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

Neuroprotective effects of Anshen Bunao Syrup on cognitive dysfunction in Alzheimer's disease rat models

Alzheimer's disease (AD) presents a significant challenge due to its prevalence and lack of cure, driving the quest for effective treatments. Anshen Bunao Syrup, a traditional Chinese medicine known for its neuroprotective properties, shows promise in addressing this need. However, understanding its precise mechanisms in AD remains elusive. This study aimed to investigate Anshen Bunao Syrup's therapeutic potential in AD treatment using a scopolamine-induced AD rat model. Assessments included novel-object recognition and Morris water maze tasks to evaluate spatial learning and memory, alongside Nissl staining and ELISA analyses for neuronal damage and biomarker levels. Results demonstrated that Anshen Bunao Syrup effectively mitigated cognitive dysfunction by inhibiting amyloid-β and phosphorylation Tau aggregation, thereby reducing neuronal damage. Metabolomics profiling of rats cortex revealed alterations in key metabolites implicated in tryptophan and fatty acid metabolism pathways, suggesting a role in the therapeutic effects of Anshen Bunao Syrup. Additionally, ELISA and correlation analyses indicated attenuation of oxidative stress and immune response through metabolic remodeling. In conclusion, this study provides compelling evidence for the neuroprotective effects of Anshen Bunao Syrup in AD models, shedding light on its potential as a therapeutic agent for AD prevention and treatment.

Ferroptosis inhibitors: past, present and future

Ferroptosis is a non-apoptotic mode of programmed cell death characterized by iron dependence and lipid peroxidation. Since the ferroptosis was proposed, researchers have revealed the mechanisms of its formation and continue to explore effective inhibitors of ferroptosis in disease. Recent studies have shown a correlation between ferroptosis and the pathological mechanisms of neurodegenerative diseases, as well as diseases involving tissue or organ damage. Acting on ferroptosis-related targets may provide new strategies for the treatment of ferroptosis-mediated diseases. This article specifically describes the metabolic pathways of ferroptosis and summarizes the reported mechanisms of action of natural and synthetic small molecule inhibitors of ferroptosis and their efficacy in disease. The paper also describes ferroptosis treatments such as gene therapy, cell therapy, and nanotechnology, and summarises the challenges encountered in the clinical translation of ferroptosis inhibitors. Finally, the relationship between ferroptosis and other modes of cell death is discussed, hopefully paving the way for future drug design and discovery.

Icariin attenuates dopaminergic neural loss in haloperidol-induced Parkinsonism in rats via GSK-3β and tyrosine hydroxylase regulation mechanism

Parkinson's Disease (PD) is an age-dependent, incessant, dynamic neurodegenerative illness. In animal models, the administration of the dopaminergic D2 antagonist Haloperidol (HP) affects the nigrostriatal pathway, inducing catalepsy, a state of immobility like PD, bradykinesia, and akinesia. The present study investigated the neural effects of Icariin (ICA), a flavonoid derived from Herba Epimedii, against HP-induced PD in rats compared to a standard drug levodopa (L-DOPA). Twenty-four adult male rats were divided into 4 groups: the control group treated with vehicle, the 2nd group treated with HP intraperitoneally, the 3rd group treated with the same dose of HP+L-DOPA orally, and the 4th one, treated with the same dose of HP+ICA orally. All the groups were treated for fourteen consecutive days. Two days before the last dose, locomotor activity was assessed in open field and rotarod tasks. At the end of the experiment, the malondialdehyde, nitric oxide (NO), iron, glycogen synthase kinase-3beta (GSK-3β), and tyrosine hydroxylase (TH) contents, glutathione S-transferase, catalase, superoxide dismutase, activities were estimated in the midbrain. Also, cortex and midbrain monoamine contents (norepinephrine, dopamine, and serotonin) were determined. Moreover, the midbrain histopathology was detected in all treated groups. The results suggested that the neuroleptic effect of HP was completely improved by ICA. This improvement occurred by decreasing the neurotoxicity via lowering midbrain lipid peroxidation, NO, GSK-3β contents, increasing antioxidant biomarkers, TH, and recovering the treated groups' cortex and midbrain monoamines contents. In conclusion, this study suggests that ICA is a suitable treatment for Parkinson's induced by HP.

Icariin ameliorates glycolytic dysfunction in Alzheimer's disease models by activating the Wnt/β-catenin signaling pathway

It was reported that the Wnt/β-catenin pathway is involved in the regulation of aerobic glycolysis and that brain glycolytic dysfunction results in the development of Alzheimer's disease (AD). Icariin (ICA), an active component extracted from Epimedii Folium, has been reported to produce neuroprotective effects in multiple models of AD, but its underlying mechanism remains to be fully described. We aimed to investigate the protective effects of ICA on animal and cell models of AD and confirm whether the Wnt/β-catenin pathway has functions in the neuroprotective function of ICA. The 3 × Tg-AD mice were treated with ICA. HT22 cells, the Aβ25-35 peptide and Dickkopf-1 (DKK1) agent (a specific inhibitor of the Wnt/β-catenin pathway) were used to further explore the underlying mechanism of ICA that produces anti-AD effects. Behavioral examination, western blotting assay, staining analysis, biochemical test, and lactate dehydrogenase (LDH) assays were applied. We first demonstrated that ICA significantly improved cognitive function and autonomous behavior, reduced neuronal damage, and reversed the protein levels and activities of glycolytic key enzymes, and expression of protein molecules of the canonical Wnt signaling pathway, in 3 × Tg-AD mice back to wild-type levels. Next, we further found that ICA increased cell viability and effectively improved the dysfunctional glycolysis in HT22 cells injured by Aβ25-35 . However, when canonical Wnt signaling was inhibited by DKK1, the above effects of ICA on glycolysis were abolished. In summary, ICA exerts neuroprotective effects in 3 × Tg-AD animals and AD cellular models by enhancing the function of glycolysis through activation of the Wnt/β-catenin pathway.

A literature review of bioactive substances for the treatment of periodontitis: In vitro, in vivo and clinical studies

Periodontitis is a common chronic inflammatory disease of the supporting tissues of the tooth that involves a complex interaction of microorganisms and various cell lines around the infected site. To prevent and treat this disease, several options are available, such as scaling, root planning, antibiotic treatment, and dental surgeries, depending on the stage of the disease. However, these treatments can have various side effects, including additional inflammatory responses, chronic wounds, and the need for secondary surgery. Consequently, numerous studies have focused on developing new therapeutic agents for more effective periodontitis treatment. This review explores the latest trends in bioactive substances with therapeutic effects for periodontitis using various search engines. Therefore, this study aimed to suggest effective directions for therapeutic approaches. Additionally, we provide a summary of the current applications and underlying mechanisms of bioactive substances, which can serve as a reference for the development of periodontitis treatments.

Icariin improves learning and memory function in Aβ1-42-induced AD mice through regulation of the BDNF-TrκB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedium brevicornu Maxim. is a traditional medicinal Chinese herb that is enriched with flavonoids, which have remarkably high medicinal value. Icariin (ICA) is a marker compound isolated from the total flavonoids of Epimedium brevicornu Maxim. It has been shown to improve Neurodegenerative disease, therefore, ICA is probably a potential drug for treating AD.

MATERIALS AND METHODS

The 6-8-week-old SPF-class male ICR mice were randomly divided into 8 groups for modeling, and then the mice were administered orally with ICA for 21 days. The behavioral experiments were conducted to evaluate if learning and memory behavior were absent in mice, confirming that infusion of Amyloid β-protein (Aβ)1-42 caused significant memory impairment. The morphological changes and damage of neurons in the mice's brains were observed by HE and Nissl staining. The spinous protrusions (dendritic spines) on neuronal dendrites were investigated by Golgi-Cox staining. The molecular mechanism of ICA was examined by Western Blot. The protein docking of ICA and Donepezil with BDNF were analyzed to determine their interaction.

RESULTS

The behavioral experimental results showed that in Aβ1-42-induced AD mice, the learning and memory abilities were improved after using ICA. At the same time, the low, medium, and high doses of ICA could reduce the content of Aβ1-42 in the hippocampus of AD mice, repair neuronal damage, enhance synaptic plasticity, as well as increase the expression of BDNF, TrκB, CREB, Akt, GAP43, PSD95, and SYN proteins in the hippocampus of mice. However, the effect with high doses of ICA is more pronounced. The high-dose administration of ICA has the best therapeutic effect on AD mice. After administering the inhibitor k252a, the therapeutic effect of ICA was reversed. The macromolecular docking results of ICA and BDNF protein demonstrated a strong interaction of -7.8 kcal/mol, which indicates that ICA plays a therapeutic role in AD mice by regulating the BDNF-TrκB signaling pathway.

CONCLUSIONS

The results confirm that ICA can repair neuronal damage, enhance synaptic plasticity, as well as ultimately improve learning and memory impairment through the regulation of the BDNF-TrκB signaling pathway.

Role of multi-targeted bioactive natural molecules and their derivatives in the treatment of Alzheimer's disease: an insight into structure-activity relationship

Alzheimer's disease (AD) is a complex neurodegenerative disorder involving cognitive dysfunction like short-term memory and behavioral changes as the disease progresses due to other unaltered physiological factors. The solution for this problem is Multi-targeted Drugs (MTDs), which can affect multiple determinants to realize the multifunctional effects. Acetylcholinesterase (AChE) inhibitors donepezil, rivastigmine, galantamine, and N-methyl-D-aspartate (NMDA) receptor antagonist memantine are FDA-approved drugs used to treat AD symptomatically. The key objective of this review is to understand multitargeted bioactive natural molecules that could be considered as leads for further development as effective drugs for treating AD, along with understanding its pharmacology and structure-activity relationship (SAR). Understanding the molecular mechanism of the AD pathophysiology, the role of existing drugs, treatment of AD via amyloid beta (Aβ) plaque, and neurofibrillary tangle (NFT) inhibition by natural bioactive molecules were also discussed in the review. The current quest and recent advancements with natural bioactive compounds like physostigmine, resveratrol, curcumin, and catechins, along with the study of in silico SAR, were reported in the present study. This review summarises the structural properties required for bioactive natural molecules to show anti-Alzheimer's activity by emphasizing on SAR of several bioactive natural molecules targeting various AD pathologies, their key molecular interactions that are critical for target specificity, their role as multitargeted ligands, used with adjunctive therapy for AD followed by related US patents granted recently. This article highlights the significance of the structural features of natural bioactive molecules in the treatment of AD and establishes a connection between them.Communicated by Ramaswamy H. Sarma.

De novo biosynthesis of anticarcinogenic icariin in engineered yeast

Icariin (ICA) has wide applications in nutraceuticals and medicine with strong anticancer activities. However, the structural complexity and low abundance in plants of ICA lead to the unsustainable and high-cost supply from chemical synthesis and plant extraction. Here, the whole biosynthesis pathway of ICA was elucidated, then was constructed in Saccharomyces cerevisiae, including a 13-step heterologous ICA pathway from eleven kinds of plants as well as deletions or overexpression of ten yeast endogenous genes. Spatial regulation of 8-C-prenyltransferase to mitochondria and three-stage sequential control of 4'-O-methyltransferase, 3-OH rhamnosyltransferase, and 7-OH glycosyltransferase expression successfully achieved the de novo synthesis of ICA with a titer of 130 μg/L under shake-flask culture. The ICA synthesis from glucose represents the longest reconstructed pathway of flavonoid in microbe so far. This study provides a potential choice for the sustainable microbial production of number of complex flavonoids.

Understanding the neuronal synapse and challenges associated with the mitochondrial dysfunction in mild cognitive impairment and Alzheimer's disease

Synaptic mitochondria are crucial for maintaining synaptic activity due to their high energy requirements, substantial calcium (Ca2+) fluctuation, and neurotransmitter release at the synapse. To provide a continuous energy supply, neurons use special mechanisms to transport and distribute healthy mitochondria to the synapse while eliminating the damaged mitochondria from the synapse. Along the neuron, mitochondrial membrane potential (ψ) gradient exists and is highest in the somal region. Lower ψ in the synaptic region renders mitochondria more vulnerable to oxidative stress-mediated damage. Secondly, mitochondria become susceptible to the release of cytochrome c, and mitochondrial DNA (mtDNA) is not shielded from the reactive oxygen species (ROS) by the histone proteins (unlike nuclear DNA), leading to activation of caspases and pronounced oxidative DNA base damage, which ultimately causes synaptic loss. Both synaptic mitochondrial dysfunction and synaptic failure are crucial factors responsible for Alzheimer's disease (AD). Furthermore, amyloid beta (Aβ) and hyper-phosphorylated Tau, the two leading players of AD, exaggerate the disease-like pathological conditions by reducing the mitochondrial trafficking, blocking the bi-directional transport at the synapse, enhancing the mitochondrial fission via activating the mitochondrial fission proteins, enhancing the swelling of mitochondria by increasing the influx of water through mitochondrial permeability transition pore (mPTP) opening, as well as reduced ATP production by blocking the activity of complex I and complex IV. Mild cognitive impairment (MCI) is also associated with decline in cognitive ability caused by synaptic degradation. This review summarizes the challenges associated with the synaptic mitochondrial dysfunction linked to AD and MCI and the role of phytochemicals in restoring the synaptic activity and rendering neuroprotection in AD.

Icariin improves cognitive impairment by inhibiting ferroptosis of nerve cells

AIM

We investigated the effect and mechanism of Icariin (ICA) on improving neurobehavioral ability of mice with Alzheimer's disease (AD).

METHODS

We selected 10-month-old APP/PS1 mice (AD) and wild-type C57BL/6J mice (Normal). After intragastric administration of ICA, Morris water maze was employed to detect neurobehavioral improvements, and to assay key ferroptosis indicators and oxidative stress levels. The common target of ICA for resisting ferroptosis and AD was predicted by network pharmacology.

RESULTS

ICA could improve the neurobehavioral, memory and motor abilities of AD mice. It could lower the ferroptosis level and enhance the resistance to oxidative stress. After inhibition of MDM2, ICA could no longer improve the cognitive ability of AD mice, nor could it further inhibit ferroptosis. Network pharmacological analysis revealed that MDM2 might be the target of ICA action.

CONCLUSIONS

We found that ICA can inhibit ferroptosis of nerve cells, thereby ameliorating neural damage in mice with AD.

Advancements in the Biotransformation and Biosynthesis of the Primary Active Flavonoids Derived from Epimedium

Epimedium is a classical Chinese herbal medicine, which has been used extensively to treat various diseases, such as sexual dysfunction, osteoporosis, cancer, rheumatoid arthritis, and brain diseases. Flavonoids, such as icariin, baohuoside I, icaritin, and epimedin C, are the main active ingredients with diverse pharmacological activities. Currently, most Epimedium flavonoids are extracted from Epimedium plants, but this method cannot meet the increasing market demand. Biotransformation strategies promised huge potential for increasing the contents of high-value Epimedium flavonoids, which would promote the full use of the Epimedium herb. Complete biosynthesis of major Epimedium flavonoids by microbial cell factories would enable industrial-scale production of Epimedium flavonoids. This review summarizes the structures, pharmacological activities, and biosynthesis pathways in the Epimedium plant, as well as the extraction methods of major Epimedium flavonoids, and advancements in the biotransformation and complete microbial synthesis of Epimedium flavonoids, which would provide valuable insights for future studies on Epimedium herb usage and the production of Epimedium flavonoids.

Inhibitory effects of Jasminum grandiflorum L. essential oil on lipopolysaccharide-induced microglia activation-integrated characteristic analysis of volatile compounds, network pharmacology, and BV-2 cell

Neuroinflammation is considered to have a prominent role in the pathogenesis of Alzheimer's disease (AD). Microglia are the resident macrophages of the central nervous system, and modulating microglia activation is a promising strategy to prevent AD. Essential oil of Jasminum grandiflorum L. flowers is commonly used in folk medicine for the relief of mental pressure and disorders, and analyzing the volatile compound profiles and evaluating the inhibitory effects of J. grandiflorum L. essential oil (JGEO) on the excessive activation of microglia are valuable for its application. This study aims to explore the potential active compounds in JGEO for treating AD by inhibiting microglia activation-integrated network pharmacology, molecular docking, and the microglia model. A headspace solid-phase microextraction combined with the gas chromatography-mass spectrometry procedure was used to analyze the volatile characteristics of the compounds in J. grandiflorum L. flowers at 50°C, 70°C, 90°C, and 100°C for 50 min, respectively. A network pharmacological analysis and molecular docking were used to predict the key compounds, key targets, and binding energies based on the detected compounds in JGEO. In the lipopolysaccharide (LPS)-induced BV-2 cell model, the cells were treated with 100 ng/mL of LPS and JGEO at 7.5, 15.0, and 30 μg/mL, and then, the morphological changes, the production of nitric oxide (NO) and reactive oxygen species, and the expressions of tumor necrosis factor-α, interleukin-1β, and ionized calcium-binding adapter molecule 1 of BV-2 cells were analyzed. A total of 34 compounds with significantly different volatilities were identified. α-Hexylcinnamaldehyde, nerolidol, hexahydrofarnesyl acetone, dodecanal, and decanal were predicted as the top five key compounds, and SRC, EGFR, VEGFA, HSP90AA1, and ESR1 were the top five key targets. In addition, the binding energies between them were less than -3.9 kcal/mol. BV-2 cells were activated by LPS with morphological changes, and JGEO not only could clearly reverse the changes but also significantly inhibited the production of NO and reactive oxygen species and suppressed the expressions of tumor necrosis factor-α, interleukin-1β, and ionized calcium-binding adapter molecule 1. The findings indicate that JGEO could inhibit the overactivation of microglia characterized by decreasing the neuroinflammatory and oxidative stress responses through the multi-compound and multi-target action modes, which support the traditional use of JGEO in treating neuroinflammation-related disorders.

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.

Icariin as a potential anticancer agent: a review of its biological effects on various cancers

Numerous chemical compounds used in cancer treatment have been isolated from natural herbs to address the ever-increasing cancer incidence worldwide. Therein is icariin, which has been extensively studied for its therapeutic potential due to its anti-inflammatory, antioxidant, antidepressant, and aphrodisiac properties. However, there is a lack of comprehensive and detailed review of studies on icariin in cancer treatment. Given this, this study reviews and examines the relevant literature on the chemopreventive and therapeutic potentials of icariin in cancer treatment and describes its mechanism of action. The review shows that icariin has the property of inhibiting cancer progression and reversing drug resistance. Therefore, icariin may be a valuable potential agent for the prevention and treatment of various cancers due to its natural origin, safety, and low cost compared to conventional anticancer drugs, while further research on this natural agent is needed.

Icariin protects cerebral neural cells from ischemia‑reperfusion injury in an in vitro model by lowering ROS production and intracellular calcium concentration

Ischemia is one of the major causes of stroke. The present study investigated the protection of cultured neural cells by icariin (ICA) against ischemia-reperfusion (I/R) injury and possible mechanisms underlying the protection. Neural cells were isolated from neonatal rats and cultured in vitro. The cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD-R) as an I/R mimic to generate I/R injury, and were post-OGD-R treated with ICA. Following the treatments, cell viability, apoptosis, reactive oxygen species (ROS), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and Ca²⁺ concentration were assessed using Cell Counting Kit-8 assay, flow cytometry, CyQUANT™ LDH Cytotoxicity Assay, H₂DCFDA and SOD colorimetric activity kit. After OGD-R, considerable I/R injury was observed in the neural cells, as indicated by reduced cell viability, increased apoptosis and increased production of ROS and LDH (P<0.05). Cellular Ca²⁺ concentration was also increased, while SOD activity remained unchanged. Post-OGD-R ICA treatments increased cell viability up to 87.1% (P<0.05) and reduced apoptosis as low as 6.6% (P<0.05) in a concentration-dependent manner. The treatments also resulted in fewer ROS (P<0.05), lower extracellular LDH content (440.5 vs. 230.3 U/l; P<0.05) and reduced Ca²⁺ increase (P<0.05). These data suggest that ICA protects the neural cells from I/R injury in an in vitro model through antioxidation activity and maintaining cellular Ca²⁺ homeostasis. This function may be explored as a potential therapeutic strategy for ischemia-related diseases after further in vivo studies.

Dual role of nitric oxide in Alzheimer's Disease

Nitric oxide (NO), an enzymatic product of nitric oxide synthase (NOS), has been associated with a variety of neurological diseases such as Alzheimer's disease (AD). NO has long been thought to contribute to neurotoxic insults caused by neuroinflammation in AD. This perception shifts as more attention is paid to the early stages before cognitive problems manifest. However, it has revealed a compensatory neuroprotective role for NO that protects synapses by increasing neuronal excitability. NO can positively affect neurons by inducing neuroplasticity, neuroprotection, and myelination, as well as having cytolytic activity to reduce inflammation. NO can also induce long-term potentiation (LTP), a process by which synaptic connections among neurons become more potent. Not to mention that such functions give rise to AD protection. Notably, it is unquestionably necessary to conduct more research to clarify NO pathways in neurodegenerative dementias because doing so could help us better understand their pathophysiology and develop more effective treatment options. All these findings bring us to the prevailing notion that NO can be used either as a therapeutic agent in patients afflicted with AD and other memory impairment disorders or as a contributor to the neurotoxic and aggressive factor in AD. In this review, after presenting a general background on AD and NO, various factors that have a pivotal role in both protecting and exacerbating AD and their correlation with NO will be elucidated. Following this, both the neuroprotective and neurotoxic effects of NO on neurons and glial cells among AD cases will be discussed in detail.

Icaritin alleviates cerebral ischemia‒reperfusion injury by regulating NMDA receptors through ERK signaling

N-methyl-D-aspartate (NMDA) receptors are key signaling molecules that mediate excitotoxicity during cerebral ischemia. GluN2A-containing NMDA receptors, which are mostly located in the intrasynaptic region, mediate normal physiological processes and promote neuronal survival. GluN2B-containing NMDA receptors, which are mostly located in the extrasynaptic region, mediate excitotoxicity injury and promote neuronal death during ischemia. This study investigated the ability of icaritin (ICT) to protect against cerebral ischemia‒reperfusion injury (CI/RI) by regulating GluN2B-containing NMDA receptors through extracellular signaling regulatory kinases/death associated protein kinase 1 (ERK/DAPK1) signaling. A rat CI/RI model was established by transient middle cerebral artery occlusion (tMCAO). Following treatment with ICT and the ERK-specific inhibitor U0126, cerebral infarction, neurological function, and excitotoxicity-related molecule expression were assessed 24 h after reperfusion. ICT treatment significantly decreased cerebral infarct volume, improved neurological function, and regulated NMDA receptor subtype expression and ERK/DAPK1 signaling activation. The ability of ICT to increase GluN2A and postsynaptic density protein 95 (PSD95) mRNA and protein expression, inhibit GluN2B expression, and regulate DAPK1 activation was reversed after administration of the ERK-specific inhibitor U0126. These data indicated that ICT inhibited excitotoxicity injury and exerted a protective effect against CI/RI that was likely mediated by increased ERK signaling pathway activation and regulation of extrasynaptic and intrasynaptic NMDA receptor function, providing a new therapeutic target for ischemic encephalopathy.

Regulatory mechanism of icariin in cardiovascular and neurological diseases

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

Icariin synergizes therapeutic effect of dexamethasone on adriamycin-induced nephrotic syndrome

BACKGROUND

Glomerular damage is a common clinical indicator of nephrotic syndrome. High-dose hormone treatment often leads to hormone resistance in patients. How to avoid resistance and improve the efficiency of hormone therapy draws much attention to clinicians.

METHODS

Adriamycin (ADR) was used to induce nephropathy model in SD rats. The rats were treated with dexamethasone (DEX), icariin (ICA), and DEX + ICA combination therapy. The changes in urinary protein (UP), urea nitrogen (BUN), and serum creatinine (SCR) contents in rats were detected by enzyme-linked immunosorbent assay (ELISA), and the degree of pathological injury and the expression level of podocin were detected by HE staining and immunohistochemistry, to test the success of the model and the therapeutic effects of three different ways. The effect of treatments on podocytes autophagy was evaluated via transfection of mRFP-GFP-LC3 tandem adenovirus in vitro.

RESULTS

The contents of UP, SCR, and BUN were significantly increased, the glomerulus was seriously damaged, and the expression of Nephrosis2 (NPHS2) was significantly decreased in the ADR-induced nephrotic syndrome rat model compared to that of the control group. DEX, ICA, and the DEX + ICA combined treatment significantly alleviated these above changes induced by ADR. The combined treatment of DEX + ICA exhibited better outcome than single treatment. The combined treatment also restored the podocyte autophagy, increased the expression of microtubule-associated protein light-chain 3II (LC3II), and reduced the expression of p62 in vitro. The combined treatment protects podocytes by mediating the PI3K/AKT/mTOR (rapamycin complex) signaling pathway.

CONCLUSION

ICA enhances the therapeutic effect of DEX on the nephrotic syndrome.

Icariin: A Promising Natural Product in Biomedicine and Tissue Engineering

Among scaffolds used in tissue engineering, natural biomaterials such as plant-based materials show a crucial role in cellular function due to their biocompatibility and chemical indicators. Because of environmentally friendly behavior and safety, green methods are so important in designing scaffolds. A key bioactive flavonoid of the Epimedium plant, Icariin (ICRN), has a broad range of applications in improving scaffolds as a constant and non-immunogenic material, and in stimulating the cell growth, differentiation of chondrocytes as well as differentiation of embryonic stem cells towards cardiomyocytes. Moreover, fusion of ICRN into the hydrogel scaffolds or chemical crosslinking can enhance the secretion of the collagen matrix and proteoglycan in bone and cartilage tissue engineering. To scrutinize, in various types of cancer cells, ICRN plays a decisive role through increasing cytochrome c secretion, Bax/Bcl2 ratio, poly (ADP-ribose) polymerase as well as caspase stimulations. Surprisingly, ICRN can induce apoptosis, reduce viability and inhibit proliferation of cancer cells, and repress tumorigenesis as well as metastasis. Moreover, cancer cells no longer grow by halting the cell cycle at two checkpoints, G0/G1 and G2/M, through the inhibition of NF-κB by ICRN. Besides, improving nephrotoxicity occurring due to cisplatin and inhibiting multidrug resistance are the other applications of this biomaterial.

A Phytomolecule Icariin Protects from Sarcopenia Partially by Suppressing Myosin Heavy Chain Degradation in Orchiectomized Rats

Treatments are lacking for sarcopenia, which is an age-related disease characterized by loss of skeletal muscle mass, strength, and/or physical performance. Icariin is a phytomolecule from herbal Epimedium, a traditional Chinese medicine widely used to treat musculoskeletal disorders for thousands of years. Here the effects of icariin against sarcopenia are investigated and the underlying mechanism is elucidated. A classic rat model of bilaterally orchiectomized (ORX) is used to induce sarcopenia. After administration for 8 weeks, compared to the control group, the forelimb grip strength, the specific tetanic forces of the soleus (SOL) and extensor digitorum longus muscle (EDL) are higher, and the fiber cross-sectional areas (CSAs) of the gastrocnemius and tibialis anterior muscle are larger in the icariin group. In addition, icariin promotes mRNA and protein expressions of myosin heavy chain (MyHC) both in SOL and EDL. Mechanistically, icariin significantly suppresses the mRNA and protein expressions of FOXO3a, atrogin-1, and MuRF-1, which are related to the degradation of myosin heavy chain. Collectively, icariin protects from sarcopenia in ORX rats characterized by enhancing grip strength and skeletal muscle contraction, as well as increasing skeletal muscle CSA by inhibiting the ubiquitination degradation of the MyHC in skeletal muscle fibers.

Role of Nrf2 and HO-1 in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a common age-related disease with clinical manifestations of lumbar and leg pain and limited mobility. The pathogenesis of IDD is mainly mediated by the death of intervertebral disc (IVD) cells and the imbalance of extracellular matrix (ECM) synthesis and degradation. Oxidative stress and inflammatory reactions are the important factors causing this pathological change. Therefore, the regulation of reactive oxygen species and production of inflammatory factors may be an effective strategy to delay the progression of IDD. In recent years, nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream regulated protein heme oxygenase-1 (HO-1) have received special attention due to their antioxidant, anti-inflammatory and anti-apoptotic protective effects. Recent studies have elucidated the important role of these two proteins in the treatment of IDD disease. However, Nrf2 and HO-1 have not been systematically reported in IDD-related diseases. Therefore, this review describes the biological characteristics of Nrf2 and HO-1, the relationship between Nrf2- and HO-1-regulated oxidative stress and the inflammatory response and IDD, and the progress in research on some extracts targeting Nrf2 and HO-1 to improve IDD. Understanding the role and mechanism of Nrf2 and HO-1 in IDD may provide novel ideas for the clinical treatment and development of Nrf2- and HO-1-targeted drugs.

Exosomes: A novel insight into traditional Chinese medicine

Exosomes are small extracellular vesicles and play an essential role in the mediation of intercellular communication both in health and disease. Traditional Chinese medicine (TCM) has historically been used to maintain human health and treat various diseases up till today. The interplay between exosomes and TCM has attracted researchers’ growing attention. By integrating the available evidence, TCM formulas and compounds isolated from TCM as exosome modulators have beneficial effects on multiple disorders, such as tumors, kidney diseases, and hepatic disease, which may associate with inhibiting cells proliferation, anti-inflammation, anti-oxidation, and attenuating fibrosis. Exosomes, a natural delivery system, are essential in delivering compounds isolated from TCM to target cells or tissues. Moreover, exosomes may be the potential biomarkers for TCM syndromes, providing strategies for TCM treatment. These findings may provide a novel insight into TCM from exosomes and serve as evidence for better understanding and development of TCM.

Better Bioactivity, Cerebral Metabolism and Pharmacokinetics of Natural Medicine and Its Advanced Version

Currently, many people are afflicted by cerebral diseases that cause dysfunction in the brain and perturb normal daily life of people. Cerebral diseases are greatly affected by cerebral metabolism, including the anabolism and catabolism of neurotransmitters, hormones, neurotrophic molecules and other brain-specific chemicals. Natural medicines (NMs) have the advantages of low cost and low toxicity. NMs are potential treatments for cerebral diseases due to their ability to regulate cerebral metabolism. However, most NMs have low bioavailability due to their low solubility/permeability. The study is to summarize the better bioactivity, cerebral metabolism and pharmacokinetics of NMs and its advanced version. This study sums up research articles on the NMs to treat brain diseases. NMs affect cerebral metabolism and the related mechanisms are revealed. Nanotechnologies are applied to deliver NMs. Appropriate delivery systems (exosomes, nanoparticles, liposomes, lipid polymer hybrid nanoparticles, nanoemulsions, protein conjugation and nanosuspensions, etc.) provide better pharmacological and pharmacokinetic characteristics of NMs. The structure-based metabolic reactions and enzyme-modulated catalytic reactions related to advanced versions of NMs alter the pharmacological activities of NMs.

Zein-Stabilized Nanospheres as Nanocarriers for Boosting the Aphrodisiac Activity of Icariin: Response Surface Optimization and In Vivo Assessment

Icariin (ICA), a main active compound of the Epimedium genus, is used as an aphrodisiac in traditional Chinese herbal medicine. Despite its therapeutic efficacy, ICA displays reduced oral absorption, and therefore, low bioavailability hindered its clinical application. Implementing nanotechnology in the field of formulation has been a focus to improve the efficacy of ICA. In this regard, polymeric nanoparticles find a potential application as drug delivery systems. A nanosphere formula was designed, aiming to improve the drug’s efficacy. The proposed ICA nanosphere formula (tocozeinolate) was optimized using D-optimal response surface design. The concentrations of ICA (X₁), D-α-tocopherol polyethylene glycol 1000 succinate (TPGS, X₂), zein (X₃), and sodium deoxycholate (SDC, X₄) expressed as percentages were investigated as quantitative independent variables. As per the experimental design, 23 formulations were developed, which were investigated for particle size (PS, nm), zeta potential (ZP, mV), and entrapment efficiency (EE, %) as response parameters. Numerical optimization and desirability approach were employed to predict the optimized variable levels that, upon combination, could result in minimized size and maximized zeta potential and ICA entrapment. The optimized ICA–tocozeinolate nanospheres showed a particle size of 224.45 nm, zeta potential of 0.961 mV, and drug entrapment of 65.29% that coincide well with the predicted values. The optimized ICA–tocozeinolate nanospheres were evaluated for sexual behavior in Wistar male rats compared to raw ICA at equivalent doses (20 mg/kg). In vivo assessment results showed significant sexual behavior enhancement by the optimized formulation, as evidenced by decreased average time of both mount latency (ML) and ejaculation latency (EL) to almost half those of raw ICA. Additionally, intromission latency (IL) time was reduced by 41% compared to the raw ICA. These results highlighted the potential of the proposed ICA–tocozeinolate nanospheres as a promising platform for improving the delivery and efficacy of therapeutic agents.

Icaritin Preparation from Icariin by a Special Epimedium Flavonoid-Glycosidase from Aspergillus sp.y848 Strain

In this study, to obtain icaritin with high pharmacological activities from icariin, which has a content ratio of over 58% in the total flavonoids of Epimedium herb, a special Epimedium flavonoid-glycosidase was produced, purified and characterized from Aspergillus sp.y848 strain. The optimal enzyme production was gained in a medium containing 5% (w/v) wheat bran extract and 0.7% (w/v) Epimedium leaf powder as the enzyme inducer, and strain culture at 30°C for 6-7 days. The molecular weight of the enzyme was approximately 73.2 kDa; the optimal pH and temperature were 5.0 and 40°C. The enzyme Km and Vmax values for icariin were 15.63 mM and 55.56 mM/h. Moreover, the enzyme hydrolyzed the 7-O-glucosides of icariin into icariside II, and finally hydrolyzed 3-O-rhamnoside of icariside II into icaritin. The enzyme also hydrolyzed 7-O-glucosides of epimedin B to sagittatoside B, and then further hydrolyzed terminal 3-O-xyloside of sagittatoside B to icarisiede II, before finally hydrolyzing 3-O-rhamnoside of icarisiede II into icaritin. The enzyme only hydrolyzed 7-O-glucoside of epimedin A or epimedin C into sagittatoside A or sagittatoside C. It is possible to prepare icaritin from the high-content icariin in Epimedium herb using this enzyme. When 2.5% icariin was reacted at 40°C for 18-20 h by the low-cost crude enzyme, 5.04 g icaritin with 98% purity was obtained from 10 g icariin. Also, the icaritin molar yield was 92.5%. Our results showed icaritin was successfully produced via cost-effective and relatively simple methods from icariin by crude enzyme. Our results should be very useful for the development of medicines from Epimedium herb.

Icaritin attenuates 6-OHDA-induced MN9D cell damage by inhibiting oxidative stress

Background

We assessed whether ICT can alleviate 6-OHDA-induced cell damage via inhibition of oxidative stress by evaluating the protective effect of icaritin (ICT) against 6-hydroxydopamine (6-OHDA)-induced MN9D cell damage and further determined the mechanism by which ICT reduces oxidative stress.

Methods

MN9D cells were treated with 6-OHDA, to study the mechanism underlying the neuroprotective effect of ICT. MN9D cell damage was assessed by the CCK-8 assay, flow cytometry was performed to measure the content of reactive oxygen species (ROS) in cells, a superoxide dismutase (SOD) kit was used to evaluate SOD activity, and Western blotting was used to measure the expression of α-synuclein (α-Syn), Tyrosine hydroxylase (TH), nuclear factor erythroid-2 related factor 2 (Nrf2), and heme oxygenase-1 (HO-1).

Results

ICT reduced damage to MN9D cells induced by 6-OHDA. ICT increased SOD activity and TH expression and reduced ROS production and α-Syn expression. ICT promoted the translocation of Nrf2 from the cytoplasm to the nucleus and further increased the protein expression of HO-1.

Conclusions

ICT protects against 6-OHDA-induced dopaminergic neuronal cell injury by attenuating oxidative stress, and the mechanism is related to modulate the activities of Nrf2, HO-1 protein, and SOD.

Antiosteoporosis Effects, Pharmacokinetics, and Drug Delivery Systems of Icaritin: Advances and Prospects

Osteoporosis is a systemic skeletal disorder affecting over 200 million people worldwide and contributes dramatically to global healthcare costs. Available anti-osteoporotic drug treatments including hormone replacement therapy, anabolic agents, and bisphosphonates often cause adverse events which limit their long-term use. Therefore, the application of natural products has been proposed as an alternative therapy strategy. Icaritin (ICT) is not only an enzyme-hydrolyzed product of icariin but also an intestinal metabolite of eight major flavonoids of the traditional Chinese medicinal plant Epimedium with extensive pharmacological activities, such as strengthening the kidney and reinforcing the bone. ICT displays several therapeutic effects, including osteoporosis prevention, neuroprotection, antitumor, cardiovascular protection, anti-inflammation, and immune-protective effect. ICT inhibits bone resorption activity of osteoclasts and stimulates osteogenic differentiation and maturation of bone marrow stromal progenitor cells and osteoblasts. As for the mechanisms of effect, ICT regulates relative activities of two transcription factors Runx2 and PPARγ, determines the differentiation of MSCs into osteoblasts, increases mRNA expression of OPG, and inhibits mRNA expression of RANKL. Poor water solubility, high lipophilicity, and unfavorable pharmacokinetic properties of ICT restrict its anti-osteoporotic effects, and novel drug delivery systems are explored to overcome intrinsic limitations of ICT. The paper focuses on osteogenic effects and mechanisms, pharmacokinetics and delivery systems of ICT, and highlights bone-targeting strategies to concentrate ICT on the ideal specific site of bone. ICT is a promising potential novel therapeutic agent for osteoporosis.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

Icariin attenuates cyclophosphamide-induced cystitis via down-regulation of NF-кB and up-regulation of Nrf-2/HO-1 signaling pathways in mice model

Cystitis is a chronic bladder pain associated with frequency and nocturia. In the present study, Icariin a prenylated flavonoid extracted from Epimedium koreanum, was investigated against cyclophosphamide (CYP)-induced cystitis pain in mice model. Preliminarily in an acute model, single dose of CYP (150 mg/kg; i.p) was administered followed by Icariin (5, 25 and 50 mg/kg, i.p.). The visceral sensitivity and nociceptive behaviors were significantly ameliorated by pretreatment with Icariin (25, 50 mg/kg) that were assessed by spontaneous pain scoring, von Frey test and clinical scoring. Further, in chronic model Icariin (25 mg/kg, i.p.) was administered for 10 consecutive days prior to CYP (75 mg/kg; i.p) challenged every 3rd day for the duration of 10 days. Icariin not only had a protective effect on edema including bladder wet weight and hemorrhage but also had a potential to reduce vascular permeability, mast cells infiltration and tissue fibrosis. Evidently, Icariin prevented the neutrophilia/lymphopenia caused by CYP, and markedly improved the antioxidant enzymes level including superoxide dismutase, glutathione sulfo-transferase, catalase, glutathione level and reduced Malondialdehyde level, myeloperoxidase activity and nitric oxide, and also decreased the production of tumor necrosis factor-α (TNF-α) and interleukin-1 beta (IL-1β) in bladder. Icariin markedly enhanced the Nrf-2, heme oxygenase (HO-1) and IкB-α expression, while attenuated the expression level of Keap1, TLR-4, NF-кB, i-NOS, COX-2 and TRPV1 as compared to negative group. This research illustrated the anti-inflammatory properties of Icariin and effectively improved CYP-induced cystitis pain.

Re-appraising the role of flavonols, flavones and flavonones on osteoblasts and osteoclasts- A review on its molecular mode of action

Bone disorders have become a global concern illustrated with decreased bone mineral density and disruption in microarchitecture of natural bone tissue organization. Natural compounds that promote bone health by augmenting osteoblast functions and suppressing osteoclast functions has gained much attention and offer greater therapeutic value compared to conventional therapies. Amongst several plant-based molecules, flavonoids act as a major combatant in promoting bone health through their multi-faceted biological activities such as antioxidant, anti-inflammatory, and osteogenic properties. They protect bone loss by regulating the signalling cascades involved in osteoblast and osteoclast functions. Flavonoids augment osteoblastogenesis and inhibits osteoclastogenesis through their modulation of various signalling pathways. This review discusses the role of various flavonoids and their molecular mechanisms involved in maintaining bone health by regulating osteoblast and osteoclast functions.

Phyto-targeting the CEMIP Expression as a Strategy to Prevent Pancreatic Cancer Metastasis

INTRODUCTION

Metastasis of primary pancreatic cancer (PC) to adjacent or distant organs is responsible for the poor survival rate of affected individuals. Chemotherapy, radiotherapy, and immunotherapy are currently being prescribed to treat PC in addition to surgical resection. Surgical resection is the preferred treatment for PC that leads to 20% of 5-year survival, but only less than 20% of patients are eligible for surgical resection because of the poor prognosis. To improve the prognosis and clinical outcome, early diagnostic markers need to be identified, and targeting them would be of immense benefit to increase the efficiency of the treatment. Cell migration-inducing hyaluronan-binding protein (CEMIP) is identified as an important risk factor for the metastasis of various cancers, including PC. Emerging studies have pointed out the crucial role of CEMIP in the regulation of various signaling mechanisms, leading to enhanced migration and metastasis of PC.

METHODS

The published findings on PC metastasis, phytoconstituents, and CEMIP were retrieved from Pubmed, ScienceDirect, and Cochrane Library. Computational tools, such as gene expression profiling interactive analysis (GEPIA) and Kaplan-Meier (KM) plotter, were used to study the relationship between CEMIP expression and survival of PC individuals.

RESULTS

Gene expression analysis using the GEPIA database identified a stupendous increase in the CEMIP transcript in PC compared to adjacent normal tissues. KM plotter analysis revealed the impact of CEMIP on the overall survival (OS) and disease-free survival (DFS) among PC patients. Subsequently, several risk factors associated with PC development were screened, and their ability to regulate CEMIP gene expression was analyzed using computational tools.

CONCLUSION

The current review is focused on gathering information regarding the regulatory role of phytocomponents in PC migration and exploring their possible impact on the CEMIP expression.

Flavonoids Synergistically Enhance the Anti-Glioblastoma Effects of Chemotherapeutic Drugs

Flavonoids are polyphenolic plant secondary metabolites with pleiotropic biological properties, including anti-cancer activities. These natural compounds have potential utility in glioblastoma (GBM), a malignant central nervous system tumor derived from astrocytes. Conventional GBM treatment modalities such as chemotherapy, radiation therapy, and surgical tumor resection are beneficial but limited by extensive tumor invasion and drug/radiation resistance. Therefore, dietary flavonoids—with demonstrated anti-GBM properties in preclinical research—are potential alternative therapies. This review explores the synergistic enhancement of the anti-GBM effects of conventional chemotherapeutic drugs by flavonoids. Primary studies published between 2011 and 2021 on flavonoid–chemotherapeutic synergy in GBM were obtained from PubMed. These studies demonstrate that flavonoids such as chrysin, epigallocatechin-3-gallate (EGCG), formononetin, hispidulin, icariin, quercetin, rutin, and silibinin synergistically enhance the effects of canonical chemotherapeutics. These beneficial effects are mediated by the modulation of intracellular signaling mechanisms related to apoptosis, proliferation, autophagy, motility, and chemoresistance. In this light, flavonoids hold promise in improving current therapeutic strategies and ultimately overcoming GBM drug resistance. However, despite positive preclinical results, further investigations are necessary before the commencement of clinical trials. Key considerations include the bioavailability, blood–brain barrier (BBB) permeability, and safety of flavonoids; optimal dosages of flavonoids and chemotherapeutics; drug delivery platforms; and the potential for adverse interactions.

Dietary Phytoestrogens and Their Metabolites as Epigenetic Modulators with Impact on Human Health

The impact of dietary phytoestrogens on human health has been a topic of continuous debate since their discovery. Nowadays, based on their presumptive beneficial effects, the amount of phytoestrogens consumed in the daily diet has increased considerably worldwide. Thus, there is a growing need for scientific data regarding their mode of action in the human body. Recently, new insights of phytoestrogens’ bioavailability and metabolism have demonstrated an inter-and intra-population heterogeneity of final metabolites’ production. In addition, the phytoestrogens may have the ability to modulate epigenetic mechanisms that control gene expression. This review highlights the complexity and particularity of the metabolism of each class of phytoestrogens, pointing out the diversity of their bioactive gut metabolites. Futhermore, it presents emerging scientific data which suggest that, among well-known genistein and resveratrol, other phytoestrogens and their gut metabolites can act as epigenetic modulators with a possible impact on human health. The interconnection of dietary phytoestrogens’ consumption with gut microbiota composition, epigenome and related preventive mechanisms is discussed. The current challenges and future perspectives in designing relevant research directions to explore the potential health benefits of dietary phytoestrogens are also explored.

Identifying mechanisms of Epimedii Folium against Alzheimer’s disease via a network pharmacology approach Epimedii Folium treats Alzheimer’s disease via PI3K-AKT

To elucidate the mechanism of the multi-target action of Epimedii Folium on Alzheimer’s disease, this study focuses on the analysis of network pharmacology. Based on a bioinformatics approach, this study obtained the effective components of Epimedium through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform, predicted the compound targets through the Pharmapper and Swiss target prediction database and then through Gene Expression Omnibus Datasets and Therapeutic Target Database. We collected and analysed of heral and disease targets, constructed the network. Through the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, Gene Ontology enrichment, then the key targets and pathways of Epimedii Folium to cope with Alzheimer’s disease have been identified. Twenty-three bioactive components and 477 potential target genes of Epimedii Folium were identified. A total of 1612 target diseases were identified. Through network module analysis, 30 hub target genes were identified. Through enrichment analysis of the KEGG pathway, hub target genes were largely enriched in the PI3K-AKT signaling pathway. Through the analysis of network pharmacology, it was found that Epimedii Folium might play the role of multi-compound and multi-target therapy through the PI3K-AKT signaling pathway. These findings provide helpful directions for future clinical studies.

An overview on therapeutic and medicinal potential of poly-hydroxy flavone viz. Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone for management of Alzheimer's and Parkinson's diseases: a critical analysis on mechanistic insight

Neurodegenerative disorders occur when nerve cells in the brain or peripheral nervous system partial or complete fail in their functions and sometimes even die due to some injuries or aging. Neurodegenerative disorders such as Alzheimer's Disease (AD) and Parkinson's Disease (PD), have been majorly resulted due to degeneration of neurons and neuroinflammation progressively. There are many similarities that correlates both AD and PD on a cellular and sub-cellular level. Therefore, a hope for therapeutic advancement for simultaneous upgradation in both the diseases are directly depending on the discovery of common mechanism at molecular and cellular level. Recent and past evidences from scientific literature supporting the efficacy of plants flavonoids in treatment and protection of both AD and PD. Further, dietary flavones, specially Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone gains recently much more attention for producing many health beneficiary effects including neuroprotection. Despite of these evidence a detailed updated overview of neuroprotective effects against both AD and PD by Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone are still missing. In this context several published studies were assessed by using various online electronic search engines/databases to meet the objective from 1981 to 2021 (Approx. 224). Therefore, present review was designed to deliver the detailed description on these flavones including therapeutic benefits in AD, PD and other CNS complications with critical analysis on underlying mechanisms.

Neuroprotective Effects of Palmatine via the Enhancement of Antioxidant Defense and Small Heat Shock Protein Expression in Aβ-Transgenic Caenorhabditis elegans

Palmatine is a naturally occurring isoquinoline alkaloid that has been reported to display neuroprotective effects against amyloid-β- (Aβ-) induced neurotoxicity. However, the mechanisms underlying the neuroprotective activities of palmatine remain poorly characterized in vivo. We employed transgenic Caenorhabditis elegans models containing human Aβ_1-42 to investigate the effects and possible mechanisms of palmatine-mediated neuroprotection. Treatment with palmatine significantly delayed the paralytic process and reduced the elevated reactive oxygen species levels in Aβ-transgenic C. elegans. In addition, it increased oxidative stress resistance without affecting the lifespan of wild-type C. elegans. Pathway analysis suggested that the differentially expressed genes were related mainly to aging, detoxification, and lipid metabolism. Real-time PCR indicated that resistance-related genes such as sod-3 and shsp were significantly upregulated, while the lipid metabolism-related gene fat-5 was downregulated. Further studies demonstrated that the inhibitory effects of palmatine on Aβ toxicity were attributable to the free radical-scavenging capacity and that the upregulated expression of resistance-related genes, especially shsp, whose expression was regulated by HSF-1, played crucial roles in protecting cells from Aβ-induced toxicity. The research showed that there were significantly fewer Aβ deposits in transgenic CL2006 nematodes treated with palmatine than in control nematodes. In addition, our study found that Aβ-induced toxicity was accompanied by dysregulation of lipid metabolism, leading to excessive fat accumulation in Aβ-transgenic CL4176 nematodes. The alleviation of lipid disorder by palmatine should be attributed not only to the reduction in fat synthesis but also to the inhibition of Aβ aggregation and toxicity, which jointly maintained metabolic homeostasis. This study provides new insights into the in vivo neuroprotective effects of palmatine against Aβ aggregation and toxicity and provides valuable targets for the prevention and treatment of AD.

Icariin, an Up-and-Coming Bioactive Compound Against Neurological Diseases: Network Pharmacology-Based Study and Literature Review

Icariin is a biologically active substance in Epimedii herba that is used for the treatment of neurologic disorders. However, a comprehensive analysis of the molecular mechanisms of icariin is lacking. In this review, we present a brief history of the use of icariin for medicinal purposes; describe the active chemical components of Epimedii herba; and examine the evidence from experimental studies that have uncovered molecular targets of icariin in different diseases. We also constructed a protein–protein interaction network and carried out Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses to predict the therapeutic actions of icariin in nervous system diseases including Alzheimer disease, Parkinson disease, ischemic stroke, depressive disorder, multiple sclerosis, glioblastoma, and hereditary spastic paraplegias. The results of our analyses can guide future studies on the application of icariin to the treatment of neurologic disorders.

Icariin ameliorate Alzheimer's disease by influencing SIRT1 and inhibiting Aβ cascade pathogenesis

Of all types of dementia, Alzheimer's disease is the type that has the highest proportion of cases and is the cause of substantial medical and economic burden. The mechanism of Alzheimer's disease is closely associated with the aggregation of amyloid-β protein and causes neurotoxicity and extracellular accumulation in the brain and to intracellular neurofibrillary tangles caused by tau protein hyperphosphorylation in the brain tissue. Previous studies have demonstrated that sirtuin1 downregulation is involved in the pathological mechanism of Alzheimer's disease. The decrease of sirtuin1 level would cause Alzheimer's disease by means of promoting the amyloidogenic pathway to generate amyloid-β species and thereby triggering amyloid-β cascade reaction, such as tau protein hyperphosphorylation, neuron autophagy, neuroinflammation, oxidative stress, and neuron apoptosis. Currently, there is no effective treatment for Alzheimer's disease, it is necessary to develop new treatment strategies. According to the theory of traditional Chinese medicine and based on the mechanism of the disease, tonifying the kidneys is one of the principles for the treatment of Alzheimer's disease and Epimedium is a well-known Chinese medicine for tonifying kidney. Therefore, investigating the influence of the components of Epimedium on the pathological characteristics of Alzheimer's disease may provide a reference for the treatment of Alzheimer's disease in the future. In this article, we summarise the effects and mechanism of icariin, the main ingredient extracted from Epimedium, in ameliorating Alzheimer's disease by regulating sirtuin1 to inhibit amyloid-β protein and improve other amyloid-β cascade pathogenesis.

Natural Products of Pharmacology and Mechanisms in Nucleus Pulposus Cells and Intervertebral Disc Degeneration

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain (LBP), which severely reduces the quality of life and imposes a heavy financial burden on the families of affected individuals. Current research suggests that IDD is a complex cell-mediated process. Inflammation, oxidative stress, mitochondrial dysfunction, abnormal mechanical load, telomere shortening, DNA damage, and nutrient deprivation contribute to intervertebral disc cell senescence and changes in matrix metabolism, ultimately causing IDD. Natural products are widespread, structurally diverse, afford unique advantages, and exhibit great potential in terms of IDD treatment. In recent years, increasing numbers of natural ingredients have been shown to inhibit the degeneration of nucleus pulposus cells through various modes of action. Here, we review the pharmacological effects of natural products on nucleus pulposus cells and the mechanisms involved. An improved understanding of how natural products target signalling pathways will aid the development of anti-IDD drugs. This review focuses on potential IDD drugs.

Icariin Ameliorates Diabetic Renal Tubulointerstitial Fibrosis by Restoring Autophagy via Regulation of the miR-192-5p/GLP-1R Pathway

Tubulointerstitial fibrosis is one of the most common pathological features of diabetic nephropathy. Autophagy, an intracellular mechanism to remove damaged or dysfunctional cell parts and maintain metabolic homeostasis, is inhibited in diabetic neuropathy. Icariin is a traditional Chinese medicine extract known for nourishing the kidney and reinforcing Yang. In this study, we investigated the effects and mechanism of Icariin on renal function, autophagy, and fibrosis in type 2 diabetic nephropathic rats and in high-glucose-incubated human renal tubular epithelial cells and rat renal fibroblasts (in vitro). Icariin improved diabetes, renal function, restored autophagy, and alleviated fibrosis in type 2 diabetic neuropathic rats and in vitro. After we applied autophagy-related gene 5-small interfering RNA, we found that fibrosis improvement by Icariin was related to autophagy restoration. By detecting serum sex hormone levels, and using dihydrotestosterone, siRNA for androgen receptor, and the androgen receptor antagonist Apalutamide (ARN-509), we found that Icariin had an androgen-like effect and restored autophagy and reduced fibrosis by regulating the androgen receptor. In addition, miR-192-5p levels were increased under high glucose but reduced after dihydrotestosterone and Icariin treatment. Furthermore, dihydrotestosterone and Icariin inhibited miR-192-5p overexpression-induced fibrosis production and autophagy limitation. Glucagon-like peptide-1 receptor (GLP-1R) was downregulated by high glucose and overexpression of miR-192-5p and could be restored by dihydrotestosterone and Icariin. By using ARN-509, we found that Icariin increased GLP-1R expression by regulating the androgen receptor. GLP-1R-siRNA transfection weakened the effects of Icariin on autophagy and fibrosis. These findings indicate that Icariin alleviates tubulointerstitial fibrosis by restoring autophagy through the miR-192-5p/GLP-1R pathway and is a novel therapeutic option for diabetic fibrosis.

Improving Cognition with Nutraceuticals Targeting TGF-β1 Signaling

Rescue of cognitive function represents an unmet need in the treatment of neurodegenerative disorders such as Alzheimer’s disease (AD). Nutraceuticals deliver a concentrated form of a presumed bioactive(s) agent(s) that can improve cognitive function alone or in combination with current approved drugs for the treatment of cognitive disorders. Nutraceuticals include different natural compounds such as flavonoids and their subclasses (flavan-3-ols, catechins, anthocyanins, and flavonols), omega-3, and carnosine that can improve synaptic plasticity and rescue cognitive deficits through multiple molecular mechanisms. A deficit of transforming growth factor-β1 (TGF-β1) pathway is an early event in the pathophysiology of cognitive impairment in different neuropsychiatric disorders, from depression to AD. In the present review, we provide evidence that different nutraceuticals, such as Hypericum perforatum (hypericin and hyperforin), flavonoids such as hesperidin, omega-3, and carnosine, can target TGF-β1 signaling and increase TGF-β1 production in the central nervous system as well as cognitive function. The bioavailability of these nutraceuticals, in particular carnosine, can be significantly improved with novel formulations (nanoparticulate systems, nanoliposomes) that increase the efficacy and stability of this peptide. Overall, these studies suggest that the synergism between nutraceuticals targeting the TGF-β1 pathway and current approved drugs might represent a novel pharmacological approach for reverting cognitive deficits in AD patients.

Icariin enhances youth-like features by attenuating the declined gut microbiota in the aged mice

We previously reported the neuroprotective effects of icariin in rat cortical neurons. Here, we present a study on icariin's anti-aging effect in 24-month aged mice by treating them with a single daily dose of 100 mg/kg of icariin for 15 consecutive days. Icariin treatment improved motor coordination and learning skills while lowered oxidative stress biomarkers in the serum, brain, kidney, and liver of the aged mice. In addition, icariin improved the intestinal integrity of the aged mice by upregulating tight junction adhesion molecules and the Paneth and goblet cells, along with the reduction of iNOS and pro-inflammatory cytokines (IL-1β, TNF-α, IL-2 and IL-6, and IL-12). Icariin treatments also significantly upregulated aging-related signaling molecules, Sirt 1, 3 & 6, Pot1α, BUB1b, FOXO1, Ep300, ANXA3, Calb1, SNAP25, and BDNF in old mice. Through gut microbiota (GM) analysis, we observed icariin-associated improvements in GM composition of aged mice by reinstating bacteria found in the young mice, while suppressing some bacteria found in the untreated old mice. To clarify whether icariin's anti-aging effect is rooted in the GM, we performed fecal microbiota transfer (FMT) from icariin-treated old mice to the old mice. FMT-recipients exhibited similar improvements in the rotarod score and age-related biomarkers as observed in the icariin-treated old mice. Equal or better improvement on the youth-like features was noticed when aged mice were FMT with feces from young mice. Our study shows that both direct treatments with icariin and fecal transplant from the icariin-treated aged mice produce similar anti-aging phenotypes in the aged mice. We prove that GM plays a pivotal role in the healing abilities of icariin. Icariin has the potentials to be developed as a medicine for the wellness of the aged adults.

Flavonoids, the compounds with anti-inflammatory and immunomodulatory properties, as promising tools in multiple sclerosis (MS) therapy: A systematic review of preclinical evidence

Multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), an animal model of MS, are diseases resulting in neurological disabilities that are regarded as chronic, inflammatory, and autoimmune diseases of central nervous system (CNS). In this respect, the use of anti-inflammatory compounds including flavonoids, polyphenolic compounds abundantly found in vegetables and fruits, has proposed to combat MS to dampen the inflammation and thereby ameliorating the disease severity. The objective of this study was to clarify the probable therapeutic effect of flavonoids for treatment of MS. Therefore, only English published articles that reported the therapeutic effect of flavonoids alone or in combination with other anti-MS therapeutic agents on MS, were selected by searching scientific electronic databases including PubMed, Scopus and Web of Science. Evaluation of the selected researches (686) showed that a total of 13 studies were suitable to be included in this systematic review. Interestingly, all of the studies (11 studies concerning EAE and 2 studies concerning MS) reported positive outcomes for the therapeutic effect of flavonoids on EAE and MS. All flavonoid compounds which are mentioned herein could successfully decrease the maximum clinical score of EAE, which is particularly connected to the anti-inflammatory property of these compounds. The literature review clearly discloses that flavonoids alone or in combination with other anti-MS therapeutic agents can pave the way for improving MS therapeutic strategies.

Potential roles of natural products in the targeting of proteinopathic neurodegenerative diseases

Defective proteostasis is associated with the gradual accumulations of misfolded proteins and is a hallmark of many age-associated neurodegenerative diseases. In the aged brain, maintenance of the proteostasis network presents a substantial challenge, and its loss contributes to the onset and progression of neurological diseases associated with cognitive decline due to the generation of toxic protein aggregates, a process termed 'proteinopathy'. Emerging evidence suggests that reversing proteinopathies by boosting proteostasis might provide an effective means of preventing neurodegeneration. From this perspective, phytochemicals may play significant roles as potent modulators of the proteostasis network, as previous reports have suggested they can interact with various network components to modify pathologies and confer neuroprotection. This review focuses on some potent phytochemicals that directly or indirectly modulate the proteostasis network and on their possible molecular targets. In addition, we propose strategies for the natural product-based modulation of proteostasis machinery that target proteinopathies.

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.

Bioactive Icariin/β-CD-IC/Bacterial Cellulose with Enhanced Biomedical Potential

A "super" bioactive antibacterial hydrogel, Icariin-β-CD-inclusion complex/Bacterial cellulose and an equally capable counterpart Icariin-Bacterial cellulose (ICBC) were successfully produced with excellent antioxidant properties. The highly porous hydrogels demonstrated very high fluid/liquid absorption capability and were functionally active as Fourier Transform Infrared Spectrometer (FTIR) test confirmed the existence of abundant hydroxyls (-OH stretching), carboxylic acids (-CH₂/C-O stretching), Alkyne/nitrile (C≡C/C≡N stretching with triple bonds) and phenol (C-H/N-O symmetric stretching) functional groups. Scanning electron microscope (SEM) and X-ray diffraction (XRD) tests confirmed a successful β-CD-inclusion complexation with Icariin with a great potential for sustained and controlled drug release. In vitro drug release test results indicated a systemic and controlled release of the drug (Icariin) from the internal cavities of the β-CD inclusion complex incorporated inside the BC matrix with high Icariin (drug) release rates. Impressive inactivation rates against Gram-negative bacteria Escherichia coli ATCC 8099 and gram-positive bacteria Staphylococcus aureus ATCC 6538; >99.19% and >98.89% respectively were recorded, as the materials proved to be non-toxic on L929 cells in the in vitro cytotoxicity test results. The materials with promising versatile multipurpose administration of Icariin for wound dressing (as wound dressers), can also be executed as implants for tissue regeneration, as well as face-mask for cosmetic purposes.