Modification of alterations in cardiac function and sarcoplasmic reticulum by astragaloside IV in myocardial injury in vivo

Qifu Yixin Formula Improves Heart Failure by Enhancing β-Arrestin2 Mediated the SUMOylation of SERCA2a

Purpose

This study aimed to elucidate the protective mechanism of Traditional Chinese Medicine (TCM) Qifu Yixin formula (QFYXF) to improve heart failure (HF) by promoting β-arrestin2 (β-arr2)-mediated SERCA2a SUMOylation.

Materials and Methods

The transverse aortic constriction (TAC)-induced HF mice were treated with QFYXF or carvedilol for 8 weeks. β-arr2-KO mice and their littermate wild-type (WT) mice were used as controls. Neonatal rat cardiomyocytes (NRCMs) were used in vitro. Cardiac function was evaluated by echocardiography and serum NT-proBNP. Myocardial hypertrophy and myocardial fibrosis were assessed by histological staining. β-arr2, SERCA2a, SUMO1, PLB and p-PLB expressions were detected by Western blotting, immunofluorescence and immunohistochemistry. SERCA2a SUMOylation was detected by Co-IP. The molecular docking method was used to predict the binding ability of the main active components of QFYXF to β-arr2, SERCA2a, and SUMO1, and the binding degree of SERCA2a to SUMO1 protein.

Results

The HF model was constructed 8 weeks after TAC. QFYXF ameliorated cardiac function, inhibiting myocardial hypertrophy and fibrosis. QFYXF promoted SERCA2a expression and SERCA2a SUMOylation. Further investigation showed that QFYXF promoted β-arr2 expression, whereas Barbadin (β-arr2 inhibitor) or β-arr2-KO reduced SERCA2a SUMOylation and attenuated the protective effect of QFYXF improved HF. Molecular docking showed that the main active components of QFYXF had good binding activities with β-arr2, SERCA2a, and SUMO1, and SERCA2a had a high binding degree with SUMO1 protein.

Conclusion

QFYXF improves HF by promoting β-arr2 mediated SERCA2a SUMOylation and increasing SERCA2a expression.

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.

Bidirectional effects and mechanisms of traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

The bidirectional property of traditional Chinese medicines (TCMs) was recorded in the classic work Medicine Origin (Yi Xue Qi Yuan) as early as the Jin and Yuan dynasties of ancient China. Since then, this imperative theory has been applied to guide the clinical application of TCMs. Studies have been performed to investigate this phenomenon only over the last three decades. A limited number of reviews on the bidirectional role of TCMs have been published, and almost all current studies are published in the Chinese language.

AIM OF THE REVIEW

The aim of this review is to provide the first comprehensive evidence regarding the bidirectional effects and the underlying mechanisms of TCMs and their active compounds.

MATERIALS AND METHODS

Information relevant to opposing pharmacological activities or opposing properties exerted by TCM prescriptions, herbal medicines, and their active compound, as well as their mechanisms was summarized by searching Chinese and English databases, including the Chinese National Knowledge Infrastructure (CNKI), Wan Fang Data, Chinese Scientific Journal Database (VIP), Google Scholar, PubMed, Web of Science, Science Direct, and Wiley Online Library.

RESULTS

Although the bidirectional regulation of TCMs has been applied in the clinic since ancient times in China, only limited reviews have been published in Chinese. The existing data showed that bidirectional effects can be found in TCM prescriptions, herbal medicines, and pure active compounds. Additionally, the bidirectional role of TCMs was primarily reported in the modulation of immune function, blood circulation and hemostasis, gastrointestinal motility, the central nervous system and blood pressure. This may because the therapeutic outcomes of these disorders are more obvious than those of other complicated diseases. Intriguingly, some herbal medicines have multiple bidirectional activities; for instance, Panax ginseng C. A. Meyer showed bidirectional regulation of immune function and the central nervous system; Astragalus membranaceus can bidirectionally regulate blood pressure and immune function; and Rheum officinale Baill exerts bidirectional effects on blood circulation and hemostasis, gastrointestinal motility and immune function. The mechanisms underlying the bidirectional effects of TCMs are largely attributed to the complexity of herbal constituents, dosage differences, the processing of herbal medicine, and compatibility of medicines, the physiological conditions of patients and adaptogenic effects.

CONCLUSION

Uncovering the bidirectional effects and mechanisms of TCMs is of great importance for both scientific research and clinical applications. This review may help to facilitate the recognition of the bidirectional role of TCMs, to explain some seemingly-opposite phenomena in the pharmacological study of herbal medicines and to provide guidance for TCM practitioners.

Astragaloside IV attenuate MI-induced myocardial fibrosis and cardiac remodeling by inhibiting ROS/caspase-1/GSDMD signaling pathway

Astragalus membranaceus is a traditional Chinese medicine and has been widely used in treating cardiovascular diseases (CVDs), such as asthma, edema, and chest tightness. Astragaloside IV (AS-IV), one of the major active components extracted from Astragalus membranaceus, has a series of pharmacological effects, including inhibiting inflammation, regulating energy metabolism, reducing oxidative stress and apoptosis. However, the effect of AS-IV on myocardial infarction (MI) and the underlying molecular mechanism remains unclear. The purpose of our study is to investigate the effects of AS-IV on MI-induced myocardial fibrosis and cardiac remodeling and to elucidate its underlying mechanisms. MI was induced by ligation of the left anterior descending (LAD) coronary artery. Echocardiography was used to evaluate cardiac function in mice. Pathological changes in cardiac tissues were analyzed with hematoxylin and eosin (H&E) staining, Masson staining, and wheat germ agglutinin (WGA) staining. Immunohistochemistry was used to detect the expression of fibrosis and inflammation-related proteins. Immunofluorescence and flow cytometry were used to detect ROS level. The expressions of α-SMA, Collagen I, NLRP3, cleaved cas-1, cleaved IL-18, cleaved IL-β, GSDMD-N, and cleaved caspase-1 were examined using western blot. The results of cardiac ultrasound showed that AS-IV could improve poor ventricular remodeling, myocardial pathological staining showed that AS-IV could significantly reduce the myocardial fibrosis and myocardial hypertrophy, ROS levels were also significantly reduced, and the protein expression of NLRP3/Caspase-1/GSDMD signaling pathway was remarkably decreased in the AS-IV group. Furthermore, immunohistochemical staining results showed that the expression of myocardial macrophages and neutrophils in AS-IV group decreased significantly, to further investigate whether the reduction of myocardial pyroptosis by AS-IV is related to the regulation of macrophages, in vitro, AS-IV was selected to stimulate bone marrow-derived macrophages (BMDMs). Our findings indicated that AS-IV protective effect of the heart might be related to the reduction of macrophage pyroptosis. These results demonstrate that AS-IV alleviated MI-induced myocardial fibrosis and cardiac remodeling by suppressing ROS/Caspase-1/GSDMD signaling pathway, AS-IV should be further studied in the future.

A Single, Acute Astragaloside IV Therapy Protects Cardiomyocyte Through Attenuating Superoxide Anion-Mediated Accumulation of Autophagosomes in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion (I/R) injury, characterized by myocardial cell death (e.g., apoptosis) and generation of reactive oxygen species (ROS) such as superoxide (O2 ·-) and hydrogen peroxide (H2O2), is a serious threat to human health and property. Saponin astragaloside IV (ASIV), extracted from Chinese herbal medicine astragalus, is effective in resolving multiple pathological issues including myocardial I/R injury. Recent studies have shown that autophagy is regulated by ROS and plays an important role in myocardial I/R injury. However, regulation of autophagy by ASIV during myocardial I/R injury and the role of specific ROS involved in the process have been rarely reported. In the present study, we found that SOD2 was downregulated and O2 ·- was upregulated in H2O2-induced H9C2 cardiac myocyte injury in vitro and myocardial I/R injury in vivo, while such alterations were reversed by ASIV. ASIV possessed the ability to alleviate myocardial I/R injury via attenuating I/R-caused autophagosome accumulation. Upregulate of O2 ·- by 2-methoxyestradiol (2-ME) reversed the effect of ASIV-mediated autophagy regulation, which suggested that O2 ·- was vital in this process. In conclusion, our results contribute to understanding the mechanism of ASIV-induced cardioprotective effect.

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 ameliorates intermittent hypoxia-induced inflammatory dysfunction by suppressing MAPK/NF-κB signalling pathways in Beas-2B cells

PURPOSE

Intermittent hypoxia is a characteristic pathological change in obstructive sleep apnoea (OSA) that can initiate oxidative stress reaction and pro-inflammatory cytokine release. The purpose of this study was to assess the effect and protective mechanism of Astragaloside IV (AS-IV) in intermittent hypoxia-induced human lung epithelial Beas-2B cells.

METHODS

Human lung epithelial Beas-2B cells were exposed to intermittent hypoxia or normoxia in the absence or presence of AS-IV. MTT assay was performed to determine the cell viability. The levels of reactive oxygen species (ROS), lactate dehydrogenase (LDH), malonaldehyde (MDA), and superoxide dismutase (SOD) were measured to evaluate oxidative stress. The levels of cytokines interleukin (IL)-8, IL-1β, and IL-6 were evaluated by enzyme-linked immunosorbent assay and real-time PCR. The expression of Toll-like receptor 4 (TLR4), mitogen-activated protein kinase (MAPK), and nuclear transcription factor-kappa B (NF-κB) signalling pathways was analysed by western blot.

RESULTS

The results showed that AS-IV significantly reduced the levels of ROS, LDH, MDA, IL-8, IL-1β, and IL-6, and increased the level of SOD in intermittent hypoxia-induced Beas-2B cells. It also suppressed the phosphorylation of MAPKs, including P38, c-Jun N-terminal kinase and extracellular signal-regulated kinase, and inhibited the activation of the NF-κB signalling pathway by reducing the phosphorylation of IκBα and p65.

CONCLUSIONS

AS-IV attenuates inflammation and oxidative stress by inhibiting TLR4-mediated MAPK/NF-κB signalling pathways in intermittent hypoxia-induced Beas-2B cells.

Recruitment of Mesenchymal Stem Cells to Damaged Sites by Plant-Derived Components

Mesenchymal stem cells (MSCs) are capable of differentiating into a limited number of diverse cells and secrete regenerative factors that contribute to the repair of damaged tissue. In response to signals emitted by tissue damage, MSCs migrate from the bone marrow and area surrounding blood vessels within tissues into the circulating blood, and accumulate at the site of damage. Hence, MSC transplantation therapy is beginning to be applied to the treatment of various intractable human diseases. Recent medicinal plants studies have shown that plant-derived components can activate cell functions. For example, several plant-derived components activate cell signaling pathways, such as phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK), enhance expression of the CXCL12/CXCR4 axis, stimulate extracellular matrix remodeling, and consequently, promote cell migration of MSCs. Moreover, plant-derived components have been shown to promote recruitment of MSCs to damaged tissues and enhance healing in disease models, potentially advancing their therapeutic use. This article provides a comprehensive review of several plant-derived components that activate MSC migration and homing to damaged sites to promote tissue repair.

Astragaloside IV attenuates chronic intermittent hypoxia-induced myocardial injury by modulating Ca2+ homeostasis

Obstructive sleep apnea syndrome (OSAS) is an important consequence of chronic intermittent hypoxia (CIH). Astragaloside IV (AS-IV) exerts multiple protective effects in diverse diseases. However, whether AS-IV can attenuate CIH-induced myocardial injury is unclear. In this study, rats exposed to CIH were established and treated with AS-IV for 4 weeks. In vitro, H9C2 cardiomyocytes subjected to CIH exposure were treated with AS-IV for 48 hours. Then the cardiac function, morphology, fibrosis, apoptosis and Ca²⁺ homeostasis were determined to assess cardiac damage. Results showed that AS-IV attenuated cardiac dysfunction and histological lesions in CIH rats. The increased TUNEL-positive cells and activated apoptotic proteins in CIH rats were reduced by AS-IV. We also noticed that AS-IV reversed the accumulation of Ca²⁺ and altered expressions of Ca²⁺ handling proteins (decreases of SERCA2a and RYR2, and increases of p-CaMKII and NCX1) under CIH exposure. Furthermore, CIH-induced reduction of SERCA2a activity was increased by AS-IV in rats. Similar results were also observed in H9C2 cells. Altogether, these findings indicate that AS-IV modulates Ca²⁺ homeostasis to inhibit apoptosis, protecting against CIH-induced myocardial injury eventually, suggesting it may be a potential agent for cardiac damage of OSAS patients. SIGNIFICANCE OF THE STUDY: Chronic intermittent hypoxia (CIH) is a great contributor of OSAS, which is closely associated with cardiovascular diseases. It is necessary for developing a promising drug to attenuate CIH-induced myocardial injury. This work suggests that AS-IV can attenuate myocardial apoptosis and calcium disruption, thus protecting against CIH-induced myocardial injury. It may represent a novel therapeutic for cardiac damage of OSAS.

Evaluation of Phytochemical, Antioxidant and Antibacterial Activity on Astragalus Chrysostachys Boiss. Roots

Astragalus is a well-known genus in Leguminosae family that represented more than 800 species growing in Iran. Nevertheless, there are a few reports on Astragalus plants endemic to Iran. The roots of Astragalus plants are rich in saponins, flavonoids and polysaccharides that possess various pharmacological activities. In the present study, chemical components, antioxidant and antibacterial activity of Astragalus chrysostachys Boiss. roots were evaluated. For determination of phytochemicals in Astragalus chrysostachys Boiss. roots, total hydroalcoholic extract was fractionated with ethyl acetate and n-butanol. Ethyl acetate extract as a flavonoid rich extract was analyzed using vacuum liquid chromatography and preparative TLC and consequently a major flavonoid was isolated. The structure of the obtained compound was elucidated with 1D and 2D NMR experiments. Additionally, the essential oil of the roots was analyzed by GC-MS. Antioxidant activity of all extracts was evaluated by different assays. Moreover, antibacterial activities of the extracts were also investigated against 2 Gram-positive and 2 Gram-negative bacteria using Micro-dilution Broth method. Apigenin-6, 8-di-C-glucoside was detected in ethyl acetate extract for the first time in genus Astragalus. In addition, m-tolualdehyde, acetophenone, croweacin were found to be characteristics of the volatile oil of roots. Ethyl acetate extracts revealed notable antioxidant activity in DPPH scavenging assay with IC50 value of 14.6 µg/mL. Evaluation of antibacterial activity on the tested extracts showed mild activity against Gram-positive bacteria. Since there have been no reports on Astragalus chrysostachys Boiss. to date, the present data might be promising for application of this plant derivatives in phytotherapeutic practice.

Astragalosides increase the cardiac diastolic function and regulate the "Calcium sensing receptor-protein kinase C-protein phosphatase 1" pathway in rats with heart failure

This study was designed to investigate the effects of astragalosides on cardiac diastolic function, and an emphasis was placed on the variation of the upstream molecular regulators of phospholamban. Chronic heart failure (CHF) rats were induced by ligaturing the left anterior coronary artery, and rats in the therapeutic groups were treated with either a 50 mg/kg dose of captopril, 10 mg/kg dose of astragalosides or 20 mg/kg dose of astragalosides. Four weeks after treatment, the ratio of the early and atrial peak filling velocities (E/A) and maximal slope diastolic pressure decrement (-dp/dt) both decreased in CHF rats (by 30.3% and 25.5%, respectively) and significantly increased in 20 mg/kg astragalosides and captopril-treated rats. The protein phosphatase-1 activity was lower in the 20 mg/kg astragalosides group than in the CHF group (0.22 vs 0.44, P < 0.01), and the inhibitor-1 levels in the astragalosides and captopril-treated groups were increased. Chronic heart failure increased expression of protein kinase C-α and calcium-sensing receptor, and these changes were attenuated by astragalosides therapy. Astragalosides restored the diastolic dysfunction of chronic heart failure rats, possibly by downregulation of calcium-sensing receptor and protein kinase C-α, which in turn augmented inhibitor-1 expression, reduced protein phosphatase-1 activity and increased phospholamban phosphorylation.

Astragaloside IV Inhibits Membrane Ca[Formula: see text] Current but Enhances Sarcoplasmic Reticulum Ca[Formula: see text] Release

Astragaloside IV (AS-IV) is one of the active ingredients in Astragalus membrananceus (Huangqi), a traditional Chinese medicine. The present study investigated the effects of AS-IV on Ca[Formula: see text] handling in cardiac myocytes to elucidate its possible mechanism in the treatment of cardiac disease. The results showed that AS-IV at 1 and 10[Formula: see text][Formula: see text]M reduced KCl-induced [Ca[Formula: see text]]_i increase ([Formula: see text] from 1.33[Formula: see text][Formula: see text][Formula: see text]0.04 (control, [Formula: see text] 28) to 1.22[Formula: see text][Formula: see text][Formula: see text]0.02 ([Formula: see text], [Formula: see text] 29) and 1.22[Formula: see text][Formula: see text][Formula: see text]0.02 ([Formula: see text] 0.01, [Formula: see text]), but it enhanced Ca[Formula: see text] release from SR ([Formula: see text] from 1.04[Formula: see text][Formula: see text][Formula: see text]0.01 (control, [Formula: see text]) to 1.44[Formula: see text][Formula: see text][Formula: see text]0.03 ([Formula: see text], [Formula: see text]) and 1.60[Formula: see text][Formula: see text][Formula: see text]0.04 ([Formula: see text] 0.01, [Formula: see text]0), in H9c2 cells. Similar results were obtained in native cardiomyocytes. AS-IV at 1 and 10[Formula: see text][Formula: see text]M inhibited L-type Ca[Formula: see text] current ([Formula: see text] from [Formula: see text]4.42[Formula: see text][Formula: see text][Formula: see text]0.58 pA/pF of control to [Formula: see text]2.25[Formula: see text][Formula: see text][Formula: see text]0.12 pA/pF ([Formula: see text] 0.01, [Formula: see text] 5) and [Formula: see text]1.78[Formula: see text][Formula: see text][Formula: see text]0.28 pA/pF ([Formula: see text] 0.01, [Formula: see text] 5) respectively, when the interference of [Ca[Formula: see text]]_i was eliminated due to the depletion of SR Ca[Formula: see text] store by thapsigargin, an inhibitor of Ca[Formula: see text] ATPase. Moreover, when BAPTA, a rapid Ca[Formula: see text] chelator, was used, CDI (Ca[Formula: see text]-dependent inactivation) of [Formula: see text] was eliminated, and the inhibitory effects of AS-IV on I_CaL were significantly reduced at the same time. These results suggest that AS-IV affects Ca[Formula: see text] homeostasis through two opposite pathways: inhibition of Ca[Formula: see text] influx through L-type Ca[Formula: see text] channel, and promotion of Ca[Formula: see text] release from SR.

Astragaloside IV Attenuates Podocyte Apoptosis Mediated by Endoplasmic Reticulum Stress through Upregulating Sarco/Endoplasmic Reticulum Ca2+-ATPase 2 Expression in Diabetic Nephropathy

Sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) plays a central role in the pathogenesis of diabetes. This protein has been recognized as a potential target for diabetic therapy. In this study, we identified astragaloside IV (AS-IV) as a potent modulator of SERCA inhibiting renal injury in diabetic status. Increasing doses of AS-IV (2, 6, and 18 mg kg^-1 day^-1) were administered intragastrically to db/db mice for 8 weeks. Biochemical and histopathological approaches were conducted to evaluate the therapeutic effects of AS-IV. Cultured mouse podocytes were used to further explore the underlying mechanism in vitro. AS-IV dose-dependently increased SERCA activity and SERCA2 expression, and suppressed ER stress-mediated and mitochondria-mediated apoptosis in db/db mouse kidney. AS-IV also normalized glucose tolerance and insulin sensitivity, improved renal function, and ameliorated glomerulosclerosis and renal inflammation in db/db mice. In palmitate stimulated podocytes, AS-IV markedly improved inhibitions of SERCA activity and SERCA2 expression, restored intracellular Ca²⁺ homeostasis, and attenuated podocyte apoptosis in a dose-dependent manner with a concomitant abrogation of ER stress as evidenced by the downregulation of GRP78, cleaved ATF6, phospho-IRE1α and phospho-PERK, and the inactivation of both ER stress-mediated and mitochondria-mediated apoptotic pathways. Furthermore, SERCA2b knockdown eliminated the effect of AS-IV on ER stress and ER stress-mediated apoptotic pathway, whereas its overexpression exhibited an anti-apoptotic effect. Our data obtained from in vivo and in vitro studies demonstrate that AS-IV attenuates renal injury in diabetes subsequent to inhibiting ER stress-induced podocyte apoptosis through restoring SERCA activity and SERCA2 expression.

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.

Arsenic trioxide triggered calcium homeostasis imbalance and induced endoplasmic reticulum stress-mediated apoptosis in adult rat ventricular myocytes

Arsenic trioxide (ATO) is a potent anticancer drug agent but its clinical use is often limited by severe cardiotoxicity. However, its exact mechanism remains poorly understood. In this study, we simultaneously explored the direct effect of ATO on cardiac contraction in adult rat ventricular myocytes and its effects on Ca²⁺ transient in real time by using an IonOptix MyoCam system. The results showed that ATO increased the amplitude of sarcomere shortening, the maximal velocity of relengthening and shortening (-dL/dt_max and +dL/dt_max), time-to-90% relengthening (TR90), and time-to-peak shortening (TPS), resulting in abnormal cardiomyocyte contraction. Meanwhile, ATO markedly increased the resting Ca²⁺ ratio, amplitude/resting calcium, the maximal velocity of Ca²⁺ shortening and relaxation (+d[Ca²⁺]/dt_max and -d[Ca²⁺]/dt_max), time-to-50% peak [Ca²⁺] _i and the decay rate of [Ca²⁺] _i transients, suggesting that ATO leads to intracellular imbalance of calcium homeostasis. ATO also inhibited sarcoplasmic reticulum Ca²⁺-ATPase 2a (SERCA2a) activity in a time-dependent manner and activated the endoplasmic reticulum (ER) stress reaction. These results revealed that ATO dramatically aggravates Ca²⁺ overload and promotes ER stress, eventually causing abnormal cardiomyocyte contraction in a dose-dependent and time-dependent manner.

Astragaloside IV protects cardiomyocytes from anoxia/reoxygenation injury by upregulating the expression of Hes1 protein

Astragaloside IV (ASI), a traditional Chinese medicine, is a main active ingredient of Astragalus membranaceus. Many clinical studies have found that ASI protects cardiomyocytes in cardiovascular diseases, but the underlying mechanisms remain obscure. The aim of this study was to investigate the molecular mechanisms responsible for the protective effects of ASI in cardiomyocytes from anoxia/reoxygenation (A/R) injury. According to the previous studies, we hypothesized that the cardioprotective effects of ASI against A/R injury might be associated with Notch1/Hes1 signaling pathway. In this study, neonatal rat primary cardiomyocytes were preconditioned with ASI prior to A/R injury. Our results showed that ASI effectively increased the cell viability, decreased the content of MDA, decreased the activities of CPK and LDH, increased the activities of GSH-Px and SOD, and reduced the reactive oxygen species (ROS) generation and the loss of mitochondrial membrane potential (Δψm). ASI inhibited the mitochondrial permeability transition pore (mPTP) opening and activation of caspase-3, and finally decreased the cell apoptosis in cardiomyocytes. Furthermore, ASI upregulated Hes1 protein expression. However, pretreatment with DAPT, a Notch1 inhibitor, effectively attenuated the cardioprotective effects of ASI against A/R injury, except MDA, SOD, GSH-Px, and the ROS generation. Taken together, we demonstrated that ASI could protect against A/R injury via the Notch1/Hes1 signaling pathway.

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.

Determination of astragaloside III in rat plasma by liquid chromatography-tandem mass spectrometry and its application to a rat pharmacokinetic study

Astragaloside III (AST III), a naturally occurring saponin compound isolated from Radix Astragali, has been demonstrated to have anti-gastric ulcer, immunomodulatory and antitumor effects. To evaluate its pharmacokinetics in rats, a rapid, sensitive and specific high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method has been developed and validated for the quantification of astragaloside III in rat plasma. Samples were pretreated using a simple protein precipitation with methanol-acetonitrile (50:50, v/v) and the chromatographic separation was performed on a C18 column by a gradient elution using a mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid. Astragaloside III and the internal standard (buspirone) were detected using a tandem mass spectrometer in positive multiple reaction monitoring mode. Method validation revealed excellent linearity over the range of 5.00-5000 ng/mL together with satisfactory intra- and inter-day precision, accuracy and recovery. Stability testing showed that astragaloside III spiked into rat plasma was stable for 24 h at 20°C temperature, for up to 30 days at -80°C, and during three freeze-thaw cycles. The method was successfully used to investigate the pharmacokinetic profile of AST III after oral (10 mg/kg) and intravenous (1.0 mg/kg) administration in rats. The oral absolute bioavailability of AST III was calculated to be 4.15 ± 0.67% with an elimination half-life value of 2.13 ± 0.11 h, suggesting its poor absorption and/or strong metabolism in vivo.

Astragaloside IV inhibits NF- κ B activation and inflammatory gene expression in LPS-treated mice

In this study we investigated the role of astragaloside IV (AS-IV), one of the major active constituents purified from the Chinese medicinal herb Astragalus membranaceus, in LPS-induced acute inflammatory responses in mice in vivo and examined possible underlying mechanisms. Mice were assigned to four groups: vehicle-treated control animals; AS-IV-treated animals (10 mg/kg b.w. AS-IV daily i.p. injection for 6 days); LPS-treated animals; and AS-IV plus LPS-treated animals. We found that AS-IV treatment significantly inhibited LPS-induced increases in serum levels of MCP-1 and TNF by 82% and 49%, respectively. AS-IV also inhibited LPS-induced upregulation of inflammatory gene expression in different organs. Lung mRNA levels of cellular adhesion molecules, MCP-1, TNFα, IL-6, and TLR4 were significantly attenuated, and lung neutrophil infiltration and activation were strongly inhibited, as reflected by decreased myeloperoxidase content, when the mice were pretreated with AS-IV. Similar results were observed in heart, aorta, kidney, and liver. Furthermore, AS-IV significantly suppressed LPS-induced NF-κB and AP-1 DNA-binding activities in lung and heart. In conclusion, our data provide new in vivo evidence that AS-IV effectively inhibits LPS-induced acute inflammatory responses by modulating NF-κB and AP-1 signaling pathways. Our results suggest that AS-IV may be useful for the prevention or treatment of inflammatory diseases.

Electrophysiological effect and the gating mechanism of astragaloside IV on L-type Ca(2+) channels of guinea-pig ventricular myocytes

Astragaloside IV (AS-IV) is one of the main active ingredients of Astragalus membranaceus. This study is aimed to investigate AS-IV׳s effects on Ca(2+) channel activity of single cardiomyocytes and single Ca(2+) channels. Whole-cell Ca(2+) currents in freshly dissociated cardiomyocytes were measured using the whole-cell patch-clamp technique. Single Ca(2+) channel currents were examined in cell-attached patches and inside-out patches. In the whole-cell recording, AS-IV reduced the amplitude of L-type Ca(2+) currents (ICaL) in a concentration-dependent manner. Although AS-IV did not alter the steady-state activation curves, the voltage dependence of the current inactivation curves was negatively shifted by AS-IV in a concentration dependent manner. Consistent with the results of the whole-cell recording, in the inside-out configuration the ensemble average of single Ba(2+) current via L-type Ca(2+) channel was dose-dependently reduced by AS-IV. The reduction of unitary Ba(2+) current at 0.1 or 1 µM AS-IV was accounted for a decrease in the channel activity (NPo). In addition to the decrease in NPo, there was a reduction of Po without a change in channel number or an apparent change in single channel current. Furthermore, we found that the open-closed kinetics of the channel were affected by AS-IV. AS-IV induced the shift of L-type Ca(2+) channels from either brief openings (mode 1) or long-lasting openings (mode 2) to no active opening (mode 0). Our results suggest that AS-IV blocks the currents through Ca(2+) channels in guinea-pig ventricular myocytes by affecting the open-closed kinetics of L-type Ca(2+) channels to inhibit the channel activities. This study could provide theoretical basis for the drug exploiting of the monomer of Astragalus membranaceus.

Phospholamban phosphorylation, mutation, and structural dynamics: a biophysical approach to understanding and treating cardiomyopathy

We review the recent development of novel biochemical and spectroscopic methods to determine the site-specific phosphorylation, expression, mutation, and structural dynamics of phospholamban (PLB), in relation to its function (inhibition of the cardiac calcium pump, SERCA2a), with specific focus on cardiac physiology, pathology, and therapy. In the cardiomyocyte, SERCA2a actively transports Ca²⁺ into the sarcoplasmic reticulum (SR) during relaxation (diastole) to create the concentration gradient that drives the passive efflux of Ca²⁺ required for cardiac contraction (systole). Unphosphorylated PLB (U-PLB) inhibits SERCA2a, but phosphorylation at S16 and/or T17 (producing P-PLB) changes the structure of PLB to relieve SERCA2a inhibition. Because insufficient SERCA2a activity is a hallmark of heart failure, SERCA2a activation, by gene therapy (Andino et al. 2008; Fish et al. 2013; Hoshijima et al. 2002; Jessup et al. 2011) or drug therapy (Ferrandi et al. 2013; Huang 2013; Khan et al. 2009; Rocchetti et al. 2008; Zhang et al. 2012), is a widely sought goal for treatment of heart failure. This review describes rational approaches to this goal. Novel biophysical assays, using site-directed labeling and high-resolution spectroscopy, have been developed to resolve the structural states of SERCA2a-PLB complexes in vitro and in living cells. Novel biochemical assays, using synthetic standards and multidimensional immunofluorescence, have been developed to quantitate PLB expression and phosphorylation states in cells and human tissues. The biochemical and biophysical properties of U-PLB, P-PLB, and mutant PLB will ultimately resolve the mechanisms of loss of inhibition and gain of inhibition to guide therapeutic development. These assays will be powerful tools for investigating human tissue samples from the Sydney Heart Bank, for the purpose of analyzing and diagnosing specific disorders.

Effect of the total saponins of Aralia elata (Miq) Seem on cardiac contractile function and intracellular calcium cycling regulation

ETHNOPHARMACOLOGICAL RELEVANCE

Total saponins of Aralia elata (Miq) Seem (AS) from the Chinese traditional herb Longya Aralia chinensis L. can improve cardiac function, although the active mechanism remains poorly understood. The present study aimed to determine the direct effect of AS on cardiac function in dogs and the effects on Ca2+ transient and contractions in isolated rat cardiomyocytes.

MATERIAL AND METHODS

In anesthetized dogs, hemodynamic indexes and myocardial oxygen consumption were determined before and after AS was administered. In isolated adult rat cardiomyocytes, contractile and intracellular Ca2+ properties were determined simultaneously in real time by using an IonOptix MyoCam system.

RESULTS

Our results showed that AS directly induced a positive inotropic effect and improved coronary blood flow and energy metabolism, indicating that AS induced a beneficial effect to treat myocardial ischemia/reperfusion injury. Moreover, AS increased sarcomere shortening, maximal velocity of shortening/relengthening (±dL/dt), amplitude of [Ca2+]i transients and SERCA activity in a concentration-dependent manner. PKCε was also activated after the cells were treated with AS.

CONCLUSION

These findings revealed the positive inotropic effect of AS on canine myocardium and isolated rat cardiomyocytes. This effect was possibly associated with an increase in amplitude of the [Ca2+]i transient and PKCε-dependent signaling pathway.

Effects of salvianolic acid and notoginseng triterpenes on angiogenesis in EA-hy926 cells in vitro

AIM

To investigate the different effects of salvianolic acid and notoginseng triterpenes on proliferation, angiogenesis and expression of vascular endothelial growth factor in EA-hy926 cells in vitro.

METHODS

EA-hy926 cells were cultured in vitro. Salvianolic acid and notoginseng triterpenes at concentrations of 0.4, 0.8 and 1.2 mg·L(-1) were used to culture EA-hy926 cells. EA-hy926 cells in a blank control group were grown in culture solution only. Viability of cells was assessed by CCK-8, and after treated for 12 h, capillary-like structures were examined. After 24 h culture, the expression of VEGF was detected by real-time PCR.

RESULTS

Salvianolic acid at 0.4, 0.8 mg·L(-1), the same as notoginseng triterpenes, increased VEGF content in EA-hy926 cells. Expression of VEGF protein in the salvianolic acid at 1.2 mg·L(-1) group, was up-regulated as compared with notoginseng triterpenes group (P < 0.05).

CONCLUSION

Salvianolic acid and notoginseng triterpenes can promote EA-hy926 cell proliferation, angiogenesis and expression of VEGF protein. This analysis also provided evidence that salvianolic acid had the better effects as compared with notoginseng triterpenes.

Tanshinone IIA and astragaloside IV promote the migration of mesenchymal stem cells by up-regulation of CXCR4

Mesenchymal stem cells (MSCs) have a therapeutic potential to treat cardiovascular diseases. However, a significant barrier to MSC therapy is insufficient MSC engraftment in ischemic myocardium after systemic administration. Here, we investigated the modulatory effects of tanshinone IIA and astragaloside IV on the migration of MSCs and further defined the underlying mechanisms. CXCR4 expression in MSCs was determined by using flow cytometry, real-time PCR, and western blotting. The results showed that CXCR4 expression was significantly higher in tanshinone IIA- and astragaloside IV-stimulated MSCs than that of the control. MSC migration toward stromal cell-derived factor-1α (SDF-1α) was studied using a transwell system. MSCs treated with tanshinone IIA and astragaloside IV showed stronger migration than that of the control. Moreover, this enhanced migration ability was abrogated by a CXCR4 inhibitor. In a rat acute myocardial infarction model, MSCs stimulated with tanshinone IIA and astragaloside IV were stained with Dio and injected into model rats via the tail vein. Dio-labeled cells in myocardium sections were observed by fluorescence microscopy. Tanshinone IIA- and astragaloside IV-stimulated MSCs showed enhanced capacities to home to ischemic myocardium sites. In addition, there was no significant difference in the SDF-1α expression among groups. These data suggest that tanshinone IIA and astragaloside IV regulate MSC mobilization, at least partially via modulation of the CXCR4 expression.

A systems biology approach to uncovering pharmacological synergy in herbal medicines with applications to cardiovascular disease

Background. Clinical trials reveal that multiherb prescriptions of herbal medicine often exhibit pharmacological and therapeutic superiority in comparison to isolated single constituents. However, the synergistic mechanisms underlying this remain elusive. To address this question, a novel systems biology model integrating oral bioavailability and drug-likeness screening, target identification, and network pharmacology method has been constructed and applied to four clinically widely used herbs Radix Astragali Mongolici, Radix Puerariae Lobatae, Radix Ophiopogonis Japonici, and Radix Salviae Miltiorrhiza which exert synergistic effects of combined treatment of cardiovascular disease (CVD). Results. The results show that the structural properties of molecules in four herbs have substantial differences, and each herb can interact with significant target proteins related to CVD. Moreover, the bioactive ingredients from different herbs potentially act on the same molecular target (multiple-drug-one-target) and/or the functionally diverse targets but with potentially clinically relevant associations (multiple-drug-multiple-target-one-disease). From a molecular/systematic level, this explains why the herbs within a concoction could mutually enhance pharmacological synergy on a disease. Conclusions. The present work provides a new strategy not only for the understanding of pharmacological synergy in herbal medicine, but also for the rational discovery of potent drug/herb combinations that are individually subtherapeutic.

Astragaloside IV stimulates angiogenesis and increases hypoxia-inducible factor-1α accumulation via phosphatidylinositol 3-kinase/Akt pathway

Astragaloside IV is the major active constituent of Astragalus membranaceus, which has been widely used for the treatment of cardiovascular diseases in China. The aim of this study was to determine the angiogenic effect of astragaloside IV and its underlying mechanism. We used the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay, Western blotting, real-time polymerase chain reaction, and immunofluorescence to detect the effect of astragaloside IV on proliferation of human umbilical vein endothelial cells (HUVECs), the phospho-Akt protein level, hypoxia-inducible factor-1α (HIF-1α) accumulation, vascular endothelial growth factor mRNA expression, and applied cell migration, tube formation, and chick chorioallantoic membrane assays to study the angiogenic effect of astragaloside IV. Results indicate that astragaloside IV promoted cell proliferation and stimulated HIF-1α accumulation during hypoxia. Mechanism studies revealed that astragaloside IV did not affect the degradation of HIF-1α protein or the level of HIF-1α mRNA. In contrast, astragaloside IV apparently activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which regulates HIF-1α protein synthesis. Moreover, astragaloside IV also stimulated cell migration, increased tube formation, and promoted angiogenesis in the chick chorioallantoic membrane assay. All angiogenic effects of astragaloside IV were reversed by the PI3K inhibitor. Taken together, our data collectively reveal that astragaloside IV is a novel regulator of HIF-1α and angiogenesis through the PI3K/Akt pathway in HUVECs that are exposed to hypoxia.

Astragalosides rescue both cardiac function and sarcoplasmic reticulum Ca²⁺ transport in rats with chronic heart failure

The study investigated the beneficial effects of astragalosides (AS) on cardiac performance in rats with chronic heart failure. Chronic heart failure was produced by left anterior descending coronary artery ligation, and the therapeutic efficacy of astragalosides at 10, 20 and 40 mg/kg was evaluated. Five weeks after the operation, cardiac function was deficient and sarcoplasmic reticulum Ca²⁺-ATPase (SERCA) activity was significantly reduced. Moreover, SERCA mRNA decreased, while expression of the SERCA down-regulator phospholamban (PLB) was significantly increased. Phosphorylated phospholamban (P-PLB), the form that does not inhibit SERCA, was also reduced by chronic heart failure. Treatment with AS improved left ventricle function and cardiac structure, reversed the depression of SERCA activity, and increased P-PLB. These results suggest that the cardioprotective effect of AS may be due to the increase in P-PLB protein, which disinhibits SERCA activity. Rescue of sarcoplasmic reticulum Ca²⁺ cycling by astragalosides could normalize excitation-contraction coupling and improve overall cardiac function.

Astragalus Improved Cardiac Function of Adriamycin-Injured Rat Hearts by Upregulation of SERCA2a Expression

The traditional Chinese medical herb Astragalus, the dried root of Astragalus membranaceus (Fisch.) Bge., has been widely applied to treat patients with cardiovascular disease in China and has profound cardioprotective effects. This study investigated the effect of Astragalus on hemodynamic changes in adriamycin (ADR)-injured rat hearts and its underlying molecular mechanism. Sprague-Dawley rats were divided into four groups: control, ADR only, ADR + low dose of Astragalus and ADR + high dose of Astragalus. Rats were injected intraperitoneally with 6 equal doses of ADR (cumulative dose, 12 mg/kg) over a period of 2 weeks. Treatment of Astragalus began 1 day before the onset of ADR injection and was given orally once a day for 50 days (3.3 or 10 g/kg/day). Five weeks after the final injection of ADR, rats treated with ADR only showed a significant inhibition of cardiac diastolic function accompanied by the presence of ascites, a remarkable reduction in body weight and heart weight as well as survival rate compared to the controls. Moreover, SERCA2a mRNA and protein expressions in hearts were obviously downregulated by ADR. However, this impaired cardiac function was significantly improved in both doses of Astragalus feeding groups. The amount of ascites was also reduced in a similar extent in these 2 groups. Only the high dose treatment of Astragalus significantly attenuated the changes of SERCA2a expression in injured hearts and improved survival. These results indicated that Astragalus could improve cardiac function of ADR-injured rat hearts, which was partly mediated by upregulation of SERCA2a expression.

Effect of traditional Chinese medicine Shu-mai-tang on angiogenesis, arteriogenesis and cardiac function in rats with myocardial ischemia

Ischemic heart disease is one of the leading causes of morbidity and mortality worldwide. Shu-mai-tang (SMT) is a traditional Chinese medicine for the treatment of ischemic heart disease. To better understand the underlying cardioprotection mechanisms of SMT on myocardial ischemia (MI), the effect of SMT on angiogenesis, arteriogenesis and cardiac function was investigated in a rat model of MI, as well as the potential mechanism. Rats with a ligated left anterior descending coronary artery (MI model) were randomized (24 rats/group) to receive SMT/LY294002 [phosphatidylinositol 3-kinase (PI3K) inhibitor], SMT or no treatment. A sham-operation group was included. It was demonstrated that 2 and 4 weeks after treatment the oral administration of SMT significantly increased capillaries and arterioles, suppressed myocardial fibrosis, as well as significantly increased cardiac phosphorylation of Akt, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF-BB) levels and functional improvement. PI3K inhibitor down-regulated SMT-induced angiogenesis and arteriogenesis. These novel therapeutic properties of SMT to induce the reconstitution of stable blood supply networks, reverse LV remodeling may offer an alternative therapy for the treatment of ischemic heart disease. The potential mechanism may be that SMT promotes VEGF and PDGF-BB-mediated angiogenesis and arteriogenesis through the PI3K/Akt signaling pathway.

Inhibitory effects of astragaloside IV on ovalbumin-induced chronic experimental asthma

Astragaloside IV, a new cycloartane-type triterpene glycoside extract of Astragalus membranaceus Bunge, has been identified for its potent immunoregulatory, antiinflammatory, and antifibrotic actions. Here we investigated whether astragaloside IV could suppress the progression of airway inflammation, airway hyperresponsiveness, and airway remodeling in a murine model of chronic asthma. BALB/c mice sensitized to ovalbumin (OVA) were chronically challenged with aerosolized OVA for 8 weeks. Astragaloside IV was orally administered at a dose of 50 mg x kg-1 x day-1 during each OVA challenge. Astragaloside IV treatment resulted in significant reduction of eosinophilic airway inflammation, airway hyperresponsiveness, interleukin (IL)-4 and IL-13 levels in bronchoalveolar lavage fluid, and total immunoglobulin E levels in serum. Furthermore, astragaloside IV treatment markedly inhibited airway remodeling, including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. In addition, the expression of transforming growth factor-beta1 in the lung was also reduced by astragaloside IV. These data indicate that astragaloside IV may mitigate the development of characteristic features in chronic experimental asthma.