Astragalus membranaceus prevents daunorubicin-induced apoptosis of cultured neonatal cardiomyocytes: role of free radical effect of Astragalus membranaceus on daunorubicin cardiotoxicity

Assessing Drug-Induced Mitochondrial Toxicity in Cardiomyocytes: Implications for Preclinical Cardiac Safety Evaluation

Drug-induced cardiotoxicity not only leads to the attrition of drugs during development, but also contributes to the high morbidity and mortality rates of cardiovascular diseases. Comprehensive testing for proarrhythmic risks of drugs has been applied in preclinical cardiac safety assessment for over 15 years. However, other mechanisms of cardiac toxicity have not received such attention. Of them, mitochondrial impairment is a common form of cardiotoxicity and is known to account for over half of cardiovascular adverse-event-related black box warnings imposed by the U.S. Food and Drug Administration. Although it has been studied in great depth, mitochondrial toxicity assessment has not yet been incorporated into routine safety tests for cardiotoxicity at the preclinical stage. This review discusses the main characteristics of mitochondria in cardiomyocytes, drug-induced mitochondrial toxicities, and high-throughput screening strategies for cardiomyocytes, as well as their proposed integration into preclinical safety pharmacology. We emphasize the advantages of using adult human primary cardiomyocytes for the evaluation of mitochondrial morphology and function, and the need for a novel cardiac safety testing platform integrating mitochondrial toxicity and proarrhythmic risk assessments in cardiac safety evaluation.

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.

A New Method for Screening Natural Products to Stimulate IFN-γ Production in Jurkat Human T Lymphocytes

Interferon-γ (IFN-γ) is a critical cytokine in the defense against viral and bacterial infection. It is mainly produced by natural killer cells and activated T cells. Given its regulatory role in coordinating cellular and humoral immune responses, IFN-γ is considered to be an effective therapeutic agent in the treatment of viral infection. Here we established a fluorescence-based high-content screening model to find small molecules that can stimulate the production of IFN-γ in human Jurkat cells. After a primary screening of 267 natural products, two hits, Astragalus polyphenols and 6-shogaol, were identified to promote the activity of the IFN-γ promoter and subsequently validated by the flow cytometry assay. Obviously, both Astragalus polyphenols and 6-shogaol exhibited potential to induce the transcription and expression of IFN-γ in a dose-dependent manner. These results indicated that our high-content screening model could be a credible and useful platform to contribute to the discovery of novel molecules to promote the expression of IFN-γ and provide leading compounds for the treatment of viral infectious diseases.

Halofuginone protects against advanced glycation end products‑induced injury of H9C2 cells via alleviating endoplasmic reticulum stress‑associated apoptosis and inducing autophagy

Advanced glycation end products (AGEs) have been reported to serve an important role in the stiffening of cardiac tissues and myocardial cell injury. Serious myocardial cell injury can result in various heart diseases with high mortality. Halofuginone (HF), which possesses marked anti-inflammatory and antifibrotic effects, has recently been applied to inhibit the effects of cardiac stress. The present study aimed to investigate the potential effects of HF and its underlying mechanism in the treatment of AGEs-induced H9C2 cardiomyocyte damage. The western blot results of the present study demonstrated that HF may reduce the expression levels of myocardial injury markers, including myoglobin, creatine kinase MB and cardiac troponin I. In addition, flow cytometric analysis indicated that the production of reactive oxygen species (ROS) was significantly decreased by HF. Additionally, endoplasmic reticulum (ER) stress was suppressed in response to treatment with HF, as observed by low expression levels of ER stress-associated proapoptotic proteins (CCAAT/enhancer-binding protein homologous protein and cleaved caspase-12); overexpression of prosurvival proteins (growth arrest and DNA damage-inducible protein GADD34 and binding immunoglobulin protein) was also reported. Furthermore, the expression levels of microtubule-associated proteins 1A/1B light chain 3B (LC3)II/LC3I and Beclin 1 were elevated, whereas P62 expression levels were reduced following treatment with HF. These findings, together with immunofluorescence staining of LC3, indicated that HF may induce autophagy. Finally, the protective effects of HF on AGEs-treated H9C2 cells were reversed following treatment with the inhibitor 3-methyladenine, as indicated by inhibition of autophagy, and increases in apoptosis, ROS production and the ER stress response. Collectively, the findings of the present study suggested that the protective effects of HF against AGEs-induced myocardial cell injury may be associated with the induction of autophagy and amelioration of ROS-mediated ER stress and apoptosis. These findings may contribute to the development of a novel therapeutic method to inhibit the progression of myocardial cell injury.

The Extracts and Major Compounds Derived from Astragali Radix Alter Mitochondrial Bioenergetics in Cultured Cardiomyocytes: Comparison of Various Polar Solvents and Compounds

Astragali Radix (AR) is a widely used "Qi-invigorating" herb in China for its tonic effects in strengthening biological tissues. The extract of AR contains abundant antioxidants, including astragalosides and isoflavonoids. However, very few reports have systematically measured the effects of the major components of AR on cell mitochondrial bioenergetics. Here, a systemic approach employing an extracellular flux analyzer was developed to evaluate mitochondrial respiration in cultured cardiomyocyte cells H9C2. The effects of different polar extractives, as well as of the major compounds of AR, were compared. The contents of astragaloside IV, calycosin, formononetin, and genistein in the AR extracts obtained by using water, 50% ethanol, and 90% ethanol were measured by liquid chromatograph-mass spectrometer (LC⁻MS). The antioxidant activities of the AR extracts, as well as of their major compounds, were determined by measuring the free radical scavenging activity and protective effects in tert-butyl hydroperoxide (tBHP)-treated H9C2 cells. By monitoring the real-time oxygen consumption rate (OCR) in tBHP-treated cardiomyocytes with a Seahorse extracellular flux analyzer, the tonic effects of the AR extracts and of their main compounds on mitochondrial bioenergetics were evaluated. AR water extracts possessed the strongest antioxidant activity and protective effects in cardiomyocytes exposed to oxidative stress. The protection was proposed to be mediated via increasing the spare respiratory capacity and mitochondrial ATP production in the stressed cells. The major compounds of AR, astragaloside IV and genistein, showed opposite effects in regulating mitochondrial bioenergetics. These results demonstrate that highly polar extracts of AR, especially astragaloside-enriched extracts, possess better tonic effects on mitochondrial bioenergetics of cultured cardiomyocytes than extracts with a lower polarity.

Formononetin, an active compound of Astragalus membranaceus (Fisch) Bunge, inhibits hypoxia-induced retinal neovascularization via the HIF-1α/VEGF signaling pathway

BACKGROUND

It has been reported that formononetin (FMN), one of the main ingredients from famous traditional Chinese medicine "Huang-qi" (Astragalus membranaceus [Fisch] Bunge) for Qi-tonifying, exhibits the effects of immunomodulation and tumor growth inhibition via antiangiogenesis. Furthermore, A. membranaceus may alleviate the retinal neovascularization (NV) of diabetic retinopathy. However, the information of FMN on retinal NV is limited so far. In the present study, we investigated the effects of FMN on the hypoxia-induced retinal NV and the possible related mechanisms.

MATERIALS AND METHODS

The VEGF secretion model of acute retinal pigment epithelial-19 (ARPE-19) cells under chemical hypoxia was established by the exposure of cells to 150 μM CoCl₂ and then cells were treated with 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1, a potent HIF-1α inhibitor, 1.0 μg/mL) or different concentrations of FMN (0.2 μg/mL, 1.0 μg/mL, and 5.0 μg/mL). The supernatants of cells were collected 48 hours later to measure the VEGF concentrations, following the manufacturer's instruction. The mRNA expressions of VEGF, HIF-1α, PHD-2, and β-actin were analyzed by quantitative reverse transcription polymerase chain reaction, and the protein expressions of HIF-1α and PHD-2 were determined by Western blot analysis. Furthermore, the rats with retinopathy were treated by intraperitoneal administration of conbercept injection (1.0 mg/kg) or FMN (5.0 mg/kg and 10.0 mg/kg) in an 80% oxygen atmosphere. The retinal avascular areas were assessed through visualization of the retinal vasculature by adenosine diphosphatase staining and hematoxylin and eosin staining.

RESULTS

FMN can indeed inhibit the VEGF secretion of ARPE-19 cells under hypoxia, downregulate the mRNA expression of VEGFA and PHD-2, and decrease the protein expression of VEGF, HIF-1α, and PHD-2 in vitro. Furthermore, FMN can prevent hypoxia-induced retinal NV in vivo.

CONCLUSION

FMN can ameliorate retinal NV via the HIF-1α/VEGF signaling pathway, and it may become a potential drug for the prevention and treatment of diabetic retinopathy.

A systematic review of anticancer effects of radix astragali

OBJECTIVE

To review the anticancer effects of Radix astragali (RA), one of the most commonly used herbs to manage cancer in East Asia, and its constituents and to provide evidence of clinical usage through previously performed clinical studies.

METHODS

Preclinical and clinical studies related to the anticancer effects of RA were searched from inception to November 2013 in electronic databases. Two reviewers independently investigated 92 eligible studies, extracted all the data of studies and appraised methodological quality of clinical trials. The studies were categorized into in vitro and in vivo experimental studies and clinical studies, and analyzed by saponins, polysaccharides, and flavonoids of RA constituents, RA fraction, and whole extract.

RESULTS

In preclinical studies, RA was reported to have tumor growth inhibitory effects, immunomodulatory effects, and attenuating adverse effects by cytotoxic agents as well as chemopreventive effects. Saponins seemed to be the main constituents, which directly contributed to suppression of tumor growth through the activation of both intrinsic and extrinsic apoptotic pathway, modulation of intracellular signaling pathway, and inhibition of invasion and angiogenesis. Flavonoids suppressed tumor growth through the similar mechanisms with saponins. Polysaccharides showed immunomodulatory effects, contributing tumor shrinkages in animal models, despite the low cytotoxicity to cancer cells. Most of the clinical studies were performed with low evidence level of study designs because of various limitations. RA whole extracts and polysaccharides of RA were reported to improve the quality of life and ameliorate myelosuppression and other adverse events induced by cytotoxic therapies.

CONCLUSION

The polysaccharides, saponins, and flavonoids of RA, and the whole extract of RA have been widely reported with their anticancer effects in preclinical studies and showed a potential application as a adjunctive cancer therapeutics with the activities of immunomodulation, anti-proliferation and attenuation of adverse effects induced by cytotoxic therapy.

Extracts from Astragalus membranaceus limit myocardial cell death and improve cardiac function in a rat model of myocardial ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Astragalus membranaceus, known as "huang-qi", is one of the most widely used Chinese herbal medicines for the prevention and treatment of myocardial ischemic diseases. However, the mechanisms governing its therapeutic effects are largely unknown.

AIMS OF THE STUDY

The aims of the present study were to investigate the cardioprotective effect of the root extract of Astragalu membranaceus (EAM) in myocardial ischemia and to explore its underlying mechanisms in ROS-mediated signaling cascade in vivo and in vitro.

MATERIALS AND METHODS

The saponins in EAM were analyzed using HPLC. The tests for the cardioprotective effects of EAM and its mechanisms were performed in vivo and in vitro. In vivo, the rat model of persistent myocardial ischemia was produced by occlusion of the left anterior descending (LAD) coronary artery. In vitro, the cardiomyocyte model of oxidative stress was mimicked by the direct free radical donor, H2O2.

RESULTS

In vivo, the increased myocardial infarct size and the increased serum levels of lactate dehydrogenase (LDH), creatine kinase isoform MB (CK-MB), and cardiac troponin (cTnI) were significantly decreased by pre-treatment with EAM. Moreover, cardiac function, as assessed by±dP/dt, left ventricular developed pressure (LVDP), and left ventricular end-diastolic pressure (LVEDP), was dramatically improved. An oxidative stress biomarker, malondialdehyde (MDA), was reduced, and the antioxidant enzyme superoxide dismutase (SOD) was induced. In vitro, H2O2-triggered myocardial cell death and cytoplasm Ca(2+) overload were blocked by treatment with EAM. Furthermore, the KATP channel blocker (5-HD, glibenclamide) blocked the anti-apoptotic protective effect of EAM on cardiomyocytes injured by H2O2.

CONCLUSIONS

The cardioprotection of EAM was manifested as a protection of tissue structure and as a decrease in serum markers of ischemic injury. The mechanisms underlying the EAM-mediated protective effects may involve improving cardiac function, attenuating the oxidative injury via a decrease in MDA, a maintenance in SOD, and a reduction in free radical-induced myocardial cell injury. Additionally, EAM enhanced the myocardial cell viability via arresting the influx of Ca(2+) to block cell death and opening mitochondrial KATP channels to reduce cell apoptosis.

Neuroprotective effects of the Chinese Yi-Qi-Bu-Shen recipe extract on injury of rat hippocampal neurons induced by hypoxia/reoxygenation

OBJECTIVE

To explore the protective effects of the Chinese Yi-Qi-Bu-Shen recipe (YB) against neuronal injury induced by hypoxia-reoxygenation, which has shown beneficial effect in improving the brain function of type 2 diabetics likely through its antihyperglycemic, antioxidant activity, and investigate its mechanisms.

METHODS

The bilateral hippocampus was collected from newborn rats to establish single cell suspension. On the 10th day, the primarily cultured hippocampal neurons were randomly divided into five groups: the normal group (NG), the hypoxia/reoxygenation group (HG), and groups protected with small, medium and large dosages of YB (SG, MG and LG, respectively). The YB-protected groups were treated with different concentrations of YB containing serum before reoxygenation. The metabolic rate of MTT, the malondialdehyde (MDA) content, and the activity of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) were measured with assay kits. The apoptosis rate of hippocampal neurons were tested using flow cytometry analysis. RT-PCR was used to evaluate the mRNA expressions of bcl-2 and bax genes.

RESULTS

The SOD activity, the cell survival rate, the bcl-2/bax ratio, and the bcl-2mRNA expression in the HG group were significantly lower (all P<0.01), but the levels of MDA and LDH, the apoptosis rate, and the bax mRNA expression were higher (all P<0.01) than those in the NG group. The SOD activity, the cell survival, the bcl-2mRNA expression, and the bcl-2/bax ratio were significantly higher in all of the YB-protected groups (all P<0.01), but the level of MDA and LDH, the apoptosis rate, and the bax mRNA expression were lower (P<0.01, P<0.05) than those in the HG group in a dose dependent manner.

CONCLUSION

The YB extract has a protective effect on hippocampal neurons against injury induced by hypoxia/reoxygenation, through its antioxidant activity and the regulation of apoptosis.

Astragalus membranaceus ameliorates reproductive toxicity induced by cyclophosphamide in male mice

The root of Astragalus membranaceus B(UNGE) (AM) is a medicinal herb that has been capable of reducing the adverse effects of conventional chemotherapy. To investigate the effects of AM on cyclophosphamide (CP)-induced reproductive toxicity in mouse testes, 5-week-old male imprinting control region mice were divided into five groups; CP was treated on the first day of each week for 5 weeks (100 mg/kg, i.p.), and AM was treated for 5 days a week for 5 weeks. At the end of the treatment period, the testes were taken out, cleared of the adhering tissues, and weighed. Epididymis was taken out and used for sperm analysis. Testis samples were frozen for real-time quantitative PCR and Western blot analysis. AM treatment increased diminished relative testes weight, and sperm count and motility in mice treated with CP. CP treatment has detrimental effects on the expression of cAMP-responsive element modulator (CREM), a transcription factor that is highly expressed in male germ cells and is crucial to post-meiotic germ cell differentiation. AM restored CREM at both the mRNA and protein levels. AM has beneficial influences and appears able to ameliorate relative testes weight, sperm parameters, and CREM expression against CP-induced reproductive toxicity.

Astragalus polysaccharides enhance the humoral and cellular immune responses of hepatitis B surface antigen vaccination through inhibiting the expression of transforming growth factor β and the frequency of regulatory T cells

Astragalus polysaccharides (APS), extracted from the root of Astragalus membranaceus, a traditional Chinese medicinal herb, have extensive pharmacological and strong immunomodulatory effects. In this study, the potential adjuvant effect of APS on humoral and cellular immune responses to hepatitis B subunit vaccine was investigated. Coadministration of APS with recombinant hepatitis B surface antigen significantly increased antigen-specific antibody production, T-cell proliferation and CTL (cytotoxic T lymphocyte) activity. Production of interferon-γ (IFN-γ), interleukin-2 (IL-2) and IL-4 in CD4(+) T cells and of IFN-γ in CD8(+) T cells were dramatically increased. Furthermore, expression of the genes PFP, GraB, Fas L and Fas were up-regulated; interestingly, expression of transforming growth factor β (TGF-β) and the frequency of CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg cells) were down-regulated. Expression of Toll-like receptor 4 (TLR4) was significantly increased by administration of APS. Together, these results suggest that APS is a potent adjuvant for the hepatitis B subunit vaccine and can enhance both humoral and cellular immune responses via activating the TLR4 signaling pathway and inhibit the expression of TGF-β and frequency of Treg cells.

Mitochondrial protection and anti-aging activity of Astragalus polysaccharides and their potential mechanism

The current study was performed to investigate mitochondrial protection and anti-aging activity of Astragalus polysaccharides (APS) and the potential underlying mechanism. Lipid peroxidation of liver and brain mitochondria was induced by Fe²⁺–Vit C in vitro. Thiobarbituric acid (TBA) colorimetry was used to measure the content of thiobarbituric acid reactive substances (TBARS). Mouse liver mitochondrial permeability transition (PT) was induced by calcium overload in vitro and spectrophotometry was used to measure it. The scavenging activities of APS on superoxide anion (O₂^•−) and hydroxyl radical (•OH), which were produced by reduced nicotinamide adenine dinucleotide (NADH)—N-Methylphenazonium methyl sulfate (PMS) and hydrogen peroxide (H₂O₂)–Fe²⁺ system respectively, were measured by 4-nitrobluetetrazolium chloride (NBT) reduction and Fenton reaction colorimetry respectively. The Na₂S₂O₃ titration method was used to measure the scavenging activities of APS on H₂O₂. APS could inhibit TBARS production, protect mitochondria from PT, and scavenge O₂^•−, •OH and H₂O₂ significantly in a concentration-dependent manner respectively. The back of the neck of mice was injected subcutaneously with D-galactose to induce aging at a dose of 100 mg/kg/d for seven weeks. Moreover, the activities of catalase (CAT), surperoxide dismutase (SOD) and glutathione peroxidase (GPx) and anti-hydroxyl radical which were assayed by using commercial monitoring kits were increased significantly in vivo by APS. According to this research, APS protects mitochondria by scavenging reactive oxygen species (ROS), inhibiting mitochondrial PT and increasing the activities of antioxidases. Therefore, APS has the effect of promoting health.