Review on the protective mechanism of astragaloside IV against cardiovascular diseases

Cardiovascular disease is a global health problem. Astragaloside IV (AS-IV) is a saponin compound extracted from the roots of the Chinese herb Astragalus. Over the past few decades, AS-IV has been shown to possess various pharmacological properties. It can protect the myocardium through antioxidative stress, anti-inflammatory effects, regulation of calcium homeostasis, improvement of myocardial energy metabolism, anti-apoptosis, anti-cardiomyocyte hypertrophy, anti-myocardial fibrosis, regulation of myocardial autophagy, and improvement of myocardial microcirculation. AS-IV exerts protective effects on blood vessels. For example, it can protect vascular endothelial cells through antioxidative stress and anti-inflammatory pathways, relax blood vessels, stabilize atherosclerotic plaques, and inhibit the proliferation and migration of vascular smooth muscle cells. Thus, the bioavailability of AS-IV is low. Toxicology indicates that AS-IV is safe, but should be used cautiously in pregnant women. In this paper, we review the mechanisms of AS-IV prevention and treatment of cardiovascular diseases in recent years to provide a reference for future research and drug development.

Natural compounds regulate the PI3K/Akt/GSK3β pathway in myocardial ischemia-reperfusion injury

The PI3K/Akt/GSK3β pathway is crucial in regulating cardiomyocyte growth and survival. It has been shown that activation of this pathway alleviates the negative impact of ischemia-reperfusion. Glycogen synthase kinase-3 (GSK3β) induces apoptosis through stimulation of transcription factors, and its phosphorylation has been suggested as a new therapeutic target for myocardial ischemia-reperfusion injury (MIRI). GSK3β regulatory role is mediated by the reperfusion injury salvage kinase (RISK) pathway, and its inhibition by Akt activation blocks mitochondrial permeability transition pore (mPTP) opening and enhances myocardial survival. The present article discusses the involvement of the PI3K/Akt/GSK3β pathway in cardioprotective effects of natural products against MIRI.Abbreviations: Akt: protein kinase B; AMPK: AMP-activated protein kinase; ATP: adenosine triphosphate; Bad: bcl2-associated agonist of cell death; Bax: bcl2-associated x protein; Bcl-2: B-cell lymphoma 2; CK-MB: Creatine kinase-MB; CRP: C-reactive-protein; cTnI: cardiac troponin I; EGCG: Epigallocatechin-3-gallate; Enos: endothelial nitric oxide synthase; ER: endoplasmic reticulum; ERK ½: extracellular signal‑regulated protein kinase ½; GSK3β: glycogen synthase kinase-3; GSRd: Ginsenoside Rd; GSH: glutathione; GSSG: glutathione disulfide; HO-1: heme oxygenase-1; HR: hypoxia/reoxygenation; HSYA: Hydroxysafflor Yellow A; ICAM-1: Intercellular Adhesion Molecule 1; IKK-b: IκB kinase; IL: interleukin; IPoC: Ischemic postconditioning; IRI: ischemia-reperfusion injury; JNK: c-Jun N-terminal kinase; Keap1: kelch-like ECH-associated protein- 1; LDH: lactate dehydrogenase; LVEDP: left ventricular end diastolic pressure; LVP: left ventricle pressure; LVSP: left ventricular systolic pressure; MAPK: mitogen-activated protein kinase; MDA: malondialdehyde; MIRI: myocardial ischemia-reperfusion injury; MnSOD: manganese superoxide dismutase; mPTP: mitochondrial permeability transition pore; mtHKII: mitochondria-bound hexokinase II; Nrf-1: nuclear respiratory factor 1; Nrf2: nuclear factor erythroid 2-related factor; NO: nitric oxide; PGC-1α: peroxisome proliferator‑activated receptor γ coactivator‑1α; PI3K: phosphoinositide 3-kinases; RISK: reperfusion injury salvage kinase; ROS: reactive oxygen species; RSV: Resveratrol; SOD: superoxide dismutase; TFAM: transcription factor A mitochondrial; TNF-α: tumor necrosis factor-alpha; VEGF-B: vascular endothelial growth factor B.

Molecular Mechanism of Astragaloside IV in Improving Endothelial Dysfunction of Cardiovascular Diseases Mediated by Oxidative Stress

Endothelial dysfunction, induced by oxidative stress, is an essential factor affecting cardiovascular disease. Uncoupling of endothelial nitric oxide synthase (eNOS) leads to a decrease in nitric oxide (NO) production, an increase in reactive oxygen species (ROS) production, NO consumption, and NO synthesis. As a main active ingredient of astragalus, astragaloside IV can reduce the apoptosis of endothelial cells during oxidative stress. This review is aimed at exploring the mechanism of astragaloside IV in improving oxidative stress-mediated endothelial dysfunction relevant to cardiovascular diseases. The findings showed that the astragaloside IV can prevent or reverse the uncoupling of eNOS, increase eNOS and NO, and enhance several activating enzymes to activate the antioxidant system. In-depth validation and quantitative experiments still need to be implemented.

Therapeutic options of TCM for organ injuries associated with COVID-19 and the underlying mechanism

BACKGROUND

Coronavirus disease-2019 (COVID-19) caused by infection with severe acute respiratory coronavirus-2 (SARS-CoV-2) has been spreading rapidly throughout China and in other countries since the end of 2019. The World Health Organization (WHO) has declared that the epidemic is a public health emergency of international concerns. The timely and appropriate measures for treating COVID-19 in China, which are inseparable from the contribution of traditional Chinese medicine (TCM), have won much praise of the world.

PURPOSE

This review aimed to summarize and discuss the essential role of TCM in protecting tissues from injuries associated with COVID-19, and accordingly to clarify the possible action mechanisms of TCM from the perspectives of anti-inflammatory, antioxidant and anti-apoptotic effects.

METHODS

Electronic databases such as Pubmed, ResearchGate, Science Direct, Web of Science, medRixv and Wiley were used to search scientific literatures.

RESULTS

The present review found that traditional Chinese herbs commonly used for the clinical treatment of organ damages caused by COVID-19, such as Scutellaria baicalensis, Salvia miltiorrhizaSalvia miltiorrhiza, and ginseng, could act on multiple signaling pathways involved in inflammation, oxidative stress and apoptosis.

CONCLUSION

TCM could protect COVID-19 patients from tissue injuries, a protection that might be, at least partially, attributed to the anti-inflammatory, antioxidant and anti-apoptotic effects of the TCM under investigation. This review provides evidence and support for clinical treatment and novel drug research using TCM.

Phytochemistry and cardiovascular protective effects of Huang-Qi (Astragali Radix)

Huang-Qi (Astragali Radix) is an herbal tonic widely used in China and many other countries. It is derived from the roots of Astragalus membranaceus and A. membranaceus var. mongholicus and shows potent cardiovascular protective effects. In this article, we comprehensively reviewed 189 small molecules isolated from the two Astragalus species and discussed the interspecies chemical differences. Moreover, we summarized the pharmacological activities and mechanisms of action of Huang-Qi and its major bioactive compounds for the treatment of cardiovascular diseases. This review covers 171 references published between February 1983 and March 2020.

Astragaloside IV: An Effective Drug for the Treatment of Cardiovascular Diseases

Cardiovascular disease (CVD), the number one cause of death worldwide, has always been the focus of clinical and scientific research. Due to the high number of deaths each year, it is essential to find alternative therapies that are safe and effective with minimal side effects. Traditional Chinese medicine (TCM) has a long history of significant impact on the treatment of CVDs. The mode of action of natural active ingredients of drugs and the development of new drugs are currently hot topics in research on TCM. Astragalus membranaceus is a commonly used Chinese medicinal herb. Previous studies have shown that Astragalus membranaceus has anti-tumor properties and can regulate metabolism, enhance immunity, and strengthen the heart. Astragaloside IV (AS-IV) is the active ingredient of Astragalus membranaceus, which has a prominent role in cardiovascular diseases. AS-IV can protect against ischemic and hypoxic myocardial cell injury, inhibit myocardial hypertrophy and myocardial fibrosis, enhance myocardial contractility, improve diastolic dysfunction, alleviate vascular endothelial dysfunction, and promote angiogenesis. It can also regulate blood glucose and blood lipid levels and reduce the risk of cardiovascular diseases. In this paper, the mechanism of AS-IV intervention in cardiovascular diseases in recent years is reviewed in order to provide a reference for future research and new drug development.

Astragaloside IV regulates the HIF/VEGF/Notch signaling pathway through miRNA-210 to promote angiogenesis after ischemic stroke

BACKGROUND

Astragaloside IV (AS-IV) is one of the main active ingredients of Astragalusmembranaceus. Studies have shown that AS-IV stimulates angiogenesis, including cell proliferation, migration, and neovascularization. However, the relevant mechanism remains unclear.

OBJECTIVE

This study aims to investigate whether AS-IV activates the HIF/VEGF/Notch signaling pathway through miRNA-210 to promote angiogenesisafter ischemic stroke.

METHODS

The present study established a rat model of middle cerebral artery occlusion (MCAO) and cultured human umbilical vein endothelial cells (HUVECs) under hypoxic conditions in vitro to investigate the role of AS-IV in promoting angiogenesis and reveal its underlying mechanism. Through in vivo studies, the area of cerebral infarction was determined by 2,3,5-triPhenyltetrazolium chloride (TTC) staining. Immunofluorescence staining and RT-qPCR were used to detect the expression changes of miRNA-210 and ephrinA3 in the ischemic cortex after ischemia. Through in vitro studies, cell proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Subsequently, angiogenesis experiments were performed to observe the angiogenic ability.

RESULTS

Results revealed that AS-IV significantly reduced infarct size, promoted cell proliferation and ductal formation, and inhibited the expression of the target gene ephrinA3 by increasing the expression of miRNA-210 and inducing activation of the HIF-VEGF-Notch signaling pathway.

CONCLUSIONS

AS-IV promotes cerebral protection following angiogenesis and ischemic brain injury. The specific mechanism was activating the HIF/VEGF/Notch signaling pathway via miRNA-210.

Astragaloside IV Protects Against Oxidative Stress in Calf Small Intestine Epithelial Cells via NFE2L2-Antioxidant Response Element Signaling

Oxidative stress can damage intestinal epithelial cell integrity and function, causing gastrointestinal disorders. Astragaloside IV (ASIV) exhibits a variety of biological and pharmacological properties, including anti-inflammatory and antioxidant effects. The purpose of this research was to investigate the cytoprotective action of ASIV and its mechanisms in calf small intestine epithelial cells with hydrogen peroxide (H₂O₂)-induced oxidative stress. ASIV pretreatment not only increased cell survival, but it also decreased reactive oxygen species generation and apoptosis, enhanced superoxide dismutase, catalase, and glutathione peroxidase levels, and it reduced malondialdehyde formation. Furthermore, pretreatment with ASIV elevated the mRNA and protein levels of nuclear factor erythroid 2-related factor 2 (NFE2L2), heme oxygenase-1 (HMOX1), and NAD(P)H quinone dehydrogenase 1 (NQO1). The NFE2L2 inhibitor ML385 inhibited NFE2L2 expression and then blocked HMOX1 and NQO1 expression. These results demonstrate that ASIV treatment effectively protects against H₂O₂-induced oxidative damage in calf small intestine epithelial cells through the activation of the NFE2L2-antioxidant response element signaling pathway.

Astragaloside IV alleviates myocardial ischemia-reperfusion injury in rats through regulating PI3K/AKT/GSK-3β signaling pathways

Purpose:

To investigate the effect of astragaloside IV (As-IV) on myocardial ischemia-reperfusion (I/R) injury in rats and reltaed mechanisms.

Methods:

Sixty rats were randomly divided into sham-operated, control I/R and 2.5, 5 and 10 mg/kg As-IV groups, 12 rats in each group. The later three groups were intragastrically administered with As-IV for 7 days, with a dose of 2.5, 5 and 10 mg/kg, respectively. The myocardial I/R injury model was constructed in later four groups. At the end of reperfusion, the cardiac function indexes, serum lactate dehydrogenase (LDH) and creatine kinase (CK) levels, heart weight (HW)/body weight (BW) ratio and infarct size, and expressions of phosphatidylinositol-3 kinase/serine-threonine protein kinase (PI3K/AKT) and glycogen synthase kinase-3β (GSK-3β) proteins and the phosphorylated forms (p-AKT, p-GSK-3β) were determined.

Results:

Compared with control I/R group, in 5 and 10 mg/kg As-IV groups the left ventricular systolic pressure, fractional shortening and ejection fraction were increased, the left ventricular end-diastolic pressure was decreased, the serum LDH and CK levels were decreased, the HW/BW ratio and myocardial infarct size were decreased, and the p-Akt/Akt ratio and p-GSK-3β/GSK-3β ratio were increased (all P < 0.05).

Conclusion:

As-IV can alleviate the myocardial I/R injury in rats through regulating PI3K/AKT/GSK-3β signaling pathways.

The effects of Astragalus Membranaceus Active Extracts on Autophagy-related Diseases

Autophagy is an evolutionarily conserved 'self-eating' process that maintains cellular, tissue, and organismal homeostasis. New studies on autophagy, mediated by subsets of autophagy proteins, are emerging in many physiological and pathological processes. Astragalus membranaceus (AM), also named Huangqi, is one of the fundamental herbs in traditional Chinese medicine and its extracts have been proved to possess many biological activities related to autophagy, including anti-oxidation, anti-inflammation, anticancer, anti-photoaging, and improvement of cardiomyocyte function. Evidence suggests that AM extracts can have therapeutic potential in autophagy dysregulation-associated diseases because of their biological positive effects. Here we will review the literature concerning the effects of AM extracts on autophagy dysregulation-associated diseases.

Protective Effects of Astragaloside IV Combined with Budesonide in Bronchitis in Rats by Regulation of Nrf2/Keap1 Pathway

BACKGROUND This study was conducted to evaluate the effects of astragaloside IV and budesonide on bronchitis in rats and to explore the mechanism involved. MATERIAL AND METHODS Eighty Sprague-Dawley (SD) rats were randomly divided into 5 groups, including a Bronchitis model group (BM), a Budesonide group (BG), an Astragaloside IV group (AG), an Astragaloside IV combined with Budesonide group (CG), and a blank control group (BC). Lung tissue was stained with hematoxylin and eosin (H&E). The activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were detected by enzyme-linked immunosorbent assay (ELISA). The nuclear factor erythroid 2 [NF-E2]-related factor 2 (Nrf2), Kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1 (Keap1), BTB and CNC homology 1 (Bach1), B-cell lymphoma-2(Bcl-2), and BCl-2-associated X protein (Bax) mRNA and protein were examined by RT-PCR and Western blot, respectively. RESULTS Compared with the Bronchitis model group, the lung tissue lesions in the Budesonide group, Astragaloside IV group, and Astragaloside IV combined with Budesonide group were effectively ameliorated and the airway resistance was significantly decreased. The activities of SOD, GSH-Px, and CAT were increased after treatment with drugs, while the content of MDA was decreased. The levels of Nrf2, Keap1, and Bcl-2 proteins were increased and the levels of Bach1 and Bax were decreased after treatment with Budesonide and Astragaloside IV. CONCLUSIONS Astragaloside IV combined with budesonide can ameliorate the lesions caused by bronchitis in rats through activating the Nrf2/Keap1 pathway, which plays a protective role on anti-oxidative stress injury.

Protective effects of astragaloside IV against hypoxic pulmonary hypertension

The present study aimed to evaluate the protective effects of astragaloside IV (As-IV) against hypoxic pulmonary hypertension (HPH) and its mechanisms of action. Sprague-Dawley rats were used in a model of HPH induced by chronic hypoxia. After hypoxia, the mean pulmonary arterial pressure (mPAP), right ventricular pressure (RVP), and right ventricular hypertrophy index (RVHI) were monitored. Relaxation of the pulmonary artery in response to As-IV was measured. The levels of endothelin-1 (ET-1), angiotensin II (Ang II), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in serum were assessed. Cell proliferation was detected by the cell counting kit-8 (CCK-8) assay. Treatment with As-IV significantly decreased mPAP, RVP and RV/(LV + S) and attenuated the development of HPH. Moreover, As-IV time-dependently relaxed the pulmonary arteries from HPH rats. In addition, As-IV decreased the levels of ET-1, Ang II, TNF-α, and IL-6 in serum of HPH rats. In vitro experiments demonstrated that As-IV also significantly inhibited the proliferation of pulmonary artery smooth muscle cells (PASMCs) subjected to hypoxia. Our findings suggested the therapeutic potential of As-IV in the treatment of pulmonary hypertension.

Effect of astragaloside IV on indoxyl sulfate-induced kidney injury in mice via attenuation of oxidative stress

Background

Astragalus membranaceus, a traditional Chinese medicine (TCM), has been widely used in the treatment of chronic kidney disease (CKD) in China. Astragaloside IV is one of the major compounds of Astragalus membranaceus. Recent research has shown that astragaloside IV demonstrates pharmacological effects, such as anti-inflammatory, anti-fibrotic and anti-oxidative stress activities. Our aim was to investigate the effects of astragaloside IV on indoxyl sulfate (IS)-induced kidney injury in vivo, and to study the underlying mechanism.

Methods

Forty C57BL/6 mice with ½ nephrectomy were divided into four groups: control group (n = 10), IS group (n = 10), IS plus 10 mg/kg of astragaloside IV group (n = 10) and IS plus 20 mg/kg of astragaloside IV group (n = 10). IS intraperitoneal injection and astragaloside IV treatment were administered continuously for 1 month. Next, the blood urea nitrogen (BUN) level, serum IS level, tubulointerstitial injury, renal oxidative stress and inflammatory injury were assessed.

Results

The IS intraperitoneal injection mouse group showed increasing levels of serum IS, BUN, tubulointerstitial injury, renal oxidative stress and inflammatory injury. Astragaloside IV treatment couldn’t reduce the serum IS level or renal nuclear factor-κB and interleukin-1β levels. However, 20 mg/kg astragaloside IV treatment reduced the BUN level and significantly attenuated IS-induced tubulointerstitial injury. Renal oxidative stress was decreased by the administration of astragaloside IV.

Conclusions

These results suggest that astragaloside IV prevents IS-induced tubulointerstitial injury by ameliorating oxidative stress and may be a promising agent for the treatment of uremia toxin-induced injury.

Electronic supplementary material

The online version of this article (10.1186/s40360-018-0241-2) contains supplementary material, which is available to authorized users.

Vascular protective effects of Astragalus membranaceus and its main constituents in rats with chronic hyperhomocysteinemia

Hyperhomocysteinemia (HHcy) is an important factor in cardiovascular disease. However, is currently no cure available in western medicine for HHcy-evoked cardiovascular disease. The present study explored the vascular protective effects of Astragalus membranaceus (AM), a traditional Chinese medicine. Rats with HHcy were induced by feeding high-methionine diets and treated with total extract of AM (TEA) and its constituents, including Astragalus saponins (ASP), Astragalus total flavonoids (ATF) and Astragalus polysaccharides (APS). Examination of the rats indicated that TEA and ASP controlled blood pressure and ameliorated HHcy-induced impairment of endothelium-dependent vasorelaxation by increasing the nitric oxide content and nitric oxide synthase activity of the abdominal aorta. Furthermore, they decreased the accumulation of hydrogen peroxide and superoxide anion, and attenuated the inhibition of superoxide dismutase and catalase activities in rats with HHcy. Additionally, TEA and ASP attenuated the HHcy-induced increases of matrix metalloproteinase (MMP)-2 and -9 concentrations. However, similar effects were not observed for ATF and APS. In conclusion, TEA and ASP are beneficial to vascular disease, and their effects may be attributed to protective actions against oxidation, activity of the MMPs and endothelial dysfunction.

Research review on the pharmacological effects of astragaloside IV

Astragalus membranaceus Bunge has been used to treat numerous diseases for thousands of years. As the main active substance of Astragalus membranaceus Bunge, astragaloside IV (AS-IV) also demonstrates the potent protective effect on focal cerebral ischemia/reperfusion, cardiovascular disease, pulmonary disease, liver fibrosis, and diabetic nephropathy. Based on studies published during the past several decades, the current state of AS-IV research and the pharmacological effects are detailed, elucidated, and summarized. This review systematically summarizes the pharmacological effects, metabolism mechanism, and the toxicity of AS-IV. AS-IV has multiple pharmacologic effects, including anti-inflammatory, antifibrotic, antioxidative stress, anti-asthma, antidiabetes, immunoregulation, and cardioprotective effect via numerous signaling pathways. According to the existing studies and clinical practices, AS-IV possesses potential for broad application in many diseases.

Effects of fisetin on hyperhomocysteinemia-induced experimental endothelial dysfunction and vascular dementia

This study was designed to investigate the effects of fisetin (FST) on hyperhomocysteinemia (HHcy)-induced experimental endothelial dysfunction (ED) and vascular dementia (VaD) in rats. Wistar rats were randomly divided into 8 groups: control, vehicle control, l-methionine, FST (5, 10, and 25 mg/kg, p.o.), FST-per se (25 mg/kg, p.o.), and donepezil (0.1 mg/kg, p.o.). l-Methionine administration (1.7 g/kg, p.o.) for 32 days induced HHcy. ED and VaD induced by HHcy were determined by vascular reactivity measurements, behavioral analysis using Morris water maze and Y-maze, along with a biochemical and histological evaluation of thoracic aorta and brain tissues. Administration of l-methionine developed behavioral deficits; triggered brain lipid peroxidation (LPO); compromised brain acetylcholinesterase activity (AChE); and reduced the levels of brain superoxide dismutase (SOD), brain catalase (CAT), brain reduced glutathione (GSH), and serum nitrite; and increased serum homocysteine and cholesterol levels. These effects were accompanied by decreased vascular NO bioavailability, marked intimal thickening of the aorta, and multiple necrotic foci in brain cortex. HHcy-induced alterations in the activities of SOD, CAT, GSH, AChE, LPO, behavioral deficits, ED, and histological aberrations were significantly attenuated by treatment with fisetin in a dose-dependent manner. Collectively, our results indicate that fisetin exerts endothelial and neuroprotective effects against HHcy-induced ED and VaD.

IN VIVO AND IN VITRO IMMUNOMODULATORY AND ANTI-INFLAMMATORY EFFECTS OF TOTAL FLAVONOIDS OF ASTRAGALUS

Background:

Astragali Radix has long been used to improve immune function in traditional Chinese medicine. However, its main active components and potential immunomodulatory or anti-inflammatory activities have not been elucidated. In the present study, the immunomodulatory and anti-inflammatory activities of total flavonoids of Astragalus (TFA) isolated from Astragali Radix were evaluated by using in vivo animal models and in vitro cell models.

Materials and Methods:

The in vivo Immunomodulatory and anti-inflammatory activities of TFA were assessed by measuring macrophage phagocytic index, delayed type hypersensitivity, serum hemolysin level and immune organ index in mice, ear edema test in mice, paw edema test in rats, vascular permeability test in mice and granuloma test in rats. The in vitro Immunomodulatory and anti-inflammatory activities of TFA were assessed by examining its effect on cytokine and mediator production in un-stimulated and LPS-stimulated murine RAW 264.7 macrophages.

Results:

The results of in vivo experiments showed that TFA enhanced macrophage phagocytic index, delayed type hypersensitivity, serum hemolysin level and immune organ index in mice, and attenuated mouse ear edema, rat paw edema, mouse vascular permeability and rat granuloma formation. The results of in vitro experiments showed that TFA stimulated the production of NO and cytokine TNF-α, IL-Ιβ, IL-6 and IFN-γ in un-stimulated RAW 264.7 macrophages, and inhibited the overproduction of these inflammatory mediators in LPS-stimulated RAW 264.7 macrophages in a dose-dependent manner without exerting cytotoxicity.

Conclusion:

These results of this study indicate that TFA have potential immunostimulatory and anti-inflammatory effects.

Pretreatment with Astragaloside IV protects human umbilical vein endothelial cells from hydrogen peroxide induced oxidative stress and cell dysfunction via inhibiting eNOS uncoupling and NADPH oxidase - ROS - NF-κB pathway

Endothelial cell injury caused by reactive oxygen species (ROS) plays a critical role in the pathogenesis of cardiovascular disorders. Astragaloside IV (AsIV) possesses potent antioxidant properties against oxidative stress through undefined mechanism(s). We sought to investigate whether AsIV protects human umbilical vein endothelial cells (HUVECs) from hydrogen peroxide (H₂O₂) induced oxidative stress focusing on eNOS uncoupling and the NADPH oxidase - ROS - NF-κB pathway. Compared with HUVECs incubated with H₂O₂ alone, pretreatment with AsIV significantly increased the viability of HUVECs, which was accompanied with apparent increase in nitric oxide (NO) production and decrease in intracellular superoxide anion production. Furthermore, pretreatment with AsIV increased endothelial nitric oxide synthase (eNOS) dimer/monomer ratio and its critical cofactor tetrahydrobiopterin (BH₄) content, decreased Nox4 protein expression (the most abundant Nox isoform in HUVECs), inhibited translocation of NF-κB p65 subunit into nuclear fraction while enhanced the protein expression of IκB-α (the inhibitor of NF-κB p65), reduced the levels of IL-1β, IL-6, and TNF-α in HUVECs medium, and decreased iNOS protein expression. These results suggest that AsIV may protect HUVECs from H₂O₂-induced oxidative stress via inhibiting NADPH oxidase - ROS - NF-κB pathway and eNOS uncoupling.

Effect of Astragaloside IV on Neural Stem Cell Transplantation in Alzheimer's Disease Rat Models

Stem cell-based therapy is a promising treatment strategy for neurodegenerative diseases such as Alzheimer's disease (AD). However, the mechanism underlying the maintenance of renewal and replacement capabilities of endogenous progenitor cells or engrafted stem cells in a pathological environment remains elusive. To investigate the effect of astragaloside IV (ASI) on the proliferation and differentiation of the engrafted neural stem cells (NSCs), we cultured NSCs from the hippocampus of E14 rat embryos, treated the cells with ASI, and then transplanted the cells into the hippocampus of rat AD models. In vitro experimentation showed that 10⁻⁵ M ASI induced NSCs to differentiate into β-tubulin III⁺ and GFAP⁺ cells. NSCs transplantation into rat AD models resulted in improvements in learning and memory, especially in the ASI-treated groups. ASI treatment resulted in an increase in the number of β-tubulin III⁺ cells in the hippocampus. Further investigation showed that ASI inhibited PS1 expression in vitro and in vivo. The high-dose ASI downregulated the Notch intracellular domain, whereas the low-dose ASI increased Notch-1 and NICD. In conclusion, ASI treatment resulted in improvements in learning and memory of AD models by promoting NSC proliferation and differentiation partly through the Notch signal pathway.

Astragaloside IV improves the isoproterenol-induced vascular dysfunction via attenuating eNOS uncoupling-mediated oxidative stress and inhibiting ROS-NF-κB pathways

OBJECTIVE

Oxidative stress and inflammation are regarded as two important triggers of endothelial dysfunction and play pivotal role in progression of vascular damage associated with cardiac hypertrophy. Our previous studies demonstrated that astragaloside IV (AsIV) could protect against cardiac hypertrophy in rats induced by isoproterenol (Iso), but its effects on the aorta are not known. In present study, we aimed to assess the effects of AsIV on Isoinduced vascular dysfunction.

METHODS

Sprague-Dawley (SD) rats were treated with Iso (10mg/kg/d) alone or in combination with AsIV (50mg/kg/d).

RESULTS

Compared with Isotreated alone, AsIV significantly reduced the ratios of heart weight/body weight and left ventricular weight/body weight. AsIV ameliorated the increased vasoconstriction response to phenylephrine induced by Iso and suppressed superoxide anion generation in rat aorta, increased endothelial nitric oxide synthase (eNOS) dimer/monomer ratio and its critical cofactor tetrahydrobiopterin (BH4) content in aorta as well as the NO production in the serum, reduced the plasmatic peroxynitrite (ONOO-). Moreover, in contrast with Isotreatment alone, AsIV decreased the ratio of nuclear-to-cytosolic protein expression of the NF-κB p65 subunit while enhanced its inhibited protein expression of IκB-α, down-regulated mRNA expression of IL-1β, IL-6 and TNF-α of the aorta.

CONCLUSIONS

The present study suggested that AsIV protects against Isoinduced vascular dysfunction probably via attenuating eNOS uncoupling-mediated oxidative stress and inhibiting ROS-NF-κB pathways.

Gastroprotective Effects of Astragaloside IV against Acute Gastric Lesion in Rats

Background

Protection of the gastric mucosa from acute lesions induced by various irritants is a pertinent issue in the field of critical care medicine. In this study, we investigated the gastroprotective effects of astragaloside IV on acute gastric lesions in rats under stressful conditions.

Methods

Rats were randomized into six groups. Group 1 and 2 received 10% Tween 80 (vehicle). Group 3 received 20 mg/kg of omeprazole, a proton pump inhibitor. Groups 4, 5 and 6 received astragaloside IV at concentration of 1, 10, and 50 mg/kg, respectively. As a means to induce gastric lesions, Groups 2–6 were subjected to water immersion and restraint stress for 12 hours after treatment.

Results

Our present studies show that compared to rats in group 2, treatment with 1 to 50 mg/kg astragaloside IV significantly decreased the size of gastric lesions, MDA, TNFα and MCP1 levels, in addition to normalizing gastric pH, gastric mucus and SOD levels (P<0.05). Histomorphological examination confirmed that treatment with astragaloside IV elicited a dosage-dependent protective effect on the gastric mucosa. Furthermore, pretreatment with astragaloside IV resulted in significant elevations in HSP70 and reduction in Bax, along with over-expression of PLCγ response level, which was further confirmed via immunohistochemical analysis.

Conclusions

The acute gastric lesions induced are attenuated by pretreatment with astragaloside IV which is possibly due to the enhancing of the expression of HSP70 with concomitant antioxidant, anti-inflammatory and anti-apoptotic capacity.

Beneficial effects of astragaloside IV against angiotensin II-induced mitochondrial dysfunction in rat vascular smooth muscle cells

Angiotensin II (Ang II)-induced mitochondrial dysfunction is a prominent characteristic of the majority of cardiovascular diseases. Astragaloside IV (As-IV), the major active ingredient of Astragalus membranaceus (Fisch.) Bge. (a traditional Chinese herbal medicine), possesses antioxidant properties. The present study was carried out to examine whether As-IV can reverse Ang II-induced mitochondrial dysfunction in vascular smooth muscle cells (VSMCs) and to elucidate the underlying molecular mechanisms. Cultured rat aortic VSMCs treated with Ang II (1 µM) for 24 h exhibited mitochondrial dysfunction, including a decrease in mitochondrial oxygen consumption rates (OCRs), adenosine triphosphate (ATP) production and mitochondrial DNA (mtDNA) levels, as well as the disruption of mitochondrial structural integrity. Following treatment with Ang II, As-IV (50 µg/ml) was added to the culture medium followed by incubation for a further 24 h. The administration of As-IV significantly increased the mitochondrial OCRs, ATP production and the mtDNA levels, and reversed the mitochondrial morphological changes which occurred in the VSMCs. Treatment with As-IV also reversed the Ang II-induced increase in the production of reactive oxygen species (ROS), the increase in NADPH oxidase and xanthine oxidase activity, as well as the decrease in mitochondrial membrane potential (ΔΨm) and manganese superoxide dismutase (Mn-SOD) activity. Furthermore, treatment with As-IV led to an increase in the mRNA expression of peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and mitochondrial transcription factor A (Tfam), and in the protein expression of PGC-1α, parkin and dynamin 1-like protein 1 (Drp1) in the VSMCs. These results indicate that As-IV exerts beneficial effects on Ang II-induced mitochondrial dysfunction in rat VSMCs and that these effects are mediated through the inhibition of ROS overproduction, as well as the promotion of mitochondrial autophagy and mitochondrial biogenesis. These data demonstrate the antioxidant properties of As-IV.

The protective effect of astragaloside IV against benzo[a]pyrene induced endothelial progenitor cell dysfunction

AIMS

Benzo[a]pyrene (BaP), a prominent component of tobacco, has been revealed to induce damage to endothelial progenitor cells (EPCs). Astragaloside IV (AS-IV) is widely used for the treatment of cardiovascular diseases in China. In this study, we evaluated the effects of AS-IV on the function of human EPCs after BaP exposure and explored the underlying mechanism.

MATERIALS AND METHODS

Human umbilical cord blood mononuclear cells were isolated using density gradient centrifugation. Cells of the 4th passage were randomly divided into 6 groups. EPCs of experimental groups were pre-treated with different concentrations (2, 10 and 50 μg/mL) of AS-IV for 2h before exposure to BaP (20 μM) for 24h. The proliferation, migration, and adhesion of the treated EPCs were evaluated using a cell counting kit-8, Transwell assay and adhesion assay respectively. Interleukin-1β, tumor necrosis factor-α, malondialdehyde and SOD contents in the supernatant were evaluated. The expression of RAGE protein was measured by Western blotting.

KEY FINDINGS

The results demonstrated that AS-IV pre-treatment significantly improved BaP-induced dysfunction of EPCs in terms of proliferation, migration and adhesion. Furthermore, AS-IV reduced the production of reactive oxygen species, malondialdehyde, interleukin-1β and tumor necrosis factor-α of the BaP-treated EPCs. Finally AS-IV pre-treated EPCs showed an increased SOD activity and decreased RAGE protein expression.

SIGNIFICANCE

AS-IV is able to prevent BaP-mediated EPC dysfunction by at least inhibiting oxidative stress through the RAGE pathway.

Astragaloside IV and cycloastragenol are equally effective in inhibition of endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation in the endothelium

ETHNOPHARMACOLOGICAL RELEVANCE

Astragaloside IV and cycloastragenol are present together in Astragalus membranaceus Moench (Fabaceae) and this study aims to simultaneously investigate their regulation of endothelial homeostasis in the setting of endoplasmic reticulum stress (ER stress).

MATERIAL AND METHODS

We stimulated endothelial cells with palmitate (PA 100μM) to evoked ROS-associated ER stress and observed the effects of astragaloside IV and cycloastragenol on thioredoxin-interacting protein (TXNIP) expression, NLRP3 inflammasome activation and mitochondrion-dependent apoptosis.

RESULTS

Astragaloside IV and cycloastragenol inhibited ROS generation and attenuated ER stress inducer IRE1α phosphorylation, indicating the inhibition of ROS-associated ER stress. In response to ER stress, TXNIP expression increased, accompanied with NLRP3 induction and increased IL-1β and IL-6 production, but these alternations were reversed by treatment with astragaloside IV and cycloastragenol, demonstrating the inhibitory effects of astragaloside IV and cycloastragenol on TXNIP/NLRP3 inflammasome activation. Inflammasome activation led to mitochondrial cell death in endothelial cells, whereas astragaloside IV and cycloastragenol restored the loss of the mitochondrial membrane potential with inhibition of caspase-3 activity, and thereby protected cells from ER stress-induced apoptosis. Astragaloside IV and cycloastragenol enhanced AMPK phosphorylation and AMPK inhibitor compound C diminished their beneficial effects, indicative of the potential role of AMPK in their regulation.

CONCLUSIONS

Astragaloside IV and cycloastragenol suppressed ROS-associated ER stress and then inhibited TXNIP/NLRP3 inflammasome activation with regulation of AMPK activity, and thereby ameliorated endothelial dysfunction by inhibiting inflammation and reducing cell apoptosis. Simultaneous investigations further showed that astragaloside IV and cycloastragenol were equally effective in regulation of endothelial homeostasis.

Effect of Chinese herbal medicine on vascular functions during 60-day head-down bed rest

PURPOSE

Chinese herbal medicine is a promising countermeasure against cardiovascular dysfunction associated with a sedentary lifestyle. We examined the impact of the Chinese herb, Taikong Yangxin, on the micro- and macrovascular dysfunction associated with a 60-day bed rest.

METHODS

Fourteen healthy men were randomly divided into two groups: those given herbal supplement, and the control group; the two groups underwent a 60-day bed rest. The macrovasculature was assessed by sonography. Skin microvascular functions were assessed with laser Doppler. The plasma level of endothelial microparticles (EMPs), markers of endothelial injury, was determined.

RESULTS

Bed rest induced a 33 % decrease in the femoral artery diameter and compliance whereas carotid wall thickness, diameter, and compliance remained unchanged. The early phase of endothelium-dependent vasodilation to ACh was unmodified by bed rest, while the late phase was reduced by 30 % along with a twofold increase in EMPs. In those given Taikong Yangxin, the early phase was amplified by 2.5-fold, and the effects of bed rest on the late phase were prevented.

CONCLUSION

These findings indicate that Taikong Yangxin ameliorates endothelium-dependent vasodilation, likely by improving the NO pathway. The study suggests Taikong Yangxin as a new countermeasure to prevent the changes in microvascular function induced by physical inactivity.

Effect of astragaloside IV against rat myocardial cell apoptosis induced by oxidative stress via mitochondrial ATP-sensitive potassium channels

Astragaloside is one of the most common traditional Chinese medicines and is derived from Astragalus membranaceus. Astragaloside IV (AsIV) is a monomer located in an extract of astragaloside. The current study investigated the protective effects of AsIV against hydrogen peroxide (H2O2)-induced injury in cardiocytes and elucidated the mechanisms responsible for this protective effect. Cultured neonatal rat cardiocytes were divided into five experimental groups as follows: i) Dimethyl sulfoxide; ii) H2O2; iii) AsIV+H2O2; iv) AsIV+H2O2+5-hydroxydecanoate (5-HD); and v) nicorandil+H2O2. Cardiocyte survival was analyzed using an MTT assay. Lactate dehydrogenase (LDH) release was also assessed to evaluate the viability of the cells. Intracellular reactive oxygen species (ROS) were measured by 2,7-dichlorodihydrofluorescein diacetate staining. The apoptotic rate was measured by flow cytometry. Mitochondrial membrane potential (ΔΨm) and intracellular calcium were observed using a laser confocal microscopy system. The results indicated that AsIV promoted the survival of cardiocytes (P<0.05), attenuated LDH release (P<0.05), ROS production (P<0.01) and apoptosis (P<0.01), stabilized the ΔΨm and reduced intracellular calcium overload (P<0.01) compared with the H2O2 group. The mitochondrial adenosine triphosphate-sensitive potassium channel (mitoKATP) inhibitor 5-HD was observed to partially reverse the protective effect of AsIV. Following treatment with 5-HD, the survival of cardiocytes was reduced (P<0.05), LDH release (P<0.01) and ROS production (P<0.05) were stimulated, ΔΨm and intracellular calcium change were increased (P<0.01) and apoptosis was increased (P<0.01) compared with the AsIV+H2O2 group. Thus, AsIV has potential for use in the suppression of apoptosis resulting from H2O2 exposure, and mitoKATP activation may underlie this protective mechanism.

Astragaloside IV inhibits renal tubulointerstitial fibrosis by blocking TGF-β/Smad signaling pathway in vivo and in vitro

Astragaloside IV (AS-IV) is a major active ingredient from Radix astragali, which has been considered as a renoprotective agent; however, its molecular mechanisms are unclear. Thus, we designed to investigate the renoprotective effects and mechanisms of AS-IV in rat model of renal fibrosis induced by unilateral ureteral obstruction (UUO) in vivo and TGF-β1-stimulated rat renal fibroblasts (NRK-49F) in vitro. Sprague-Dawley rats were randomly divided into six groups: sham operation, UUO, UUO/AS-IV (3.3, 10, 33 mg·kg(-1)·d(-1)), and UUO/enalapril (4 mg·kg(-1)·d(-1)). Renal function, tubulointerstitial damage index score, extracellular matrix (ECM) deposition, and the expressions of TGF-β1, connective tissue growth factor (CTGF), α-SMA, fibronectin, collagen I, III, Smad2/3, phosphorylated-Smad2/3, and Smad7 were measured. In addition, the expressions of CTGF, α-SMA, fibronectin, collagen I, III, Smad2/3, phosphorylated-Smad2/3, and Smad7 were measured in TGF-β1-stiumlated NRK-49F cell line. AS-IV significantly decreased UUO-induced renal fibrosis and functional impairment, which are associated with inhibition of TGF-β1, CTGF, α-SMA, and collagen matrix expression, and a decrease in serum creatinine and urea nitrogen. The renoprotective effects of AS-IV on fibrosis were associated with up-regulation of Smad7, thereby blocking up-regulations of TGF-β1, CTGF, and α-SMA, and activation of phosphorylated-Smad2/3. These effects were further conformed in NRK-49F cell line stimulated by TGF-β1. Moreover, knockdown of Smad7 gene in NRK-49F cells was able to prevent AS-IV-induced inhibition to Smad2/3 signaling activation, expression of CTGF, α-SMA, and ECM proteins in response to TGF-β1. Renal tubulointerstitial fibrosis was attenuated by treatment with AS-IV, which was closely related to induction of Smad7, thereby inhibiting TGF-β/Smad signaling.

Neuroprotective effects of dietary supplement Kang-fu-ling against high-power microwave through antioxidant action

KFL displays a protective effect against HPM-induced cognitive impairment and histopathological changes by ameliorating oxidative stress via the Nrf2-ARE signaling pathway.

Astragaloside IV attenuates experimental autoimmune encephalomyelitis of mice by counteracting oxidative stress at multiple levels

Multiple sclerosis (MS) is a chronic autoimmune neuroinflammatory disease found mostly in young adults in the western world. Oxidative stress induced neuronal apoptosis plays an important role in the pathogenesis of MS. In current study, astragaloside IV (ASI), a natural saponin molecule isolated from Astragalus membranceus, given at 20 mg/kg daily attenuated the severity of experimental autoimmune encephalomyelitis (EAE) in mice significantly. Further studies disclosed that ASI treatment inhibited the increase of ROS and pro-inflammatory cytokine levels, down-regulation of SOD and GSH-Px activities, and elevation of iNOS, p53 and phosphorylated tau in central nervous system (CNS) as well as the leakage of BBB of EAE mice. Meanwhile, the decreased ratio of Bcl-2/Bax was reversed by ASI. Moreover, ASI regulated T-cell differentiation and infiltration into CNS. In neuroblast SH-SY5Y cells, ASI dose-dependently reduced cellular ROS level and phosphorylation of tau in response to hydrogen peroxide challenge by modulation of Bcl-2/Bax ratio. ASI also inhibited activation of microglia both in vivo and in vitro. iNOS up-regulation induced by IFNγ stimulation was abolished by ASI dose-dependently in BV-2 cells. In summary, ASI prevented the severity of EAE progression possibly by counterbalancing oxidative stress and its effects via reduction of cellular ROS level, enhancement of antioxidant defense system, increase of anti-apoptotic and anti-inflammatory pathways, as well as modulation of T-cell differentiation and infiltration into CNS. The study suggested ASI may be effective for clinical therapy/prevention of MS.

Astragaloside IV suppresses collagen production of activated hepatic stellate cells via oxidative stress-mediated p38 MAPK pathway

Oxidative stress is involved in hepatic fibrogenesis. Activation of hepatic stellate cells (HSCs), the key effectors in hepatic fibrogenesis, is characterized by overproduction of extracellular matrix. Astragaloside IV, the active component of Radix Astragali, has antioxidant properties and antifibrotic potential in renal fibrosis. Little is known about the role of astragaloside IV in liver and its involvement in hepatic fibrosis. This study aims at evaluating the antifibrotic potential of astragaloside IV and characterizing involved signal transduction pathways in culture-activated HSCs. Our results show that astragaloside IV attenuates oxidative stress in culture-activated HSCs, as demonstrated by scavenging reactive oxygen species and reducing lipid peroxidation, and elevates the level of cellular glutathione by stimulating Nrf2gene expression. Depletion of cellular glutathione by buthionine sulfoximine or abrogation of p38 MAPK by SB-203580 evidently eliminates the inhibitory effects of astragaloside IV on genes relevant to HSC activation. These results demonstrate that astragaloside IV inhibits HSC activation by inhibiting generation of oxidative stress and associated p38 MAPK activation and provide novel insights into the mechanisms of astragaloside IV as an antifibrogenic candidate in the prevention and treatment of liver fibrosis.

Interference in mevalonate pathway ameliorates homocysteine-induced endothelium-dysfunction

Homocysteine is a risk factor for atherosclerosis and hypertension and induces endothelium-dysfunction. Accumulation of cholesterol and reactive oxygen species plays a key role in the endothelium-dysfunction. This study investigated the hypothesis of an involvement of mevalonate pathway and oxidative pathway in homocysteine-induced endothelial damage. Homocysteine induced impairment of the endothelium-dependent vasorelaxation of rat aortic rings by isometric tension, while it also reduced the nitric oxide level and the nitric oxide synthase activity in human umbilical vein endothelial cells, followed by accumulation of superoxide anion and cholesterol. However, the level of asymmetric dimethylarginine remained unaffected by homocysteine. The adverse effect of homocysteine on endothelial function was found to be partially enhanced either by squalestatin-reducing cholesterol or by superoxide dismutase-reducing superoxide anion. Moreover, this effect of homocysteine could be completely ameliorated by simvastatin, very similar to that of cotreatment of squalestatin and superoxide dismutase. Respectively, mevalonolactone partly or squalene fully attenuated the effect of simvastatin or squalestatin on homocysteine-induced endothelial dysfunction. In conclusion, our results suggested that the mevalonate pathway mediates homocysteine-induced endothelium dysfunction besides the oxidative pathway. Interference in the mevalonate pathway and oxidative pathway provides effective protection of endothelial function.

Study of the effects of total flavonoids of Astragalus on atherosclerosis formation and potential mechanisms

Astragalus mongholicus Bunge has long been used to treat cardiovascular disease in Chinese traditional medicine. However, its mechanisms are not fully understood. In this study, we explored potential mechanisms and protective effects of total flavonoids of Astragalus (TFA) on cardiovascular disease using in vitro experiments and diet-induced atherosclerotic rabbits. We identified six components and their proportion in TFA. The animal experiments showed that TFA significantly reduced plasma levels of total cholesterol and LDL cholesterol (P < 0.05 to 0.01), increased HDL cholesterol levels (P < 0.01), and reduced the aortic fatty streak area by 43.6 to 63.6% (P < 0.01). We also found that TFA scavenged superoxide and hydroxyl radicals and this effect increased with higher TFA concentration. In in vivo experiments, TFA effectively inhibited the free radical spectrum in the ischemia-reperfusion module. In conclusion, TFA was the active component of Astragalus mongholicus Bunge, which benefits cardiovascular disease attributing to the potent antioxidant activity to improve the atherosclerosis profile.

Pharmacological investigations on potential of peroxisome proliferator-activated receptor-gamma agonists in hyperhomocysteinemia-induced vascular dementia in rats

The present study has been designed to investigate the potential of peroxisome proliferator-activated receptor-gamma ([PPAR]-γ) agonists, pioglitazone, and rosiglitazone in hyperhomocysteinemia-induced vascular dementia of rats. l-methionine was administered for 8 weeks to induce hyperhomocysteinemia and associated vascular dementia. Pioglitazone and rosiglitazone were administered to l-methionine-treated rats for 4 weeks (starting from 5th to 8th weeks of methionine treatment). Donepezil served as a positive control in this study. On 52nd day onward, the animals were exposed to Morris water maze (MWM) for testing learning and memory abilities. Vascular endothelial function, serum nitrite/nitrate levels, brain thiobarbituric acid reactive species (TBARS), brain reduced glutathione (GSH) levels, and brain acetylcholinesterase (AChE) activity were also measured. l-methionine-treated animals have shown impairment of learning, memory, endothelial function, decrease in serum nitrite/nitrate levels, and brain GSH levels along with increase in brain TBARS levels and AChE activity. Pioglitazone, rosiglitazone, and donepezil significantly improved hyperhomocysteinemia-induced impairment of learning, memory, endothelial dysfunction, and changes in various biochemical parameters. It is concluded that pioglitazone and rosiglitazone may be considered as potential pharmacological agents for the management of hyperhomocysteinemia-induced vascular dementia.