Tangeretin protects human brain microvascular endothelial cells against oxygen-glucose deprivation-induced injury

Exploring the Therapeutic Potential of BBB-Penetrating Phytochemicals With p38 MAPK Modulatory Activity in Addressing Oxidative Stress-Induced Neurodegenerative Disorders, With a Focus on Alzheimer's Disease

Oxidative stress plays an important role in the occurrence of neurodegenerative diseases. Previous studies indicate a strong connection between oxidative stress, inappropriate activation of the p38 MAPK signaling pathway, and the pathogenesis of neurodegenerative diseases. Although antioxidant therapy is a valid strategy to alleviate these problems, the most important limitation of this approach is the ineffectiveness of drug administration due to the limited permeability of the BBB. Therefore, BBB-penetrating p38 MAPK modulators with proper antioxidant capacity could be useful in preventing/reducing the complications of neurodegenerative disorders. The current manuscript aims to review the therapeutic capabilities of some recently reviewed naturally occurring p38 MAPK inhibitors in the management of neurodegenerative problems such as Alzheimer's disease. In data collection, we tried to use more recent studies published in high-quality journals indexed in databases Scopus, Web of Science, PubMed, and so on, but no specific time frame was considered due to the nature of the study. Our evaluations indicate that natural compounds tanshinones, protoberberines, pinocembrin, osthole, rhynchophylline, oxymatrine, schisandrin, piperine, paeonol, ferulic acid, 6-gingerol, obovatol, and trolox have significant potential for use as supplements/adjuvants in the reduction of neurodegenerative-related problems. Our findings emphasize the usefulness of BBB-penetrating phytochemicals with p38 MAPK modulatory activity as potential therapeutic options against neurodegenerative disorders. Of course, the proper use of these compounds depends on considering their toxicity/safety profile and pharmacokinetic characteristics as well as the clinical conditions of users.

The roles of dietary polyphenols at crosstalk between type 2 diabetes and Alzheimer's disease in ameliorating oxidative stress and mitochondrial dysfunction via PI3K/Akt signaling pathways

Alzheimer's disease (AD) is a fatal neurodegenerative disease in which senile plaques and neurofibrillary tangles are crucially involved in its physiological and pathophysiological processes. Growing animal and clinical studies have suggested that AD is also comorbid with some metabolic diseases, including type 2 diabetes mellitus (T2DM), and therefore, it is often considered brain diabetes. AD and T2DM share multiple molecular and biochemical mechanisms, including impaired insulin signaling, oxidative stress, gut microbiota dysbiosis, and mitochondrial dysfunction. In this review article, we mainly introduce oxidative stress and mitochondrial dysfunction and explain their role and the underlying molecular mechanism in T2DM and AD pathogenesis; then, according to the current literature, we comprehensively evaluate the possibility of regulating oxidative homeostasis and mitochondrial function as therapeutics against AD. Furthermore, considering dietary polyphenols' antioxidative and antidiabetic properties, the strategies for applying them as potential therapeutical interventions in patients with AD symptoms are assessed.

Effect of tangeretin on cisplatin-induced oxido-inflammatory brain damage in rats

Cisplatin (CIS) is a platinum-derived chemotherapeutic agent commonly utilized in the treatment of various malignant tumours. However, anticancer doses of the drug cause serious damage to the brain. This study aimed to determine the potential protective effects of tangeretin, which has antioxidant and anti-inflammatory properties, in cisplatin-induced neurotoxicity on BALB/c mice brains. Male BALB/c mice were randomized and separated into four groups. Tangeretin was given for 10 days by gavage. CIS was injected as a single dose of 10 mg/kg intraperitoneally (ip) on the 10th day. Brain tissues, malondialdehyde (MDA), total glutathione (tGSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and nitric oxide (NO) levels were measured to determine oxidative damage and myeloperoxidase, tumour necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), IL-6 and IL-10 were measured to determine inflammatory activity. In addition, 8-OHdG and caspase-3 were analysed by immunofluorescence methods. While CIS administration remarkably elevated reactive oxygen species, MDA, and NO levels in brain tissue compared to the control, tGSH, GPx, SOD and CAT levels were significantly decreased. Also, it has been detected that TNF-α, IL-1β and IL-6 obtained in CIS-treated groups increased as well as IL-10 decreased, thereby elevating the inflammatory response. In addition, 8-OHdG and caspase-3 immunoreactivity in neurons increased with CIS administration. Treatment with tangeretin ameliorated the deterioration in oxidant/antioxidant status, overpowered neuroinflammation and ameliorated neurotoxicity-induced apoptosis. This study shows that tangeretin has beneficial effects on CIS-induced neurodegeneration. Possible mechanisms underlying these beneficial effects include the antioxidant and anti-inflammatory properties of tangeretin.

An Update on the Potential of Tangeretin in the Management of Neuroinflammation-Mediated Neurodegenerative Disorders

Neuroinflammation is the major cause of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. Currently available drugs present relatively low efficacy and are not capable of modifying the course of the disease or delaying its progression. Identifying well-tolerated and brain-penetrant agents of plant origin could fulfil the pressing need for novel treatment techniques for neuroinflammation. Attention has been drawn to a large family of flavonoids in citrus fruits, which may function as strong nutraceuticals in slowing down the development and progression of neuroinflammation. This review is aimed at elucidating and summarizing the effects of the flavonoid tangeretin (TAN) in the management of neuroinflammation-mediated neurodegenerative disorders. A literature survey was performed using various resources, including ScienceDirect, PubMed, Google Scholar, Springer, and Web of Science. The data revealed that TAN exhibited immense neuroprotective effects in addition to its anti-oxidant, anti-diabetic, and peroxisome proliferator-activated receptor-γ agonistic effects. The effects of TAN are mainly mediated through the inhibition of oxidative and inflammatory pathways via regulating multiple signaling pathways, including c-Jun N-terminal kinase, phosphoinositide 3-kinase, mitogen-activated protein kinase, nuclear factor erythroid-2-related factor 2, extracellular-signal-regulated kinase, and CRE-dependent transcription. In conclusion, the citrus flavonoid TAN has the potential to prevent neuronal death mediated by neuroinflammatory pathways and can be developed as an auxiliary therapeutic agent in the management of neurodegenerative disorders.

Pharmacokinetic study on the effect of ligustrazine-tangeretin co-administration on the pharmacokinetics of ligustrazine and its potential mechanism in rats

Both ligustrazine and tangeretin are usually prescribed in the treatment of cardiovascular diseases, which makes their co-administration possible. The investigation of the interaction between ligustrazine and tangeretin is necessary for the clinical compatibility of their source herbs. This study aimed to investigate the interaction of ligustrazine and tangeretin during their co-administration. The pharmacokinetics of ligustrazine (15 mg/kg) was investigated in the presence of 50, 100, and 150 mg/kg tangeretin in rats with six of each. A single dose of ligustrazine was set as the control. The effect of tangeretin on the in vitro metabolic stability of ligustrazine was also investigated in rat liver microsomes. Tangeretin significantly reduced the system exposure of ligustrazine under all experimental concentrations. Specifically, tangeretin reduced the AUC (from 48.86 ± 12.57 to 41.02 ± 4.85 (50 mg/kg tangeretin), 31.47 ± 5.26 (100 mg/kg tangeretin), and 27.55 ± 9.60 (150 mg/kg) μg/mL × h), MRT (from 7.05 ± 0.26 to 6.33 ± 0.48, 5.53 ± 0.68, and 5.21 ± 1.31 h), C_max (from 7.45 ± 0.44 to 6.03 ± 0.44, 5.24 ± 0.47, and 5.02 ± 0.56 μg/mL), and t_1/2 (from 5.90 ± 1.27 to 4.84 ± 1.19, 3.48 ± 1.33, 3.09 ± 0.62 h) in rats. In vitro, tangeretin also reduced the metabolic stability of ligustrazine behaved as the decreased half-life and increased intrinsic clearance rate. Co-consumption of ligustrazine with tangeretin induced interactions, which shortens the system exposure of ligustrazine. This study provides theoretical guidance for the clinical prescription of ligustrazine- and tangeretin-containing herbs.

Network pharmacology and in vitro experimental verification to explore the mechanism of Sanhua decoction in the treatment of ischaemic stroke

CONTEXT

Stroke is an illness with high morbidity, disability and mortality that presents a major clinical challenge. Sanhua decoction (SHD) has been widely used to treat ischaemic stroke in the clinic. However, the potential mechanism of SHD remains unknown.

OBJECTIVE

To elucidate the multitarget mechanism of SHD in ischaemic stroke through network pharmacology and bioinformatics analyses.

MATERIALS AND METHODS

Network pharmacology and experimental validation approach was used to investigate the bioactive ingredients, critical targets and potential mechanisms of SHD against ischaemic stroke. Four herbal names of SHD, 'ischemic stroke' or 'stroke' was used as a keyword to search the relevant databases. SH-SY5Y cells were treated with various concentrations of SHD (12.5, 25, 50 or 100 μg/mL) for 4 h, exposed to oxygen and glucose deprivation (OGD) for 1 h, then reoxygenation for 24 h. The cell viability was detected by MTT, the lactate dehydrogenase (LDH) was evaluated by ELISA, and protein expression was detected by western blots.

RESULTS

SHD treatment increased the survival rate from 65.9 ± 4.3 to 85.56 ± 5.7%. The median effective dose (ED₅₀) was 47.1 μg/mL, the LDH decreased from 288.0 ± 12.0 to 122.8 ± 9.1 U/L and the cell apoptosis rate decreased from 33.6 ± 1.8 to 16.3 ± 1.2%. Western blot analysis revealed that SHD increased the levels of p-PI3k, p-Akt and p-CREB1, and decreased the expression of TNF-α and IL-6.

DISCUSSION AND CONCLUSIONS

This study suggests that SHD protects against cerebral ischaemic injury via regulation of the PI3K/Akt/CREB1 and TNF pathways.

Plant based food bioactives: A boon or bane for neurological disorders

Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.

Role of Polyphenols as Antioxidant Supplementation in Ischemic Stroke

Stroke is the second most common cause of death globally and the leading cause of death in China. The pathogenesis of cerebral ischemia injury is complex, and oxidative stress plays an important role in the fundamental pathologic progression of cerebral damage in ischemic stroke. Previous studies have preliminarily confirmed that oxidative stress should be a potential therapeutic target and antioxidant as a treatment strategy for ischemic stroke. Emerging experimental studies have demonstrated that polyphenols exert the antioxidant potential to play the neuroprotection role after ischemic stroke. This comprehensive review summarizes antioxidant effects of some polyphenols, which have the most inhibition effects on reactive oxygen species generation and oxidative stress after ischemic stroke.

Systems Pharmacology Study of the Anti-Liver Injury Mechanism of Citri Reticulatae Pericarpium

Liver diseases are mostly triggered by oxidative stress and inflammation, leading to extracellular matrix overproduction and prone to develop into liver fibrosis, cirrhosis and hepatocellular carcinoma. Liver injury (LI) refers to various pathogenic factors leading to the destruction of stem cells that then affect the liver's normal function, causing a series of symptoms and abnormal liver function indicators. Citri Reticulatae Pericarpium (CRP) is one of the most commonly used traditional Chinese medicines; it contains flavonoids including hesperidin, nobiletin, and tangeretin. CRP has antibacterial, antioxidant, and antitumor effects that reduce cholesterol, prevent atherosclerosis and decrease LI. Here we analyzed the components of CRP and their targets of action in LI treatment and assessed the relationships between them using a systems pharmacology approach. Twenty-five active ingredients against LI were selected based on ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry results and databases. The drug targets and disease-related targets were predicted. The 117 common targets were used to construct a protein-protein interaction network. We identified 1719 gene ontology items in LI treatment, including 1,525 biological processes, 55 cellular components, and 139 molecular functions. These correlated with 49 Kyoto Encyclopedia of Genes and Genomes pathways. These findings suggest that CRP may counteract LI by affecting apoptotic, inflammatory, and energy metabolism modules. In vitro experiments suggested that the mechanism may involve hesperidin and naringenin acting on CASP3, BAX, and BCL2 to affect the apoptosis pathway, attenuating liver fibrosis. Naringenin significantly inhibited AKT1 phosphorylation, which in turn mediated activation of the phosphoinositide 3-kinase-Akt signaling pathways against LI. This study provides a reference for systematically exploring the mechanism of CRP's anti-LI action and is also expands of the application of systems pharmacology in the study of traditional Chinese medicine.

Beneficial Effects of Citrus-Derived Polymethoxylated Flavones for Central Nervous System Disorders

The number of patients with central nervous system disorders is increasing. Despite diligent laboratory and clinical research over the past 30 years, most pharmacologic options for the prevention and long-term treatment of central nervous system disorders and neurodegenerative disorders have been unsuccessful. Therefore, the development of drugs and/or functional foods to prevent the onset of neurodegenerative disorders is highly expected. Several reports have shown that polymethoxylated flavones (PMFs) derived from citrus fruit, such as nobiletin, tangeretin, and 3,3',4',5,6,7,8-heptamethoxyflavone, are promising molecules for the prevention of neurodegenerative and neurological disorders. In various animal models, PMFs have been shown to have a neuroprotective effect and improve cognitive dysfunction with regard to neurological disorders by exerting favorable effects against their pathological features, including oxidative stress, neuroinflammation, neurodegeneration, and synaptic dysfunction as well as its related mechanisms. In this review, we describe the profitable and ameliorating effects of citrus-derived PMFs on cognitive impairment and neural dysfunction in various rat and murine models or in several models of central nervous system disorders and identify their mechanisms of action.

From Preclinical Stroke Models to Humans: Polyphenols in the Prevention and Treatment of Stroke

Polyphenols are an important family of molecules of vegetal origin present in many medicinal and edible plants, which represent important alimentary sources in the human diet. Polyphenols are known for their beneficial health effects and have been investigated for their potential protective role against various pathologies, including cancer, brain dysfunctions, cardiovascular diseases and stroke. The prevention of stroke promoted by polyphenols relies mainly on their effect on cardio- and cerebrovascular systems. However, a growing body of evidence from preclinical models of stroke points out a neuroprotective role of these molecules. Notably, in many preclinical studies, the polyphenolic compounds were effective also when administered after the stroke onset, suggesting their possible use in promoting recovery of patients suffering from stroke. Here, we review the effects of the major polyphenols in cellular and in vivo models of both ischemic and hemorrhagic stroke in immature and adult brains. The results from human studies are also reported.

Tangeretin: a mechanistic review of its pharmacological and therapeutic effects

To date, a large number of synthetic drugs have been developed for the treatment and prevention of different disorders, such as neurodegenerative diseases, diabetes mellitus, and cancer. However, these drugs suffer from a variety of drawbacks including side effects and low efficacy. In response to this problem, researchers have focused on the plant-derived natural products due to their valuable biological activities and low side effects. Flavonoids consist of a wide range of naturally occurring compounds exclusively found in fruits and vegetables and demonstrate a number of pharmacological and therapeutic effects. Tangeretin (TGN) is a key member of flavonoids that is extensively found in citrus peels. It has different favorable biological activities such as antioxidant, anti-inflammatory, antitumor, hepatoprotective, and neuroprotective effects. In the present review, we discuss the various pharmacological and therapeutic effects of TGN and then, demonstrate how this naturally occurring compound affects signaling pathways to exert its impacts.

The impact of endothelial cell death in the brain and its role after stroke: A systematic review

The supply of oxygen and nutrients to the brain is vital for its function and requires a complex vascular network that, when disturbed, results in profound neurological dysfunction. As part of the pathology in stroke, endothelial cells die. As endothelial cell death affects the surrounding cellular environment and is a potential target for the treatment and prevention of neurological disorders, we have systematically reviewed important aspects of endothelial cell death with a particular focus on stroke. After screening 2876 publications published between January 1, 2010 and August 7, 2019, we identified 154 records to be included. We found that endothelial cell death occurs rapidly as well as later after the onset of stroke conditions. Among the different cell death mechanisms, apoptosis was the most widely investigated (92 records), followed by autophagy (20 records), while other, more recently defined mechanisms received less attention, such as lysosome-dependent cell death (2 records) and necroptosis (2 records). We also discuss the differential vulnerability of brain cells to injury after stroke and the role of endothelial cell death in the no-reflow phenomenon with a special focus on the microvasculature. Further investigation of the different cell death mechanisms using novel tools and biomarkers will greatly enhance our understanding of endothelial cell death. For this task, at least two markers/criteria are desirable to determine cell death subroutines according to the recommendations of the Nomenclature Committee on Cell Death.

Blockade of STAT3 Signaling Contributes to Anticancer Effect of 5-Acetyloxy-6,7,8,4'-Tetra-Methoxyflavone, a Tangeretin Derivative, on Human Glioblastoma Multiforme Cells

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with poor prognosis, largely due to resistance to current radiotherapy and Temozolomide chemotherapy. The constitutive activation of Signal Transducer and Activator of Transcription 3 (STAT3) is evidenced as a pivotal driver of GBM pathogenesis and therapy resistance, and hence, is a promising GBM drug target. 5-acetyloxy-6,7,8,4'-tetramethoxyflavone (5-AcTMF) is an acetylated derivative of Tangeretin which is known to exert anticancer effects on breast, colon, lung, and multiple myeloma; however, its effect on GBM remains elusive. Herein, we reported that 5-AcTMF suppressed the viability and clonogenicity along with inducing apoptosis in multiple human GBM cell lines. Mechanistic analyses further revealed that 5-AcTMF lowered the levels of Tyrosine 705-phosphorylated STAT3 (p-STAT3), a canonical marker of STAT3 activation, but also dampened p-STAT3 upregulation elicited by Interleukin-6. Notably, ectopic expression of dominant-active STAT3 impeded 5-AcTMF-induced suppression of viability and clonogenicity plus apoptosis induction in GBM cells, confirming the prerequisite of STAT3 blockage for the inhibitory action of 5-AcTMF on GBM cell survival and growth. Additionally, 5-AcTMF impaired the activation of STAT3 upstream kinase JAK2 but also downregulated antiapoptotic BCL-2 and BCL-xL in a STAT3-dependent manner. Moreover, the overexpression of either BCL-2 or BCL-xL abrogated 5-AcTMF-mediated viability reduction and apoptosis induction in GBM cells. Collectively, we, for the first time, revealed the anticancer effect of 5-AcTMF on GBM cells, which was executed via thwarting the JAK2-STAT3-BCL-2/BCL-xL signaling axis. Our findings further implicate the therapeutic potential of 5-AcTMF for GBM treatment.