Anti-oxidative and anti-inflammatory effects of 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride on glutamate-induced neurotoxicity in rat brain

Therapeutic potential of Shilong Qingxue Granule and its extract against glutamate induced neural injury: Insights from in vivo and in vitro models

ETHNOPHARMACOLOGICAL RELEVANCE

Shilong Qingxue Granule (SQG), a traditional Chinese medicine, effectively treats the secondary neurological damage and functional deficits caused by cerebral hemorrhage, though its exact mechanism remains unclear.

AIM OF THE STUDY

This study aimed to investigate the effects of SQG and its mechanisms.

MATERIALS AND METHODS

we evaluated the effects of SQG and its extracts on glutamate induced nerve damage using in vivo and in vitro models. Brain water content was measured and brain tissue was stained with hematoxylin and eosin (HE) to evaluate the brain protective effect of SQG in rats. HPLC and UPLC-Q-TOF-MS were used to identify the chemical components in SQG. The model of PC12 cells induced by glutamate was established to detect intracellular Ca2+ and mitochondrial membrane potential (MMP), the content of intracellular reactive oxygen species (ROS), acridine orange/ethidium bromide (AO/EB), and the possible mechanism of action in vivo was explored by Western blot and RNA sequencing.

RESULTS

SQG alleviates brain edema and neuronal damage in glutamate induced rats by modulating mitochondrial apoptotic and MAPK signaling pathways. The SQG extract was separated by silica gel chromatographic column to obtain 20 components, and the S-18 improves PC12 survival under glutamate induced conditions by MMP, reducing ROS and Ca2+ levels, and protecting against cell body and nucleus damage to against apoptosis.

CONCLUSION

SQG and its extract demonstrate protective effects against glutamate induced nerve injury in vivo and in vitro, suggesting potential therapeutic benefits for neurological disorders involving glutamate excitotoxicity.

Moschus exerted protective activity against H2O2-induced cell injury in PC12 cells through regulating Nrf-2/ARE signaling pathways

The pivotal characteristics of Alzheimer's disease (AD) are irreversible memory loss and progressive cognitive decline, eventually causing death from brain failure. In the various proposed hypotheses of AD, oxidative stress is also regarded as a symbolic pathophysiologic cascade contributing to brain diseases. Using Chinese herbal medicine may be beneficial for treating and preventing AD. As a rare and valuable animal medicine, Moschus possesses antioxidant and antiapoptotic efficacy and is extensively applied for treating unconsciousness, stroke, coma, and cerebrovascular diseases. We aim to evaluate whether Moschus protects PC12 cells from hydrogen peroxide (H₂O₂)-induced cellular injury. The chemical constituents of Moschus are analyzed by GC-MS assay. The cell viability, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP) levels, oxidative stress-related indicators, and apoptotic proteins are determined. Through GC-MS analysis, nineteen active contents were identified. The cell viability loss, lactate dehydrogenase releases, MMP levels, ROS productions, and Malondialdehyde (MDA) activities decreased, and BAX, Caspase-3, and Kelch-like ECH-associated protein 1 expression also significantly down-regulated and heme oxygenase 1, nuclear factor erythroid-2-related factor 2 (Nrf-2), and quinine oxidoreductase 1 expression upregulated after pretreatment of Moschus. The result indicated Moschus has neuroprotective activity in relieving H₂O₂-induced cellular damage, and the potential mechanism might be associated with regulating the Nrf-2/ARE signaling pathway. A more in-depth and comprehensive understanding of Moschus in the pathogenesis of AD will provide a fundamental basis for in vivo AD animal model research, which may be able to provide further insights and new targets for AD therapy.

Is L-Glutamate Toxic to Neurons and Thereby Contributes to Neuronal Loss and Neurodegeneration? A Systematic Review

L-glutamate (L-Glu) is a nonessential amino acid, but an extensively utilised excitatory neurotransmitter with critical roles in normal brain function. Aberrant accumulation of L-Glu has been linked to neurotoxicity and neurodegeneration. To investigate this further, we systematically reviewed the literature to evaluate the effects of L-Glu on neuronal viability linked to the pathogenesis and/or progression of neurodegenerative diseases (NDDs). A search in PubMed, Medline, Embase, and Web of Science Core Collection was conducted to retrieve studies that investigated an association between L-Glu and pathology for five NDDs: Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Together, 4060 studies were identified, of which 71 met eligibility criteria. Despite several inadequacies, including small sample size, employment of supraphysiological concentrations, and a range of administration routes, it was concluded that exposure to L-Glu in vitro or in vivo has multiple pathogenic mechanisms that influence neuronal viability. These mechanisms include oxidative stress, reduced antioxidant defence, neuroinflammation, altered neurotransmitter levels, protein accumulations, excitotoxicity, mitochondrial dysfunction, intracellular calcium level changes, and effects on neuronal histology, cognitive function, and animal behaviour. This implies that clinical and epidemiological studies are required to assess the potential neuronal harm arising from excessive intake of exogenous L-Glu.

Tongmai granules improve rat hippocampal injury by regulating TLR4/MyD88/AP-1 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Tongmai granules (TMG) is composed of Salvia miltiorrhiza Bge., Radix puerariae Lobata., and Ligusticum chuanxiong hort. TMG is mainly used for ischemic cardiovascular, cerebrovascular diseases, atherosclerosis, coronary heart disease, cerebral infarction and cerebral ischemia. TMG is a kind of traditional compound granule, which has a protective effect on brain injury. However, the potential protective mechanism of the TMG has not been elucidated.

AIM OF THE STUDY

TMG has a good effect on brain injury, but its brain protective mechanism is still unclear. The purpose of this study was to confirm the neuroprotective mechanism of TMG, reveal its target genes and identify the active components of TMG.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was used to identify the fingerprint of TMG. UPLC-Q-TOF-MSE was used to analyze the base peak intensity (BPI) chromatograms of TMG. TMG was pre-administered for one week, brain injury and edema were induced by injection of glutamate (Glu) into the lateral ventricles of rats. HE staining was used to investigate the pathological damage caused by Glu in the hippocampus of rats, and the RNA-seq was used to analyze the changes of different genes before and after TMG treatment. Finally, changes of related proteins were analyzed by qRT-PCR, Western blot, and other molecular biological methods. Dosage of TMG were set to 0.6 g/kg, 1.2 g/kg and 2.4 g/kg.

RESULTS

We found that TMG contained many active components, including salvianolic acid, puerarin, ferulic acid, etc. TMG could improve cerebral edema and brain injury induced by Glu. After TMG treatment, differential gene analysis showed that differential genes were significantly enriched in toll-like receptor signaling pathway. qRT-PCR validation results were consistent with RNA-Seq analysis results. Combined with Western blot analysis, we found that TMG ultimately regulated the expression of inflammatory cytokines by affecting the TLR4/MyD88/AP-1 pathway.

CONCLUSIONS

In this study, we combined TMG with RNA-seq analysis to demonstrate that TMG may play a neuroprotective role by regulating Toll-like receptor signaling pathway and down-regulating the expression of inflammatory cytokine. TMG may become a kind of traditional Chinese medicine with neuroprotective potential.

Anti-inflammatory effects of N-cyclooctyl-5-methylthiazol-2-amine hydrobromide on lipopolysaccharide-induced inflammatory response through attenuation of NLRP3 activation in microglial cells

Microglial activation is closely associated with neuroinflammatory pathologies. The nucleotide-binding and oligomerization domain-like receptor containing a pyrin domain 3 (NLRP3) inflammasomes are highly organized intracellular sensors of neuronal alarm signaling. NLRP3 inflammasomes activate nuclear factor kappa-B (NF-κB) and reactive oxygen species (ROS), which induce inflammatory responses. Moreover, NLRP3 dysfunction is a common feature of chronic inflammatory diseases. The present study investigated the effect of a novel thiazol derivative, N-cyclooctyl-5-methylthiazol-2-amine hydrobromide (KHG26700), on inflammatory responses in lipopolysaccharide (LPS)-treated BV-2 microglial cells. KHG26700 significantly attenuated the expression of several pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and interleukin-6, in these cells, as well as the LPS-induced increases in NLRP3, NF-κB, and phospho-IkBα levels. KHG26700 also suppressed the LPS-induced increases in protein levels of autophagy protein 5 (ATG5), microtubule-associated protein 1 light chain 3 (LC3), and beclin-1, as well as downregulating the LPS-enhanced levels of ROS, lipid peroxidation, and nitric oxide. These results suggest that the anti-inflammatory effects of KHG26700 may be due, at least in part, to the regulation of the NLRP3-mediated signaling pathway during microglial activation.

3-(Naphthalen-2-yl(propoxy)methyl)azetidine hydrochloride attenuates MPP＋-induced cytotoxicity by regulating oxidative stress and mitochondrial dysfunction in SH-SY5Y cells

Parkinson’s disease (PD) is a common chronic neurodegenerative disease mainly caused by the death of dopaminergic neurons. However, no complete pharmacotherapeutic approaches are currently available for PD therapies. 1-methyl-4-phenylpyridinium (MPP⁺)-induced SH-SY5Y neurotoxicity has been broadly utilized to create cellular models and study the mechanisms and critical aspects of PD. In the present study, we examined the role of a novel azetidine derivative, 3-(naphthalen-2-yl(propoxy)methyl)azetidine hydrochloride (KHG26792), against MPP⁺-induced neurotoxicity in SH-SY5Y cells. Treatment of KHG26792 significantly attenuated MPP⁺-induced changes in the protein levels of Bcl-2 and Bax together with efficient suppression of MPP⁺-induced activation of caspase-3 activity. KHG26792 also attenuated mitochondrial potential and levels of ROS, Ca²⁺, and ATP in MPP⁺-treated SH-SY5Y cells. Additionally, KHG26792 inhibited the induced production of nitric oxide and malondialdehyde. Moreover, the protective effect of KHG26792 is mediated through regulation of glutathione peroxidase and GDNF levels. Our results suggest a possibility that KHG26792 treatment significantly protects against MPP⁺-induced neurotoxicity in SH-SY5Y cells and KHG26792 may be a valuable therapeutic agent for the treatment of PD induced by an environmental toxin.

Protective effect of 5-HT7 receptor activation against glutamate-induced neurotoxicity in human neuroblastoma SH-SY5Y cells via antioxidative and antiapoptotic pathways

Serotonin exerts anti-inflammatory, antioxidant and antiapoptotic effects through 5-HT7 receptors. The present study determined the role of 5-HT7 receptors in glutamate-induced neurotoxicity by using human SH-SY5Y neuroblastoma cells. The cells were pretreated with different concentrations of 5-HT7 receptor agonist LP44 and antagonist SB269970 for 60 min, followed by treatment with glutamate. Cell proliferation was measured using xCELLigence system. Treatment with all the concentrations of LP44 significantly protected the cells from the toxic effects of glutamate after 24, 48 and 72 h. Although 5-HT7 receptor expression was significantly upregulated in glutamate-treated cells, it was downregulated in LP44-pretreated cells. Furthermore, LP44 treatment significantly decreased malondialdehyde levels and increased superoxide dismutase activities and glutathione levels. Moreover, LP44 treatment significantly decreased tumor necrosis factor alpha (TNF-α) levels and inhibited caspase 3 and caspase 9 mRNA expression. In contrast, SB269970 treatment exerted an insignificant effect on oxidative stress, inflammation and apoptosis. These findings suggest that exogenous stimulation of the 5-HT7 receptors may be protective in glutamate-induced neurotoxicity and that 5-HT7 receptor agonists can be used as therapeutic agents for preventing glutamate-induced neurological disorders.

Ecdysterones from Rhaponticum carthamoides (Willd.) Iljin reduce hippocampal excitotoxic cell loss and upregulate mTOR signaling in rats

Glutamate-induced excitotoxicity is a key pathological mechanism in many neurological disease states. Ecdysterones derived from Rhaponticum carthamoides (Willd.) Iljin (RCI) have been shown to alleviate glutamate-induced neuronal damage; although their mechanism of action is unclear, some data suggest that they enhance signaling in the mechanistic target of rapamycin (mTOR) signaling pathway. This study sought to elucidate the mechanisms underlying ecdysterone-mediated neuroprotection. We used in silico target prediction and simulation methods to identify putative ecdysterone binding targets, and to specifically identify those that represent nodes where several neurodegenerative diseases converge. We then used histological analyses in a rat hippocampal excitotoxicity model to test the effectiveness of ecdysterones in vivo. We found that RCI-derived ecdysterones should bind to glutamatergic NMDA-type receptors (NMDARs); specifically, in vivo modeling showed binding to the GRIN2B subunit of NMDARs, which was found also to be a node of convergence in several neurodegenerative disease pathways. Computerized network construction by using pathway information from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database showed putative links between GRIN2B and mTOR pathway elements including phosphoinositide-3kinase (PI3K), mTOR, and protein kinase C (PKC); these elements are associated with neuronal survival. Brain tissue western blots of ecdysterone-treated rats showed upregulated PI3K, Akt, mTOR, and phosphorylated Akt and mTOR, and down regulated GRIN2B and the apoptotic enzyme cleaved caspase-3. Ecdysterone treatment also prevented glutamate-induced rat hippocampal cell loss. In summary, RCI-derived ecdysterones appear to prevent glutamatergic excitotoxicity by increasing mTOR/Akt/PI3K signaling activity.

N-Propargylamines: versatile building blocks in the construction of thiazole cores

Thiazoles and their hydrogenated analogues are not only key structural units in a wide variety of natural products but they also constitute important building blocks in medicinal chemistry. Therefore, the synthesis of these compounds using new protocols is always interesting. It is well known that N-propargylamines can undergo a number of cyclization reactions to produce various nitrogen-containing heterocycles. In this review, we highlight the most important developments on the synthesis of thiazole and its derivatives starting from N-propargylamines. This review will be helpful in the development of improved methods for the synthesis of natural and biologically important compounds.

N-Adamantyl-4-methylthiazol-2-amine suppresses amyloid β-induced neuronal oxidative damage in cortical neurons

Recently, we have reported that N-adamantyl-4-methylthiazol-2-amine (KHG26693) successfully reduced the production of oxidative stress in streptozotocin-induced diabetic rats and lipopolysaccharide-induced BV-2 microglial cells by increasing their antioxidant capacity. However, antioxidative effects of KHG26693 against Aβ (Aβ)-induced oxidative stress have not yet been reported. In the present study, we further investigated the antioxidative function of KHG26693 in Aβ-mediated primary cultured cortical neurons. We showed here that KHG26693 attenuated Aβ-induced cytotoxicity, increase of Bax/Bcl-2 ratio, elevation of caspase-3 expression, and impairment of mitochondrial membrane potential in cultured primary cortical neurons. KHG26693 also decreases the Aβ-mediated formation of malondialdehyde, reactive oxygen species, and NO production by decreasing nitric oxide synthase (iNOS) and NADPH oxidase level. Moreover, KHG26693 suppress the Aβ-induced oxidative stress through a possible mechanism involving attenuation of GSH and antioxidant enzyme activities such as glutathione reductase and glutathione peroxidase (GPx). Finally, pretreatment of cortical neurons with KHG26693 significantly reduced the Aβ-induced protein oxidation and nitration. To our knowledge, this is the first report, showing that KHG26693 significantly attenuates Aβ-induced oxidative stress in primary cortical neurons, and may prove attractive strategies to reduce Aβ-induced neural cell death.

The azetidine derivative, KHG26792 protects against ATP-induced activation of NFAT and MAPK pathways through P2X7 receptor in microglia

Azetidine derivatives are of interest for drug development because they may be useful therapeutic agents. However, their mechanisms of action remain to be completely elucidated. Here, we have investigated the effects of 3-(naphthalen-2-yl(propoxy)methyl)azetidine hydrochloride (KHG26792) on ATP-induced activation of NFAT and MAPK through P2X7 receptor in the BV-2 mouse microglial cell line. KHG26792 decreased ATP-induced TNF-α release from BV-2 microglia by suppressing, at least partly, P2X7 receptor stimulation. KHG26792 also inhibited the ATP-induced increase in IL-6, PGE2, NO, ROS, CXCL2, and CCL3. ATP induced NFAT activation through P2X7 receptor, with KHG26792 reducing the ATP-induced NFAT activation. KHG26792 inhibited an ATP-induced increase in iNOS protein and ERK phosphorylation. KHG26792 prevented an ATP-induced increase in MMP-9 activity through the P2X7 receptor as a result of degradation of TIMP-1 by cathepsin B. Our data provide mechanistic insights into the role of KHG26792 in the inhibition of TNF-α produced via P2X7 receptor-mediated activation of NFAT and MAPK pathways in ATP-treated BV-2 cells. This study highlights the potential use of KHG26792 as a therapeutic agent for the many diseases of the CNS related to activated microglia.

Antioxidative effects of ethyl 2-(3-(benzo[d]thiazol-2-yl)ureido)acetate against amyloid β-induced oxidative cell death via NF-κB, GSK-3β and β-catenin signaling pathways in cultured cortical neurons

We have previously shown that 2-(3-(benzo[d]thiazol-2-yl)ureido)acetate (KHG21834) attenuates amyloid beta(Aβ)25-35-induced apoptotic death and shows anti-inflammatory activity against Aβ25-35-induced microglial activation. However, antioxidative effects of KHG21834 against Aβ-induced oxidative stress have not yet been reported. In the present study, we investigated the antioxidative function of KHG21834 in primary cultured cortical neurons, to expand the potential therapeutic efficacy of KHG21834. Pretreatment with KHG21834 protected against Aβ-induced neuronal cell death and mitochondrial damage, and significantly restored GSH levels and the activities of catalase, superoxide dismutase, and glutathione peroxidase, and also suppressed the production of reactive oxygen species and protein oxidation. These results imply that KHG21834 may play a role in cellular defense mechanisms against Aβ-induced oxidative stress in cultured cortical neurons. Furthermore, KHG21834 significantly attenuated the effects of Aβ treatment on levels of NF-κB, β-catenin, and GSK-3β proteins in cortical neurons. Taken together, our results suggest that the antioxidant effects of KHG21834 may result at least in part from its ability to regulate the NF-κB, β-catenin, and GSK-3β signaling pathways. To our knowledge, this is the first report showing that KHG21834 significantly attenuates Aβ25-35-induced oxidative stress in primary cortical neurons, and provides novel insights into KHG21834 as a possible therapeutic agent for the treatment of Aβ-mediated neurotoxicity involving oxidative stress.

2-Cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride protects against beta-amyloid-induced activation of the apoptotic cascade in cultured cortical neurons

Aggregated β-amyloid, implicated in the pathogenesis of Alzheimer's disease (AD), induces neurotoxicity by evoking a cascade of oxidative damage-dependent apoptosis in neurons. We investigated the molecular mechanisms underlying the protective effect of 2-cyclopropylimino-3-methyl-1,3-thiazoline hydrochloride (KHG26377) against the beta-amyloid (Aβ25-35)-induced primary cortical neuronal cell neurotoxicity. Treatment with KHG26377 attenuated the Aβ25-35-induced apoptosis by decreasing the Bax/Bcl-2 ratio and suppressing the activation of caspase-3. A marked increase in calcium influx and in the level of reactive oxygen species together with a decrease in glutathione levels was found after Aβ25-35 exposure; however, KHG26377 treatment reversed these changes in a concentration-dependent manner. In addition, KHG26377 significantly suppressed Aβ25-35-induced toxicity concomitant with a reduction in the activation of extracellular signal-regulated kinases 1 and 2 and nuclear factor kappa B. The KHG26377-induced protection of neuronal cells against Aβ toxicity was also mediated by suppressing the expression of glycogen synthase kinase-3β, increasing the levels of β-catenin, and reducing the levels of phosphorylated tau. Our findings suggest that KHG26377 may modulate the neurotoxic effects of β-amyloid and provide a rationale for treatment of AD.

Effects of N-adamantyl-4-methylthiazol-2-amine on hyperglycemia, hyperlipidemia and oxidative stress in streptozotocin-induced diabetic rats

Thiazole derivatives are attractive candidates for drug development because they can be efficiently synthesized and are active against a number of diseases and conditions, including diabetes. In our present study, we investigated the anti-inflammatory and antioxidant properties of N-adamantyl-4-methylthiazol-2-amine (KHG26693), a new thiazole derivative, in a streptozotocin (STZ)-induced model of diabetes mellitus. STZ-induced diabetic rats were intraperitoneally administered KHG26693 (3mg/kg-body weight/day) for 4 weeks. KHG26693 administration significantly decreased blood glucose, triglycerides, and cholesterol and increased insulin. KHG26693 also suppressed several inflammatory responses in STZ-induced diabetic rats, as evidenced by decreased levels of serum tumor necrosis factor-α, interleukin-1β, and nitric oxide. Additionally, KHG26693 significantly modulated hepatic lipid peroxidation, catalase and superoxide dismutase activity, and the nonenzymatic antioxidant status (e.g., vitamins C and E), and reduced the glutathione content. These anti-inflammatory/antioxidative actions occurred as a result of the downregulation of inducible nitric oxide synthase and nuclear factor-kappa B. Taken together, our results suggest that KHG26693 successfully reduces the production of oxidative stress in STZ-induced diabetic rats by regulating the oxidation-reduction system, specifically increasing antioxidant capacity. Furthermore, KHG26693 treatment significantly reverted the key enzymes of glucose metabolism, such as glucokinase, glucose-6-phosphatase, glycogen synthase, glycogen phosphorylase, and fructose-1,6-bisphosphatase, to near-normal levels in liver tissues. These results indicate that KHG26693 normalizes disturbed glucose metabolism by enhancing glucose utilization and decreasing liver glucose production via insulin release, suggesting the possibility of future diabetes treatments.