Icariside II, a novel phosphodiesterase-5 inhibitor, attenuates streptozotocin-induced cognitive deficits in rats

Icariside II alleviates lipopolysaccharide-induced acute lung injury by inhibiting lung epithelial inflammatory and immune responses mediated by neutrophil extracellular traps

AIMS

Acute lung injury (ALI) is a life-threatening lung disease characterized by inflammatory cell infiltration and lung epithelial injury. Icariside II (ICS II), one of the main active ingredients of Herba Epimedii, exhibits anti-inflammatory and immunomodulatory effects. However, the effect and mechanism of ICS II in ALI remain unclear. The purpose of the current study was to investigate the pharmacological effect and underlying mechanism of ICS II in ALI.

MAIN METHODS

Models of neutrophil-like cells, human peripheral blood neutrophils, and lipopolysaccharide (LPS)-induced ALI mouse model were utilized. RT-qPCR and Western blotting determined the gene and protein expression levels. Protein distribution and quantification were analyzed by immunofluorescence.

KEY FINDINGS

ICS II significantly reduced lung histopathological damage, edema, and inflammatory cell infiltration, and it reduced pro-inflammatory cytokines in ALI. There is an excessive activation of neutrophils leading to a significant production of NETs in ALI mice, a process mitigated by the administration of ICS II. In vivo and in vitro studies found that ICS II could decrease NET formation by targeting neutrophil C-X-C chemokine receptor type 4 (CXCR4). Further data showed that ICS II reduces the overproduction of dsDNA, a NETs-related component, thereby suppressing cGAS/STING/NF-κB signalling pathway activation and inflammatory mediators release in lung epithelial cells.

SIGNIFICANCE

This study suggested that ICS II may alleviate LPS-induced ALI by modulating the inflammatory response, indicating its potential as a therapeutic agent for ALI treatment.

The potential therapeutic effect of phosphodiesterase 5 inhibitors in the acute ischemic stroke (AIS)

Acute ischemic stroke (AIS) is a focal neurological disorder that accounts for 85% of all stroke types, due to occlusion of cerebral arteries by thrombosis and emboli. AIS is also developed due to cerebral hemodynamic abnormality. AIS is associated with the development of neuroinflammation which increases the severity of AIS. Phosphodiesterase enzyme (PDEs) inhibitors have neuro-restorative and neuroprotective effects against the development of AIS through modulation of the cerebral cyclic adenosine monophosphate (cAMP)/cyclic guanosine monophosphate (cGMP)/nitric oxide (NO) pathway. PDE5 inhibitors through mitigation of neuroinflammation may decrease the risk of long-term AIS-induced complications. PDE5 inhibitors may affect the hemodynamic properties and coagulation pathway which are associated with thrombotic complications in AIS. PDE5 inhibitors reduce activation of the pro-coagulant pathway and improve the microcirculatory level in patients with hemodynamic disturbances in AIS. PDE5 inhibitors mainly tadalafil and sildenafil improve clinical outcomes in AIS patients through the regulation of cerebral perfusion and cerebral blood flow (CBF). PDE5 inhibitors reduced thrombomodulin, P-selectin, and tissue plasminogen activator. Herein, PDE5 inhibitors may reduce activation of the pro-coagulant pathway and improve the microcirculatory level in patients with hemodynamic disturbances in AIS. In conclusion, PDE5 inhibitors may have potential roles in the management of AIS through modulation of CBF, cAMP/cGMP/NO pathway, neuroinflammation, and inflammatory signaling pathways. Preclinical and clinical studies are recommended in this regard.

Therapeutic Potential of Natural Compounds from Herbs and Nutraceuticals in Alleviating Neurological Disorders: Targeting the Wnt Signaling Pathway

As an important signaling pathway in multicellular eukaryotes, the Wnt signaling pathway participates in a variety of physiological processes. Recent studies have confirmed that the Wnt signaling pathway plays an important role in neurological disorders such as stroke, Alzheimer's disease, and Parkinson's disease. The regulation of Wnt signaling by natural compounds in herbal medicines and nutraceuticals has emerged as a potential strategy for the development of new drugs for neurological disorders. Purpose: The aim of this review is to evaluate the latest research results on the efficacy of natural compounds derived from herbs and nutraceuticals in the prevention and treatment of neurological disorders by regulating the Wnt pathway in vivo and in vitro. A manual and electronic search was performed for English articles available from PubMed, Web of Science, and ScienceDirect from the January 2010 to February 2023. Keywords used for the search engines were "natural products,″ "plant derived products,″ "Wnt+ clinical trials,″ and "Wnt+,″ and/or paired with "natural products″/″plant derived products", and "neurological disorders." A total of 22 articles were enrolled in this review, and a variety of natural compounds from herbal medicine and nutritional foods have been shown to exert therapeutic effects on neurological disorders through the Wnt pathway, including curcumin, resveratrol, and querctrin, etc. These natural products possess antioxidant, anti-inflammatory, and angiogenic properties, confer neurovascular unit and blood-brain barrier integrity protection, and affect neural stem cell differentiation, synaptic formation, and neurogenesis, to play a therapeutic role in neurological disorders. In various in vivo and in vitro studies and clinical trials, these natural compounds have been shown to be safe and tolerable with few adverse effects. Natural compounds may serve a therapeutic role in neurological disorders by regulating the Wnt pathway. This summary of the research progress of natural compounds targeting the Wnt pathway may provide new insights for the treatment of neurological disorders and potential targets for the development of new drugs.

Icariside II protects dopaminergic neurons from 1‑methyl‑4‑phenylpyridinium‑induced neurotoxicity by downregulating HDAC2 to restore mitochondrial function

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease (AD). Icariside II (ICS II) is known to confer notable therapeutic effects against a variety of neurodegenerative diseases, such as AD. Therefore, the present study aimed to evaluate the possible effects of ICS II on 1-methyl-4-phenylpyridinium (MPP+)-induced SK-N-SH cell injury, in addition to understanding the underlying mechanism of action. The MPP+-induced SK-N-SH cell model was used to simulate PD in vitro. The viability and mitochondrial membrane potential of SK-N-SH cells were detected by MTT assay and JC-1 staining, respectively. Lactate dehydrogenase (LDH) release, ATP levels and complex I activity in treated SK-N-SH cells were measured using LDH activity, ATP and Complex I assay kits, respectively. The protein expression levels of histone deacetylase 2 (HDAC2) and γ-H2A histone family member X and the copy number of mitochondrial DNA were measured by western blotting or reverse transcription-quantitative PCR, respectively. Autodock 4.2 was used to predict the molecular docking site of ICS II on HDAC2. The results of the present study demonstrated that ICS II mitigated SK-N-SH cytotoxicity induced by MPP+. Specifically, ICS II alleviated DNA damage and restored mitochondrial function in SK-N-SH cells treated with MPP+. In addition, ICS II reduced the HDAC2 protein expression levels in MPP+-induced SK-N-SH cells. However, overexpression of HDAC2 reversed the protective effects of ICS II on DNA damage and mitochondrial dysfunction in MPP+-induced SK-N-SH cells. In conclusion, the results of the present study suggest that ICS II can protect dopaminergic neurons from MPP+-induced neurotoxicity by downregulating HDAC2 expression to restore mitochondrial function.

Effect of icariin in a rat model of colchicine-induced cognitive deficit: role of βamyloid proteolytic enzymes

ABSTRACTThe deposition of β-amyloid plaques, either due to their over-production or insufficient clearance, is an important pathological process in cognitive impairment and dementia. Icariin (ICA), a flavonoid compound extracted from Epimedium, has recently gained attention for numerous age-related diseases, such as neurodegenerative diseases. We aimed to explore the possible neuro-protective effect of ICA supplementation in colchicine-induced cognitive deficit rat model and exploring its effect on the β-amyloid proteolytic enzymes. The study included four groups (10 rats each): normal control, untreated colchicine, colchicine + 10 mg/kg ICA, and colchicine + 30 mg/ kg ICA. Results revealed that intra-cerebro-ventricular colchicine injection produced neuronal morphological damage, β amyloid deposition, and evident cognitive impairment in the behavioral assessment. Icariin supplementation in the two doses for 21 days attenuated neuronal death, reduced the β amyloid levels, and improved memory consolidation. This was associated with modulation of the proteolytic enzymes (Neprilysin, Matrix Metalloproteinase-2, and insulin-degrading enzyme) concluding that β-amyloid enzymatic degradation may be the possible therapeutic target for ICA.

Liver protecting effects and molecular mechanisms of icariin and its metabolites

As a detoxification and metabolism organ, the liver plays a vital role in human health. However, an excessive consumption of drugs and toxins, exposure to pathogenic viruses, and unhealthy living habits can lead to liver damage, which may even develop into liver cirrhosis and liver cancer. Epimedium brevicornum Maxim. is a traditional Chinese medicine and dietary supplement in which the flavonoid icariin is a main functional component. Although the protective mechanisms of icariin and its metabolites against liver injury are not yet comprehensively understood, an increasing number of studies have confirmed their liver-protective and anticancer effects. Indeed, icaritin, one of the metabolites of icariin, is currently utilized as an active component of an anti-cancer drug. This paper presents a review of the molecular mechanisms through which icariin and its metabolites actively protect against the occurrence and development of liver injury, and, thus, provides a comprehensive reference for further research and their application in liver protection.

UPLC-MS/MS method for Icariin and metabolites in whole blood of C57 mice: development, validation, and pharmacokinetics study

Icariin, a Chinese medicinal herb with significant effects on Alzheimer's disease, lacks pharmacokinetic data in mice. To address this, a UPLC-MS/MS method was developed and validated for quantifying Icariin and its metabolites, Icariside I and Icariside II, in the whole blood of mice. The method processed micro-whole blood from serial collections of the same C57 mouse, with well-fitted linearity (0.25-800 ng mL-1) and intra- and inter-day precision and accuracy within 15%. Short-time and autosampler stability were verified, with acceptable extraction recoveries and matrix effects over 74.55%. After intravenous administration (15 mg kg-1) of Icariin in C57 mice, Icariside I and Icariside II were detected within 2 min. However, after the intragastric administration (30, 90, and 150 mg kg-1) of Icariin in C57 mice, Icariin and Icariside I were not detected, and Icariin was rapidly converted into Icariside II. Furthermore, the Cmax and AUC0-t of three doses (30, 90, and 150 mg kg-1) of Icariside II increased as the dose increased. In conclusion, this method improves the traditional method of collecting only one blood sample from each mouse, detecting Icariin and its metabolites in the whole blood of mice, especially for serial collection of micro-whole blood.

Alzheimer's disease and neuroinflammation: will new drugs in clinical trials pave the way to a multi-target therapy?

Despite extensive research, no disease-modifying therapeutic option, able to prevent, cure or halt the progression of Alzheimer's disease [AD], is currently available. AD, a devastating neurodegenerative pathology leading to dementia and death, is characterized by two pathological hallmarks, the extracellular deposits of amyloid beta (Aβ) and the intraneuronal deposits of neurofibrillary tangles (NFTs) consisting of altered hyperphosphorylated tau protein. Both have been widely studied and pharmacologically targeted for many years, without significant therapeutic results. In 2022, positive data on two monoclonal antibodies targeting Aβ, donanemab and lecanemab, followed by the 2023 FDA accelerated approval of lecanemab and the publication of the final results of the phase III Clarity AD study, have strengthened the hypothesis of a causal role of Aβ in the pathogenesis of AD. However, the magnitude of the clinical effect elicited by the two drugs is limited, suggesting that additional pathological mechanisms may contribute to the disease. Cumulative studies have shown inflammation as one of the main contributors to the pathogenesis of AD, leading to the recognition of a specific role of neuroinflammation synergic with the Aβ and NFTs cascades. The present review provides an overview of the investigational drugs targeting neuroinflammation that are currently in clinical trials. Moreover, their mechanisms of action, their positioning in the pathological cascade of events that occur in the brain throughout AD disease and their potential benefit/limitation in the therapeutic strategy in AD are discussed and highlighted as well. In addition, the latest patent requests for inflammation-targeting therapeutics to be developed in AD will also be discussed.

Icariside II, a Prenyl-Flavonol, Alleviates Inflammatory and Neuropathic Pain by Inhibiting T-Type Calcium Channels and USP5-Cav3.2 Interactions

Cav3.2 channels play an important role in the afferent nociceptive pathway, which is responsible for both physiological and pathological pain transmission. Cav3.2 channels are upregulated during neuropathic pain or peripheral inflammation in part due to an increased association with the deubiquitinase USP5. In this study, we investigated nine naturally occurring flavonoid derivatives which we tested for their abilities to inhibit transiently expressed Cav3.2 channels and their interactions with USP5. Icariside II (ICA-II), one of the flavonols studied, inhibited the biochemical interactions between USP5 and Cav3.2 and concomitantly and effectively blocked Cav3.2 channels. Molecular docking analysis predicts that ICA-II binds to the cUBP domain and the Cav3.2 interaction region. In addition, ICA-II was predicted to interact with residues in close proximity to the Cav3.2 channel's fenestrations, thus accounting for the observed blocking activity. In mice with inflammatory and neuropathic pain, ICA-II inhibited both phases of the formalin-induced nocifensive responses and abolished thermal hyperalgesia induced by injection of complete Freund's adjuvant (CFA) into the hind paw. Furthermore, ICA-II produced significant and long-lasting thermal anti-hyperalgesia in female mice, whereas Cav3.2 null mice were resistant to the action of ICA-II. Altogether, our data show that ICA-II has analgesic activity via an action on Cav3.2 channels.

Synaptic loss and gliosis in the nucleus tractus solitarii with streptozotocin-induced Alzheimer's disease

Obstructive sleep apnea is highly prevalent in Alzheimer's disease (AD). However, brainstem centers controlling respiration have received little attention in AD research, and mechanisms behind respiratory dysfunction in AD are not understood. The nucleus tractus solitarii (nTS) is an important brainstem center for respiratory control and chemoreflex function. Alterations of nTS integrity, like those shown in AD patients, likely affect neuronal processing and adequate control of breathing. We used the streptozotocin-induced rat model of AD (STZ-AD) to analyze cellular changes in the nTS that corroborate previously documented respiratory dysfunction. We used 2 common dosages of STZ (2 and 3 mg/kg STZ) for model induction and evaluated the early impact on cell populations in the nTS. The hippocampus served as control region to identify site-specific effects of STZ. There was significant atrophy in the caudal nTS of the 3 mg/kg STZ-AD group only, an area known to integrate chemoafferent information. Also, the hippocampus had significant atrophy with the highest STZ dosage tested. Both STZ-AD groups showed respiratory dysfunction along with multiple indices for astroglial and microglial activation. These changes were primarily located in the caudal and intermediate nTS. While there was no change of astrocytes in the hippocampus, microglial activation was accompanied by a reduction in synaptic density. Together, our data demonstrate that STZ-AD induces site-specific effects on all major cell types, primarily in the caudal/intermediate nTS. Both STZ dosages used in this study produced a similar outcome and can be used for future studies examining the initial symptoms of STZ-AD.

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.

A Review on the Pharmacological Importance of PDE5 and Its Inhibition to Manage Biomedical Conditions

Phosphodiesterase type 5 (PDE5) is a cyclic GMP (cGMP) specific protein. It hydrolyzes the phosphodiesterase linkage and catalyzes the conversion of cGMP to 5’ GMP, which controls different physiological activities of the body. PDE5 is associated with biomedical conditions like neurological disorders, pulmonary arterial hypertension, cardiomyopathy, cancer, erectile dysfunction, and lower urinary tract syndrome. Inhibition of PDE5 has now been proven pharmaceutically effective in a variety of therapeutic conditions. Avanafil, tadalafil, sildenafil, and vardenafil are the most commonly used PDE5 inhibitors (PDE5i) today which are often used for the management of erectile dysfunction, lower urinary tract syndromes, malignancy, and pulmonary arterial hypertension. However, these synthetic PDE5i come with a slew of negative effects. Some of the most common side effects include mild headaches, flushing, dyspepsia, altered color vision, back discomfort, priapism, melanoma, hypotension and dizziness, non-arteritic anterior ischemic optic neuropathy (NAION), and hearing loss. In light of the potential negative effects of this class of medications, there is a lot of room for new, selective PDE5 inhibitors to be discovered. We have found 25 plant botanical compounds effectively inhibiting PDE5 which might be useful in treating a variety of disorders with minimal or no adverse effects.

Icariside II Attenuates Methamphetamine-Induced Neurotoxicity and Behavioral Impairments via Activating the Keap1-Nrf2 Pathway

Chronic and long-term methamphetamine (METH) abuse is bound to cause damages to multiple organs and systems, especially the central nervous system (CNS). Icariside II (ICS), a type of flavonoid and one of the main active ingredients of the traditional Chinese medicine Epimedium, exhibits a variety of biological and pharmacological properties such as anti-inflammatory, antioxidant, and anticancer activities. However, whether ICS could protect against METH-induced neurotoxicity remains unknown. Based on a chronic METH abuse mouse model, we detected the neurotoxicity after METH exposure and determined the intervention effect of ICS and the potential mechanism of action. Here, we found that METH could trigger neurotoxicity, which was characterized by loss of dopaminergic neurons, depletion of dopamine (DA), activation of glial cells, upregulation of α-synuclein (α-syn), abnormal dendritic spine plasticity, and dysfunction of motor coordination and balance. ICS treatment, however, alleviated the above-mentioned neurotoxicity elicited by METH. Our data also indicated that when ICS combated METH-induced neurotoxicity, it was accompanied by partial correction of the abnormal Kelch 2 like ECH2 associated protein 1 (Keap1)-nuclear factor erythroid-2-related factor 2 (Nrf2) pathway and oxidative stress response. In the presence of ML385, an inhibitor of Nrf2, ICS failed to activate the Nrf2-related protein expression and reduce the oxidative stress response. More importantly, ICS could not attenuate METH-induced dopaminergic neurotoxicity and behavioral damage when the Nrf2 was inhibited, suggesting that the neuroprotective effect of ICS on METH-induced neurotoxicity was dependent on activating the Keap1-Nrf2 pathway. Although further research is needed to dig deeper into the actual molecular targets of ICS, it is undeniable that the current results imply the potential value of ICS to reduce the neurotoxicity of METH abusers.

Tadalafil and bergapten mitigate streptozotocin-induced sporadic Alzheimer's disease in mice via modulating neuroinflammation, PI3K/Akt, Wnt/β-catenin, AMPK/mTOR signaling pathways

Sporadic Alzheimer's disease (SAD) is a slowly progressive neurodegenerative disorder. This study aimed to investigate neuroprotective potential of tadalafil (TAD) and bergapten (BG) in SAD-induced cognitive impairment in mice. SAD was induced by single injection of streptozotocin (STZ; 3 mg/kg, ICV). STZ resulted in AD-like pathologies including Aβ deposition, tau aggregation, impaired insulin and Wnt/β-catenin signaling, as well as autophagic dysfunction and neuroinflammation. Administration of TAD or BG at doses of 20 and 25 mg/kg, respectively, for 21 consecutive days attenuated STZ-induced hippocampal insult, preserved neuronal integrity, and improved cognitive function in the Morris water maze and object recognition tests paralleled by reduction in Aβ expression by 79 and 89% and tau hyperphosphorylation by 60 and 61%, respectively. TAD and BG also enhanced protein expression of pAkt, pGSK-3β, beclin-1 and methylated protein phosphatase 2A (PP2A) and gene expression of cyclin D1, while raised BDNF immunoreactivity. Furthermore, TAD and BG boosted hippocampal levels of cGMP, PKG, Wnt3a, and AMPK and reduced expression of β-catenin and mTOR by 74% and 51%, respectively. TAD and BG also halted neuroinflammation by reducing IL-23 and IL-27 levels, as well as protein expression of NF-κB by 62% & 61%, respectively. In conclusion, this study offers novel insights on the neuroprotective effects of TAD or BG in the management of SAD as evidenced by improved cognitive function and histological architecture. This could be attributed to modulation of the crosstalk among PI3K/Akt/GSK-3β, PP2A, mTOR/autophagy, cGMP/PKG, and Wnt/β-catenin signaling cascades and mitigation of neuroinflammation.

A network pharmacological approach to investigate the pharmacological effects of CZ2HF decoction on Alzheimer's disease

Background

Alzheimer's disease (AD) is the most common type of dementia, which brings tremendous burden to the sufferers and society. However, ideal tactics are unavailable for AD. Our previous study has shown that CZ2HF, a Chinese herb preparation, mitigates cognitive impairment in AD rats; whereas, its detailed mechanism has not been elucidated.

Methods

Public databases were applied to collect and identify the chemical ingredients of eight herbs in CZ2HF. Criteria of absorption, distribution, metabolism, and excretion was used to screen oral bio-availability and drug-likeness. STITCH database and Therapeutic Target Database were applied to decipher the relationship between compounds and genes related to AD. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology term analyses were used to identify the involved signaling pathways. Cytoscape was adopted to establish the networks The molecular docking was used to validate the interactions between the candidate compounds and their potential targets.

Results

914 compounds were identified in eight herbal medicines of CZ2HF. Among them, 9 compounds and 28 genes were highly involved in the pathologic process of AD. Furthermore, the mechanism of CZ2HF to AD was based on its anti-inflammatory effects mainly through lipopolysaccharide-mediated signaling pathway and TNF signaling pathway. Core genes in this network were TNF, ICAM1, MMP9 and IL-10.

Conclusion

This study predicts the active compounds in CZ2HF and uncovers their protein targets using holistic network pharmacology methods. It will provide a insight into the underlying mechanism of CZ2HF to AD from a multi-scale perspective.

Potential effect of herbal antidepressants on cognitive deficit: Pharmacological activity and possible molecular mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Cognitive symptom is a "core" symptom of major depressive disorder (MDD) patients with clear deficit in memory, social and occupational function, and may persist during the remitting phase. Therefore, the remission of cognitive symptom has been considered as one of the main objectives in the treatment of MDD. Herbal antidepressants have been used to treat MDD, and there has been great advances in the understanding of the ability of these herbs to improve cognitive deficit linked to brain injury and various diseases including depression, Alzheimer disease, diabetes and age-related disorders. This systematic review summarizes the evidence from preclinical studies and clinical trials of herbal antidepressants with positive effects on cognitive deficit. The potential mechanisms by which herbal antidepressants prevent cognitive deficit are also reviewed. This review will facilitate further research and applications.

MATERIALS AND METHODS

We conducted an open-ended, English restricted search of MEDLINE (PubMed), Web of Science and Scopus for all available articles published or online before 31 December 2019, using terms pertaining to medical herb/phytomedicine/phytochemical/Chinese medicine and depression/major depressive disorder/antidepressant and/or cognitive impairment/cognitive deficit/cognitive dysfunction.

RESULTS

7 prescriptions, more than 30 individual herbs and 50 phytochemicals from China, Japan, Korea and India with positive effects on the depressive state and cognitive deficit are reviewed herein. The evidence from preclinical studies and clinical trials proves that these herbal antidepressants exhibit positive effects on one or more aspects of cognitive defect including spatial, episodic, aversive, and short- and long-term memory. The action mode of the improvement of cognitive deficit by these herbal antidepressants is mediated mainly through two pathways. One pathway is to promote hippocampal neurogenesis through activating brain derived neurotrophic factor-tropomyosin-related kinase B signaling. The other pathway is to prevent neuronal apoptosis through the inhibition of neuro-inflammation and neuro-oxidation.

CONCLUSION

These herbal antidepressants, having potential therapy for cognitive deficit, may prevent pathological processes of neurodegenerative diseases. Furthermore, these herbal medicines should provide a treasure trove, which will accelerate the development of new antidepressants that can effectively improve cognitive symptom in MDD. Studies on their molecular mechanisms may provide more potential targets and therapeutic approaches for new drug discovery.

Icariside II, a PDE5 Inhibitor, Suppresses Oxygen-Glucose Deprivation/Reperfusion-Induced Primary Hippocampal Neuronal Death Through Activating the PKG/CREB/BDNF/TrkB Signaling Pathway

Background

Ischemic stroke remains the leading cause of death and adult disability. Cerebral ischemic/reperfusion (I/R) injury is caused by ischemic stroke thereafter aggravates overwhelming neuronal apoptosis and even the death of neurons. Of note, hippocampus is more susceptive to cerebral I/R injury than the other brain region. This study was designed to explore the effects and mechanism of icariside II (ICS II), a pharmacologically active compound exists in herbal Epimedii with previous study-proved as a phosphodiesterase 5 (PDE5) inhibitor, on the oxygen glucose deprivation/reoxygenation (OGD/R)-induced primary hippocampal neurons injury.

Methods

Effects of ICS II on primary hippocampal neuronal impairment and apoptosis induced by OGD/R were examined by MTT, lactate dehydrogenase (LDH) release, TUNEL staining, and flow cytometry, respectively. Activation of memory-related signaling pathways was measured using Western blot analysis. The direct interaction between ICS II and PDE5 was further evaluated by molecular docking.

Results

ICS II (12.5, 25, 50 μM) markedly abrogated OGD/R-induced hippocampal neuronal death as suggested by the increase in neurons viability and the decrease in cellular LDH release. Furthermore, ICS II not only effectively decreased the protein expression and activity of PDE5, restored the 3′5′-cyclic guanosine monophosphate (cGMP) level and its downstream target protein kinase G (PKG) activity but also increased the phosphorylation of cAMP response element binding protein (CREB) level, expressions of brain derived neurotrophic factor (BDNF), and tyrosine protein kinase B (TrkB). Mechanistically, the inhibitory effects of ICS II were abrogated by Rp-8-Br-cGMP (a PKG inhibitor) or ANA-12 (a TrkB inhibitor), which further confirmed that the favorable effects of ICS II were attributed to its activation of the PKG/CREB/BDNF signaling pathways. Intriguingly, ICS II might effectively bind and inhibited PDE5 activity as demonstrated by relatively high binding scores (−6.52 kcal/mol).

Conclusions

ICS II significantly rescues OGD/R-induced hippocampal neuronal injury. The mechanism is, at least partly, due to inhibition of PDE5 and activation of PKG/CREB/BDNF/TrkB signaling pathway. Hence it is thought that ICS II might be a potential naturally PDE5 inhibitor to combat cerebral I/R injury.

Icariside II inhibits lipopolysaccharide-induced inflammation and amyloid production in rat astrocytes by regulating IKK/IκB/NF-κB/BACE1 signaling pathway

β-amyloid (Aβ) is one of the inducing factors of astrocytes activation and neuroinflammation, and it is also a crucial factor for the development of Alzheimer's disease (AD). Icariside II (ICS II) is an active component isolated from a traditional Chinese herb Epimedium, which has shown to attnuate lipopolysaccharide (LPS)-induced neuroinflammation through regulation of NF-κB signaling pathway. In this study we investigated the effects of ICS II on LPS-induced astrocytes activation and Aβ accumulation. Primary rat astrocytes were pretreated with ICS II (5, 10, and 20 μM) or dexamethasone (DXMS, 1 μM) for 1 h, thereafter, treated with LPS for another 24 h. We found that ICS II pretreatment dose dependently mitigated the levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) in the astrocytes. Moreover, ICS II not only exerted the inhibitory effect on LPS-induced IκB-α degradation and NF-κB activation, but also decreased the levels of Aβ1-40, Aβ1-42, amyloid precursor protein (APP) and beta secretase 1 (BACE1) in the astrocytes. Interestingly, molecular docking revealed that ICS II might directly bind to BACE1. It is concluded that ICS II has potential value as a new therapeutic agent to treat neuroinflammation-related diseases, such as AD.

Pharmacological effects of icariin

Icariin (ICA) is a principal active component from traditional Chinese medicine Epimedium grandiflorum. To explain its traditional medical usages by modern science, a variety of pharmacological effects have been studied for ICA. In this review, we summarized the pharmacokinetics of ICA as well as its pharmacological mechanisms in neurodegenerative disease, cardiovascular disease, anti-osteoporosis, anti-inflammation, anti-oxidative stress, anti-depression and anti-tumors.

CZYH Alleviates β-Amyloid-Induced Cognitive Impairment and Inflammation Response via Modulation of JNK and NF-κB Pathway in Rats

Cu-Zhi-Yi-Hao (CZYH), an empirical formula of traditional Chinese medicine (TCM), has been used for amnesia treatment in clinical practice. However, its underlying pharmacological mechanism has not been fully illuminated. The current study was designed to investigate the neuroprotective effect of CZYH on a β-amyloid 25-35- (Aβ_25-35-) induced learning and memory deficit rat model. CZYH (200, 400, or 800 mg/kg), donepezil (1.0 mg/kg), or distilled water was given to Aβ_25-35-stimulated animals for 17 days consecutively. The Morris water maze test revealed that CZYH (400 or 800 mg/kg) administration improved the Aβ_25-35-induced cognitive impairments in rats, and Nissl staining demonstrated that CZYH mitigated the Aβ-caused neuron loss. In addition, CZYH treatment markedly inhibited the activation of microglia as evidenced by a decreased level of IBA-1 and increased YM-1/2 protein expression. The protein expression levels of TNF-α, IL-1β, and COX-2 were also repressed by CZYH. Besides, CZYH treatment alleviated Aβ-induced IκB-α degradation and NF-κB p65 phosphorylation, as well as reduced the JNK phosphorylation level. In conclusion, the present study suggests that CZYH could improve learning and memory abilities and relieve neuron loss in Aβ_25-35-induced rats, at least partly through inhibition of the neuroinflammatory response via inhibiting the JNK-dependent NF-κB activation, indicating that CZYH might be a promising formula for the treatment of AD.

Phosphodiesterase 5 inhibitors as novel agents for the treatment of Alzheimer's disease

Alzheimer's disease (AD), characterized by a progressive impairment of memory and cognition, is a major health problem in both developing and developed countries. Currently, no drugs can reverse the progression of AD. Phosphodiesterase 5 (PDE5) is a critical component of the cyclic guanosine monophosphate/protein kinase G (cGMP/PKG) signaling pathway in neurons, the inhibition of which has produced neuroprotective effects, and PDE5 inhibitors have recently been thought to be potential therapeutic agents for AD. In this paper, we summarized the outstanding progress that has been made in PDE5 inhibitors as anti-AD agents with encouraging results in animal studies, clinical trials and the investigations on the underlying mechanisms. The novel PDE5 inhibitors reported recently in the treatment of AD were also reviewed and discussed.

Icariin and Its Metabolites as Potential Protective Phytochemicals Against Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder affecting more than 35 million people worldwide. As the prevalence of AD is dramatically rising, there is an earnest need for the identification of effective therapies. Available drug treatments only target the symptoms and do not halt the progression of this disorder; thus, the use of natural compounds has been proposed as an alternative intervention strategy. Icariin, a prenylated flavonoid, has several therapeutic effects, including osteoporosis prevention, sexual dysfunction amelioration, immune system modulation, and improvement of cardiovascular function. Substantial studies indicate that icariin may be beneficial to AD by reducing the production of extracellular amyloid plaques and intracellular neurofibrillary tangles and inhibiting phosphodiesterase-5 activity. Moreover, increasing evidence has indicated that icariin exerts a protective role in AD also by limiting inflammation, oxidative stress and reducing potential risk factors for AD such as atherosclerosis. This mini-review discusses the multiple potential mechanisms of action of icariin on the pathobiology of AD including explanation regarding its bioavailability, metabolism and pharmacokinetic.

Icariside II Ameliorates Cognitive Impairments Induced by Chronic Cerebral Hypoperfusion by Inhibiting the Amyloidogenic Pathway: Involvement of BDNF/TrkB/CREB Signaling and Up-Regulation of PPARα and PPARγ in Rats

Chronic cerebral hypoperfusion (CCH) is regarded as a high-risk factor for cognitive decline of vascular dementia (VD) as it is conducive to induce beta-amyloid (Aβ) aggregation. Icariside II (ICS II), a plant-derived flavonoid compound, has showed neuroprotective effect on animal models of Alzheimer’s disease (AD) by decreasing Aβ levels. Here, we assessed the effect of ICS II on CCH-induced cognitive deficits and Aβ levels in rats, and the possible underlying mechanisms were also explored. It was disclosed that CCH induced by bilateral common carotid artery occlusion (BCCAO) caused cognitive deficits, neuronal injury and increase of Aβ_1-40 and Aβ_1-42 levels in the rat hippocampus, while oral administration of ICS II for 28 days abolished the above deficits in the hippocampus of BCCAO rats. Meanwhile, ICS II significantly decreased the expression of beta-amyloid precursor protein (APP) and β-site amyloid precursor protein cleavage enzyme 1 (BACE1), as well as increased the expression of a disintegrin and metalloproteinase domain 10 (ADAM10) and insulin-degrading enzyme (IDE). ICS II also activated peroxisome proliferator-activated receptor (PPAR)α and PPARγ, enhanced the expression of brain-derived neurotrophic factor (BDNF), tyrosine receptor kinase B (TrkB), levels of Akt and cAMP response element binding protein (CREB) phosphorylation. Together, these findings suggested that ICS II attenuates CCH-induced cognitive deficits by inhibiting the amyloidogenic pathway via involvement of BDNF/TrkB/CREB signaling and up-regulation of PPARα and PPARγ in rats.

An outline for the pharmacological effect of icariin in the nervous system

Icariin is a major active component of the traditional herb Epimedium, also known as Horny Goat Weed. It has been extensively studied throughout the past several years and is known to exert anti-oxidative, anti-neuroinflammatory, and anti-apoptotic effects. It is now being considered as a potential therapeutic agent for a wide variety of disorders, ranging from neoplasm to cardiovascular disease. More recent studies have shown that icariin exhibits potential preventive and/or therapeutic effects in the nervous system. For example, icariin can prevent the production of amyloid β (1-42) and inhibit the expression of amyloid precursor protein (APP) and β-site APP cleaving enzyme 1 (BACE-1) in animal models of Alzheimer's disease (AD). Icariin has been shown to mitigate pro-inflammatory responses of microglia in culture and in animal models of cerebral ischemia, depression, Parkinson's disease (PD), and multiple sclerosis (MS). Icariin also prevents the neurotoxicity induced by hydrogen peroxide (H₂O₂), endoplasmic reticulum (ER) stress, ibotenic acid, and homocysteine. In addition, icariin is implicated in facilitating learning and memory in both normal aging animals and disease models. To date, we still have no consolidated source of knowledge about the pharmacological effects of icariin in the nervous system, though its roles in other tissues have been reviewed in recent years. Here, we summarize the pharmacological development of icariin as well as its possible mechanisms in prevention and/or therapy of disorders afflicting the nervous system in hope of expanding the knowledge about the preventive and/or therapeutic effect of icariin in brain disorders.

Toll-like receptor 4 shRNA attenuates lipopolysaccharide-induced epithelial-mesenchymal transition of intrahepatic biliary epithelial cells in rats

BACKGROUND AND AIM

Intrahepatic biliary epithelial cells (IBECs) of the bile duct in liver tissue of patients with hepatolithiasis promoted the development of diseases through epithelial-mesenchymal transition (EMT). This study investigated whether lipopolysaccharide (LPS), a cell-wall constituent of gram-negative bacteria, could induce EMT of IBECs and toll-like receptor 4 (TLR4) had a regulatory role via activating the nuclear factor-κB (NF-κB)/Snail signaling pathway during this process in vivo.

METHODS

TLR4 short hairpin RNA (shRNA) adenovirus or negative control shRNA (NC shRNA) adenovirus (1 × 10⁹ plaque-forming unit (PFU), respectively) was injected into the caudal vein of rats. After 96 h, 1 mg/kg LPS was infused retrogradely into the common bile duct for 48 h per rat. The effects of TLR4 shRNA on LPS-induced EMT were determined by evaluating the histopathological changes in IBECs using hematoxylin and eosin staining and the changes in the levels of EMT markers, TLR4, NF-κB p65, pNF-κB p65, and Snail using real-time polymerase chain reaction and Western blot analysis.

RESULTS

Compared with normal saline treatment, a loss of epithelial cell markers (E-cadherin and cytokeratin 7) and a gain of mesenchymal cell markers (N-cadherin and matrix metalloproteinase 2) were revealed. The levels of TLR4, NF-κB phosphorylation, and Snail significantly increased after LPS treatment, whereas pretreatment with TLR4 shRNA inhibited the LPS-induced EMT by downregulating the NF-κB/Snail signaling pathway.

CONCLUSIONS

LPS induced the EMT of IBECs by activating TLR4. The RNAi-mediated knockdown of TLR4 suppressed EMT occurrence via downregulating the NF-κB/Snail signaling pathway, implicating TLR4 as a new target for human hepatolithiasis.

Phytoconstituents and their Possible Mechanistic Profile for Alzheimer's Disease - A Literature Review

Memory is an associated part of life without which livelihood of a human being becomes miserable. As the global aged population is increasing tremendously, time has come to concentrate on tail end life stage diseases. Alzheimer's disease (AD) is one of such diseases whose origin is enigmatic, having an impact on later stage of life drastically due to irreparable damage of cognition, characterised by the presence of neurotoxic amyloid-beta (Aβ) plaques and hyper phosphorylated Tau protein as fibrillary tangles. Existing therapeutic regimen mainly focuses on symptomatic relief by targeting neurotransmitters that are secondary to AD pathology. Plant derived licensed drugs, Galantamine and Huperzine-A were studied extensively due to their AChE inhibitory action for mild to moderate cases of AD. Although many studies have proved the efficacy of AChEIs as a preferable symptom reliever, they cannot offer long term protection. The future generation drugs of AD is expected to alter various factors that underlie the disease course with a symptomatic benefit promise. As AD involves complex pathology, it is essential to consider several molecular divergent factors apart from the events that result in the production of toxic plaques and neurofibrillary tangles. Even though several herbals have shown neuroprotective actions, we have mentioned about the phytoconstituents that have been tested experimentally against different Alzheimer's pathology models. These phytoconstituents need to be considered by the researchers for further drug development process to make them viable clinically, which is currently a lacuna.

Targeting Cellular Stress Mechanisms and Metabolic Homeostasis by Chinese Herbal Drugs for Neuroprotection

Traditional Chinese medicine has been practiced for centuries in East Asia. Herbs are used to maintain health and cure disease. Certain Chinese herbs are known to protect and improve the brain, memory, and nervous system. To apply ancient knowledge to modern science, some major natural therapeutic compounds in herbs were extracted and evaluated in recent decades. Emerging studies have shown that herbal compounds have neuroprotective effects or can ameliorate neurodegenerative diseases. To understand the mechanisms of herbal compounds that protect against neurodegenerative diseases, we summarize studies that discovered neuroprotection by herbal compounds and compound-related mechanisms in neurodegenerative disease models. Those compounds discussed herein show neuroprotection through different mechanisms, such as cytokine regulation, autophagy, endoplasmic reticulum (ER) stress, glucose metabolism, and synaptic function. The interleukin (IL)-1β and tumor necrosis factor (TNF)-α signaling pathways are inhibited by some compounds, thus attenuating the inflammatory response and protecting neurons from cell death. As to autophagy regulation, herbal compounds show opposite regulatory effects in different neurodegenerative models. Herbal compounds that inhibit ER stress prevent neuronal death in neurodegenerative diseases. Moreover, there are compounds that protect against neuronal death by affecting glucose metabolism and synaptic function. Since the progression of neurodegenerative diseases is complicated, and compound-related mechanisms for neuroprotection differ, therapeutic strategies may need to involve multiple compounds and consider the type and stage of neurodegenerative diseases.

Protective effects of evodiamine in experimental paradigm of Alzheimer's disease

Evodiamine, a major component of Evodia rutaecarpa, has been reported to possess various pharmacological activities, including anti-inflammatory, antioxidative stress, and neuroprotective effects. Our previous study has shown that the potential effects of evodiamine on the learning and memory impairments in the transgenic mouse model of Alzheimer's disease (AD). The present study was designed to investigate neuroprotective mechanism and therapeutic potential of evodiamine against intracerebroventricular streptozotocin (ICV-STZ)-induced experimental sporadic Alzheimer's disease in mice. STZ was injected twice intracerebroventrically (3 mg/kg ICV) on alternate days (day 1 and day 3) in mice. Daily oral administration with evodiamine (50 or 100 mg/kg per day) starting from the first dose of STZ for 21 days showed an improvement in STZ induced cognitive deficits as assessed by novel object recognition and Morris water maze test. Evodiamine significantly decreased STZ induced elevation in acetylcholinesterase activity and malondialdehyde level, and significantly increased STZ induced reduction in glutathione activities and superoxide dismutase activities in the hippocampus compared to control. Furthermore, evodiamine inhibited significantly glial cell activation and neuroinflammation (TNF-α, IL-1β, and IL-6 levels) in the hippocampus. Moreover, evodiamine increased the activity of AKT/GSK-3β signalling pathway and inhibited the activity of nuclear factor κB. In summary, our study suggests that evodiamine can be a novel therapeutic agent for the management of sporadic AD.

Icariside II overcomes TRAIL resistance of melanoma cells through ROS-mediated downregulation of STAT3/cFLIP signaling

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising antitumor agent. However, many melanoma cells show weak responses to TRAIL. Here, we investigated whether Icariside II (IS), an active component of Herba Epimedii, could potentiate antitumor effects of TRAIL in melanoma cells. Melanoma cells were treated with IS and/or TRAIL and cell death, apoptosis and signal transduction were analyzed. We showed that IS promoted TRAIL-induced cell death and apoptosis in A375 melanoma cells. Mechanistically, IS reduced the expression levels of cFLIP in a phospho-STAT3 (pSTAT3)-dependent manner. Ectopic expression of STAT3 abolished IS-induced cFLIP down-regulation and the associated potentiation of TRAIL-mediated cell death. Moreover, IS-induced reactive oxygen species (ROS) production preceded down-regulation of pSTAT3/cFLIP via activating AKT, and the consequent sensitization of cells to TRAIL. We also found that IS treatment down-regulated cFLIP via ROS-mediated NF-κB pathway. In addition, IS converted TRAIL-resistant melanoma MeWo and SK-MEL-28 cells into TRAIL-sensitive cells. Taken together, our results indicated that IS potentiated TRAIL-induced apoptosis through ROS-mediated down-regulation of STAT3/cFLIP signaling.

Effects of icariside II ameliorates diabetic cardiomyopathy in streptozotocin-induced diabetic rats by activating Akt/NOS/NF-κB signaling

Icariside II is a flavonoid extracted from Epimedium that has antioxidant, anti‑inflammatory and antiapoptotic effects. The aim of the present study was to evaluate the effects icariside II on diabetic cardiomyopathy in streptozotocin-induced diabetic rats. Icariside II treatment improved body weight, heart/body weight ratio and fasting blood glucose in diabetic model rats. Icariside II was demonstrated to reduce the expression levels of creatine kinase and lactate dehydrogenase in serum, and to lower cardiac oxidative stress, inflammation and apoptosis levels in diabetic rats. Icariside II treatment induced phosphoinositide 3‑kinase and phosphorylated‑Akt expression, and suppressed inducible nitric oxide synthase (iNOS) and nuclear factor (NF)‑κB protein expression in diabetic rat. Results from the present study suggested that treatment with icariside II improved diabetic cardiomyopathy in streptozotocin‑induced diabetic rats by activating the Akt/NOS/NF‑κB pathway.

IcarisideII improves left ventricular remodeling in spontaneously hypertensive rats by inhibiting the ASK1-JNK/p38 signaling pathway

Inhibition or removal of excess reactive oxygen species can effectively protect cellular function or reduce cell death because oxidative stress is the main cause of cellular damage in many diseases. The flavonoid compound IcarisideII having a slight inhibitory effect on PDE5, is the main active components of epimedium in vivo and has a wide range of pharmacological effects on oxidation and apoptosis. However, whether IcarisideII has the same protective effect on ventricular remodeling in spontaneously hypertensive rats (SHR) is unknown. We found that compared with WKY rats, SHRs exhibited noticeable arterial hypertension. Additionally, echocardiography showed that the diameter of the left ventricle was enlarged, wall thickness was increased, and ejection fraction and short axis shortening rate were reduced. H&E staining demonstrated that SHR cells were disordered and noticeably hypertrophic. Masson trichrome staining revealed significant myocardial fibrosis in the myocardium. Tunel staining indicated that 4.39 times the percent of apoptotic cells were present in SHRs compared to WKY rats. In our study, intra-gastric administration of IcarisideII decreased blood pressure, promoted heart function recovery and improved ventricular remodeling in SHRs. Additionally, it reduced myocardial fibrosis, inhibited myocardial apoptosis, decreased the generation of reactive oxygen species and improved SOD activity. IcarisideII down-regulated the activation of the oxidative stress associated proteins ASK1, p38 and JNK; inhibited the expression of p53, Bax and cleaved-caspase3 in the mitochondrial apoptosis pathway; and up-regulated the expression of Bcl-2. In conclusion, this study indicates that IcarisideII can inhibit myocardial apoptosis and improve left ventricular remodeling in SHRs. It can be inferred that this mechanism may be related to the inhibition of the ASK1-JNK/p38 signaling pathway.

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.

Icariside II Effectively Reduces Spatial Learning and Memory Impairments in Alzheimer's Disease Model Mice Targeting Beta-Amyloid Production

Icariside II (ICS II) is a broad-spectrum anti-cancer natural compound extracted from Herba Epimedii Maxim. Recently, the role of ICS II has been investigated in central nervous system, especially have a neuroprotective effect in Alzheimer’s disease (AD). In this study, we attempted to investigate the effects of ICS II, on cognitive deficits and beta-amyloid (Aβ) production in APPswe/PS1dE9 (APP/PS1) double transgenic mice. It was found that chronic ICS II administrated not only effectively ameliorated cognitive function deficits, but also inhibited neuronal degeneration and reduced the formation of plaque burden. ICS II significantly suppressed Aβ production via promoting non-amyloidogenic APP cleavage process by up-regulating a disintegrin and metalloproteinase domain 10 (ADAM10) expression, inhibited amyloidogenic APP processing pathway by down-regulating amyloid precursor protein (APP) and β-site amyloid precursor protein cleavage enzyme 1 (BACE1) expression in APP/PS1 transgenic mice. Meanwhile, ICS II attenuated peroxisome proliferator-activated receptor-γ (PPARγ) degradation as well as inhibition of eukaryotic initiation factor α phosphorylation (p-eIF2α) and PKR endoplasmic reticulum regulating kinase phosphorylation (p-PERK). Moreover, phosphodiesterase type 5 inhibitors (PDE5-Is) have recently emerged as a possible therapeutic target for cognitive enhancement via inhibiting Aβ levels, and we also found that ICS II markedly decreased phosphodiesterase-5A (PDE5A) expression. In conclusion, the present study demonstrates that ICS II could attenuate spatial learning and memory impairments in APP/PS1 transgenic mice. This protection appears to be due to the increased ADAM10 expression and decreased expression of both APP and BACE1, resulting in inhibition of Aβ production in the hippocampus and cortex. Inhibition of PPARγ degradation and PERK/eIF2α phosphorylation are involved in the course, therefore suggesting that ICS II might be a promising potential compound for the treatment of AD.

Icariside II, a Broad-Spectrum Anti-cancer Agent, Reverses Beta-Amyloid-Induced Cognitive Impairment through Reducing Inflammation and Apoptosis in Rats

Beta-amyloid (Aβ) deposition, associated neuronal apoptosis and neuroinflammation are considered as the important factors which lead to cognitive deficits in Alzheimer's disease (AD). Icariside II (ICS II), an active flavonoid compound derived from Epimedium brevicornum Maxim, has been extensively used to treat erectile dysfunction, osteoporosis and dementia in traditional Chinese medicine. Recently, ICS II attracts great interest due to its broad-spectrum anti-cancer property. ICS II shows an anti-inflammatory potential both in cancer treatment and cerebral ischemia-reperfusion. It is not yet clear whether the anti-inflammatory effect of ICS II could delay progression of AD. Therefore, the current study aimed to investigate the effects of ICS II on the behavioral deficits, Aβ levels, neuroinflammatory responses and apoptosis in Aβ25-35-treated rats. We found that bilateral hippocampal injection of Aβ25-35 induced cognitive impairment, neuronal damage, along with increase of Aβ, inflammation and apoptosis in hippocampus of rats. However, treatment with ICS II 20 mg/kg could improve the cognitive deficits, ameliorate neuronal death, and reduce the levels of Aβ in the hippocampus. Furthermore, ICS II could suppress microglial and astrocytic activation, inhibit expression of IL-1β, TNF-α, COX-2, and iNOS mRNA and protein, and attenuate the Aβ induced Bax/Bcl-2 ratio elevation and caspase-3 activation. In conclusion, these results showed that ICS II could reverse Aβ-induced cognitive deficits, possibly via the inhibition of neuroinflammation and apoptosis, which suggested a potential protective effect of ICS II on AD.

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.