Curculigoside attenuates myocardial ischemia‑reperfusion injury by inhibiting the opening of the mitochondrial permeability transition pore

Silver nanoparticle-induced cell damage via impaired mtROS-JNK/MnSOD signaling pathway

This study investigated the mechanism of silver nanoparticle (AgNP) cytotoxicity from a mitochondrial perspective. The effect of AgNP on manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant enzyme, against oxidative stress has not been studied in detail. We demonstrated that AgNP decreased MnSOD mRNA level, protein expression, and activity in human Chang liver cells in a time-dependent manner. AgNP induced the production of mitochondrial reactive oxygen species (mtROS), particularly superoxide anion. AgNP was found to increase mitochondrial calcium level and disrupt mitochondrial function, leading to reduced ATP level, succinate dehydrogenase activity, and mitochondrial permeability. AgNP induced cytochrome c release from the mitochondria into the cytoplasm, attenuated the expression of the anti-apoptotic proteins phospho Bcl-2 and Mcl-1, and induced the expression of the pro-apoptotic proteins Bim and Bax. In addition, c-Jun N-terminal kinase (JNK) phosphorylation was significantly increased by AgNP. Treatment with elamipretide (a mitochondria-targeted antioxidant) and SP600125 (a JNK inhibitor) showed the involvement of MnSOD and JNK in these processes. These results indicated that AgNP damaged human Chang liver cells by destroying mitochondrial function through the accumulation of mtROS.

Lipid-lowering effect and oral transport characteristics study of curculigoside

Introduction

The incidence of metabolic disorders during pregnancy is increasing year by year, with diseases including hypertension and hyperlipidemia. Statins are the primary drugs for treating hyperlipidemia or atherosclerosis, yet some patients remain unresponsive to them, and pregnant women are prohibited from taking statins. Curculigoside is the major biologically active natural product present in Curculigo orchioides.

Methods

In this study, A high-fat mice model was developed to study the lipid-lowering effect of curculigoside. Using intestinal Caco-2 cell monolayer, the curculigoside transport properties at two temperatures and possible transporters were systemically studied.

Results

Curculigoside at concentrations used during the experiments have no toxic effect to Caco-2 cells. The curculigoside transfer from the apical to the basolateral side was strongly influenced by temperature. P-glycoprotein, breast cancer resistance protein, and efflux transporters are crucial components of the human intestinal cell line Caco-2. The curculigoside can significantly affect the contents of total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol in mice.

Discussion

The transport properties and potential mechanism of curculigoside offer valuable insights for the design of development of hypolipidemic drugs like anti-atherosclerotic drugs and also be helpful to the further study of the pharmacological activity of curculigoside.

Mitochondria as novel mediators linking gut microbiota to atherosclerosis that is ameliorated by herbal medicine: A review

Atherosclerosis (AS) is the main cause of cardiovascular disease (CVD) and is characterized by endothelial damage, lipid deposition, and chronic inflammation. Gut microbiota plays an important role in the occurrence and development of AS by regulating host metabolism and immunity. As human mitochondria evolved from primordial bacteria have homologous characteristics, they are attacked by microbial pathogens as target organelles, thus contributing to energy metabolism disorders, oxidative stress, and apoptosis. Therefore, mitochondria may be a key mediator of intestinal microbiota disorders and AS aggravation. Microbial metabolites, such as short-chain fatty acids, trimethylamine, hydrogen sulfide, and bile acids, also affect mitochondrial function, including mtDNA mutation, oxidative stress, and mitophagy, promoting low-grade inflammation. This further damages cellular homeostasis and the balance of innate immunity, aggravating AS. Herbal medicines and their monomers can effectively ameliorate the intestinal flora and their metabolites, improve mitochondrial function, and inhibit atherosclerotic plaques. This review focuses on the interaction between gut microbiota and mitochondria in AS and explores a therapeutic strategy for restoring mitochondrial function and intestinal microbiota disorders using herbal medicines, aiming to provide new insights for the prevention and treatment of AS.

Therapeutic targets by traditional Chinese medicine for ischemia-reperfusion injury induced apoptosis on cardiovascular and cerebrovascular diseases

Traditional Chinese medicine (TCM) has a significant role in treating and preventing human diseases. Ischemic heart and cerebrovascular injuries are two types of diseases with different clinical manifestations with high prevalence and incidence. In recent years, it has been reported that many TCM has beneficial effects on ischemic diseases through the inhibition of apoptosis, which is the key target to treat myocardial and cerebral ischemia. This review provides a comprehensive summary of the mechanisms of various TCMs in treating ischemic cardiovascular and cerebrovascular diseases through anti-apoptotic targets and pathways. However, clinical investigations into elucidating the pharmacodynamic ingredients of TCM are still lacking, which should be further demystified in the future. Overall, the inhibition of apoptosis by TCM may be an effective strategy for treating ischemic cardio-cerebrovascular diseases.

Pretreatment with Panaxatriol Saponin Attenuates Mitochondrial Apoptosis and Oxidative Stress to Facilitate Treatment of Myocardial Ischemia-Reperfusion Injury via the Regulation of Keap1/Nrf2 Activity

Myocardial ischemia-reperfusion injury (MIRI) is a type of severe injury to the ischemic myocardium that can occur following recovery of blood flow, and for which, there is no effective treatment. Panaxatriol saponin (PTS), a major active component of P. notoginseng, has been used clinically to treat ischemia-related encephalopathy due to its antioxidant activity, but its effect on ischemic cardiomyopathy and underlying mechanism of action is still unclear. This study was performed to investigate the protective effect of PTS against MIRI and explore the potential underlying mechanisms. Hydrogen peroxide (H₂O₂) was used to stimulate cardiomyocytes, to mimic MIRI in vitro. Cell viability was tested using the CCK-8 method. The antioxidant activity of PTS in the H9c2 rat cardiomyocyte cell line was examined using 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA). The levels of superoxide dismutase-1 (SOD1), SOD2, and heme oxygenase (HO-1) were determined by Western blotting and/or immunofluorescence. The antiapoptotic effect of PTS was determined. In addition, mitochondrial permeability transition pore (mPTP) opening and mitochondrial membrane potential (ΔΨm) changes were assessed. Changes in Keap1/Nrf2 activation were evaluated by Western blotting analysis, molecular docking, and immunoprecipitation. An in vivo MIRI model was established in rats, and the myocardial infarct size was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Myocardial enzyme activities were determined by ELISA or biochemical analyses. Furthermore, changes in Nrf2 activation were evaluated, and the regulatory effect of PTS on cardiomyocyte apoptosis was examined using the Nrf2 blocker, ML385. The results showed that PTS ameliorated the cardiomyocyte injury induced by H₂O₂, characterized by increased cell viability, decreased reactive oxygen species (ROS) production, and promotion of SOD1, SOD2, and HO1 expression. PTS inhibited cardiomyocyte apoptosis in vivo and in vitro. PTS also reduced mPTP opening and stabilized ΔΨm in H9c2 cells. Molecular docking and immunoprecipitation study revealed that PTS can disrupt Keap1/Nrf2 interaction by directly blocking the binding site of Nrf2 in the Keap1 protein. In vivo, PTS decreased the area of myocardial infarction and attenuated pathological damage in ischemia-reperfusion (I/R) rats. In addition, the activities of myocardial injury markers were decreased by PTS. Finally, PTS regulated nuclear translocation of Nrf2, and ML385 blocked the therapeutic effect of PTS in vivo and in vitro. These results suggested that PTS has therapeutic potential for MIRI by targeting Keap1/Nrf2 activity.

Urocortin I Protects against Myocardial Ischemia/Reperfusion Injury by Sustaining Respiratory Function and Cardiolipin Content via Mitochondrial ATP-Sensitive Potassium Channel Opening

Objective

Our experiments were aimed at probing whether urocortin I postconditioning was beneficial for maintaining the mitochondrial respiratory function and inhibiting the surging of reactive oxygen species. In addition, our experiments also intended to reveal the relationships between urocortin I postconditioning and mitochondrial ATP-sensitive potassium channel.

Methods

Langendorff and MPA perfusion systems were used to establish myocardial ischemia-reperfusion injury model and cardiomyocytes hypoxia-reoxygenation injury model in rats, respectively. Isolated hearts and cardiomyocytes were randomly divided into normal group, ischemia-reperfusion/hypoxia-reoxygenation group, urocortin I postconditioning group, and 5-hydroxysolanoic acid (5-HD)+urocortin I group. At the end of balance (T₁) and reperfusion (T₂), cardiac functions, mitochondrial state3 respiratory, respiratory control ratio, mitochondrial respiratory enzyme activity, and mitochondrial cardiolipin content were measured. Our experiments also observed the ultrastructure of myocardium. The changes of cardiomyocyte mitochondrial permeability transition pore, mitochondrial membrane potential, reactive oxygen species, expression of apoptosis protein, and cardiomyocytes activity were detected at the end of reoxygenation.

Results

The cardiac functions, mitochondrial respiratory function, and enzyme activity of the normal group were better than other three groups at T₂, and urocortin I postconditioning group was better than the IR group and 5-HD+urocortin I group. LVEDP, +dp/dt_max, mitochondrial respiratory function, and enzyme activity of IR group were worse than 5-HD+urocortin I group. Cardiolipin content of the normal group was higher than the other three groups at T₂, urocortin I postconditioning group was higher than the IR group and 5-HD+urocortin I group, and 5-HD+urocortin I group was still higher than the IR group. The ultrastructure of the normal group maintained the most integrated than the other groups, IR group suffered the most serious damage, and ultrastructure of the urocortin I postconditioning group was better than the IR group and 5-HD+urocortin I group. At the end of reoxygenation, activity of mitochondrial permeability transition pore and generation of reactive oxygen species of normal group were lower than the other groups, HR group and 5-HD+urocortin I group were higher than the urocortin I postconditioning group, and 5-HD+urocortin I group was still higher than the urocortin I postconditioning group. Normal group had the highest level of mitochondrial membrane potential at the end of reoxygenation, and the urocortin I postconditioning group was higher than the HR group and 5-HD+urocortin I group. The normal group had the lowest expression level of Bax and the highest expression level of Bcl-2 at the end of reoxygenation. Urocortin I postconditioning group had lower Bax expression but higher Bcl-2 expression than the HR and 5-HD+urocortin I group. Accordingly, the normal group had the highest activity of cardiomyocytes, and the urocortin I postconditioning group was higher than the HR group and 5-HD+urocortin I group.

Conclusions

Urocortin I postconditioning can protect the activity of cardiomyocytes after hypoxia-reoxygenation injury, improve the mitochondrial respiratory function, and enhance the contractility of isolated heart after myocardial ischemia-reperfusion injury. The alleviation of myocardial injury relates to the opening of mitochondrial ATP-sensitive potassium channel.

Research on natural products from traditional Chinese medicine in the treatment of myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a complicated pathologic process that involves multiple factors including oxidative stress (free radical damage), inflammatory response, calcium overloading, and apoptosis in cardiomyocytes. According to Traditional Chinese Medicine (TCM), MIRI belongs to the categories of "chest numbness", "palpitations" and "angina pectoris". Present data indicate that the application of TCM in myocardial ischemia-reperfusion injury is promising and continues to attract research attention. While the efficacy of Chinese herbal medicine has been well-proven, the underlying molecular mechanisms remain elusive. The common proven mechanisms of Chinese herbal medicine in the treatment of MIRI include regulating lipid metabolism, protecting mitochondria, and improving energy metabolism, attenuating calcium (Ca²⁺) overload, scavenging oxygen free radicals, inhibiting apoptosis, and reducing autophagy. Others are the regulation of inflammatory cytokine expressions and healing of inflammatory lesions, modulation of cell signaling pathways, improvement of endothelial cell function, and protection of myocardial cells. In this review, we highlight recent studies that focus on elucidating these molecular mechanisms and the therapeutic effects of natural compounds deriving from TCM in MIRI, to ascertain the research progress made and the prospects in this field.

The effect of curculigo orchioides (Xianmao) on kidney energy metabolism and the related mechanism in rats based on metabolomics

The Chinese materia medica Xianmao (XM) is widely used in Chinese clinics and the traditional Chinese medicine diets. Although XM is often used to study its kidney-yang effect, the research on its effect on kidney energy metabolism and its mechanism is still relatively lacking. In this study, rats were given different doses of XM water extract for 4 weeks. Biochemical method was used to detect the content of serum biochemical indexes of liver and kidney function and blood lipid indicators, and HE staining method was used to observe the histopathological of liver and kidney in rats. The kidney Na+-K+-ATPase, Ca2+-Mg2+-ATPase, SDH (succinate dehydrogenase) enzyme activity, and the content of ATP in rats were measured. Metabolomics technology was used to analyze the potential biomarkers related to the effects of XM on kidney energy metabolism, and then, the metabolic pathways were analyzed. RT-PCR was used to detect the expression of Ampk, Sirt1, Ppar-α, and Pgc-1α mRNA in kidney of rats. The results showed, compared with the blank control group, there was no significant effect on liver and kidney function in XMH, XMM, and XML groups. These significantly increased the kidney Na+-K+-ATPase, Ca2+-Mg2+-ATPase, SDH enzyme activity, and ATP content in XMH, XMM, and XML groups. Mitochondrial metabolic rate was inhibited in XMH group, but it was significantly increased in XMM and XML groups. The number of mitochondria was increased in XMH, XMM, and XML groups. Overall, these effects may be mediated by TCA cycle metabolism, butanoate metabolism, propanoate metabolism, alanine, aspartate, and glutamate metabolism, retinol metabolism, purine metabolism, pentose phosphate metabolism, aminoacyl-tRNA biosynthesis, valine, leucine, and isoleucine biosynthesis, and degradation metabolism pathways, as well as by increasing expression of upstream genes Ampk, Sirt1, Ppar-α, and Pgc-1α mRNA.

Phytochemistry and Pharmacological Activity of Plants of Genus Curculigo: An Updated Review Since 2013

The genus Curculigo, as a folk herbal medicine, has been used for many years in China, treating impotence, limb limpness, and arthritis of the lumbar and knee joints. The last systematic review of the genus Curculigo was written in 2013, scientifically categorizing the phytochemistry and biological activities. Hitherto, the original compounds and their pharmacological activities were presented as the development of this genus, but there is not an updated review. To conclude the progression of the genus Curculigo, we collected the new literature published from 2013 to 2021 in PubMed, Web of Science, Google Scholar databases, and the Chinese National Knowledge Infrastructure. The novel chlorophenolic glucosides, curculigine, phenolic glycosides, orcinosides and polysaccharides were isolated from Curculigo. The new analyzing methods were established to control the quality of Curculigo as a herbal medicine. In addition, the pharmacological effects of Curculigo focused on anti-diabetes, antibacterial, anti-inflammatory, osteoporosis, antioxidation, etc. The antitumor and neuroprotective activities were newly explored in recent years. The application of herbal medicine was gradually developed in scientific methods. The medicinal value of the genus Curculigo needs to further investigate its pharmacological mechanisms. This new review offers more insights into the exploitation of the pharmacological value of the genus Curculigo.

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

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

Brazilin prevents against myocardial ischemia-reperfusion injury through the modulation of Nrf2 via the PKC signaling pathway

Background

Brazilin, a major ingredient of Caesalpinia sappan L., possesses multiple pharmaceutical activities, although whether or not brazilin exerts any protective effect on myocardial ischemia-reperfusion injury (MIRI) has not yet been reported. The present study determined the cardioprotective effects of brazilin, and elucidated the role of nuclear factor E2-associated factor 2 (Nrf2) in this process.

Methods

Following treatment with brazilin, H9c2 cells were subjected to 6 h of hypoxia/3 h of reoxygenation. CCK-8 assay and flow cytometry were employed to detect cell viability and apoptosis, respectively. Furthermore, after brazilin treatment, isolated rat hearts underwent 30 min of ischemia, followed by 90 min of reperfusion. Triphenyltetrazolium chloride (TTC) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining were performed to measure myocardial infarct size and apoptosis, respectively. The changes in the levels of proteins were detected by western blotting.

Results

Brazilin treatment dose-dependently led to a significant enhancement in cell viability, a reduction in myocardial infarct size, and a decrease in release of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH). Moreover, brazilin also remarkably inhibited apoptosis and led to various improvements in cardiac function. Additionally, brazilin treatment caused a marked alleviation of oxidative stress, as evidenced by the fact that brazilin reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activities of superoxide dismutase (SOD) and glutathione peroxidase (GXH-Px). Mechanistically, it was found that brazilin induced Nrf2 nuclear translocation, with a concomitant upregulation of both heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase (NQO1) expression. Furthermore, the phosphorylation level and transcriptional activity of Nrf2 were enhanced by brazilin, although these enhancements were abrogated by treatment with a protein kinase C (PKC) inhibitor. Finally, it was observed that the protective effects of brazilin could be negated through inhibition of Nrf2, which suggested that the cardioprotection afforded by brazilin was Nrf2-dependent.

Conclusions

Taken together, our results have demonstrated that brazilin may afford protection against MIRI through the activation of Nrf2 via the PKC signaling pathway. These results may lay the foundation for the further use of brazilin in the prevention of MIRI in clinical practice.

Overexpression of IκBα in cardiomyocytes alleviates hydrogen peroxide-induced apoptosis and autophagy by inhibiting NF-κB activation

Background

Inflammation and oxidative stress play predominant roles in the initiation and progression of ischaemia/reperfusion (I/R) injury, with nuclear factor kappa B (NF-κB) serving as a crucial mediator. Overexpression of the inhibitor of κB alpha (IκBα) gene is hypothesized to have protective effects against apoptosis and autophagy in cardiomyocytes subjected to hydrogen peroxide (H₂O₂) by inhibiting the NF-κB pathway.

Methods

The IκBα^{S32A, S36A} gene was transfected via adeno-associated virus serotype 9 (AAV9) delivery into neonatal rat ventricular cardiomyocytes (NRVMs) prior to H₂O₂ treatment. NRVMs were divided into control, H₂O₂, GFP + H₂O₂, IκBα+H₂O₂, and pyrrolidine dithiocarbamate (PDTC) + H₂O₂ groups. Nuclear translocation of the NF-κB p65 subunit was evaluated by immunofluorescence and Western blotting. Cell viability was assessed by Cell Counting Kit-8 assay. Supernatant lactate dehydrogenase (LDH) and intracellular malondialdehyde (MDA) were measured to identify H₂O₂-stimulated cytotoxicity. Apoptosis was determined by Annexin V-PE/7-AAD staining, and the mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining. Western blotting was used to detect apoptosis- and autophagy-related proteins.

Results

IκBα transfection significantly increased cell viability and ΔΨm but decreased the supernatant LDH and cellular MDA levels in cardiomyocytes exposed to H₂O₂. Meanwhile, IκBα overexpression decreased H₂O₂-induced apoptosis by upregulating the Bcl-2/Bax ratio and reduced autophagy by downregulating the expression of Beclin-1 and the LC3-II/LC3-I ratio. These effects partly accounted for the ability of IκBα to inhibit the NF-κB signalling pathway, as evidenced by decreases in p65 phosphorylation and nuclear translocation. Indeed, the effects of inactivation of NF-κB signalling with the specific inhibitor PDTC resembled the cardioprotective effects of IκBα during H₂O₂ stimulation.

Conclusion

IκBα overexpression can ameliorate H₂O₂-induced apoptosis, autophagy, oxidative injury, and ΔΨm loss through inhibition of the NF-κB signalling pathway. These findings suggest that IκBα transfection can result in successful resistance to oxidative stress-induced damage by inhibiting NF-κB activation, which may provide a potential therapeutic target for the prevention of myocardial I/R injury.