Icariin Exerts Protective Effect Against Myocardial Ischemia/Reperfusion Injury in Rats

Roles of flavonoids in ischemic heart disease: Cardioprotective effects and mechanisms against myocardial ischemia and reperfusion injury

BACKGROUND

Flavonoids are extensively present in fruits, vegetables, grains, and medicinal plants. Myocardial ischemia and reperfusion (MI/R) comprise a sequence of detrimental incidents following myocardial ischemia. Research indicates that flavonoids have the potential to act as cardioprotective agents against MI/R injuries. Several specific flavonoids, e.g., luteolin, hesperidin, quercetin, kaempferol, and puerarin, have demonstrated cardioprotective activities in animal models.

PURPOSE

The objective of this review is to identify the cardioprotective flavonoids, investigate their mechanisms of action, and explore their application in myocardial ischemia.

METHODS

A search of PubMed database and Google Scholar was conducted using keywords "myocardial ischemia" and "flavonoids". Studies published within the last 10 years reporting on the cardioprotective effects of natural flavonoids on animal models were analyzed.

RESULTS

A total of 55 natural flavonoids were identified and discussed within this review. It can be summarized that flavonoids regulate the following main strategies: antioxidation, anti-inflammation, calcium modulation, mitochondrial protection, ER stress inhibition, anti-apoptosis, ferroptosis inhibition, autophagy modulation, and inhibition of adverse cardiac remodeling. Additionally, the number and position of OH, 3'4'-catechol, C2=C3, and C4=O may play a significant role in the cardioprotective activity of flavonoids.

CONCLUSION

This review serves as a reference for designing a daily diet to prevent or reduce damages following ischemia and screening of flavonoids for clinical application.

Icariin improves cardiac function and remodeling via the TGF-β1/Smad signaling pathway in rats following myocardial infarction

BACKGROUND

Postinfarction cardiac remodeling presents a compensatory mechanism aimed at mitigating congestive heart failure. It is distinguished by progressive dilatation and hypertrophy of the ventricular chambers, fibrotic alterations, and prolonged apoptosis of cardiomyocytes. The primary objective of this study was to assess the effects of icariin on myocardial fibrosis and ventricular remodeling in rats subjected to myocardial infarction (MI).

METHODS

Male Sprague‒Dawley (SD) rats were subjected to randomization and subsequently divided into distinct groups: the control group, the sham group (undergoing sham operation), the MI group (experiencing ligation of the left anterior descending artery), and the icariin group. Within the icariin group, rats were further categorized into three different dose groups based on the administered icariin dosage: the MI30 group (30 mg/kg/day), the MI60 group (60 mg/kg/day), and the MI120 group (120 mg/kg/day). Cardiac function evaluation was carried out using echocardiography. Histological examinations, including hematoxylin and eosin (HE) staining, Masson staining, and immunohistochemistry studies, were conducted 90 days after the occurrence of MI. Additionally, Western blotting was employed to assess TGF-β1, p-Smad2, and p-Smad3 levels.

RESULTS

The administration of icariin revealed a noteworthy enhancement in cardiac function among rats afflicted with left anterior descending coronary artery (LAD) ligation. In comparison to the icariin groups, the MI group exhibited reduced EF and FS, along with elevated LVEDD and LVESD. Furthermore, the cardiac fibrosis levels in the MI group rats exhibited a considerable increase compared to those in the icariin group. Notably, the levels of Collagen I, Collagen III, MMP2, and MMP9 were significantly higher in the MI group than in the icariin group, with evident distinctions. Moreover, the expression levels of TGF-β, IL-13, p-Smad2, and p-Smad3 were notably upregulated in the MI group compared to the icariin group.

CONCLUSIONS

In an experimental rat model of MI, the administration of icariin resulted in the amelioration of both cardiac function and remodeling processes, operating through the intricate TGF-β1/Smad signaling pathway.

Multidisciplinary strategies to enhance therapeutic effects of flavonoids from Epimedii Folium: Integration of herbal medicine, enzyme engineering, and nanotechnology

Flavonoids such as baohuoside I and icaritin are the major active compounds in Epimedii Folium (EF) and possess excellent therapeutic effects on various diseases. Encouragingly, in 2022, icaritin soft capsules were approved to reach the market for the treatment of hepatocellular carcinoma (HCC) by National Medical Products Administration (NMPA) of China. Moreover, recent studies demonstrate that icaritin can serve as immune-modulating agent to exert anti-tumor effects. Nonetheless, both production efficiency and clinical applications of epimedium flavonoids have been restrained because of their low content, poor bioavailability, and unfavorable in vivo delivery efficiency. Recently, various strategies, including enzyme engineering and nanotechnology, have been developed to increase productivity and activity, improve delivery efficiency, and enhance therapeutic effects of epimedium flavonoids. In this review, the structure-activity relationship of epimedium flavonoids is described. Then, enzymatic engineering strategies for increasing the productivity of highly active baohuoside I and icaritin are discussed. The nanomedicines for overcoming in vivo delivery barriers and improving therapeutic effects of various diseases are summarized. Finally, the challenges and an outlook on clinical translation of epimedium flavonoids are proposed.

Regulatory mechanism of icariin in cardiovascular and neurological diseases

Cardiovascular diseases (CVDs) and neurological diseases are widespread diseases with substantial rates of morbidity and mortality around the world. For the past few years, the preventive effects of Chinese herbal medicine on CVDs and neurological diseases have attracted a great deal of attention. Icariin (ICA), the main constituent of Epimedii Herba, is a flavonoid. It has been shown to provide neuroprotection, anti-tumor, anti-osteoporosis, and cardiovascular protection. The endothelial protection, anti-inflammatory, hypolipidemic, antioxidative stress, and anti-apoptosis properties of ICA can help stop the progression of CVDs and neurological diseases. Therefore, our review summarized the known mechanisms and related studies of ICA in the prevention and treatment of cardio-cerebrovascular diseases (CCVDs), to better understand its therapeutic potential.

Icariin exhibits protective effects on cisplatin-induced cardiotoxicity via ROS-mediated oxidative stress injury in vivo and in vitro

BACKGROUND

Cisplatin-induced cardiotoxicity severely limits its clinical application as an antitumor drug and increases the risk of cardiovascular disease. Icariin (ICA), the main flavonoid isolated from Epimedii Folium, has been demonstrated to have various beneficial effects on cardiovascular disease. However, the protective effect of ICA against cisplatin-induced cardiotoxicity remains unclear.

PURPOSE

In present study, we explored the protective action of ICA against cisplatin-induced cardiotoxicity and its possible molecular mechanisms in vitro and in vivo.

METHODS

Mice were intraperitoneally injected with cisplatin 4 mg/kg every other day for 7 times to establish myocardial injury model. ICA (15, 30 mg/kg) was administered to mice by gavage for 21 days. H9c2 cells were treated with ICA (3, 6, 12 µM) in the presence or absence of cisplatin (40 µM), and then cell viability, oxidative stress, apoptosis, and mitochondrial function were evaluated.

RESULTS

Biochemical index detection and histopathological staining analysis showed that ICA had a good protective effect on cisplatin-induced cardiotoxicity. Cellular experiments showed that ICA inhibited cisplatin-induced oxidative stress in a dose-dependent manner by regulating the levels of glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA). ICA could inhibit the expression of NF-κB and the secretion of inflammatory factors, thereby alleviating the inflammatory injury caused by cisplatin. In addition, ICA could alleviate cisplatin-induced myocardial injury by activating SIRT1 and PI3K/Akt signaling pathways and inhibiting MAPKs signaling pathway.

CONCLUSION

These results suggest that ICA could attenuate cisplatin-induced cardiac injury by inhibiting oxidative stress, inflammation and apoptosis, laying a foundation for ICA to reduce chemotherapy-induced cardiotoxicity in clinical practice.

Molecular mechanisms regulating the pharmacological actions of icariin with special focus on PI3K-AKT and Nrf-2 signaling pathways

Icariin is a primary active component of the traditional Chinese medicinal plant Epimedium grandiflorum. A range of pharmacological effects of icariin has been researched by modern science to explain its traditional medicinal uses. Attributing to the wide range of pharmacological properties like anti-osteoporosis, anti-inflammation, anti-oxidative stress, anti-depression, and anti-tumor property possessed by icariin, it is now being considered a potential therapeutic agent for a wide variety of disorders ranging from neoplasm, neurodegenerative disorders, osteoporosis, and cardiovascular diseases. Various signaling pathways including NFκB/NALP3, IGF-1, MiR-223-3p/ NALP3, TLR4/ NFκB, and WNT1/β-catenin are involved in the different biological actions exerted by icariin. Apart from these pathways, PI3K-AKT (Phosphoinositide 3 kinase-Protein kinase B) and Nrf-2 (nuclear erythroid 2-related factor 2) signaling pathways are two important pathways that form the fundamental basis for the pharmaceutical efficacy of icariin. This review gives an overview of previous in vitro and in vivo studies that investigated the potential role of icariin via PI3K-AKT and Nrf-2 signaling pathways to provide greater insights into its potential clinical use in a variety of disorders.

Promising Therapeutic Candidate for Myocardial Ischemia/Reperfusion Injury: What Are the Possible Mechanisms and Roles of Phytochemicals?

Percutaneous coronary intervention (PCI) is one of the most effective reperfusion strategies for acute myocardial infarction (AMI) despite myocardial ischemia/reperfusion (I/R) injury, causing one of the causes of most cardiomyocyte injuries and deaths. The pathological processes of myocardial I/R injury include apoptosis, autophagy, and irreversible cell death caused by calcium overload, oxidative stress, and inflammation. Eventually, myocardial I/R injury causes a spike of further cardiomyocyte injury that contributes to final infarct size (IS) and bound with hospitalization of heart failure as well as all-cause mortality within the following 12 months. Therefore, the addition of adjuvant intervention to improve myocardial salvage and cardiac function calls for further investigation. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in Chinese herbal medicine. Great effort has been put into phytochemicals because they are often in line with the expectations to improve myocardial I/R injury without compromising the clinical efficacy or to even produce synergy. We summarized the previous efforts, briefly outlined the mechanism of myocardial I/R injury, and focused on exploring the cardioprotective effects and potential mechanisms of all phytochemical types that have been investigated under myocardial I/R injury. Phytochemicals deserve to be utilized as promising therapeutic candidates for further development and research on combating myocardial I/R injury. Nevertheless, more studies are needed to provide a better understanding of the mechanism of myocardial I/R injury treatment using phytochemicals and possible side effects associated with this approach.

Icariin Protects H9c2 Rat Cardiomyoblasts from Doxorubicin-Induced Cardiotoxicity: Role of Caveolin-1 Upregulation and Enhanced Autophagic Response

Doxorubicin (Doxo) is a widely used antineoplastic drug which often induces cardiomyopathy, leading to congestive heart failure through the intramyocardial production of reactive oxygen species (ROS). Icariin (Ica) is a flavonoid isolated from Epimedii Herba (Berberidaceae). Some reports on the pharmacological activity of Ica explained its antioxidant and cardioprotective effects. The aim of our study was to assess the protective activities of Ica against Doxo-detrimental effects on rat heart-tissue derived embryonic cardiac myoblasts (H9c2 cells) and to identify, at least in part, the molecular mechanisms involved. Our results showed that pretreatment of H9c2 cells with 1 μM and 5 μM of Ica, prior to Doxo exposure, resulted in an improvement in cell viability, a reduction in ROS generation, the prevention of mitochondrial dysfunction and mPTP opening. Furthermore, for the first time, we identified one feasible molecular mechanism through which Ica could exerts its cardioprotective effects. Indeed, our data showed a significant reduction in Caveolin-1(Cav-1) expression levels and a specific inhibitory effect on phosphodiesterase 5 (PDE5a) activity, improving mitochondrial function compared to Doxo-treated cells. Besides, Ica significantly prevented apoptotic cell death and downregulated the main pro-autophagic marker Beclin-1 and LC3 lipidation rate, restoring physiological levels of activation of the protective autophagic process. These results suggest that Ica might have beneficial cardioprotective effects in attenuating cardiotoxicity in patients requiring anthracycline chemotherapy through the inhibition of oxidative stress and, in particular, through the modulation of Cav-1 expression levels and the involvement of PDE5a activity, thereby leading to cardiac cell survival.

Icariin inhibits hypoxia/reoxygenation-induced ferroptosis of cardiomyocytes via regulation of the Nrf2/HO-1 signaling pathway

Myocardial infarction (MI) is caused by the formation of plaques in the arterial walls, leading to a decrease of blood flow to the heart and myocardium injury as a result of hypoxia. Ferroptosis is a crucial event in myocardial injury, and icariin (ICA) exerts protective effects against myocardial injury. Here, we investigated the protective mechanism of ICA in hypoxia/reoxygenation (H/R)-induced ferroptosis of cardiomyocytes. H9C2 cells were subjected to H/R induction. The content of lactate dehydrogenase and the levels of oxidative stress and intracellular ferrous ion Fe²⁺ were measured. The levels of ferroptosis markers (ACSL4 and GPX4) were detected. H/R-induced H9C2 cells were cultured with ICA in the presence or absence of ferroptosis inducer (erastin). Znpp (an HO-1 inhibitor) was added to ICA-treated H/R cells to verify the role of the Nrf2/HO-1 pathway. H/R-induced H9C2 cells showed reduced viability, enhanced oxidative stress and lactate dehydrogenase content, increased levels of Fe²⁺ and ACSL4, and decreased levels of GPX4. ICA inhibited H/R-induced ferroptosis and oxidative stress in cardiomyocytes. Erastin treatment reversed the inhibitory effect of ICA on ferroptosis in H/R cells. The expression of Nrf2 and HO-1 in H/R-induced H9C2 cells was reduced, whereas ICA treatment reversed this trend. Inhibition of the Nrf2/HO-1 pathway reversed the protective effect of ICA on H/R-induced ferroptosis. Collectively, our results suggest that ICA attenuates H/R-induced ferroptosis of cardiomyocytes by activating the Nrf2/HO-1 signaling pathway.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Multiple Progressive Thermopreconditioning Improves Cardiac Ischemia/Reperfusion-induced Left Ventricular Contractile Dysfunction and Structural Abnormality in Rat

BACKGROUND

Triple progressive thermopreconditioning (3PTP) may induce high Hsp-70 expression to maintain cardiac function. We suggest that 3PTP may reduce myocardial ischemia/reperfusion (I/R) injury during organ transplantation through Bag3/Hsp-70 mediated defense mechanisms.

METHODS

Male Wistar rats were divided into sham control group and 72 h after 3PTP in a 42°C water bath (3PTP) group. Rats underwent 60 min of ischemia by occlusion of the left anterior descending coronary artery followed by 240 min reperfusion. Hemodynamic parameters, including the electrocardiogram, microcirculation, heart rate, left ventricular end-diastolic pressure, maximal rate of rise (+dp/dt), and fall (-dp/dt) in the left ventricular pressure for index of contraction and relaxation were determined. Myocardial infarct size was evaluated by the Evans blue-2,3,5-triphenyltetrazolium chloride method. 3PTP-induced protective mechanisms were determined by Western blot and immunohistochemistry.

RESULTS

Cardiac I/R depressed cardiac microcirculation, induced S-T segment elevation, and R-R and P-R interval elongation increased infarct size associated with erythrocyte extravasation, leukocytes and macrophage/monocyte infiltration, granulocyte colony-stimulating factor, poly(ADP-ribose) polymerase 1 stain, and transferase-mediated dUTP-biotin nick end labeling positive cells. However, 3PTP evoked significant cardioprotection against I/R injury, characterized by the increased +dp/dt value and the decreased elevated left ventricular end-diastolic pressure, erythrocyte extravasation, leukocyte and macrophage/monocyte infiltration, granulocyte colony-stimulating factor expression, poly(ADP-ribose) polymerase 1 expression, transferase-mediated dUTP-biotin nick end labeling positive cells, and fragmentation and infarct area. In addition, 3PTP increased Hsp-70 and Bag3 expression and decreased Bax/Bcl-2 ratio, but did not affect the Beclin-1 and LC3-II/LC3-I ratio in the heart with I/R injury.

CONCLUSIONS

3PTP therapies may through Bag3 upregulation alleviate I/R injury-induced left ventricular structural deterioration and dysfunction.

Ischaemic preconditioning-induced serum exosomes protect against myocardial ischaemia/reperfusion injury in rats by activating the PI3K/AKT signalling pathway

Ischaemia/reperfusion (I/R) injury can lead to severe arrhythmia and aggravate myocardial damage. Exosomes are small-membrane vesicles that play a protective role in myocardial I/R injury. This study aimed to explore the protective effects of ischaemic preconditioning (IPC)-induced serum exosomes (IPC-Exo) on myocardial I/R injury in rats and its underlying mechanism. Serum exosomes were extracted from IPC rats and quantified using a bicinchoninic acid assay kit. IPC-Exo (50 μg) was injected into the infarcted myocardium immediately after ligation. Rats were randomly divided into Sham, I/R, IPC-Exo + I/R, I/R + LY294002, and I/R + IPC-Exo + LY294002 groups. Haemodynamic parameters were measured by physiological recording. Transthoracic echocardiography was used to detect cardiac function. The serum levels of creatine kinase isomer-MB, lactate dehydrogenase, aspartate transaminase, tumour necrosis factor-alpha, interleukin (IL)-1β, and IL-10 were detected by enzyme-linked immunosorbent assay. Triphenyl tetrazolium chloride staining was used to measure the myocardial infarct size. Apoptosis in myocardial tissues was detected by TUNEL staining. Western blotting was used to detect the levels of PI3K/AKT and apoptosis-related proteins. Our results showed that treatment with IPC-Exo ameliorated cardiac function and reduced inflammatory factor production, cardiomyocyte apoptosis, and myocardial infarct size. Moreover, IPC-Exo treatment promoted the protein expression of Bcl-2, p-PI3K, and p-AKT but inhibited that of caspase-3 and Bax. However, treatment with LY294002 significantly reversed that IPC-Exo-induced increase in p-PI3K and p-AKT levels, improvement of haemodynamics, and decrease of inflammatory factor production and apoptosis in the I/R + IPC-Exo group. Taken together, our results suggest that IPC-Exo may alleviate I/R injury via activating the PI3K/AKT signalling pathway.

An injectable liposome for sustained release of icariin to the treatment of acute blunt muscle injury

OBJECTIVES

Icariin, extracted from Epimedium, is a kind of flavonoid and possesses osteogenesis and antioxidant. This study aimed to evaluate the therapeutic effects of icariin liposome on acute blunt skeletal muscle injury in rats.

METHODS

Icariin liposome was prepared by the thin-film dispersion method. After muscle injury, the corresponding treatment measures were given every day for two weeks. Recovery and mechanism of muscle injury were evaluated by QRT-PCR, HE, immunohistochemistry, malondialdehyde, superoxide dismutase and serological tests.

KEY FINDINGS

The particle size, polydispersity index, zeta potential, encapsulation efficiency and drug loading of icariin liposomes were 171.37 ± 38.23 nm, 0.27 ± 0.01, -5.59 ± 1.36 mV, 78.15 ± 2.04% and 15.62%, respectively. The QRT-PCR showed that icariin liposome significantly promoted the expression of MHCIIB and vimentin. Through HE, immunohistochemistry, ELISA and serological tests, we found that icariin liposome effectively promoted desmin expression, reduced collagen I expression and inhibited the production of pro-inflammatory factors, including TNF-α and IL-6. Icariin liposome therapy significantly reduced the level of malondialdehyde and increased the activity of superoxide dismutase.

CONCLUSIONS

Icariin liposome has excellent therapeutic effects on acute blunt muscle injury in rats by improving immunity, repairing cytoskeleton and cellular integrity, anti-inflammation, anti-fibrosis and antioxidant stress.

Icariin Ameliorates Diabetic Cardiomyopathy Through Apelin/Sirt3 Signalling to Improve Mitochondrial Dysfunction

Myocardial contractile dysfunction in diabetic cardiomyocytes is a significant promoter of heart failure. Herein, we investigated the effect of icariin, a flavonoid monomer isolated from Epimedium, on diabetic cardiomyopathy (DCM) and explored the mechanisms underlying its unique pharmacological cardioprotective functions. High glucose (HG) conditions were simulated in vitro using cardiomyocytes isolated from neonatal C57 mice, while DCM was stimulated in vivo in db/db mice. Mice and cardiomyocytes were treated with icariin, with or without overexpression or silencing of Apelin and Sirt3 via transfection with adenoviral vectors (Ad-RNA) and specific small hairpin RNAs (Ad-sh-RNA), respectively. Icariin markedly improved mitochondrial function both in vivo and in vitro, as evidenced by an increased level of mitochondrial-related proteins via western blot analysis (PGC-1α, Mfn2, and Cyt-b) and an increased mitochondrial membrane potential, as observed via JC-1 staining. Further, icariin treatment decreased cardiac fibrogenesis (Masson staining), and inhibited apoptosis (TUNEL staining). Together, these changes improved cardiac function, according to multiple transthoracic echocardiography parameters, including LVEF, LVSF, LVESD, and LVEDD. Moreover, icariin significantly activated Apelin and Sirt3, which were inhibited by HG and DCM. Importantly, when Ad-sh-Apelin and Ad-sh-Sirt3 were transfected in cardiomyocytes or injected into the heart of db/db mice, the cardioprotective effects of icariin were abolished and mitochondrial homeostasis was disrupted. Further, it was postulated that since Ad-Apelin induced different results following increased Sirt3 expression, icariin may have attenuated DCM development by preventing mitochondrial dysfunction through the Apelin/Sirt3 pathway. Hence, protection against mitochondrial dysfunction using icariin may prove to be a promising therapeutic strategy against DCM in diabetes.

Technetium-99 m-PEGylated dendrimer-G2-(Dabcyle-Lys6,Phe7)-pHBSP: A novel Nano-Radiotracer for molecular and early detecting of cardiac ischemic region

In cardiac ischemic disorder, pyroglutamate helix B surface peptide (pHBSP) which derived from erythropoietin causes to increase cell stability. To improve the serum stability of pHBSP, two lipophilic amino acids Arg⁶, Ala⁷ were replaced with Fmoc-(Dabcyle)-Lys-OH and Fmoc-Phe-OH during the peptide synthesis. This peptide was subsequently conjugated to PEGylated dendrimer-G₂ and labeled with ^99mTcO₄^- to detect cardiac ischemic region. Radiochemical purity (RCP) of ^99mTc-PEGylated dendrimer-G₂-(Dabcyle-Lys⁶,Phe⁷)-pHBSP was evaluated by ITLC method. In addition, the radiopeptide was investigated for stability in human serum and binding affinity to hypoxic cells in myocardium H9c2 cell lines. Biodistribution and SPECT/CT scintigraphy were assessed in cardiac ischemic rats. Radiochemical yield indicated that the anionic dendrimer has a very high potential to complex formation with ^99mTcO^-₄ (RCP > 94%) which was stable in human serum with RCP 89% up to 6 h. The binding of ^99mTc- nanoconjugate to hypoxic cells was significantly more than normoxic cells (3-fold higher compared to normoxic cells at 1 h). In biodistribution studies, erythropoietin receptor-Beta common receptor (EPO-BcR)-positive uptake in the cardiac ischemic region was 3.62 ± 0.44% ID/g 30 min post injection. SPECT imaging showed a prominent uptake of ^99mTc-nanoconjugate in EPO-BcR expressing ischemic heart.

Icariin protects against radiation-induced mortality and damage in vitro and in vivo

Purpose: The present study aimed to investigate the potential protective effects of icariin both in vivo and in vitro, an active flavonoid glucoside derived from medicinal herb Epimedium, and its possible mechanisms against radiation-induced injury. Methods: Male C57BL/6 mice were exposed to lethal dose (7 Gy) or sub-lethal dose (4 Gy) of whole body radiation by X-ray at a dose rate of ∼0.55 Gy/min, and icariin was given three times at 24 h and 30 min before and 24 h after the irradiation. After irradiation, hematological, biochemical, and histological evaluations were performed. We further determined the effect of icariin on radiation-induced cytotoxicity and changes in apoptosis-related protein expression. Results: Icariin enhanced the 30-day survival rates (20 and 40 mg/kg) in a dose-dependent manner, and protected the radiosensitive organs such as intestine and testis from the radiation damages. Moreover, hematopoietic damage by radiation was significantly decreased in icariin-treated mice as demonstrated by the increases in number of peripheral blood cells, bone marrow cells (1.7-fold), and spleen colony forming units (1.7-fold). In addition, icariin decreased the radiation-induced oxidative stress by modulating endogenous antioxidant levels. Subsequent in vitro studies showed that icariin effectively increased cell viability (1.4-fold) and suppressed the expression of apoptosis-related proteins after irradiation. Conclusion: These results suggest that icariin has significant protective effects against radiation-induced damages partly through its anti-oxidative and anti-apoptotic properties.

Hydromorphine postconditioning protects isolated rat heart against ischemia-reperfusion injury via activating P13K/Akt/eNOS signaling

INTRODUCTION

Myocardial ischemia/reperfusion injury (myocardial I/R injury) has a high disability rate and mortality. Novel treatments for myocardial I/R injury are necessary.

AIM

In order to explore the protective effect of hydromorphine on myocardial I/R injury, we illuminate the underlying mechanism of the protective effect.

RESULTS

Hydromorphine significantly reduced myocardial infarct size (IFN/AAR), CKMB (Creatine Kinase MB) and TN-T (Troponin T) release, and improved cardiac function compared with I/R group. However, these advantageous effects were partly suppressed in the presence of hydromorphine. Myocardial I/R injury significantly decreased the phosphorylation of Akt and eNOS, and down-regulated total nitric oxide and nitrotyrosine content, while these inhibitory effects were partly abolished by hydromorphine. Conversely, the activated effects of hydromorphine on the phosphorylation of Akt and eNOS, and NO release were totally reversed by LY294002, which, used individually, show the same influence on reperfusion injury.

CONCLUSIONS

These findings suggest that hydromorphine postconditioning may protect isolated rat heart against reperfusion injury via activating P13K/Akt/eNOS signaling.

Icariin protects cardiomyocytes against ischaemia/reperfusion injury by attenuating sirtuin 1-dependent mitochondrial oxidative damage

BACKGROUND AND PURPOSE

Icariin, a major active ingredient in traditional Chinese medicines, is attracting increasing attention because of its unique pharmacological effects against ischaemic heart disease. The histone deacetylase, sirtuin-1, plays a protective role in ischaemia/reperfusion (I/R) injury, and this study was designed to investigate the protective role of icariin in models of cardiac I/R injury and to elucidate the potential involvement of sirtuin-1.

EXPERIMENTAL APPROACH

I/R injury was simulated in vivo (mouse hearts), ex vivo (isolated rat hearts) and in vitro (neonatal rat cardiomyocytes and H9c2 cells). Prior to I/R injury, animals or cells were exposed to icariin, with or without inhibitors of sirtuin-1 (sirtinol and SIRT1 siRNA).

KEY RESULTS

In vivo and in vitro, icariin given before I/R significantly improved post-I/R heart contraction and limited the infarct size and leakage of creatine kinase-MB and LDH from the damaged myocardium. Icariin also attenuated I/R-induced mitochondrial oxidative damage, decreasing malondialdehyde content and increasing superoxide dismutase activity and expression of Mn-superoxide dismutase. Icariin significantly improved mitochondrial membrane homeostasis by increasing mitochondrial membrane potential and cytochrome C stabilization, which further inhibited cell apoptosis. Sirtuin-1 was significantly up-regulated in hearts treated with icariin, whereas Ac-FOXO1 was simultaneously down-regulated. Importantly, sirtinol and SIRT1 siRNA either blocked icariin-induced cardioprotection or disrupted icariin-mediated mitochondrial homeostasis.

CONCLUSIONS AND IMPLICATIONS

Pretreatment with icariin protected cardiomyocytes from I/R-induced oxidative stress through activation of sirtuin-1 /FOXO1 signalling.

[Icariin alleviates lipid peroxidation after spinal cord injury in rats]

OBJECTIVE

To assess the effects of intragastric administration of icariin on lipid peroxidation after spinal cord injury in rats.

METHODS

Seventy-two healthy adult male SD rats were randomized equally into icariin group, control group and sham-operated group. In the control and icariin groups, spinal cord injury was induced using modified Allen's method, and the rats in the sham-operated group underwent laminotomy without damaging the spinal cord. Immediately after the surgery, the rats in icariin group were subjected to intragastric administration of icariin (100 mg/kg), and those in the control and sham-operated groups received an equal volume of saline in the same manner once a day. At 24 h after the operation, malondialdehyde (MDA) content was detected using thiobarbituric acid method, superoxide dismutase (SOD) activity was measured with xanthine oxidase method, and the water content in the spinal cord was measured using dry-wet weight method. At 48 h after the operation, the ultrastructure of the spinal cord was observed with transmission electron microscopy and scored using Kaptanoglu scoring method. The motor function of the rats was assessed using BBB scoring at 7, 14, 21 and 28 days after the operation.

RESULTS

At 24 h after the operation, MDA content was significantly higher in the control group and icariin group than in the sham-operated group, and was significantly lower in icariin group than in the control group (P<0.05); SOD activity was significantly higher in icariin group than in the control group, and was both significantly lower than that in the sham-operated group (P<0.05). At 48 h after operation, the water content and ultrastructure score of the spinal cord were the highest in sham-operated group (P<0.05), and were significantly lower in icariin group than in the control group (P<0.05). At all the time points of measurement, the BBB scores were significantly lower in the control and icariin groups than in the sham-operated group (P<0.05), and were significantly higher in icariin group than in the control group (P<0.05).

CONCLUSION

Icariin can significantly reduce MDA content, increase SOD activity, and ameliorate lipid peroxidation, spinal cord edema, and histopathological damage of the spinal cord to improve motor function of rats with spinal cord injury.

Icariin protects against ischemia‑reperfusion injury in H9C2 cells by upregulating heat shock protein 20

Icariin (ICA) has been implicated in certain biological and pathological processes, including myocardial ischemia/reperfusion (I/R) injury. The aim of the present study was to investigate the role of ICA in I/R‑induced cardiomyocyte injury and the potential underlying mechanism. Cell proliferation and apoptosis of H9C2 cells was determined by cell counting kit‑8 and flow cytometry assays. In addition, reactive oxygen species (ROS) production in H9C2 cells was measured by flow cytometry. Reverse transcription‑quantitative polymerase chain reaction and western blot assay were performed to examine the expression levels of proteins, including HSP20, B‑cell lymphoma 2 (Bcl‑2), cytochrome complex (Cyt‑c), apoptotic protease activating factor 1 (APAF1), caspase‑9 andcaspase‑3, and the phosphorylation of Akt (p‑Akt) in H9C2 cells. The present results demonstrated that, compared with the control group, the I/R group demonstrated significantly reduced levels of HSP20 expression and cell proliferation, and increased apoptosis and ROS production in H9C2 cells. In parallel, the expression levels of Cyt‑c, APAF1, caspase‑9 and caspase‑3 were significantly increased in the I/R group, although Bcl‑2 and p‑Akt/Akt expression levels were decreased. Furthermore, compared with the I/R group, ICA treatment and/or HSP20 overexpression significantly improved cardiac function, as evidenced by promoted cell proliferation and inhibited apoptosis of H9C2 cells. The current study indicates that ICA exerts a cardioprotective effect against I/R injury, which is associated with the upregulation of HSP20.

Icariin Prevents H2O2-Induced Apoptosis via the PI3K/Akt Pathway in Rat Nucleus Pulposus Intervertebral Disc Cells

Icariin is a prenylated flavonol glycoside derived from the Chinese herb Epimedium sagittatum. This study investigated the mechanism by which icariin prevents H₂O₂-induced apoptosis in rat nucleus pulposus (NP) cells. NP cells were isolated from the rat intervertebral disc and they were divided into five groups after 3 passages: (A) blank control; (B) 200 μM H₂O₂; (C) 200 μM H₂O₂ + 20 μM icariin; (D) 20 μM icariin + 200 μM H₂O₂ + 25 μM LY294002; (E) 200 μM H₂O₂ + 25 μM LY294002. LY294002 is a selective inhibitor of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. NP cell viability, apoptosis rate, intracellular reactive oxygen species levels, and the expression of AKT, p-AKT, p53, Bcl-2, Bax, caspase-3 were estimated. The results show that, compared with the control group, H₂O₂ significantly increased NP cell apoptosis and the level of intracellular ROS. Icariin pretreatment significantly decreased H₂O₂-induced apoptosis and intracellular ROS and upregulated p-Akt and BCL-2 and downregulated caspase-3 and Bax. LY294002 abolished the protective effects of icariin. Our results show that icariin can attenuate H2O2-induced apoptosis in rat nucleus pulposus cells and PI3K/AKT pathway is at least partly included in this protection effect.

The Anticancer Properties of Herba Epimedii and Its Main Bioactive Componentsicariin and Icariside II

Cancer is one of the leading causes of deaths worldwide. Compounds derived from traditional Chinese medicines have been an important source of anticancer drugs and adjuvant agents to potentiate the efficacy of chemotherapeutic drugs and improve the side effects of chemotherapy. HerbaEpimedii is one of most popular herbs used in China traditionally for the treatment of multiple diseases, including osteoporosis, sexual dysfunction, hypertension and common inflammatory diseases. Studies show HerbaEpimedii also possesses anticancer activity. Flavonol glycosides icariin and icariside II are the main bioactive components of HerbaEpimedii. They have been found to possess anticancer activities against various human cancer cell lines in vitro and mouse tumor models in vivo via their effects on multiple biological pathways, including cell cycle regulation, apoptosis, angiogenesis, and metastasis, and a variety of signaling pathways including JAK2-STAT3, MAPK-ERK, and PI3k-Akt-mTOR. The review is aimed to provide an overview of the current research results supporting their therapeutic effects and to highlight the molecular targets and action mechanisms.

Icariin attenuated oxidative stress induced-cardiac apoptosis by mitochondria protection and ERK activation

Our previous study showed that Icariin (ICA) has anti-cardiac hypertrophy effect in rats with an unknown mechanism. In the present study, we aimed to clarify the cardiac protective effect and mechanism of ICA in vitro. H9C2 cardiac myocytes were incubated with H₂O₂ to build up the oxidative stress injury model. The results showed that pre-treatment of ICA protected cells against the toxicity induced by H₂O₂. H₂O₂ treatment significantly reduced H₂O₂-induced apoptosis, evidenced by lower Annexin V/PI stained cells and less PARP and caspase-3/9 activation. Mitochondria membrane potential (MMP) dissipation occurred following the exposure of H₂O₂, which could be prevented by ICA treatment. Moreover, Ca²⁺ homeostasis was preserved by ICA and ROS generation was significantly suppressed by ICA incubation. Interestingly, ICA treatment increased the phosphorylation of upstream ERK mitogen-activated protein kinase (MAPK) while ERK inhibitor U1026 could reverse the protective effect of ICA. Overall, ICA seems to protect the cardiac cells from oxidative stress injury through ROS scavenge and stimulation of ERK pathway which may explain its effects in vivo.

Anthocyanins in cardioprotection: A path through mitochondria

Constantly growing experimental data from in vitro, in vivo and epidemiological studies show the great potential of anthocyanin-containing fruit and berry extracts or pure individual anthocyanins as cardioprotective food components or pharmacological compounds. In general it is regarded that the cardioprotective activity of anthocyanins is related to their antioxidant properties. However there are recent reports that certain anthocyanins may protect the heart against ischemia/reperfusion-induced injury by activating signal transduction pathways and sustaining mitochondrial functions instead of acting solely as antioxidants. In this review, we summarize the proposed mechanisms of direct or indirect actions of anthocyanins within cardiac cells with the special emphasis on recently discovered their pharmacological effects on mitochondria in cardioprotection: reduction of cytosolic cytochrome c preventing apoptosis and sustainment of electron transfer between NADH dehydrogenase and cytochrome c supporting oxidative phosphorylation in ischemia-damaged mitochondria.