Tetramethylpyrazine Nitrone Promotes the Clearance of Alpha-Synuclein via Nrf2-Mediated Ubiquitin-Proteasome System Activation.

Aggregation of α-synuclein (α-syn) and α-syn cytotoxicity are hallmarks of sporadic and familial Parkinson's disease (PD). Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent enhancement of the expression of the 20S proteasome core particles (20S CPs) and regulatory particles (RPs) increases proteasome activity, which can promote α-syn clearance in PD. Activation of peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) may reduce oxidative stress by strongly inducing Nrf2 gene expression. In the present study, tetramethylpyrazine nitrone (TBN), a potent-free radical scavenger, promoted α-syn clearance by the ubiquitin-proteasome system (UPS) in cell models overexpressing the human A53T mutant α-syn. In the α-syn transgenic mice model, TBN improved motor impairment, decreased the products of oxidative damage, and down-regulated the α-syn level in the serum. TBN consistently up-regulated PGC-1α and Nrf2 expression in tested models of PD. Additionally, TBN similarly enhanced the proteasome 20S subunit beta 8 (Psmb8) expression, which is linked to chymotrypsin-like proteasome activity. Furthermore, TBN increased the mRNA levels of both the 11S RPs subunits Pa28αß and a proteasome chaperone, known as the proteasome maturation protein (Pomp). Interestingly, specific siRNA targeting of Nrf2 blocked TBN's effects on Psmb8, Pa28αß, Pomp expression, and α-syn clearance. In conclusion, TBN promotes the clearance of α-syn via Nrf2-mediated UPS activation, and it may serve as a potentially disease-modifying therapeutic agent for PD.

Tetramethylpyrazine Nitrone alleviates D-galactose-induced murine skeletal muscle aging and motor deficits by activating the AMPK signaling pathway.

Tetramethylpyrazine nitrone (TBN), a novel derivative of tetramethylpyrazine (TMP) designed and synthesized by our group, possesses multi-functional mechanisms of action and displays broad protective effects in vitro and in animal models of age-related brain disorders such as stroke, Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Parkinson's disease (PD). In the present report, we investigated the effects of TBN on aging, specifically on muscle aging and the associated decline of motor functions. Using a D-galactose-induced aging mouse model, we found that TBN could reverse the levels of several senescence and aging markers including p16, p21, ceramides, and telomere length and increase the wet-weight ratio of gastrocnemius muscle tissue, demonstrating its efficacy in ameliorating muscle aging. Additionally, the pharmacological effects of TBN on motor deficits (gait analysis, pole-climbing test and grip strength test), muscle fibrosis (hematoxylin & eosin (HE), Masson staining, and αSMA staining), inflammatory response (IL-1ß, IL-6, and TNF-α), and mitochondrial function (ATP, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were also confirmed in the D-galactose-induced aging models. Further experiments demonstrated that TBN alleviated muscle aging and improved the decline of age-related motor deficits through an AMPK-dependent mechanism. These findings highlight the significance of TBN as a potential anti-aging agent to combat the occurrence and development of aging and age-related diseases.

Tetramethylpyrazine nitrone exerts neuroprotection via activation of PGC-1α/Nrf2 pathway in Parkinson's disease models.

INTRODUCTION: Parkinson's disease (PD) is common neurodegenerative disease where oxidative stress and mitochondrial dysfunction play important roles in its progression. Tetramethylpyrazine nitrone (TBN), a potent free radical scavenger, has shown protective effects in various neurological conditions. However, the neuroprotective mechanisms of TBN in PD models remain unclear. OBJECTIVES: We aimed to investigate TBN's neuroprotective effects and mechanisms in PD models. METHODS: TBN's neuroprotection was initially measured in MPP+/MPTP-induced PD models. Subsequently, a luciferase reporter assay was used to detect peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) promoter activity. Effects of TBN on antioxidant damage and the PGC-1α/Nuclear factor erythroid-2-related factor 2 (Nrf2) pathway were thoroughly investigated. RESULTS: In MPP+-induced cell model, TBN (30-300 µM) increased cell survival by 9.95 % (P < 0.05), 16.63 % (P < 0.001), and 24.09 % (P < 0.001), respectively. TBN enhanced oxidative phosphorylation (P < 0.05) and restored PGC-1α transcriptional activity suppressed by MPP+ (84.30 % vs 59.03 %, P < 0.01). In MPTP-treated mice, TBN (30 mg/kg) ameliorated motor impairment, increased striatal dopamine levels (16.75 %, P < 0.001), dopaminergic neurons survival (27.12 %, P < 0.001), and tyrosine hydroxylase expression (28.07 %, P < 0.01). Selegiline, a positive control, increased dopamine levels (15.35 %, P < 0.001) and dopaminergic neurons survival (25.34 %, P < 0.001). Additionally, TBN reduced oxidative products and activated the PGC-1α/Nrf2 pathway. PGC-1α knockdown diminished TBN's neuroprotective effects, decreasing cell viability from 73.65 % to 56.87 % (P < 0.001). CONCLUSION: TBN has demonstrated consistent effectiveness in MPP+-induced midbrain neurons and MPTP-induced mice. Notably, the therapeutic effect of TBN in mitigating motor deficits and neurodegeneration is superior to selegiline. The neuroprotective mechanisms of TBN are associated with activation of the PGC-1α/Nrf2 pathway, thereby reducing oxidative stress and maintaining mitochondrial function. These findings suggest that TBN may be a promising therapeutic candidate for PD, warranting further development and investigation.

Evaluation of therapeutic effects of tetramethylpyrazine nitrone in Alzheimer's disease mouse model and proteomics analysis.

The pathophysiology of Alzheimer's disease (AD) is multifactorial with characteristic extracellular accumulation of amyloid-beta (Aß) and intraneuronal aggregation of hyperphosphorylated tau in the brain. Development of disease-modifying treatment for AD has been challenging. Recent studies suggest that deleterious alterations in neurovascular cells happens in parallel with Aß accumulation, inducing tau pathology and necroptosis. Therefore, therapies targeting cellular Aß and tau pathologies may provide a more effective strategy of disease intervention. Tetramethylpyrazine nitrone (TBN) is a nitrone derivative of tetramethylpyrazine, an active ingredient from Ligusticum wallichii Franchat (Chuanxiong). We previously showed that TBN is a potent scavenger of free radicals with multi-targeted neuroprotective effects in rat and monkey models of ischemic stroke. The present study aimed to investigate the anti-AD properties of TBN. We employed AD-related cellular model (N2a/APPswe) and transgenic mouse model (3×Tg-AD mouse) for mechanistic and behavioral studies. Our results showed that TBN markedly improved cognitive functions and reduced Aß and hyperphosphorylated tau levels in mouse model. Further investigation of the underlying mechanisms revealed that TBN promoted non-amyloidogenic processing pathway of amyloid precursor protein (APP) in N2a/APPswe in vitro. Moreover, TBN preserved synapses from dendritic spine loss and upregulated synaptic protein expressions in 3×Tg-AD mice. Proteomic analysis of 3×Tg-AD mouse hippocampal and cortical tissues showed that TBN induced neuroprotective effects through modulating mitophagy, MAPK and mTOR pathways. In particular, TBN significantly upregulated PINK1, a key protein for mitochondrial homeostasis, implicating PINK1 as a potential therapeutic target for AD. In summary, TBN improved cognitive functions in AD-related mouse model, inhibited Aß production and tau hyperphosphorylation, and rescued synaptic loss and neuronal damage. Multiple mechanisms underlie the anti-AD effects of TBN including the modulation of APP processing, mTOR signaling and PINK1-related mitophagy.

TBN improves motor function and prolongs survival in SOD1G93A and TDP-43M337V mouse model of ALS / 中国药理学与毒理学杂志

OBJECTIVE Amyotrophic lateral sclerosis(ALS)is a fetal neurodegenerative disease characterized by the progressive loss of upper and lower motor neu-rons,leading to skeletal muscle atrophy,weakness,and paralysis.Oxidative stress plays a crucial role in ALS pathogenesis,including the familial forms of the disease arising from mutations in the gene coding for superox-ide dismutase(SOD1).Additionally,the abnormal accu-mulation of TAR DNA-binding protein of 43 ku(TDP-43)is a pathological feature present in almost all patients,even though the pathogenesis of ALS is unclear.Current-ly,there is no drug that can cure ALS/FTLD.Tetramethyl-pyrazine nitrone(TBN)is a derivative of tetramethylapyr-azine,derived from traditional Chinese medicine Ligusti-cum chuanxiong,which has been extensively proven to have therapeutic effects on various models of neurode-generative diseases.METHODS We investigated the therapeutic effect of TBN in the SOD1G93A and TDP-43M337V ALS mouse models.In the SOD1G93A trans-genic mouse model,TBN was administered to mice via intraperitoneal or intragastric injection after the onset of motor deficits.We injected the TDP-43M337V virus into the striatum of mice unilaterally and bilaterally,and then administered TBN 30 mg·kg-1 intragastrically to observe changes in behavior and survival rate of mice.RESULTS TBN slowed the progression of motor neuron disease,as evidenced by improved motor performance,reduced spi-nal motor neuron loss and associated glial response,and decreased skeletal muscle fiber denervation and fibrosis.TBN treatment activated mitochondrial antioxidant activity through the PGC-1α/Nrf2/HO-1 pathway and decreased the expression of human SOD1.In the mice with unilateral injection of TDP-43M337V into the striatum,TBN improved motor deficits and cognitive impairment in the early stages of disease progression.In mice with bilateral injection of TDP-43M337V into the striatum,TBN not only improved motor function but also prolonged survival.Moreover,we demonstrate that its therapeutic effect may be through activation of the Akt/mTOR/GSK-3β and AMPK/PGC-1α/Nrf2 signaling pathways.CONCLUSION TBN shows promise as an agent for the treatment of ALS/FTLD.TBN is currently undergoing clinical investigation for several indications,including a Phase Ⅱ trial for ALS.

Tetramethylpyrazine nitrone activates hypoxia-inducible factor and regulates iron homeostasis to improve renal anemia.

Renal anemia is one of the most common complications of chronic kidney disease and diabetic kidney disease. Despite the progress made in recent years, there is still an urgent unmet clinical need for renal anemia treatment. In this research, we investigated the efficacy and mechanism of action of the novel tetramethylpyrazine nitrone (TBN). Animal models of anemia including the streptozotocin (STZ)-induced spontaneously hypertensive rats (SHR) and the cisplatin (CDDP)-induced C57BL/6J mice are established to study the TBN's effects on expression of hypoxia-inducible factor and erythropoietin. To explore the mechanism of TBN's therapeutic effect on renal anemia, cobalt chloride (CoCl2) is used in Hep3B/HepG2 cells to simulate a hypoxic environment. TBN is found to increase the expression of hypoxia-inducible factor HIF-1α and HIF-2α under hypoxic conditions and reverse the reduction of HIFs expression caused by saccharate ferric oxide (SFO). TBN also positively regulates the AMPK pathway. TBN stimulates nuclear transcription and translation of erythropoietin by enhancing the stability of HIF-1α expression. TBN has a significant regulatory effect on several major biomarkers of iron homeostasis, including ferritin, ferroportin (FPN), and divalent metal transporter-1 (DMT1). In conclusion, TBN regulates the AMPK/mTOR/4E-BP1/HIFs pathway, and activates the hypoxia-inducible factor and regulates iron homeostasis to improve renal anemia.

Phase I safety, tolerability, and pharmacokinetic studies of tetramethylpyrazine nitrone in healthy Chinese volunteers.

BACKGROUND: The purpose of this study was to investigate the safety, tolerability and pharmacokinetics of tetramethylpyrazine nitrone (TBN) in healthy Chinese volunteers. METHODS: A single-ascending-dose (SAD) study where 68 subjects were randomized to a single dose of placebo or TBN (50, 100, 200, 400, 700, 1,000, 1,400, or 1,800 mg) through IV infusion over 30 min. A multiple-ascending-dose (MAD) study where 24 subjects received TBN twice daily (with 12 hr interval) for total 6.5 days at doses of either 700 or 1,400 mg. Adverse events were recorded and pharmacokinetic samples were collected during the whole study period. RESULTS: No serious adverse events were found in the study. All of the observed adverse events, including increased white blood cell (4.4% subjects) and neutrophil counts (4.4% subjects), and decreased hemoglobin levels (4.2% subjects), were laboratory test abnormalities. All the adverse events were mild and tolerable, and returned to normal without any intervention. In the SAD study, linear Cmax values were observed in the dose interval of 50-1,800 mg. In the MAD study, the average steady-state concentrations (Cavg.ss ) of TBN in the 700 and 1,400 mg dose group were 2,407 and 5,837 ng/ml, respectively. No drug accumulation was observed in this study. CONCLUSIONS: TBN is well tolerated in healthy volunteers. Linear Cmax values were observed in the interval of 50-1,800 mg, and target exposures of TBN were achieved without accumulation after twice daily administration to subjects. (This study has been registered at ChiCTR.org.cn. Identifier: ChiCTR1800016225 and ChiCTR1800019627.).

Polyurethane End-Capped by Tetramethylpyrazine-Nitrone for Promoting Endothelialization Under Oxidative Stress.

Thrombus and restenosis are two main factors that cause the failure of vascular implants. Constructing a functional and confluent layer of endothelial cells (ECs) is considered an ideal method to prevent these problems. However, oxidative stress induced by the disease and implantation can damage ECs and hinder the endothelialization of implants. Thus, developing biomaterials that can protect ECs adhesion and proliferation from oxidative stress is urgently needed for the rapid endothelialization of vascular implants. In this work, a novel polyurethane (PU-TBN) is synthesized by employing tetramethylpyrazine-nitrone (TBN) as end-group to endow polymers with dual functions of antioxidant activity and promoting endothelialization. Common PU without TBN is also prepared to be control. Compared to PU, PU-TBN significantly promotes human umbilical vein endothelial cells (HUVECs) adhesion and proliferation, where cells spread well and a confluent endothelial layer is formed. PU-TBN also shows obvious free radical scavenging activity, and thus effectively attenuates oxidative stress to protect HUVECs from oxidative apoptosis. Moreover, PU-TBN exhibits enhanced antiplatelets effect, excellent biocompatibility, and similar mechanical properties to PU. These characteristics can endow PU-TBN with great potential to be used as vascular implants or coatings of other materials for rapid endothelialization under complex oxidative stress environment.

Tetramethylpyrazine Nitrone Reduces Oxidative Stress to Alleviate Cerebral Vasospasm in Experimental Subarachnoid Hemorrhage Models.

Cerebral vasospasm is one of the deleterious complications after subarachnoid hemorrhage (SAH), leading to delayed cerebral ischemia and permanent neurological deficits or even death. Free radicals and oxidative stress are considered as crucial causes contributing to cerebral vasospasm and brain damage after SAH. Tetramethylpyrazine nitrone (TBN), a derivative of the clinically used anti-stroke drug tetramethylpyrazine armed with a powerful free radical scavenging nitrone moiety, has been reported to prevent brain damage from ischemic stroke. The present study aimed to investigate the effects of TBN on vasospasm and brain damage after SAH. Two experimental SAH models were used, a rat model by endovascular perforation and a rabbit model by intracisternal injection of autologous blood. The effects of TBN on SAH were evaluated assessing basilar artery spasm, neuronal apoptosis, and neurological deficits. TBN treatment significantly attenuated vasospasm, improved neurological behavior functions and reduced the number of apoptotic neurons in both the SAH rats and rabbits. Mechanistically, TBN suppressed the increase in 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine immuno-positive cells in the cortex of SAH rat brain. Western blot analyses indicated that TBN effectively reversed the altered expression of Bcl-2, Bax and cytochrome C, and up-regulated nuclear factor erythroid-derived 2-like 2 (Nrf2) and hemeoxygenase-1 (HO-1) protein expressions. In the in vitro studies, TBN inhibited H2O2-induced bEnd.3 cell apoptosis and reduced ROS generation. Additionally, TBN alleviated the contraction of rat basilar artery rings induced by H2O2 ex vivo. In conclusion, TBN ameliorated SAH-induced cerebral vasospasm and neuronal damage. These effects of TBN may be attributed to its anti-oxidative stress effect and up-regulation of Nrf2/HO-1.

[Effects of tetramethylypyrazine nitrone on proliferation and differentiation of neural stem cells in vitro].

OBJECTIVES: To investigate the role of tetramethylpyrazine(TMP) nitrone in proliferation and differentiation of neural stem cells (NSCs). METHODS: We separated and cultivated the original generation of NSCs from cerebral cortex of 14 days rat embryo, and the phenotype characteristics of the third-generation NSCs was tested by immunofluorescence. The experiment was divided into control group, ß-mercaptoethanol positive control group, tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + ethylene glycol tetraacetic acid(EGTA) group (n=4). The third-generation cultivation of NSCs was used in the experiment. The effect of tetramethylpyrazine nitrone on the number of NSCs proliferation was determined by BrdU and MTT, and the differentiation of NSCs was determined by Western blot. RESULTS: The primary NSCs was isolated successfully, neurospheres with typical NSCs morphology and expressing nestin was formed at 3-5 days. As BrdU and MTT assay results shown, compared with the control group andß-mercaptoethanol positive control group, the NSCs proliferation numbers of tetramethylpyrazine nitrone group increased significantly(P<0.05). The results of Western blot showed that the neuronal differentiation rate of NSCs was increased significantly in both the tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + EGTA group, and the differentiation rate of NSCs in tetramethylpyrazine nitrone + EGTA group increased more significantly(P<0.05). CONCLUSIONS: Tetramethylpyrazine nitrone can significantly enhance the proliferation and neuronal differentiation rate of NSCs. Decrease in extracellular Ca2+ can promote the differentiation of NSCs into neurons induced by tetramethylpyrazine nitrone. Ca2+ signaling plays an important role in the differentiation of NSCs into neurons.

Effects of tetramethylypyrazine nitrone on proliferation and differentiation of neural stem cells / 中国应用生理学杂志

OBJECTIVES@#To investigate the role of tetramethylpyrazine(TMP) nitrone in proliferation and differentiation of neural stem cells (NSCs).@*METHODS@#We separated and cultivated the original generation of NSCs from cerebral cortex of 14 days rat embryo, and the phenotype characteristics of the third-generation NSCs was tested by immunofluorescence. The experiment was divided into control group, β-mercaptoethanol positive control group, tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + ethylene glycol tetraacetic acid(EGTA) group (=4). The third-generation cultivation of NSCs was used in the experiment. The effect of tetramethylpyrazine nitrone on the number of NSCs proliferation was determined by BrdU and MTT, and the differentiation of NSCs was determined by Western blot.@*RESULTS@#The primary NSCs was isolated successfully, neurospheres with typical NSCs morphology and expressing nestin was formed at 3-5 days. As BrdU and MTT assay results shown, compared with the control group andβ-mercaptoethanol positive control group, the NSCs proliferation numbers of tetramethylpyrazine nitrone group increased significantly(<0.05). The results of Western blot showed that the neuronal differentiation rate of NSCs was increased significantly in both the tetramethylpyrazine nitrone group and tetramethylpyrazine nitrone + EGTA group, and the differentiation rate of NSCs in tetramethylpyrazine nitrone + EGTA group increased more significantly(<0.05).@*CONCLUSIONS@#Tetramethylpyrazine nitrone can significantly enhance the proliferation and neuronal differentiation rate of NSCs. Decrease in extracellular Ca can promote the differentiation of NSCs into neurons induced by tetramethylpyrazine nitrone. Ca signaling plays an important role in the differentiation of NSCs into neurons.

Neuroprotective and axonal outgrowth-promoting effects of tetramethylpyrazine nitrone in chronic cerebral hypoperfusion rats and primary hippocampal neurons exposed to hypoxia.

Chronic cerebral hypoperfusion is an important risk factor for vascular dementia and other brain dysfunctions, for which there are currently no effective medications available. We investigated the neuroprotective and axonal outgrowth promoting effects of tetramethylpyrazine nitrone (TBN) in a permanent bilateral occlusion of the common carotid arteries (2VO) rat model and in primary hippocampal neurons exposed to oxygen glucose deprivation (OGD). At 6th week after 2VO, TBN increased the time spent in novel arms in the Y-maze test and improved the discrimination ratio in object reorganization task. TBN attenuated axonal damage, and reduced oxidative DNA injury and lipid peroxidation in white matter. TBN also attenuated the neuronal apoptosis and ameliorated accumulation of astrocytes in parietal cortex and CA1 region of hippocampus. Western blot analyses indicated that TBN increased Bcl-2 expression, decreased Bax and Caspase 3 expressions, and upregulated the phosphorylation levels of high-molecular weight neurofilament (p-NFH), Akt (p-Akt) and glycogen synthase kinase-3ß (p-GSK3ß) in hippocampus at 6th week after chronic hypoperfusion. In vitro, TBN rescued hippocampal neuronal viability and axonal elongation from OGD damage. The p-Akt and p-GSK3ß upregulation by TBN was abolished by a specific phosphoinositide 3-kinase (PI3K) inhibitor LY294002, resulting in suppression of axonal outgrowth. Collectively, the results showed that TBN alleviated white matter lesion and impairment of cortex and hippocampus, attenuated oxidative damage and enhanced axonal outgrowth through the regulation of PI3K/Akt/GSK3ß signaling pathway, leading to improved cognitive deficit in a rat chronic hypoperfusion model.