatment of myocardial infarction.

The Natural Flavone Acacetin Confers Cardiomyocyte Protection Against Hypoxia/Reoxygenation Injury via AMPK-Mediated Activation of Nrf2 Signaling Pathway

The present study investigates the potential signal pathway of acacetin in cardioprotection against ischemia/reperfusion injury using an in vitro hypoxia/reoxygenation model in primary cultured neonatal rat cardiomyocytes and H9C2 cardiomyoblasts. It was found that acacetin (0.3–3 μM) significantly decreased the apoptosis and reactive oxygen species production induced by hypoxia/reoxygenation injury in cardiomyocytes and H9C2 cardiomyoblasts via reducing the pro-apoptotic proteins Bax and cleaved-caspase-3 and increasing the anti-apoptotic protein Bcl-2. In addition, acacetin not only suppressed the release of pro-inflammatory cytokines TLR-4 and IL-6 induced by hypoxia/reoxygenation injury, but also increased the secretion of anti-inflammatory cytokine IL-10. Moreover, acacetin increased Nrf2 and HO-1 in a concentration-dependent manner, and rescued SOD1 and SOD2 reduction induced by hypoxia/reoxygenation insult. These beneficial effects of acacetin disappeared in cells with silenced Nrf2, suggesting that Nrf2 activation participates in the cardioprotective effect of acacetin against hypoxia/reoxygenation insult. However, acacetin-induced Nrf2 activation was not observed in cells with silenced AMPK and in ventricular tissues of rat hearts treated with the AMPK inhibitor Compound C and subjected to ischemia/reperfusion injury. Our results demonstrate for the first time that AMPK-mediated Nrf2 activation is involved in the cardiomyocytes protection of acacetin against hypoxia/reoxygenation injury by activating a series of intracellular signals involved in anti-oxidation, anti-inflammation, and anti-apoptosis.

Acacetin protects against cardiac remodeling after myocardial infarction by mediating MAPK and PI3K/Akt signal pathway

Since inhibiting cardiac remodeling is a critical treatment goal after myocardial infarction (MI), many drugs have been evaluated for this purpose. Acacetin is a flavonoid compound that has been shown to have anti-cancer, anti-mutagenic, anti-inflammatory and anti-peroxidative effects. In this study, we investigated whether acacetin is able to exert a protective effect against MI. One week after anterior wall standard MI surgeries or sham surgeries were performed in mice, acacetin was administered via gavage for two weeks. The results of echocardiographic and hemodynamic evaluation revealed that cardiac dysfunction significantly improved after acacetin treatment. H&E staining indicated that the ratio of the infarct size and the cardiomyocyte cross-sectional area was decreased by acacetin. Masson's staining detected that the fibrotic area ratio was evidently lower in the acacetin-treated MI group. TUNEL assays showed that acacetin ameliorated cardiomyocyte apoptosis after MI. RT-qPCR analysis showed that levels of hypertrophic and fibrotic markers were significantly decreased after acacetin treatment. Western blot analysis of various signaling pathway proteins showed that acacetin targets the MAPK and PI3K/Akt signaling pathways. Collectively, acacetin improves mouse left ventricular function and attenuates cardiac remodeling by inhibiting of the MAPK and PI3K/Akt signaling pathway.

Acacetin attenuates mice endotoxin-induced acute lung injury via augmentation of heme oxygenase-1 activity

Acacetin, a natural product, has a wide spectrum of biological activities such as antioxidant properties. In the present study, we examined whether Acacetin has any beneficial role on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and, if so, whether its effect is mediated via heme oxygenase-1 (HO-1), an antioxidant enzyme playing an important role in ALI. Male BALB/c mice were stimulated with LPS intratracheal instillation to induce ALI. Acacetin was administrated 2 h after LPS challenge. Samples were harvested 10 h after LPS administration. We demonstrated that LPS challenge significantly induced lung histological alterations such as inflammation and edema. Acacetin administration notably attenuated these changes and reduced tumor necrosis factor-α and interleukin-1β in lung tissues. The LPS-induced reactive oxygen species generation was markedly suppressed by Acacetin. Furthermore, Acacetin treatment significantly elevated pulmonary HO-1 and nuclear factor erythroid-2-related factor 2 (Nrf2) activities. However, the beneficial action of Acacetin was markedly abolished when pretreated with zinc protoporphyrin, an inhibitor of HO-1. In in vitro studies, Acacetin notably increased the HO-1 expression in pulmonary microvascular endothelial cells. During knockdown of Nrf2 by siRNA, the effect of Acacetin on HO-1 expression was significantly reversed. Acacetin attenuates LPS-induced ALI in mice. This protective effect of Acacetin may be mediated, in part, through an HO-1-dependent pathway.

Acacetin from Traditionally Used Saussurea involucrata Kar. et Kir. Suppressed Adipogenesis in 3T3-L1 Adipocytes and Attenuated Lipid Accumulation in Obese Mice

Acacetin, a flavone that can be isolated from the Saussurea involucrata plant, has anti-tumor and anti-inflammatory properties that ameliorate airway hyperresponsiveness in asthmatic mice. This study investigated whether acacetin has anti-adipogenic effects in 3T3-L1 adipocytes and whether it regulates the inflammatory response in adipocytes and macrophages. It also investigated whether acacetin ameliorates lipid accumulation in high-fat diet- (HFD) induced obese mice. Differentiated 3T3-L1 cells were treated with acacetin. The glycerol levels in the culture medium were measured, and the expression of proteins and genes involved in adipogenesis and lipolysis were assayed by Western blot and real-time PCR, respectively. Inflammatory cytokine signaling pathway activity was assessed in macrophages that were treated with acacetin and cultured with differentiated medium from 3T3-L1 cells. Intraperitoneal injections of acacetin were administered to HFD-induced obese mice twice a week for 10 weeks. Acacetin significantly increased the levels of glycerol in the culture medium and significantly inhibited lipid accumulation in adipocytes. Acacetin reduced the expression of adipogenesis-related transcription factors, including the expression of the CCAAT/enhancer-binding protein; it also increased sirtuin 1 expression and AMPK phosphorylation in adipocytes. In macrophages cultured with differentiated media from 3T3-L1 adipocytes, acacetin reduced the levels of inflammatory mediators and the activity of the mitogen-activated protein kinase and NF-κB pathways. In obese mice, acacetin reduced both body weight and visceral adipose tissue weight. These results demonstrate that acacetin inhibited adipogenesis in adipocytes and in obese mice. Acacetin also reduced the inflammatory response of macrophages that were stimulated with differentiated media from 3T3-L1 cells.