Vasorelaxant effects of icariin on isolated canine coronary artery

Icariin attenuates vascular endothelial dysfunction by inhibiting inflammation through GPER/Sirt1/HMGB1 signaling pathway in type 1 diabetic rats

Icariin, a flavonoid glycoside, is extracted from Epimedium. This study aimed to investigate the vascular protective effects of icariin in type 1 diabetic rats by inhibiting high-mobility group box 1 (HMGB1)-related inflammation and exploring its potential mechanisms. The impact of icariin on vascular dysfunction was assessed in streptozotocin (STZ)-induced diabetic rats through vascular reactivity studies. Western blotting and immunofluorescence assays were performed to measure the expressions of target proteins. The release of HMGB1 and pro-inflammation cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The results revealed that icariin administration enhanced acetylcholine-induced vasodilation in the aortas of diabetic rats. It also notably reduced the release of pro-inflammatory cytokines, including interleukin-8 (IL-8), IL-6, IL-1β, and tumor necrosis factor-alpha (TNF-α) in diabetic rats and high glucose (HG)-induced human umbilical vein endothelial cells (HUVECs). The results also unveiled that the pro-inflammatory cytokines in the culture medium of HUVECs could be increased by rHMGB1. The increased release of HMGB1 and upregulated expressions of HMGB1-related inflammatory factors, including advanced glycation end products (RAGE), Toll-like receptor 4 (TLR4), and phosphorylated p65 (p-p65) in diabetic rats and HG-induced HUVECs, were remarkably suppressed by icariin. Notably, HMGB1 translocation from the nucleus to the cytoplasm in HUVECs under HG was inhibited by icariin. Meanwhile, icariin could activate G protein-coupled estrogen receptor (GPER) and sirt1. To explore the role of GPER and Sirt1 in the inhibitory effect of icariin on HMGB1 release and HMGB-induced inflammation, GPER inhibitor and Sirt1 inhibitor were used in this study. These inhibitors diminished the effects of icariin on HMGB1 release and HMGB1-induced inflammation. Specifically, the GPER inhibitor also negated the activation of Sirt1 by icariin. These findings suggest that icariin activates GPER and increases the expression of Sirt1, which in turn reduces HMGB1 translocation and release, thereby improving vascular endothelial function in type 1 diabetic rats by inhibiting inflammation.

Icariin protects testicular damage in streptozotocin-induced diabetic rats through regulation of glycolysis pathway

OBJECTIVE

This study aims to investigate potential beneficial actions of icariin (ICA) on testicular spermatogenic function in male rats with streptozotocin (STZ)-induced diabetes and to explore the underlying mechanisms. Background: ICA was found to reduce blood glucose, regulate the endocrine function of the reproductive system, and improve testicular spermatogenic function.

METHODS

Adult rats were intraperitoneally injected with STZ (65 mg/kg) to induce type 1 diabetes mellitus (T1DM). Diabetic rats were randomly classified intoT1DM (n = 6) and T1DM + ICA (n = 6) groups. Rats without STZ and ICA treatment were assigned as control group (n = 6). The morphology of testicular tissues was examined by histological staining. The mRNA and protein expression levels were determined by quantitative real-time PCR, Western blot and immunostaining, respectively.

RESULTS

Rats from T1DM group showed a reduction in epididymis and testis weight, and a decrease in sperm count when compared to control group (p < 0.01), which was attenuated by ICA treatment (p < 0.05) Diabetic rats from T1DM group also exhibited reduced diameter and area of seminiferous tubules, along with decreased spermatogonia and primary spermatocytes number when compared to control group (p < 0.01), which was partially reversed by ICA treatment (p < 0.05) Rats from T1DM group exhibited down-regulation of PCNA mRNA and protein in the testis when compared to control group (p < 0.01); while ICA treatment up-regulated PCNA expression in the testis of diabetic rats compared to T1DM group (p < 0.05). Rats from T1DM group showed up-regulation of Bax and capase-3 and down-regulation of Bcl-2, PKM2, HK2 and lactate dehydrogenase A in the testes when compared to control group (p < 0.05), which was reversed by ICA treatment (p < 0.05).

CONCLUSION

These findings suggest that ICA may exert its protective effects on testicular damage in diabetic rats through modulation of glycolysis pathway and suppression of apoptosis.

Natural products as the calcium channel blockers for the treatment of arrhythmia: Advance and prospect

Arrhythmia is one of the commonly heart diseases with observed abnormal heart-beat rhythm that caused by the obstacles of cardiac activity and conduction. The arrhythmic pathogenesis is complex and capricious and related with other cardiovascular diseases that may lead to heart failure and sudden death. In particular, calcium overload is recognized as the main reason causing arrhythmia through inducing apoptosis in cardiomyocytes. Moreover, calcium channel blockers have been widely used as the routine drugs for the treatment of arrhythmia, but the different arrhythmic complications and adverse effects limit their further applications and demand new drug discovery. Natural products have always been the rich minerals for the development of new drugs that could be employed as the versatile player for the discovery of safe and effective anti-arrhythmia drugs with new mechanisms. In this review, we summarized natural products with the activity against calcium signaling and the relevant mechanism of actions. We are expected to provide an inspiration for the pharmaceutical chemists to develop more potent calcium channel blockers for the treatment of arrhythmia.

Icariin ameliorates metabolic syndrome-induced benign prostatic hyperplasia in rats

Metabolic syndrome (MetS) is an immense health issue that causes serious complications in aging males including BPH. Icariin (ICA) is a flavonol glycoside that exerts a plethora of pharmacological effects. The present investigation tested the potential of ICA to ameliorate benign prostatic hyperplasia (BPH) induced by MetS in rats. Animals were allocated to 5 groups in which the first and second groups were kept on water and regular food pellets. MetS was induced in the third, fourth, and fifth groups by keeping the animals on high fructose and salt diets for twelve consecutive weeks. These groups were given vehicle, ICA (25 mg/kg), and ICA (50 mg/kg), respectively. MetS was confirmed by an increase in rats' weight, accumulation of visceral fat, insulin resistance, and dyslipidemia. This was accompanied by manifestation of BPH including increased prostate weight, prostate index, and histopathological alterations. Treating the animals with both doses of ICA significantly ameliorated the increase in weight and index of the prostate as well as altered prostate histopathology. In addition, ICA significantly decreased cyclin D1 expression, upregulated Bax, and downregulated Bcl2 mRNA expression. ICA prevented lipid peroxidation, reduced glutathione depletion, and catalase exhaustion, which further lowered markers of prostate inflammation such as interleukin-6 and tumor necrosis factor-α. Moreover, ICA prevented the decrease in prostate content of phosphorylated 5'-adenosine monophosphate (AMP)-activated protein kinase (pAMPK). In conclusion, ICA protects against MetS-induced BPH. This is due to its antiproliferative, proapoptotic, antioxidant, and anti-inflammatory activities as well as the activation of AMPK.

Biomineralized Composite Liquid Crystal Fiber Scaffold Promotes Bone Regeneration by Enhancement of Osteogenesis and Angiogenesis

Liquid crystals (LCs) are appealing biomaterials for applications in bone regenerative medicine due to their tunable physical properties and anisotropic viscoelastic behavior. This study reports a novel composite poly (L-lactide) (PLLA) scaffold that is manufactured by a simple electrospinning and biomineralization technique that precisely controls the fibrous structure in liquid LC phase. The enriched-LC composites have superior mineralization ability than neat PLLA; furthermore BMSC cells were inoculated onto the HAP-PLLA/LC with hydroxyapatite (HAP) composite scaffold to test the capability for osteogenesis in vitro. The results show that the PLLA/LC with HAP produced by mineralization leads to better cell compatibility, which is beneficial to cell proliferation, osteogenic differentiation, and expression of the angiogenic CD31 gene. Moreover, in vivo studies showed that the HAP-PLLA/LC scaffold with a bone-like environment significantly accelerates new and mature lamellar bone formation by development of a microenvironment for vascularized bone regeneration. Thus, this bionic composite scaffold in an LC state combining osteogenesis with vascularized activities is a promising biomaterial for bone regeneration in defective areas.

Secondary Metabolites of Plants as Modulators of Endothelium Functions

According to the World Health Organization, cardiovascular diseases are the main cause of death worldwide. They may be caused by various factors or combinations of factors. Frequently, endothelial dysfunction is involved in either development of the disorder or results from it. On the other hand, the endothelium may be disordered for other reasons, e.g., due to infection, such as COVID-19. The understanding of the role and significance of the endothelium in the body has changed significantly over time—from a simple physical barrier to a complex system encompassing local and systemic regulation of numerous processes in the body. Endothelium disorders may arise from impairment of one or more signaling pathways affecting dilator or constrictor activity, including nitric oxide–cyclic guanosine monophosphate activation, prostacyclin–cyclic adenosine monophosphate activation, phosphodiesterase inhibition, and potassium channel activation or intracellular calcium level inhibition. In this review, plants are summarized as sources of biologically active substances affecting the endothelium. This paper compares individual substances and mechanisms that are known to affect the endothelium, and which subsequently may cause the development of cardiovascular disorders.

Icariin ameliorates endothelial dysfunction in type 1 diabetic rats by suppressing ER stress via the PPARα/Sirt1/AMPKα pathway

Icariin (ICA), as a flavonoid glycoside, is associated with the improvement of vascular complications in diabetes. However, its protective mechanisms remain to be well-established. Here, we tested the hypothesis that ICA attenuates vascular endothelial dysfunction by inhibiting endoplasmic reticulum (ER) stress in type 1 diabetes. In streptozotocin-induced diabetic rats, ICA positively affected acetylcholine-induced vasodilation and phenylephrine-induced vasoconstriction in aortas. ICA treatment significantly attenuated ER stress in diabetic rats and high-glucose induced human umbilical vein endothelial cells. Incubation with ICA in vitro attenuated vascular reactivity in diabetic rats, which was blocked by the ER stress inducer, and peroxisome proliferator-activated receptor α (PPARα), sirtuin1 (Sirt1), or AMP-activated protein kinase-α (AMPKα) inhibitors. Western blot showed that ICA activated the PPARα/Sirt1/AMPKα pathway, which contributed to reducing ER stress and activating endothelial nitric oxide synthase in vivo and vitro. Our results implicate that ICA normalizes ER stress to attenuate endothelial dysfunction by the regulation of the PPARα/Sirt1/AMPKα pathway.

Icariin treatment reduces blood glucose levels in type 2 diabetic rats and protects pancreatic function

Icariin, a flavonoid isolated from traditional oriental herbal medicines, has been demonstrated to exhibit several health benefits in animal models and in humans. The aim of the present study was to investigate the effect of Icariin on hyperglycemia in type 2 diabetes mellitus (T2DM) in rats. A model of diabetes was established in 50 Sprague Dawley rats using a high-sugar and high-fat diet and peritoneal injection of streptozotocin. Diabetic rats were divided into five groups: Diabetic control; metformin; and rats treated with three different doses of Icariin, 5, 10 and 20 mg/kg. Body weight and blood glucose levels were measured, and serum adiponectin levels, expression of phospho-AMP mediated protein kinase (p-AMPK) and glucose transporter isoform 4 (GLUT-4) were measured using ELISA, Realtime PCR and western blotting, respectively. Diabetic rats without drug treatment exhibited reduced body weight, increased blood glucose levels and decreased the number of islets. In T2DM rats treated with 10 or 20 mg/kg Icariin, the blood glucose levels were reduced, whereas serum adiponectin levels were not affected. Additionally, the mRNA and protein expression levels of p-AMPK and GLUT-4 protein were increased in the T2DM rats treated with Icariin. In conclusion, in the diabetes rat model, Icariin alleviated the severity of diabetes, and the effects may be associated with reduction of hyperglycemia by activating an AMPK/GLUT-4 pathway.

Retracted: Icariin attenuates methotrexate chemotherapy-induced bone marrow microvascular damage and bone loss in rats

Methotrexate (MTX), a widely used antimetabolite in paediatric cancer to treatment, has been widely reported to cause bone loss and bone marrow (BM) microvascular (particularly sinusoids) damage. Investigations must now investigate how MTX-induced bone loss and microvasculature damage can be attenuated/prevented. In the present study, we examined the potency of icariin, an herbal flavonoid, in reducing bone loss and the dilation/damage of BM sinusoids in rats caused by MTX treatment. Groups of young rats were treated with five daily MTX injections (0.75 mg/kg) with and without icariin oral supplementation until Day 9 after the first MTX injection. Histological analyses showed a significant reduction in the bone volume/tissue volume (BV/TV) fraction (%) and trabecular number in the metaphysis trabecular bone of MTX-treated rats, but no significant changes in trabecular thickness and trabecular spacing. However, the BV/TV (%) and trabecular number were found to be significantly higher in MTX + icariin-treated rats than those of MTX alone-treated rats. Gene expression analyses showed that icariin treatment maintained expression of osteogenesis-related genes but suppressed the induction of adipogenesis-related genes in bones of MTX-treated rats. In addition, icariin treatment attenuated MTX-induced dilation of BM sinusoids and upregulated expression of endothelial cell marker CD31 in the metaphysis bone of icariin + MTX-treated rats. Furthermore, in vitro studies suggest that icariin treatment can potentially enhance the survival of cultured rat sinusoidal endothelial cells against cytotoxic effect of MTX and promote their migration and tube formation abilities, which is associated with enhanced production of nitric oxide.

Protective effects of icariin on human vascular endothelial cells induced by oxidized low-density lipoprotein via modulating caspase-3 and Bcl-2

Icariin belongs to the family of flavonoids that is extracted from Epimedium brevicornum Maxim, and exhibits antioxidative, antitumorigenic, antiosteoporotic, immunoregulatory and antiatherosclerotic properties. To understand the mechanisms underlying the antiatherosclerotic properties of icariin, the present study investigated the effects of icariin on human vascular endothelial cells (HUVECs) following treatment with oxidized low‑density lipoprotein (ox‑LDL). Thus, following pretreatment with icariin at four various concentrations (0, 10, 20 and 40 µM), HUVECs were stimulated with ox‑LDL (100 µg/ml). The viability of cells was evaluated via an MTT assay and flow cytometry was performed to assess apoptosis. Additionally, the protein and mRNA expression levels of apoptosis regulator Bcl‑2 (Bcl‑2) and caspase‑3 were determined by western blotting and reverse transcription‑quantitative polymerase chain reaction. The findings of the present study indicated that icariin prevented injury and apoptosis in HUVECs following ox‑LDL treatment, in particular via the regulation of protein and mRNA expression levels of Bcl-2 and caspase-3.

Potential of Icariin Metabolites from Epimedium koreanum Nakai as Antidiabetic Therapeutic Agents

The therapeutic properties of Epimedium koreanum are presumed to be due to the flavonoid component icariin, which has been reported to have broad pharmacological potential and has demonstrated anti-diabetic, anti-Alzheimer’s disease, anti-tumor, and hepatoprotective activities. Considering these therapeutic properties of icariin, its deglycosylated icaritin and glycosylated flavonoids (icaeriside II, epimedin A, epimedin B, and epimedin C) were evaluated for their ability to inhibit protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase. The results show that icaritin and icariside II exhibit potent inhibitory activities, with 50% inhibition concentration (IC₅₀) values of 11.59 ± 1.39 μM and 9.94 ± 0.15 μM against PTP1B and 74.42 ± 0.01 and 106.59 ± 0.44 μM against α-glucosidase, respectively. With the exceptions of icaritin and icariside II, glycosylated flavonoids did not exhibit any inhibitory effects in the two assays. Enzyme kinetics analyses revealed that icaritin and icariside II demonstrated noncompetitive-type inhibition against PTP1B, with inhibition constant (K_i) values of 11.41 and 11.66 μM, respectively. Moreover, molecular docking analysis confirmed that icaritin and icariside II both occupy the same site as allosteric ligand. Thus, the molecular docking simulation results were in close agreement with the experimental data with respect to inhibition activity. In conclusion, deglycosylated metabolites of icariin from E. koreanum might offer therapeutic potential for the treatment of type 2 diabetes mellitus.

Icariin Inhibits AMPK-Dependent Autophagy and Adipogenesis in Adipocytes In vitro and in a Model of Graves' Orbitopathy In vivo

Graves' orbitopathy (GO), an extrathyroidal manifestation of Graves' disease, is an inflammatory autoimmune disorder of the orbit that involves the differentiation of precursor cells into mature adipocytes and retro-orbital adipose tissue accumulation. Here, we examined the involvement of autophagy in adipogenesis and explored the effects of icariin, a flavonoid isolated from the genus Epimedium with a wide range of biological and pharmacological effects, on autophagy and adipogenesis in 3T3-L1 preadipocytes and in a mouse model of GO. Microscopic examination of autophagosome formation and lipid droplet accumulation by Oil Red O staining, and western blot assessment of autophagic markers in the presence of the autophagy inhibitors Asn and 3-MA showed that autophagy is essential for adipogenesis. Icariin inhibited the differentiation of preadipocytes into mature adipocytes by suppressing autophagy, and these effects were mediated by the inhibition of AMPK/mTOR pathway activation. In a mouse model of thyroid stimulating hormone receptor induced GO, icariin reduced orbital muscle adipose tissue expansion and lipid droplet accumulation by inhibiting AMPK/mTOR mediated autophagy. Collectively, these results reveal a potential mechanism underlying the protective effects of icariin against autophagy induced adipogenesis and suggest that icariin could be developed as a new therapeutic candidate for the prevention and treatment of GO.

Icariin Attenuates High-cholesterol Diet Induced Atherosclerosis in Rats by Inhibition of Inflammatory Response and p38 MAPK Signaling Pathway

Icariin is a flavonoid isolated from the traditional Chinese herbal medicine Epimedium brevicornum Maxim and has been reported to be effective for the treatment of a variety of cardiovascular diseases. The aim of the present study was to investigate the effect and mechanism of icariin on atherosclerosis (AS) using a high-cholesterol diet (HCD)-induced rat model. Seventy male Wistar rats were divided into five groups: 20 in the control group, 20 in the AS group, 10 in the simvastatin group, 10 in the low-dose icariin group, and 10 in the high-dose icariin group. A HCD and vitamin D3 were administered to establish AS rat model. The five groups of rats received daily intragastric administration of normal saline, simvastatin, or icariin (30 mg/kg/d, 60 mg/kg/d) for 4 weeks. The levels of blood lipids, superoxide dismutase (SOD), and malonaldehyde (MDA) were measured. The mRNA levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were analyzed by real-time RT-PCR, and the serum levels of IL-6 and TNF-α were measured using ELISA kit. In addition, the expression of phosphorylated p38 (p-p38) MAPK was detected by Western blot analysis. The results indicated that AS rat models were successfully constructed. In the AS group, the levels of blood lipids including total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), and MDA were significantly increased, while high-density lipoprotein-cholesterol (HDL-C) and SOD were significantly decreased, compared with those in the control group. However, icariin succeeded in improving these biochemical parameters towards the normal values in the control group. In the simvastatin group and the icariin groups, the serum levels of IL-6 and TNF-α and the related tissue mRNA levels, as well as the expression of p-p38 MAPK, were markedly reduced compared with the AS group. In conclusion, the present study indicated that icariin inhibited the HCD-induced dyslipidemia in rats, the mechanisms may be associated with the anti-inflammation, anti-oxidative stress, and downregulation of p-p38 MAPK by icariin.

Icariin regulates PRMT/ADMA/DDAH pathway to improve endothelial function

BACKGROUND

Oxidative stress may affect PRMT/ADMA/DDAH (protein arginine methyltransferases/asymmetric dimethylarginine/dimethylarginine dimethylaminohydrolase) pathway to impair endothelial dysfunction. The present study was carried out to test the effect of icariin on endothelial function and the mechanisms responsible for this.

METHODS

Eighty mice at 12 weeks of age were separated randomly into four groups (n = 20): C57BL/6J control, untreated apolipoprotein E-deficient (ApoE(-/-)), two groups of icariin-treated (10 or 30 mg/kg body wt/day, intragastrically) ApoE(-/-). Primary human umbilical vein endothelial cells (HUVECs) were randomly divided into 7 groups: control group, vehicle of icariin (10 μmol/L) group, icariin (10 μmol/L) group, lysophosphatidylcholine (LPC) (10 μg/mL) group, LPC plus icariin (1 μmol/L) group, LPC plus icariin (3 μmol/L) group, and LPC plus icariin (10 μmol/L) group.

RESULTS

In ApoE(-/-) mice and primary HUVECs, icariin treatment decreased reactive oxygen species production, PRMT I expression, ADMA level, half-maximum effective concentration of ApoE(-/-) mice aortic rings. Icariin increased DDAH II expression, DDAH activity, maximal relaxation value and endothelium-dependent vasorelaxation in aortic rings from ApoE(-/-) mice (p < 0.05 or p < 0.01).

CONCLUSIONS

The present results suggest that icariin regulates PRMT/ADMA/DDAH pathway to improve endothelial function.

Pharmacological effects and pharmacokinetic properties of icariin, the major bioactive component in Herba Epimedii

Herba Epimedii is an important medicinal plant which has been used in various traditional Chinese formulations for thousands of years as well as in modern proprietary traditional Chinese medicine products. It has extensive clinical indications, especially for the treatment of sexual dysfunction and osteoporosis. There have been more than 260 chemical moieties identified in the genus Epimedium most of which belong to flavonoids. Icariin is the most abundant constituent in Herba Epimedii. Icariin is pharmacologically bioactive and demonstrates extensive therapeutic capacities such as osteoprotective effect, neuroprotective effect, cardiovascular protective effect, anti-cancer effect, anti-inflammation effect, immunoprotective effect and reproductive function. Particularly, the significant osteogenic effect of icariin made it a promising drug candidate in bone tissue engineering. The current review paper aims to summarize the literatures reporting the pharmacological effects of icariin. The pharmacokinetic properties of bioactive ingredients in Herba Epimedii have also been discussed.

Plant polyphenols in the treatment of age-associated diseases: revealing the pleiotropic effects of icariin by network analysis

Polyphenols are a broad class of compounds. Some are ingested in substantial quantities from nutritional sources, more are produced by medicinal plants, and some of them are taken as drugs. It is becoming clear, that a single polyphenol is impacting several cellular pathways. Thus, a network approach is becoming feasible, describing the interaction of a single polyphenol with cellular networks. Here we have selected icariin to draw a prototypic network of icariin activities. Icariin appears to be a promising drug to treat major age-related diseases, like neurodegeneration, memory and depressive disorders, chronic inflammation, diabetes, and osteoporosis. It interacts with several relevant pathways, like PDE, TGF-ß, MAPK, PPAR, NOS, IGF, Sirtuin, and others. Such networks will be useful to future comparative studies of complex effects of polyphenols.

Systems pharmacology strategies for drug discovery and combination with applications to cardiovascular diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Multi-target therapeutics is a promising paradigm for drug discovery which is expected to produce greater levels of efficacy with fewer adverse effects and toxicity than monotherapies. Medical herbs featuring multi-components and multi-targets may serve as valuable resources for network-based multi-target drug discovery.

MATERIALS AND METHODS

In this study, we report an integrated systems pharmacology platform for drug discovery and combination, with a typical example applied to herbal medicines in the treatment of cardiovascular diseases.

RESULTS

First, a disease-specific drug-target network was constructed and examined at systems level to capture the key disease-relevant biology for discovery of multi-targeted agents. Second, considering an integration of disease complexity and multilevel connectivity, a comprehensive database of literature-reported associations, chemicals and pharmacology for herbal medicines was designed. Third, a large-scale systematic analysis combining pharmacokinetics, chemogenomics, pharmacology and systems biology data through computational methods was performed and validated experimentally, which results in a superior output of information for systematic drug design strategies for complex diseases.

CONCLUSIONS

This strategy integrating different types of technologies is expected to help create new opportunities for drug discovery and combination.

Vasodilator compounds derived from plants and their mechanisms of action

The present paper reviews vasodilator compounds isolated from plants that were reported in the past 22 years (1990 to 2012) and the different mechanisms of action involved in their vasodilator effects. The search for reports was conducted in a comprehensive manner, intending to encompass those metabolites with a vasodilator effect whose mechanism of action involved both vascular endothelium and arterial smooth muscle. The results obtained from our bibliographic search showed that over half of the isolated compounds have a mechanism of action involving the endothelium. Most of these bioactive metabolites cause vasodilation either by activating the nitric oxide/cGMP pathway or by blocking voltage-dependent calcium channels. Moreover, it was found that many compounds induced vasodilation by more than one mechanism. This review confirms that secondary metabolites, which include a significant group of compounds with extensive chemical diversity, are a valuable source of new pharmaceuticals useful for the treatment and prevention of cardiovascular diseases.

Icariin delays homocysteine-induced endothelial cellular senescence involving activation of the PI3K/AKT-eNOS signaling pathway

CONTEXT

Homocysteine-induced endothelial cellular senescence may contribute to some cardiovascular disorders. Icariin (ICA), a flavonoid derived from Epimedium sagittatum Maxim. (Berberidaceae), has been reported to increase production of nitric oxide (NO) and reduce reactive oxygen species (ROS) levels in human umbilical vein endothelial cells (HUVECs).

OBJECTIVE

To observe the effects of ICA on homocysteine-induced senescence and the underlying mechanisms in HUVECs.

MATERIALS AND METHODS

ICA at concentrations of 0.1, 1, and 5 μM was added into homocysteine pretreated HUVECs. Cellular senescence was assayed by senescence-associated β-galactosidase (SA-β-gal) staining and cumulative population doublings (CPDs). ICA (5 μM) was given orally to homocysteine-treated rats, luminal surface of aortic artery of rats was subjected to SA-β-gal staining. Protein expression was measured by western blot.

RESULTS

Homocysteine significantly increased cellular senescence both in vitro and in vivo. After treatment by ICA, the percentage of SA-β-gal-positive cells, and the ROS level significantly decreased. The CPDs were partially restored. ICA also significantly reduced the mean density of SA-β-gal staining in vivo. We found that NO production and phosphorylation of AKT, ERK, and endothelial NO synthase (eNOS) were elevated by ICA in HUVECs. Furthermore, the increased level of NO production was fully abolished by the phosphatidylinositol-3-kinase (PI3K) inhibitor wortmannin. The mitogen-activated protein kinase (MEK) inhibitor PD98059, which can inhibit phosphorylation of ERK, did not show this ability.

DISCUSSION AND CONCLUSION

Our results indicate that ICA delays homocyteine-induced endothelial senescence in vitro and in vivo. Activation of PI3K/Akt-eNOS-dependent signaling pathway may be responsible for this efficacy of ICA.

High-performance liquid chromatography-based multivariate analysis to predict the estrogenic activity of an Epimedium koreanum extract

This study characterizes the correlation between the chemical fingerprint and estrogenic activity of an Epimedium koreanum extract. The estrogenic activity of 31 E. koreanum extract samples was evaluated by a luciferase reporter gene assay, and the samples were classified into 3 groups based on their bioactivity. A chemical fingerprint analysis was performed on each sample by high-performance liquid chromatography (HPLC), and 44 common peaks were selected from the chromatogram and used as a dataset for a pattern recognition analysis. A canonical discriminant analysis performed on this dataset determined a distinct distribution of the samples according to their estrogenic activity on the scoring plot. The classification results showed that 90.3% of the original grouped cases had been correctly classified. The total content of the 4 major extract compounds, epimedin A, epimedin B, epimedin C, and icariin, exhibited good correlation (r=0.784) with the estrogenic activities of the respective extracts. This chromatographic fingerprint-chemometric analysis system could be useful for predicting the E. koreanum pharmacological activity and consequent biological activity-relevant quality control assessment.

[Icariin and its pharmaceutical efficacy: research progress of molecular mechanism]

Icariin is one of the key active components of Epimedium species, which is most widely applied to supplement the kidney in traditional Chinese medicine. Scientific research has found that icariin possesses extensive therapeutic effects such as protecting neurons from injury, promoting growth of neuronal synapse, improving sexual dysfunction and bone morphogenesis, as well as anti-inflammation, anti-tumor and anti-depression functions. Considering that molecular mechanism is the fundamental basis for pharmaceutical efficacy of icariin, in this article, the authors retrospectively retrieved 122 scientific papers recorded in the PubMed database with "icariin" in the title from January 1, 1995 to January 5, 2011. It was found that icariin has been closely highlighted in the intervention of p38 mitogen-activated protein kinases and phosphatidylinositol 3-kinase/Akt signal pathways, inhibition of phosphodiesterase 5, and regulation of nuclear receptors. Besides, the authors also discussed the main orientation for molecular mechanism of icariin in future research.

Janus activated kinase 2/signal transducer and activator of transcription 3 pathway mediates icariside II-induced apoptosis in U266 multiple myeloma cells

Although the flavonoid icariside II exhibits anti-inflammatory and anti-cancer activities, its molecular targets/pathways in human multiple myeloma cells are poorly understood. To analyze the effects on signal transducer and activator of transcription 3 (STAT3) signaling and apoptosis, U266 multiple myeloma cells were treated with icariside II and performed Western blotting, electrophoretic mobility gel shift assay (EMSA), RT-PCR, proliferation assay, cell cycle analysis and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Icariside II inhibited STAT3 activation and enhanced the expression of SHP-1 and PTEN through inhibiting Janus activated kinase 2 (JAK2) and c-Src. Icariside II down-regulated the expression of STAT3 target genes Bcl-2, Bcl-x(L), survivin, cyclin D(1), COX-2 and vascular endothelial growth factor (VEGF). Also, icariside II enhanced poly (ADP-ribose) polymerase (PARP) cleavage and caspase-3 activation. Pervanadate reversed the icariside II-mediated STAT3 inactivation and also blocked the cleavages of caspase-3 and PARP, suggesting involvement of STAT3 pathway in icariside II-induced apoptosis. Furthermore, icariside II enhanced the apoptotic effects of clinically used drugs thalidomide and bortezomib in U266 cells. Icariside II could be a potential therapeutic intervention agent alone or in combination with current drugs for multiple myeloma as a novel blocker of STAT3 signaling cascades at multiple levels, contributing to its anti-proliferative and anti-apoptosis.

Icariin-mediated differentiation of mouse adipose-derived stem cells into cardiomyocytes

In this study, we investigated the ability of mouse adipose-derived stem cells (ADSCs) to differentiate into a cardiac phenotype in vitro. Icariin (ICA) has previously been shown to induce cardiomyocyte (CM) differentiation of murine embryonic stem cells in vitro, but its effect on ADSCs remains unclear. We isolated ADSCs from white adipose tissue and analyzed selected surface antigens using flow cytometry. ADSCs and CMs were co-cultured in transwell plates, with or without the addition of either ICA or ICA plus the extracellular signal-regulated kinase (ERK) inhibitor PD98059. Cardiac-specific gene expression was examined by reverse transcription-polymerase chain reaction and western blotting. ICA facilitated differentiation of ADSCs into CMs that expressed cardiac-specific genes, including the transcription factors NKX-2.5, GATA-4, MLC-2v, α-actinin, and cardiac troponin-T. Expression of α-actinin, the Z band-constituting protein, was promoted by ICA in a dose- and time-dependent manner. ICA can induce ERK activation and cardiac-specific gene expression was partially inhibited by PD98059 after treatment with ICA. These results suggest that ICA-stimulated CM differentiation of ADSCs, and that it acted partially by activating ERK-dependent signaling pathways in vitro.

Mechanisms underlying the endothelium-dependent vasodilatory effect of an aqueous extract of Elaeis Guineensis Jacq. (Arecaceae) in porcine coronary artery rings

This study was undertaken to investigate the vasodilatory effect of an aqueous extract of Elaeis guineensis Jacq (EGE) in the porcine coronary artery and elicit its possible mechanism(s) of action. Vascular effects of crude extract of dried and powdered leaves of Elaeis guineensis were evaluated on isolated coronary arteries on organ chambers. Determination of eNOS expression and the phosphorylation level of eNOS were determined by Western blot analysis. In the presence of indomethacin, EGE caused pronounced relaxations in endothelium-intact but not in endothelium-denuded coronary artery rings. Relaxations to EGE were significantly reduced by N(ω)-nitro-L-arginine (L-NA, a competitive inhibitor of NO synthase), slightly but not significantly by charybdotoxin plus apamin (two potent inhibitors of EDHF-mediated responses) and abolished by the combination of L-NA and charybdotoxin plus apamin. Relaxations to EGE were abolished by the membrane permeant, SOD mimetic, MnTMPyP, and significantly reduced by wortmannin, an inhibitor of PI3-kinase. Exposure of endothelial cells to EGE increased the phosphorylation level of eNOS at Ser1177 in a time and concentration-dependent manner. MnTMPyP abolished the EGE-induced phosphorylation of eNOS.In conclusion, the obtained data indicate that EGE induces pronounced endothelium-dependent relaxations of the porcine coronary artery, which involve predominantly NO. The stimulatory effect of EGE on eNOS involves the redox-sensitive phosphorylation of eNOS at Ser1177 most likely via the PI3-kinase pathway.

Effects of icariin combined with Panax notoginseng saponins on ischemia reperfusion-induced cognitive impairments related with oxidative stress and CA1 of hippocampal neurons in rat

Previous studies suggest that treatment with icariin (ICA) combined with Panax notoginseng saponins (PNS) improved behavior and cholinergic system disorders followed by amyloid beta-peptide(25-35) lateral ventricle injection in rats. The present study investigated whether administration of ICA + PNS had preventive and therapeutic effects on bilateral common carotid arteries (CCA) occlusion-induced cerebral ischemia-reperfusion (IR) injury in rats. Male Sprague-Dawley rats were divided randomly as follows: sham-operated, i.g. vehicle, ICA (5 mg/kg), PNS (40 mg/kg), ICA + PNS (2.5 + 20, 5 + 40 or 10 + 80 mg/kg), and ergoloid mesylate as a positive control (0.45 mg/kg) in model rats. Treatment was performed once a day for 7 days prior to ischemia. The rats were subjected to transient global IR induced by CCA occlusion in combination with intraperitoneal injection of sodium nitroprusside (2.0 mg/kg), then treated with ICA + PNS for another 14 days continuously. ICA + PNS significantly improved the rat passive avoidance task in step-down paradigms, and spatial cognition in the eight-arm radial maze, concomitant with an improvement of blood viscosity. Increased lipid peroxidation in brain after IR injury was observed, MDA being 0.56 +/- 0.10 nmol/mg prot vs 0.48 +/- 0.06 nmol/mg prot in the vehicle control (p < 0.05). Treatment with ICA + PNS 2.5 + 10, 5 + 40, 10 + 80 mg/kg produced a marked reduction in the MDA level to 0.46 +/- 0.06, 0.42 +/- 0.09 and 0.45 +/- 0.08 nmol/mg prot, respectively vs 0.56 +/- 0.10 nmol/mg prot in IR injury only control (p < 0.05, p < 0.01). A decrease in superoxide dismutase activity was observed in the brain of IR rats (the SOD activity being 72.75 +/- 4.62 U/mg prot vs 80.97 +/- 6.06 U/mg prot in control, p < 0.05). ICA + PNS 5 + 40 mg/kg prevented the IR injury mediated fall in superoxide dismutase activity being 78.90 +/- 6.61 U/mg prot versus 72.75 +/- 4.62 U/mg prot (p < 0.05). ICA + PNS tended to attenuate apoptosis in hippocampal CA1 pyramidal neurons. Either ICA or PNS treatment alone did not obviously improve cognitive impairment (except that lipid peroxidation was reduced by PNS-treatment). The results indicated that ICA + PNS may ameliorate learning and memory deficit and blood viscosity by protecting neurons from oxidative stress in ischemic brain.