Isoliquiritigenin Confers Neuroprotection and Alleviates Amyloid-β42-Induced Neuroinflammation in Microglia by Regulating the Nrf2/NF-κB Signaling

Isoliquiritigenin mitigates intervertebral disc degeneration induced by oxidative stress and mitochondrial impairment through a PPARγ-dependent pathway

OBJECTIVES

Oxidative stress, mitochondrial dysfunction, and apoptosis play significant roles in the degradation of extracellular matrix (ECM) in nucleus pulposus cells (NPCs), ultimately contributing to intervertebral disc degeneration (IVDD). This study investigates the potential of isoliquiritigenin (ISL), a natural extract known for its antioxidant, anti-inflammatory, and anti-atherosclerotic properties, to alleviate IVDD.

METHODS

The viability of NPCs treated with ISL and tert-butyl hydroperoxide (TBHP) was assessed using the CCK-8 assay. Various techniques, including Western blot, qRT-PCR, immunofluorescence (IF), and immunohistochemistry, were employed to measure the expression of ECM components, oxidative stress markers, and apoptosis-related proteins. Mitochondrial function was evaluated through Western blot and IF analyses. Network pharmacology predicted ISL targets, and the expression levels of PPARγ were assessed using the aforementioned methods. The role of PPARγ in the therapeutic effects of ISL on IVDD was examined through siRNA knockdown. The therapeutic impact of ISL on puncture-induced IVDD in rats was evaluated using X-ray, MRI, and histological staining techniques.

RESULTS

In vitro, ISL reduced oxidative stress in NPCs, restored mitochondrial function, inhibited apoptosis, and improved the ECM phenotype. In vivo, ISL slowed the progression of IVDD in a rat model. Further analysis revealed that ISL enhances PPARγ activity and promotes its expression by direct binding, contributing to the delay of IVDD progression.

CONCLUSION

This study demonstrates that ISL effectively treats puncture-induced IVDD in rats by inhibiting oxidative stress, restoring mitochondrial function, and reducing NPC apoptosis through a PPARγ-dependent mechanism. By balancing ECM synthesis and degradation, ISL presents a novel therapeutic approach for IVDD and identifies a promising target for treatment.

Isoliquiritigenin alleviates experimental autoimmune encephalomyelitis by modulating inflammatory and neuroprotective reactive astrocytes

Multiple sclerosis (MS) is an autoimmune-mediated chronic inflammatory demyelinating disease of the central nervous system (CNS) that poses significant treatment challenges. Currently, it is believed that inflammatory and neuroprotective reactive astrocytes, along with other resident CNS cells and immune cells, contribute to the pathophysiology of MS. In our study, we found that isoliquiritigenin (ILG), a bioactive chalcone compound, significantly reduces the clinical scores of experimental autoimmune encephalomyelitis (EAE) by 44 % (P < 0.05). Additionally, ILG significantly decreases the pathological scores of spinal cord inflammation and demyelination by 61 % and 65 %, respectively (both P < 0.0001). Furthermore, ILG affects the populations of CD4, Th1, Th17, and Treg cells in vivo. More importantly, ILG significantly promotes the activation of astrocytes in EAE (P < 0.0001). Additionally, ILG treatment indirectly inhibits inflammatory reactive astrocytes and promotes neuroprotective reactive astrocytes. It reduces spleen levels of TNFα, IL1α, C1qa, IL1β, and IL17A by 95 % (P < 0.001), 98 % (P < 0.01), 46 % (P < 0.05), 97 % (P < 0.001), and 60 % (P < 0.001), respectively. It also decreases CNS levels of TNFα, IL1α, C1qa, IL1β, and IL17A by 53 % (P < 0.05), 88 % (P < 0.05), 64 % (P < 0.01), 57 % (P < 0.05), and 60 % (P < 0.001), respectively. These results indicate that ILG exerts an immunoregulatory effect by inhibiting the secretion of pro-inflammatory cytokines. Consequently, ILG inhibits inflammatory reactive astrocytes, promotes neuroprotective reactive astrocytes, alleviates inflammation and improves EAE. These findings provide a theoretical basis and support for the application of ILG in the prevention and treatment of MS.

The Role of Licorice Chalcones as Molecular Genes and Signaling Pathways Modulator-A Review of Experimental Implications for Nicotine-Induced Non-Small Cell Lung Cancer Treatment

Lung cancer (LC) represents the leading cause of global cancer deaths, with cigarette smoking being considered a major risk factor. Nicotine is a major hazardous compound in cigarette smoke (CS), which stimulates LC progression and non-small cell lung cancer (NSCLC) specifically through activation of the nicotinic acetylcholine receptor (α7nAChR)-mediated cell-signaling pathways and molecular genes involved in proliferation, angiogenesis, and metastasis. Chalcones (CHs) and their derivatives are intermediate plant metabolites involved in flavonol biosynthesis. Isoliquiritigenin (ILTG), licochalcone A-E (LicoA-E), and echinatin (ECH) are the most common natural CHs isolated from the root of Glycyrrhiza (also known as licorice). In vitro and/or vivo experiments have shown that licorice CHs treatment exhibits a range of pharmacological effects, including antioxidant, anti-inflammatory, and anticancer effects. Despite advances in NSCLC treatment, the mechanisms of licorice CHs in nicotine-induced NSCLC treatment remain unknown. Therefore, the aim of this paper is to review experimental studies through the PubMed/Medline database that reveal the effects of licorice CHs and their potential mechanisms in nicotine-induced NSCLC treatment.

Neuroprotective effect of emodin on Aβ25-35-induced cytotoxicity in PC12 cells involves Nrf2/GPX4 and TLR4/p-NF-κB/NLRP3 pathways

The present study aims to investigate the neuroprotective effects of emodin in Alzheimer's disease (AD). PC12 cells were used to explore the underlying mechanism and were incubated with Aβ25-35 for 24 h as the model group, incubated with emodin at different concentrations (2.5, 5, 10 μM) as the drug administration groups. The content of MDA and the enzymic activities of CAT, GSH-Px were detected by the corresponding commercial kits. The ROS level in Aβ25-35 induced cells was decreased by emodin dose-dependently, but the MMP in these cells were elevated. The expressions of AChE, TLR4, p-NF-κB, NLRP3, IL-1β, and TNF-α in PC12 cells were increased by Aβ25-35 treatment, the expressions of Nrf2, HO-1, GPX4, xCT were decreased, all the levels of expressions were reversed by emodin. Besides, ultraviolet spectrophotometry and infrared spectrophotometry were ultilized to ascertain the production of emodin-Fe (Ⅱ) complex. The FerroOrange results showed that emodin reduced free Fe2+ in cells. The immunofluorescent intensities of Nrf2, GPX4, and p-NF-κB offered direct visible evidence for emodin's multi-targets in AD treatment. Collectively, emodin could inhibit the activity of AChE and exert neuroprotective effects against AD through antioxidant, anti-ferroptotic, anti-inflammatory properties via Nrf2/GPX4 and TLR4/p-NF-κB/NLRP3 pathways.

Natural polyphenol: Their pathogenesis-targeting therapeutic potential in Alzheimer's disease

Alzheimer's disease (AD) is a detrimental neurodegenerative disease affecting the elderly. Clinically, it is characterized by progressive memory decline and subsequent loss of broader cognitive functions. Current drugs provide only symptomatic relief but do not have profound disease-modifying effects. There is an unmet need to identify novel pharmacological agents for AD therapy. Neuropathologically, the characteristic hallmarks of the disease are extracellular senile plaques containing amyloid β-peptides and intracellular neurofibrillary tangles containing hyperphosphorylated microtubule-associated protein tau. Simultaneously, oxidative stress, neuroinflammation and mitochondrial dysfunction in specific brain regions are early events during the process of AD pathologic changes and are associated with Aβ/tau toxicity. Here, we first summarized probable pathogenic mechanisms leading to neurodegeneration and hopefully identify pathways that serve as specific targets to improve therapy for AD. We then reviewed the mechanisms that underlie disease-modifying effects of natural polyphenols, with a focus on nuclear factor erythroid 2-related factor 2 activators for AD treatment. Lastly, we discussed challenges in the preclinical to clinical translation of natural polyphenols. In conclusion, there is evidence that natural polyphenols can be therapeutically useful in AD through their multifaceted mechanism of action. However, more clinical studies are needed to confirm these effects.

Isoliquiritigenin, a potential therapeutic agent for treatment of inflammation-associated diseases

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a medicinal herb with a 2000-year history of applications in traditional Chinese medicine. Isoliquiritigenin (ISL) is a bioactive chalcone compound isolated from licorice. It has attracted increasing attention in recent years due to its excellent anti-inflammatory activity.

AIM OF THE STUDY

This study is to provide a comprehensive summary of the anti-inflammatory activity of ISL and the underlying molecular mechanisms, and discuss new insights for its potential clinical applications as an anti-inflammation agent.

MATERIALS AND METHODS

We examined literatures published in the past twenty years from PubMed, Research Gate, Web of Science, Google Scholar, and SciFinder, with single or combined key words of "isoliquiritigenin", "inflammation", and "anti-inflammatory".

RESULTS

ISL elicits its anti-inflammatory activity by mediating various cellular processes. It inhibits the upstream of the nuclear factor kappa B (NF-κB) pathway and activates the nuclear factor erythroid related factor 2 (Nrf2) pathway. In addition, it suppresses the NOD-like receptor protein 3 (NLRP3) pathway and restrains the mitogen-activated protein kinase (MAPK) pathway.

CONCLUSIONS

Current studies indicate a great therapeutical potential of ISL as a drug candidate for treatment of inflammation-associated diseases. However, the pharmacokinetics, biosafety, and bioavailability of ISL remain to be further investigated.

Analysis of cerebrospinal fluid metabolites affected by WenDanTang based on ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry

WenDanTang (WDT) is a Chinese herbal formula used to treat various diseases, including neurodegenerative diseases. However, the neuroprotective metabolic pathways and the components involved in this process are not fully understood. In this study, we examined the neuroprotective metabolic pathways of WDT in rat brains using cerebrospinal fluid metabolomics and ultra-high-performance liquid chromatography-high-resolution mass spectrometry. Twelve rats were randomly divided into a WDT (administrated with WDT solution) and a control group. The ultra-high-performance liquid chromatography technique was used to explore the components of the WDT solution and cerebrospinal fluid, and secondary mass spectra of cerebrospinal fluid were used to identify possible brain-incorporating components after WDT. The results of the differential metabolism analysis showed that eight metabolites were typically altered (all p < 0.05). By comparing the secondary mass spectra of the cerebrospinal fluid of rats and WDT solution, two possible brain-incorporating components of WDT, stachydrine and α-methoxyphenylacetic acid, were identified. The data also suggested that WDT affects nucleotide metabolism, glutathione metabolism, and B-vitamin metabolic pathways, the central differential metabolic pathways. These data suggest that WDT protects neurons through its active components, such as stachydrine, and regulates biochemical metabolism to affect the brain's energy metabolism and antioxidant capacity.

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Therapeutic considerations of bioactive compounds in Alzheimer's disease and Parkinson's disease: Dissecting the molecular pathways

Leading neurodegenerative diseases Alzheimer's disease (AD) and Parkinson's disease (PD) are characterized by the impairment of memory and motor functions, respectively. Despite several breakthroughs, there exists a lack of disease-modifying treatment strategies for these diseases, as the available drugs provide symptomatic relief and bring along side effects. Bioactive compounds are reported to bear neuroprotective properties with minimal toxicity, however, a detailed elucidation of their modes of neuroprotection is lacking. The review elucidates the neuroprotective mechanism(s) of some of the major phyto-compounds in pre-clinical and clinical studies of AD and PD to understand their potential in combating these diseases. Curcumin, eugenol, resveratrol, baicalein, sesamol and so on have proved efficient in countering the pathological hallmarks of AD and PD. Curcumin, resveratrol, caffeine and so on have reached the clinical phases of these diseases, while aromadendrin, delphinidin, cyanidin and xanthohumol are yet to be extensively explored in pre-clinical phases. The review highlights the need for extensive investigation of these compounds in the clinical stages of these diseases so as to utilize their disease-modifying abilities in the real field of treatment. Moreover, poor pharmacokinetic properties of natural compounds are constraints to their therapeutic yields and this review suggests a plausible contribution of nanotechnology in overcoming these limitations.

Protective effect of isoliquiritigenin in amiodarone-induced damage of human umbilical vein endothelial cells

OBJECTIVE

Amiodarone (AM) is a drug commonly used in patients with ventricular arrhythmias. It can damage vascular endothelial cells and easily cause phlebitis. At present, the prevention and treatment of phlebitis induced by the use of AM is not clear due to the lack of corresponding primary research. Isoliquiritigenin (ISL) has an anti-inflammatory effect, but until now, has not been explored much in the field of research in primary care nursing. The purpose of this study is to investigate the efficacy and mechanism of action of ISL in treating phlebitis induced by AM.

METHODS

In our study, we used human umbilical vein endothelial cells (HUVECs) that were divided into three groups: the NC group (normal), the AM group (AM 30 μmol/L for 24 h), and the ISL pretreatment group (isoliquiritigenin 10 μmol/L after 1 h of pretreatment with amiodarone for 24 h). We used CCK-8 to detect cell proliferation, cell scratch assay to detect the migration capability of cells, flow cytometry to measure apoptosis, angiogenesis assay to check the total length and total branches of angiogenesis, and PCR and WB to detect the expression of PCNA, casepase-3, and VEGFA. WB was used to detect NF-κBp65 and p-NF-κBp65 expression.

RESULTS

Compared with the AM group, the ISL pretreatment promoted cell proliferation and migration, inhibited cell apoptosis, increased the total length and total branches of angiogenesis, and downregulated p-NF-κBp65 expression.

CONCLUSION

ISL shows promise in the prevention and treatment of clinical phlebitis and can be used as a potential therapeutic drug to prevent phlebitis.

Isoliquiritigenin modulates the activity of LTS and non-LTS cells in the ventrolateral preoptic area via GABAA receptors

Objective

Isoliquiritigenin (ILTG) is a chalcone compound that exhibits hypnotic effects via gamma-aminobutyric acid type A (GABAA) receptors. The ventrolateral preoptic area (VLPO) is a sleep-promoting center that contains a large number of GABA-releasing cells. There are two cell types in the VLPO: one generates a low-threshold spike (LTS), whereas the other lacks an LTS (non-LTS).

Method

Whole-cell patch-clamp technology was used to detect the firing and currents of LTS and non-LTS cells in the VLPO.

Results

Bath administration of ILTG (10 μM) increased the firing rate of VLPO LTS cells, reversed by flumazenil (5 μM), a GABAA benzodiazepine site antagonist. However, the firing rate of VLPO non-LTS cells was inhibited by ILTG (10 μM), also reversed by flumazenil (5 μM). No differences were detected regarding resting membrane potential (RMP) amplitude, spike threshold, afterhyperpolarization (AHP) amplitude, or action potential duration (APD50) after ILTG (10 μM) perfusion in VLPO LTS cells. RMP amplitude was more hyperpolarized and spike threshold was higher after ILTG (10 μM) application in VLPO non-LTS cells. In addition, ILTG significantly reduced the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in VLPO LTS cells. ILTG significantly increased the amplitude of mIPSCs in VLPO non-LTS cells.

Conclusions

This study revealed that ILTG suppresses presynaptic GABA release on VLPO LTS cells, thereby increasing their excitability. ILTG enhances postsynaptic GABAA receptor function on VLPO non-LTS cells, thereby decreasing their excitability. These results suggest that ILTG may produce hypnotic effects by modulating the GABAergic synaptic transmission properties of these two cell types.

Natural antioxidants that act against Alzheimer's disease through modulation of the NRF2 pathway: a focus on their molecular mechanisms of action

Characterized by a complex pathophysiology that includes the intraneuronal formation of neurofibrillary tangles and the extracellular deposition of β-amyloid plaques, Alzheimer's disease (AD) is a terminal neurodegenerative disease that causes dementia in older adults. Oxidative stress in the brain is considered as one of the contributing factors to the pathogenesis of AD, and thus, antioxidants have attracted much interest as potential therapeutic agents against the disorder. Natural antioxidants are typically characterized by low acute and chronic toxicity, which facilitates their potential therapeutic application. One important molecular target for the beneficial effects of natural antioxidants is the nuclear factor erythroid-derived 2-related factor 2 (NFE2L2/NRF2). NRF2 is a key transcription factor that orchestrates the cellular antioxidant response through regulating the expression of oxidative stress-related genes harboring the antioxidant response element (ARE) in their promoters. Indeed, in the case of excessive oxidative damage, NRF2 migrates to the nucleus and binds to ARE, activating the transcription of antioxidant protector genes. There is increasing evidence that NRF2 is implicated in AD pathology through dysfunction and altered localization, which renders it as a potential therapeutic target for AD. Thus, this review summarizes the most recent (2018-2023) advances on the NRF2-modulating activity of natural antioxidants observed in vitro and in AD animal models. This information will help elucidate the molecular mechanisms governing the antioxidant activity of such phytochemicals to highlight their therapeutic potential against common neurodegenerative diseases, such as AD.

Interaction between Changan Granule and its main components in the plasma and CYP450 enzymes

ETHNOPHARMACOLOGICAL RELEVANCE

Changan Granule (CAG) is a Chinese patent drug developed based on an empirical prescription in accordance with the formulation theory of Traditional Chinese Medicine. The prescription is composed of eight herbal drugs which have been traditionally used by Chinese people for a long history. It has effects of invigorating spleen and supplementing qi, as well as regulating liver and ceasing diarrhea, and is indicated for the treatment of irritable bowel syndrome (IBS).

AIM OF THE STUDY

This study was aimed to investigate the interaction between CAG and its main components and cytochrome P450 (CYP450) enzymes so as to characterize the major metabolites and metabolic enzymes and evaluate the safety concerns to its clinical use.

MATERIALS AND METHODS

Both in vivo and in vitro experiments using such as diarrhea-predominant IBS (IBS-D) rat model, HepG2 cells, and human liver microsomes (HLM) were carried out to investigate the interaction between CAG and its main components and CYP450 enzymes. Real-time quantitative PCR (qPCR), ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and cocktail probes were employed to qualitatively or quantitatively measure the metabolites and metabolic enzymes.

RESULTS

CAG inhibited the enzyme activities of CYP1A2, CYP2E1, CYP2D6, CYP2C9, and CYP3A4 and the mRNA expressions of CYP2E1, CYP2C9, CYP3A4, and CYP2D6 in vitro. CAG down-regulated the increased expression of CYP1A2 and up-regulated the decreased expression of CYP3A1 in vivo. Twenty-two metabolites were characterized from the main components of CAG after incubation with HLM in vitro. CYP2D6, CYP2E1, CYP3A4 and CYP2C9 were identified as the characteristic metabolic enzymes.

CONCLUSIONS

This study provides a reference for clinical application of CAG in safety. CAG and CYP450 enzymes are interacted. CAG is mainly metabolized by CYP2E1 and CYP2D6. The expression of CYP2E1 and CYP2D6 are more susceptible to be influenced by CAG in comparison with that of CYP3A4, CYP2C9 and CYP1A2. It implies the potential risk of interaction when CAG is taken together with the drugs metabolized by CYP2E1 and CYP2D6.

Natural Products as Modulators of Nrf2 Signaling Pathway in Neuroprotection

Neurodegenerative diseases (NDs) affect the West due to the increase in life expectancy. Nervous cells accumulate oxidative damage, which is one of the factors that triggers and accelerates neurodegeneration. However, cells have mechanisms that scavenge reactive oxygen species (ROS) and alleviate oxidative stress (OS). Many of these endogenous antioxidant systems are regulated at the gene expression level by the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In the presence of prooxidant conditions, Nrf2 translocates to the nucleus and induces the transcription of genes containing ARE (antioxidant response element). In recent years, there has been an increase in the study of the Nrf2 pathway and the natural products that positively regulate it to reduce oxidative damage to the nervous system, both in in vitro models with neurons and microglia subjected to stress factors and in vivo models using mainly murine models. Quercetin, curcumin, anthocyanins, tea polyphenols, and other less studied phenolic compounds such as kaempferol, hesperetin, and icariin can also modulate Nrf2 by regulating several Nrf2 upstream activators. Another group of phytochemical compounds that upregulate this pathway are terpenoids, including monoterpenes (aucubin, catapol), diterpenes (ginkgolides), triterpenes (ginsenosides), and carotenoids (astaxanthin, lycopene). This review aims to update the knowledge on the influence of secondary metabolites of health interest on the activation of the Nrf2 pathway and their potential as treatments for NDs.

Pharmacological Modulations of Nrf2 and Therapeutic Implications in Aneurysmal Subarachnoid Hemorrhage

An aneurysmal subarachnoid hemorrhage (aSAH) is a subtype of stroke with high morbidity and mortality. The main causes of a poor prognosis include early brain injury (EBI) and delayed vasospasm, both of which play a significant role in the pathophysiological process. As an important mechanism of EBI and delayed vasospasm, oxidative stress plays an important role in the pathogenesis of aSAH by producing reactive oxygen species (ROS) through the mitochondria, hemoglobin, or enzymatic pathways in the early stages of aSAH. As a result, antioxidant therapy, which primarily targets the Nrf2-related pathway, can be employed as a potential strategy for treating aSAH. In the early stages of aSAH development, increasing the expression of antioxidant enzymes and detoxifying enzymes can relieve oxidative stress, reduce brain damage, and improve prognosis. Herein, the regulatory mechanisms of Nrf2 and related pharmacological compounds are reviewed, and Nrf2-targeted drugs are proposed as potential treatments for aSAH.

Beneficial effects of natural flavonoids on neuroinflammation

Neuroinflammation is the fundamental immune response against multiple factors in the central nervous system and is characterized by the production of inflammatory mediators, activated microglia and astrocytes, and the recruitment of innate and adaptive immune cells to inflammatory sites, that contributes to the pathological process of related brain diseases, such as Alzheimer’s disease, Parkinson’s disease, depression, and stroke. Flavonoids, as a species of important natural compounds, have been widely revealed to alleviate neuroinflammation by inhibiting the production of pro-inflammatory mediators, elevating the secretion of anti-inflammatory factors, and modulating the polarization of microglia and astrocyte, mainly via suppressing the activation of NLRP3 inflammasome, as well as NF-κB, MAPK, and JAK/STAT pathways, promoting Nrf2, AMPK, BDNF/CREB, Wnt/β-Catenin, PI3k/Akt signals and SIRT1-mediated HMGB1 deacetylation. This review will provide the latest and comprehensive knowledge on the therapeutic benefits and mechanisms of natural flavonoids in neuroinflammation, and the natural flavonoids might be developed into food supplements or lead compounds for neuroinflammation-associated brain disorders.

Isoliquiritigenin mitigates oxidative damage after subarachnoid hemorrhage in vivo and in vitro by regulating Nrf2-dependent Signaling Pathway via Targeting of SIRT1

BACKGROUND

Oxidative stress is a crucial factor leading to subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). Isoliquiritigenin has been verified as a powerful anti-oxidant in a variety of diseases models and can activate sirtuin 1 and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. However, the effects of isoliquiritigenin against EBI after SAH and the underlying mechanisms remain elusive.

PURPOSE

The primary goal of this study is to verify the therapeutic effects of isoliquiritigenin on EBI after SAH and the possible molecular mechanisms.

STUDY DESIGN

A prechiasmatic cistern SAH model in rats and a hemoglobin incubation SAH model in primary neurons were established. Isoliquiritigenin was administered after SAH induction. EX527 was employed to inhibit sirtuin 1 activation and ML385 was used to suppress Nrf2 signaling.

METHODS

In our study, neurological scores, brain edema, biochemical estimation, western blotting, and histopathological study were performed to explore the therapeutic action of isoliquiritigenin against SAH.

RESULTS

Our data revealed that isoliquiritigenin significantly mitigated oxidative damage after SAH as evidenced by decreased reactive oxygen species overproduction and enhanced intrinsic anti-oxidative system. Concomitant with the reduced oxidative insults, isoliquiritigenin improved neurological function and reduced neuronal death in the early period after SAH. Additionally, isoliquiritigenin administration significantly enhanced Nrf2 and sirtuin 1 expressions. Inhibition of Nrf2 by ML385 reversed the anti-oxidative and neuroprotective effects of isoliquiritigenin against SAH. Moreover, inhibiting sirtuin 1 by EX527 pretreatment suppressed isoliquiritigenin-induced Nrf2-dependent pathway and abated the cerebroprotective effects of isoliquiritigenin. In primary cortical neurons, isoliquiritigenin treatment also ameliorated oxidative insults and repressed neuronal degeneration. The beneficial aspects of isoliquiritigenin were attributed to the promotion of sirtuin 1 and Nrf2 signaling pathways and were counteracted by EX527.

CONCLUSION

Our findings suggest that isoliquiritigenin exerts cerebroprotective effects against SAH-induced oxidative insults by modulating the Nrf2-mediated anti-oxidant signaling in part through sirtuin 1 activation. Isoliquiritigenin might be a new potential drug candidate for SAH.

Signal pathways in the treatment of Alzheimer's disease with traditional Chinese medicine

AIM OF THE REVIEW

This study aimed to reveal the classical signal pathways and important potential targets of traditional Chinese medicine (TCM) for treating Alzheimer's disease (AD), and provide support for further investigation on TCM and its active ingredients.

MATERIALS AND METHODS

Literature survey was conducted using PubMed, Web of Science, Google Scholar, CNKI, and other databases, with "Alzheimer's disease," "traditional Chinese medicine," "medicinal herb," "Chinese herb," and "natural plant" as the primary keywords.

RESULTS

TCM could modulate signal pathways related to AD pathological progression, including NF-κB, Nrf2, JAK/STAT, ubiquitin-proteasome pathway, autophagy-lysosome pathway-related AMPK/mTOR, GSK-3/mTOR, and PI3K/Akt/mTOR, as well as SIRT1 and PPARα pathway. It could regulate crosstalk between pathways through a multitarget, thus maintaining chronic inflammatory interaction balance, inhibiting oxidative stress damage, regulating ubiquitin-proteasome system function, modulating autophagy, and eventually improving cognitive impairment in patients with AD.

CONCLUSION

TCM could be multilevel, multitargeted, and multifaceted to prevent and treat AD. In-depth research on the prevention and treatment of AD with TCM could provide new ideas for exploring the pathogenesis of AD and developing new anti-AD drugs.

Isoliquiritigenin alleviates diabetic symptoms via activating AMPK and inhibiting mTORC1 signaling in diet-induced diabetic mice

PURPOSE

To determine the effects of isoliquiritigenin (ISL), a chalcone compound isolated from licorice, on type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

8-week-old C7BL/6 mice were used to establish the T2DM animal model by feeding with high-fat-high-glucose diet (HFD) combined with intraperitoneal injection of streptozotocin. The animals were treated with ISL for 3 weeks. Blood glucose levels, oral glucose tolerance, and insulin tolerance were examined, serum parameters were determined, histologic sections were prepared, activities of enzymes related to glucolipid metabolism were analyzed, and the mitochondrial function was investigated to evaluate effects of ISL on metabolism. The underlying mechanisms of ISL alleviating insulin resistance and restoring metabolic homeostasis were analyzed in HepG2 and INS-1 cells.

RESULTS

ISL exhibits a potent activity in relieving hyperglycemia of type 2 diabetic mice. It alleviates insulin resistance and restores metabolic homeostasis without obvious adversary effects in HFD-induced diabetic mice. The metabolic benefits of ISL treatment include promoting hepatic glycogenesis, inhibiting hepatic lipogenesis, reducing hepatic steatosis, and sensitizing insulin signaling. Mechanistically, ISL activates adenosine monophosphate-activated protein kinase (AMPK) and inhibits mammalian target of rapamycin complex 1 (mTORC1). It also suppresses mitochondrial function and reduces ATP production.

CONCLUSION

Our findings demonstrate that ISL is able to significantly reduce blood glucose level and alleviate insulin resistance without obvious side effects in diabetic mice, hence uncovering a great potential of ISL as a novel drug candidate in prevention and treatment of T2DM.

γ-mangostin attenuates amyloid-β42-induced neuroinflammation and oxidative stress in microglia-like BV2 cells via the mitogen-activated protein kinases signaling pathway

BACKGROUND

Oxidative stress (OS) and neuroinflammation are related to the pathogenic mechanism of Alzheimer's disease (AD). γ-Mangostin, a xanthone derivative obtained from mangosteen pericarp, could prevent their detrimental effects in AD.

OBJECTIVE

This study focused on determining the role of γ-mangostin in protection against the amyloid-β (Aβ) 42 oligomers-induced OS and inflammation in microglial BV2 cells and investigating their precise mechanism of action.

METHODS

Lactate dehydrogenase release assay and cell counting kit-8 assay were used to estimate the drug impact in BV2 cells and functional effects of the conditioned medium (supernatant of Aβ42 oligomers-/γ-mangostin-treated BV2 cells) on neuron-like SH-SY5Y and N2a cells. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay were carried out for detecting inflammatory factor contents. In addition, nitric oxide (NO) assay, an intracellular reactive oxygen species (ROS) assay, and qRT-PCR were performed to measure OS. Western blotting was used to explore the influence of γ-mangostin on the mitogen-activated protein kinase (MAPK) pathway.

RESULTS

γ-Mangostin alleviated Aβ42 oligomer-induced inflammation by decreasing the levels of interleukin (IL) -6, IL-1β, and tumor necrosis factor-α, while attenuating OS through decreasing ROS/NO generation, and suppressing cyclo-oxygenase-2 and inducible NO synthase expressions. γ-Mangostin protected N2a and SH-SY5Ycells against the BV2 cell supernatant-induced toxicity following Aβ42 oligomer exposure. Furthermore, γ-mangostin inhibited c-Jun NH2-terminal kinase and p38 MAPK pathway activation.

CONCLUSION

This study demonstrated that γ-mangostin could attenuate OS and inflammation resulting from Aβ42 oligomers, which also protect neurons against toxic medium-induced injury, suggesting that it may exert a protective effect in AD.

Petasites japonicus leaf extract inhibits Alzheimer's-like pathology through suppression of neuroinflammation

Neuroinflammation is a crucial step involved in development and progression of Alzheimer's disease. The current study found that Petasites japonicus leaf extract inhibits neuroinflammation induced by lipopolysaccharides and amyloid beta oligomers.

Ginsenoside compound K acts via LRP1 to alleviate Amyloid β42-induced neuroinflammation in microglia by suppressing NF-κB

BACKGROUND

Alzheimer's disease (AD), has caused a mass of disability and mortality in elder populations, which increases global health burden. There are still limited effective disease-modifying drugs. Alleviating microglia-evoked neuroinflammation has become a promising treatment strategy for AD. Ginsenoside Compound K has been demonstrated to exhibit anti-inflammatory and neuroprotective benefits. Here we measured the effects of Ginsenoside Compound K in inhibiting amyloid-induced microglia inflammation and the possible molecular mechanisms and target of action in vitro.

METHODS

The cytotoxicity of all chemical reagents on BV2 cells were evaluated using the MTT assay. qRT-PCR and ELISA were carried out to detect the inflammatory cytokines levels. Western blot was utilized to determine the effect of Ginsenoside Compound K on the nuclear factor-κB (NF-κB) p65 nuclear translocation. Antagonist Receptor Associated Protein (RAP) was used to verify the engagement of low-density lipoprotein receptor-related protein 1(LRP1).

RESULTS

Ginsenoside Compound K diminished inflammatory cytokine production and reversed NF-κB p65 nuclear translocation induced by Aβ₄₂ oligomers. LRP1 expression was up-regulated by Ginsenoside Compound K. When LRP1 was blocked by antagonist RAP, the protective effect of Ginsenoside Compound K was massively eliminated.

CONCLUSION

These observations provide evidence for anti-inflammatory effect of Ginsenoside Compound K through NF-κB pathway via LRP1 activation, and support further evaluation of Ginsenoside Compound K as a potential effective modulator for AD.

Natural Product Isoliquiritigenin Activates GABAB Receptors to Decrease Voltage-Gate Ca2+ Channels and Glutamate Release in Rat Cerebrocortical Nerve Terminals

Reduction in glutamate release is a key mechanism for neuroprotection and we investigated the effect of isoliquiritigenin (ISL), an active ingredient of Glycyrrhiza with neuroprotective activities, on glutamate release in rat cerebrocortical nerve terminals (synaptosomes). ISL produced a concentration-dependent inhibition of glutamate release and reduced the intraterminal [Ca²⁺] increase. The inhibition of glutamate release by ISL was prevented after removing extracellular Ca²⁺ or blocking P/Q-type Ca²⁺ channels. This inhibition was mediated through the γ-aminobutyric acid type B (GABA_B) receptors because ISL was unable to inhibit glutamate release in the presence of baclofen (an GABA_B agonist) or CGP3548 (an GABA_B antagonist) and docking data revealed that ISL interacted with GABA_B receptors. Furthermore, the ISL inhibition of glutamate release was abolished through the inhibition of G_i/o-mediated responses or G_βγ subunits, but not by 8-bromoadenosine 3′,5′-cyclic monophosphate or adenylate cyclase inhibition. The ISL inhibition of glutamate release was also abolished through the inhibition of protein kinase C (PKC), and ISL decreased the phosphorylation of PKC. Thus, we inferred that ISL, through GABA_B receptor activation and G_βγ-coupled inhibition of P/Q-type Ca²⁺ channels, suppressed the PKC phosphorylation to cause a decrease in evoked glutamate release at rat cerebrocortical nerve terminals.