Therapeutic effects of tetramethylpyrazine nitrone in rat ischemic stroke models

Borneol-Functionalized Macrophage Membrane-Encapsulated Mesoporous Selenium Nanoparticles Loaded with Resveratrol for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a serious neurological disease that can result in paralysis. After SCI occurs, the blood-spinal cord barrier (BSCB) is disrupted, and permeability is transiently elevated. However, the permeability of the BSCB returns to normal over time, which prevents many drugs from being used in subsequent treatments. In this study, we designed a borneol-functionalized macrophage membrane encapsulating mesoporous selenium nanoparticles loaded with resveratrol (MSe-Res-BMMs) for SCI treatment. In vivo animal experiments and in vitro cell experiments demonstrated that MSe-Res-BMMs were able to protect neurons from ferroptosis by reducing ROS levels and increasing glutathione peroxidase-4 (GPx-4) activity. In addition, this treatment also reduced ROS-induced inflammation and apoptosis by decreasing the expression of inflammatory factor IL-1β and apoptotic factor Cleaved Caspase-3 at the site of injury. Therefore, MSe-Res-BMMs are expected to provide new therapeutic options for SCI treatment.

α-Phenyl-N-tert-Butylnitrone and Analogous α-Aryl-N-alkylnitrones as Neuroprotective Antioxidant Agents for Stroke

The recent advances in research on the use of the antioxidant and neuroprotective agent α-phenyl-N-tert-butylnitrone (PBN) for the therapy of stroke have been reviewed. The protective effect of PBN in the transient occlusion of the middle cerebral artery (MCAO) has been demonstrated, although there have been significant differences in the neuronal salvaging effect between PBN-treated and untreated animals, each set of data having quite large inter-experimental variation. In the transient forebrain ischemia model of gerbil, PBN reduces the mortality after ischemia and the neuronal damage in the hippocampal cornu ammonis 1 (CA1) area of the hippocumpus caused by ischemia. However, PBN fails to prevent postischemic CA1 damage in the rat. As for focal cerebral ischemia, PBN significantly reduces cerebral infarction and decreases neurological deficit after ischemia using a rat model of persistent MCAO in rats. Similarly, the antioxidant and neuroprotective capacity of a number of PBN-derived nitrones prepared in the author's laboratory have also been summarized here, showing their high potential therapeutic power to treat stroke.

Pharmacokinetics, Safety Profile, and Tolerability of Tetramethylpyrazine Nitrone Tablets After Single and Multiple Ascending Doses in Healthy Chinese Volunteers

BACKGROUND AND OBJECTIVES

Tetramethylpyrazine nitrone (TBN) is a novel tetramethylpyrazine derivative armed with a strong free radical scavenging nitrone moiety. This study aims to evaluate the pharmacokinetics, safety profile, and tolerability of TBN tablets after a single ascending dose (SAD) and multiple ascending doses (MAD) in healthy Chinese volunteers.

METHODS

This phase I, single-center, open-label study was conducted in China. The SAD portion consisted of four cohorts with dose levels of 400-1800 mg. The MAD portion included three cohorts in which subjects received doses of 600-1800 mg twice daily for 7 days (13 consecutive doses). The third portion was a randomized, two-period, crossover design to assess the influence of food with a single dose of TBN tablets (1200 mg). The safety profile was evaluated by monitoring adverse events (AEs), vital signs, electrocardiograms, physical examinations, and laboratory test results.

RESULTS

Fifty-two healthy subjects aged 18 to 45 years with a body mass index between 19.0 and 26.0 kg/m2 were enrolled. After a single dose of TBN, the median time to maximum plasma concentration (Tmax) was 2.48-3.24 h and the mean half-life (t1/2) was 1.28 to 2.10 h across all doses. In the MAD study, the median Tmax was 2.48 to 3.48 h. In the 400-1800 mg dose range, there was a tendency for less than proportional increases in the maximum plasma concentration (Cmax), the area under the concentration-time curve from 0 to time of last measurable concentration (AUC0-t), and the area under the concentration-time curve from 0 to infinity (AUC0-inf) in both single- and multiple-dose periods. A significantly higher TBN exposure was observed in females than males in both a single and multiple doses of the 600 mg and 1200 mg groups, with a geometric mean female-to-male ratio of 138.69-203.18%. Food decreased the Cmax and AUC0-t of TBN to 45.19% and 59.73%, respectively. Each dose group reached a steady state after 4 days. No drug accumulation was observed. Two subjects had drug-related AEs. A decreased neutrophil count and drug eruption in the SAD portion (1200 mg group) and an increased alanine aminotransferase level in the food effect group were found. All AEs were mild and tolerable (CTCAE grade 1) and resolved without any medical intervention.

CONCLUSION

TBN tablets had a good safety profile and were well tolerated in healthy Chinese volunteers. Steady-state concentrations were reached after 4 consecutive days of oral administration. The results of this phase I study will provide guidance for the design of future TBN clinical studies.

CHINESE CLINICAL TRIAL REGISTRY

ChiCTR1900022092.

Proteomic advance of ischemic stroke: preclinical, clinical, and intervention

Ischemic stroke (IS) is the most common type of stroke and is characterized by high rates of mortality and long-term injury. The prediction and early diagnosis of IS are therefore crucial for optimal clinical intervention. Proteomics has provided important techniques for exploring protein markers associated with IS, but there has been no systematic evaluation and review of research that has used these techniques. Here, we review the differential proteins that have been found in cell- and animal- based studies and clinical trials of IS in the past 10 years; determine the key pathological proteins that have been identified in clinical trials; summarize the target proteins affected by interventions aimed at treating IS, with a focus on traditional Chinese medicine treatments. Overall, we clarify findings and problems that have been identified in recent proteomics research on IS and provide suggestions for improvements in this area. We also suggest areas that could be explored for determining the pathogenesis and developing interventions for IS.

Ligustrazine exerts neuroprotective effects via circ_0008146/miR-709/Cx3cr1 axis to inhibit cell apoptosis and inflammation after cerebral ischemia/reperfusion injury

BACKGROUND

Ligustrazine is a traditional Chinese herbal medicine that has long been used to treat cerebral ischemic disorders. However, the molecular mechanisms of ligustrazine in cerebral ischemia/reperfusion (I/R) damage have not been clear elucidated. The aim of this study was to examine the neuroprotective mechanisms of ligustrazine in cerebral I/R.

METHODS

9 C57BL/6 mice were randomly divided to three groups: Sham group (n = 3), Middle cerebral artery occlusion (MCAO) group (n = 3), and MCAO + Ligustrazine group (n = 3). The neurological deficit score was evaluated, the cerebral infarct volume was measured by triphenylterazolium chloride (TTC) staining. Differentially expressed (DE) messenger RNAs (mRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) were analyzed using the R package DEseq2 based on P-value < 0.05 and Log2 |fold change (FC)| ≥ 2 in sham group vs MCAO group and MCAO group vs ligustrazine group by high-throughput sequencing. Function enrichment analysis, the protein-protein interaction (PPI) of neurogenesis related genes were performed. The neurogenesis related competitive endogenous RNA (ceRNA) network was constructed.

RESULTS

The expression of circ_0008146 was considerably higher in the MCAO group than the Sham group, and ligustrazine treatment markedly decreased the expression of circ_0008146 in MCAO. Next, the circ_0008146 ceRNA network was established, including circ_0008146-miR-709-Cx3cr1 ceRNA network. Besides, real time quantitative polymerase chain reaction (RT-qPCR) assay identified that miR-709 expression was considerably lower and Cx3cr1 expression was higher in the MCAO group than Sham group, and ligustrazine treatment markedly increased the miR-709 expression and reduced Cx3cr1 expression in MCAO. Further, silencing of circ_0008146 inhibited the concentration of Interleukin 6 (IL-6), Tumor Necrosis Factor alpha (TNF-α) and reduced neuron cell death and up-regulated miR-709 expression and down-regulated Cx3cr1 expression in Lipopolysaccharide (LPS) induced BV-2 cells. Dual-Luciferase reporter gene assay verified that circ_0008146 targeted miR-709.

CONCLUSION

Ligustrazine targets circ_0008146/miR-709/Cx3cr1 axis to inhibit cell apoptosis and inflammation after cerebral ischemia/reperfusion injury.

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.

An Overview of Tetramethylpyrazine (Ligustrazine) and its Derivatives as Potent Anti-Alzheimer’s Disease Agents

Abstract:

Tetramethylpyrazine (TMP), or ligustrazine, is an alkaloid isolated from the Chinese herb Ligusticum wallichii. It is known for its broad-spectrum medicinal properties against several diseases, and various studies have shown that it can modulate diverse biological targets and signaling pathways to produce neuroprotective effects, especially against Alzheimer’s disease (AD). This has attracted significant research attention evaluating TMP as a potent multitarget anti-AD agent. This review compiles the results of studies assessing the neuroprotective mechanisms exerted by TMP as well as its derivatives prepared using a multi-target-directed ligand strategy to explore its multitarget modulating properties. The present review also highlights the work done on the design, synthesis, structure-activity relationships, and mechanisms of some potent TMP derivatives that have shown promising anti-AD activities. These derivatives were designed, synthesized, and evaluated to develop anti-AD molecules with enhanced biological and pharmacokinetic activities compared to TMP. This review article paves the way for the exploration and development of TMP and TMP derivatives as an effective treatment for AD.

Tetramethylpyrazine Preserves the Integrity of Blood-Brain Barrier Associated With Upregulation of MCPIP1 in a Murine Model of Focal Ischemic Stroke

Tetramethylpyrazine (TMP), a prominent ingredient of Chinese herb Ligusticum chuanxiong Hort, is known to suppress neuroinflammation and protect blood-brain barrier (BBB) integrity. We investigated whether monocyte chemotactic protein-induced protein 1 (MCPIP1, also known as Regnase-1), a newly identified zinc-finger protein, plays a role in TMP-mediated anti-inflammation and neuroprotection. Male C57BL/6 mice were subjected to focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO) for 2 h, followed by reperfusion for 24 h. TMP (25 mg/kg or 50 mg/kg) or vehicle was administered intraperitoneally 12 h before and post MCAO. The TMP significantly upregulated MCPIP1 in the ischemic brain tissues and effectively inhibited extravasation of fluorescein isothiocyanate (FITC)-dextran, resulting in attenuation of brain edema. These effects of the TMP were associated with a significant reduction in levels of inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and MMP-9 in the ischemic brain tissues. The TMP upregulated the expression of MCPIP1 in primary cultures of neurons and protected against oxygen-glucose deprivation-induced neuron death, while this neuroprotective effect of TMP was abolished by knockdown of MCPIP1 using MCPIP1-specific siRNA. These results suggest that preservation of BBB integrity by TMP is associated with its anti-inflammatory activity. The effect of TMP is mediated, at least in part, via upregulation of MCPIP1 in the ischemic brain.

Nephroprotective Effects of Tetramethylpyrazine Nitrone TBN in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal failure, but therapeutic options for nephroprotection are limited. Oxidative stress plays a key role in the pathogenesis of DKD. Our previous studies demonstrated that tetramethylpyrazine nitrone (TBN), a novel nitrone derivative of tetramethylpyrazine with potent free radical-scavenging activity, exerted multifunctional neuroprotection in neurological diseases. However, the effect of TBN on DKD and its underlying mechanisms of action are not yet clear. Herein, we performed streptozotocin-induced rat models of DKD and found that TBN administrated orally twice daily for 6 weeks significantly lowered urinary albumin, N-acetyl-β-D-glycosaminidase, cystatin C, malonaldehyde, and 8-hydroxy-2′-deoxyguanosine levels. TBN also ameliorated renal histopathological changes. More importantly, in a nonhuman primate model of spontaneous stage III DKD, TBN increased the estimated glomerular filtration rate, decreased serum 3-nitrotyrosine, malonaldehyde and 8-hydroxy-2′-deoxyguanosine levels, and improved metabolic abnormalities. In HK-2 cells, TBN increased glycolytic and mitochondrial functions. The protective mechanism of TBN might involve the activation of AMPK/PGC-1α-mediated downstream signaling pathways, thereby improving mitochondrial function and reducing oxidative stress in the kidneys of DKD rodent models. These results support the clinical development of TBN for the treatment of DKD.

Tetramethylpyrazine nitrone improves motor dysfunction and pathological manifestations by activating the PGC-1α/Nrf2/HO-1 pathway in ALS mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of upper and lower motor neurons that results in skeletal muscle atrophy, weakness and paralysis. Oxidative stress plays a key role in the pathogenesis of ALS, including familial forms of the disease arising from mutation of the gene coding for superoxide dismutase (SOD1). We have used the SOD1^G93A ALS mouse model to investigate the efficacy of 2-[[(1,1-dimethylethyl)oxidoimino]-methyl]-3,5,6-trimethylpyrazine (TBN), a novel tetramethylpyrazine derivative armed with a powerful free-radical scavenging nitrone moiety. TBN was administered to mice by intraperitoneal or intragastric injection after the onset of motor deficits. TBN slowed the progression of motor neuron disease as evidenced by improved motor performance, reduced spinal motor neuron loss and the 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. These findings suggest that TBN holds promise as a therapeutic agent for ALS.

Homo-Tris-Nitrones Derived from α-Phenyl-N-tert-butylnitrone: Synthesis, Neuroprotection and Antioxidant Properties

Herein we report the synthesis, antioxidant and neuroprotective power of homo-tris-nitrones (HTN) 1-3, designed on the hypothesis that the incorporation of a third nitrone motif into our previously identified homo-bis-nitrone 6 (HBN6) would result in an improved and stronger neuroprotection. The neuroprotection of HTNs 1-3, measured against oligomycin A/rotenone, showed that HTN2 was the best neuroprotective agent at a lower dose (EC₅₀ = 51.63 ± 4.32 μM), being similar in EC₅₀ and maximal activity to α-phenyl-N-tert-butylnitrone (PBN) and less potent than any of HBNs 4-6. The results of neuroprotection in an in vitro oxygen glucose deprivation model showed that HTN2 was the most powerful (EC₅₀ = 87.57 ± 3.87 μM), at lower dose, but 50-fold higher than its analogous HBN5, and ≈1.7-fold less potent than PBN. HTN3 had a very good antinecrotic (IC₅₀ = 3.47 ± 0.57 μM), antiapoptotic, and antioxidant (EC₅₀ = 6.77 ± 1.35 μM) profile, very similar to that of its analogous HBN6. In spite of these results, and still being attractive neuroprotective agents, HTNs 2 and 3 do not have better neuroprotective properties than HBN6, but clearly exceed that of PBN.

Recent Advances on Nitrones Design for Stroke Treatment

The recent advances of tetramethylpyrazine nitrones and quinolylnitrones for the treatment of stroke have been reviewed and compared with other agents, showing promising therapeutic applications. As a result of a functional transformation of natural product ligustrazine, (Z)-N-tert-butyl-1-(3,5,6-trimethylpyrazin-2-yl)methanimine oxide (6) is a multitarget small nitrone showing potent thrombolytic activity and free radicals scavenging power, in addition to nontoxicity and blood-brain barrier permeability. Similarly, antioxidant (Z)-N-tert-butyl-1-(2-chloro-6-methoxyquinolin-3-yl)methanimine oxide (17) is a novel agent for cerebral ischemia therapy as it is able to scavenge different types of free radical species, showing strong neuroprotection and reduced infarct size.

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 C_max values were observed in the dose interval of 50-1,800 mg. In the MAD study, the average steady-state concentrations (C_avg.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 C_max 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.).

Protective Mechanism and Treatment of Neurogenesis in Cerebral Ischemia

Stroke is the fifth leading cause of death worldwide and is a main cause of disability in adults. Neither currently marketed drugs nor commonly used treatments can promote nerve repair and neurogenesis after stroke, and the repair of neurons damaged by ischemia has become a research focus. This article reviews several possible mechanisms of stroke and neurogenesis and introduces novel neurogenic agents (fibroblast growth factors, brain-derived neurotrophic factor, purine nucleosides, resveratrol, S-nitrosoglutathione, osteopontin, etc.) as well as other treatments that have shown neuroprotective or neurogenesis-promoting effects.

Design, synthesis, and biological evaluation of ligustrazine/resveratrol hybrids as potential anti-ischemic stroke agents

To search for potent anti-ischemic stroke agents, a series of tetramethylpyrazine (TMP)/resveratrol (RES) hybrids 6a-t were designed and synthesized. These hybrids inhibited adenosine diphosphate (ADP)- or arachidonic acid (AA)-induced platelet aggregation, among them, 6d, 6g-i, 6o and 6q were more active than TMP. The most active compound 6h exhibited more potent anti-platelet aggregation activity than TMP, RES, as well as positive control ticlopidine (Ticlid) and aspirin (ASP). Furthermore, 6h exerted strong antioxidative activity in a dose-dependent manner in rat pheochromocytoma PC12 cells which were treated with hydrogen peroxide (H₂O₂) or hydroxyl radical (·OH). Importantly, 6h significantly protected primary neuronal cells suffered from oxygen-glucose deprivation/reoxygenation (OGD/R) injury, comparable to an anti-ischemic drug edaravone (Eda). Together, our findings suggest that 6h may be a promising candidate warranting further investigation for the intervention of ischemic stroke.

5-Aryl-2-(3,5-dialkyl-4-hydroxyphenyl)-4,4-dimethyl-4H-imidazole 3-Oxides and Their Redox Species: How Antioxidant Activity of 1-Hydroxy-2,5-dihydro-1H-imidazoles Correlates with the Stability of Hybrid Phenoxyl-Nitroxides

Cyclic nitrones of the imidazole series, containing a sterically hindered phenol group, are promising objects for studying antioxidant activity; on the other hand, they can form persistent hybrid phenoxyl-nitroxyl radicals (HPNs) upon oxidation. Here, a series of 5-aryl-4,4-dimethyl-4H-imidazole 3-oxides was obtained by condensation of aromatic 2-hydroxylaminoketones with 4-formyl-2,6-dialkylphenols followed by oxidation of the initially formed N-hydroxy derivatives. It was shown that the antioxidant activity of both 1-hydroxy-2,5-dihydroimidazoles and 4H-imidazole 3-oxides increases with a decrease in steric volume of the alkyl substituent in the phenol group, while the stability of the corresponding HPNs generated from 4H-imidazole 3-oxides reveals the opposite tendency.

Sirt3-dependent deacetylation of COX-1 counteracts oxidative stress-induced cell apoptosis

The mitochondrial complexes are prone to sirtuin (Sirt)3-mediated deacetylation modification, which may determine cellular response to stimuli, such as oxidative stress. In this study, we show that the cytochrome c oxidase (COX)-1, a core catalytic subunit of mitochondrial complex IV, was acetylated and deactivated both in 2,2'-azobis(2-amidinopropane) dihydrochloride-treated NIH/3T3 cells and hydrogen peroxide-treated primary neuronal cells, correlating with apoptotic cell death induction by oxidative stress. Inhibition of Sirt3 by small interfering RNA or the inhibitor nicotinamide induced accumulation of acetylation of COX-1, reduced mitochondrial membrane potential, and increased cell apoptosis. In contrast, overexpression of Sirt3 enhanced deacetylation of COX-1 and inhibited oxidative stress-induced apoptotic cell death. Significantly, rats treated with ischemia/reperfusion injury, a typical oxidative stress-related disease, presented an inhibition of Sirt3-induced hyperacetylation of COX-1 in the brain tissues. Furthermore, K13, K264, K319, and K481 were identified as the acetylation sits of COX-1 in response to oxidative stress. In conclusion, COX-1 was discovered as a new deacetylation target of Sirt3, indicating that the Sirt3/COX-1 axis is a promising therapy target of stress-related diseases.-Tu, L.-F., Cao, L.-F., Zhang, Y.-H., Guo, Y.-L., Zhou, Y.-F., Lu, W.-Q., Zhang, T.-Z., Zhang, T., Zhang, G.-X., Kurihara, H., Li, Y.-F., He, R.-R. Sirt3-dependent deacetylation of COX-1 counteracts oxidative stress-induced cell apoptosis.

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.

Local delivery of tetramethylpyrazine eliminates the senescent phenotype of bone marrow mesenchymal stromal cells and creates an anti-inflammatory and angiogenic environment in aging mice

Aging drives the accumulation of senescent cells (SnCs) including stem/progenitor cells in bone marrow, which contributes to aging‐related bone degenerative pathologies. Local elimination of SnCs has been shown as potential treatment for degenerative diseases. As LepR⁺ mesenchymal stem/progenitor cells (MSPCs) in bone marrow are the major population for forming bone/cartilage and maintaining HSCs niche, whether local elimination of senescent LepR⁺MSPCs delays aging‐related pathologies and improves local microenvironment need to be well defined. In this study, we performed local delivery of tetramethylpyrazine (TMP) in bone marrow of aging mice, which previously showed to be used for the prevention and treatment of glucocorticoid‐induced osteoporosis (GIOP). We found the increased accumulation of senescent LepR⁺MSPCs in bone marrow of aging mice, and TMP significantly inhibited the cell senescent phenotype via modulating Ezh2‐H3k27me3. Most importantly, local delivery of TMP improved bone marrow microenvironment and maintained bone homeostasis in aging mice by increasing metabolic and anti‐inflammatory responses, inducing H‐type vessel formation, and maintaining HSCs niche. These findings provide evidence on the mechanisms, characteristics and functions of local elimination of SnCs in bone marrow, as well as the use of TMP as a potential treatment to ameliorate human age‐related skeletal diseases and to promote healthy lifespan.

Effects of tetramethylpyrazine phosphate on pancreatic islet microcirculation in SD rats

PURPOSES

Abnormal islet microcirculation impetus the insulin production and accelerates progression of Type 1 and 2 diabetes. In this study, we investigated whether tetramethylpyrazine phosphate (TMPP), a vasoactive substance, could regulate the islet microcirculation and insulin concentration and improve glycaemia in SD rats.

METHODS

SD rats were randomly divided into two groups, the control and TMPP groups. Each group was further divided into three subgroups according to the intravenous injection of either saline, 15 or 30% glucose. The non-radioactive microsphere technique was adopted to measure the organ blood flow. Nitric oxide synthase (NOS) blocker L-NAME was used to address whether NO was involved in mediating the vasoactive effects of TMPP.

RESULTS

In the TMPP group, TMPP increased the PBF (pancreatic blood flow), IBF (islet blood flow), and fIBF (fraction of islet blood flow out of pancreatic blood flow) by 57, 76 and 47%, respectively, after 30% glucose infusion, compared with the control, indicating that TMPP could regulate islet microcirculation. Furthermore, TMPP induced a 66% elevation of IBF and 37% of fIBF in the 30% glucose subgroups than the 15% ones. In 30% glucose-treated subgroups, TMPP improved the blood glucose concentration by 10%, compared with the control (19.3 ± 0.64 vs 17.32 ± 0.56 mmol/l, P < 0.05), without influencing the insulin secretion. Blocking NO formation prevented the enhanced PBF and IBF, evoking by TMPP with 30% glucose.

CONCLUSIONS

TMPP can regulate the pancreatic islet microcirculation and possess a hypoglycemia effect after glucose infusion through affecting the islet microcirculation.

Tetramethylpyrazine nitrone activates the BDNF/Akt/CREB pathway to promote post-ischaemic neuroregeneration and recovery of neurological functions in rats

BACKGROUND AND PURPOSE

Neuronal regeneration from endogenous precursors is an attractive strategy for the treatment of ischaemic stroke. However, most stroke-generated newborn neurons die over time. Therefore, a drug that is both neuroprotective and pro-neurogenic may be beneficial after stroke. Here, we assessed the neurogenic and oligodendrogenic effects of tetramethylpyrazine nitrone (TBN), a neuroprotective drug candidate for stroke, in a rat model of ischaemic stroke.

EXPERIMENTAL APPROACH

We used Sprague Dawley rats with middle cerebral artery occlusion (MCAO). TBN was administered by tail vein injection beginning at 3 h post ischaemia. Therapeutic effect of TBN was evaluated by neurological behaviour and cerebral infarction. Promotion of neurogenesis and oligodendrogenesis was determined by double immunofluorescent staining and Western blotting analyses. Primary cultures of cortical neurons were used to assess the effect of TBN on neuronal differentiation in vitro.

KEY RESULTS

TBN reduced cerebral infarction, preserved and/or restored neurological function and promoted neurogenesis and oligodendrogenesis in rats after MCAO. In addition, TBN stimulated neuronal differentiation on primary culture of cortical neurons in vitro. Pro-neurogenic effects of TBN were attributed to its activation of the AKT/cAMP responsive element-binding protein through increasing brain-derived neurotrophic factor (BDNF) expression, as shown by the abolition of the effects of TBN by a specific inhibitor of BDNF receptor ANA-12 and by the PI3K inhibitor LY294002.

CONCLUSION AND IMPLICATIONS

As TBN can simultaneously provide neuroprotection and pro-neurogenic effects, it may be a promising treatment for both acute phase neuroprotection and long-term functional recovery after ischaemic stroke.

Quinolinyl Nitrone RP19 Induces Neuroprotection after Transient Brain Ischemia

There is a need to develop additional effective therapies for ischemic stroke. Nitrones, which were first developed as reactive oxygen species (ROS)-trapping compounds, have been proposed as neuroprotective agents for ischemic stroke, a ROS-related disorder. The previous reported ROS-trapping compound, quinolyl nitrone RP19, is here being assayed to induce neuroprotection to ischemia-reperfusion injury in three experimental ischemia models: (i) oxygen-glucose deprivation (OGD) on primary neuronal cultures; (ii) transient global cerebral ischemia in four-vessel occlusion model; and (iii) transient focal cerebral ischemia in middle cerebral artery occlusion (tMCAO) model. RP19 (50 μM) induced long-term neuroprotection at 5 days of recovery after OGD in primary neuronal cultures, evaluated by cell viability assay, and decreased both ROS formation and lipid peroxidation upon recovery after OGD. Furthermore, treatment of animals with RP19 at the onset of reperfusion after either global or focal ischemia, at the dose range that was demonstrated to be neuroprotective in neuronal cultures, decreased neuronal death and apoptosis induction, reduced the size of infarct, and improved the neurological deficit scores after 48 h or 5 days of reperfusion after ischemia. The molecule proposed, quinolyl nitrone RP19, induced substantial neuroprotection on experimental ischemia in neuronal cells, and against ischemic injury following transient brain ischemia in treated animals. This molecule may have potential therapeutic interest in ischemic stroke and to reduce the reoxygenation-induced injury after induced reperfusion.

Tetramethylpyrazine reduces blood-brain barrier permeability associated with enhancement of peripheral cholinergic anti-inflammatory effects for treating traumatic brain injury

Traumatic brain injury (TBI) is a diverse group of intracranial injuries resulting from external mechanical insults to the brain. While basic and clinical research for TBI has been conducted for decades, it has not identified cost-effective medical interventions for treating TBI. Tetramethylpyrazine (TMP), which is derived from the Chinese herb, Ligusticum chuanxiong Hort (Chuan Xiong), has been clinically used for treating ischemic brain injury for years. However, whether TMP could provide effective benefits for improving the outcomes following TBI is unknown. In the present study, using controlled cortical impact (CCI) injury to create an animal model of TBI, the potential effects of TMP on improving blood-brain barrier (BBB) permeability in the early phase of the secondary injury, as well as the splenic anti-inflammatory activities, were evaluated. Cognitive functions were also assessed by Morris water maze trials following TBI. Results demonstrated that, at 24 h after CCI injury, BBB permeability was significantly reduced (P<0.05) by the application of TMP. In addition, within 24 h after CCI injury, the plasma levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α, and protein and mRNA expression levels of IL-1β and TNF-α in the spleen were significantly lowered by TMP (P<0.05). Furthermore, within 24 h after CCI injury, the activation of the splenic anti-inflammatory effects mediated by nicotinic acetylcholine receptor α7 (nAChRa7) stimulation were significantly enhanced by TMP (P<0.05). Additionally, impaired spatial memory acquisition and consolidation were significantly improved by TMP after CCI injury (P<0.05). Together, in light of these data, in the treatment of TBI, TMP could effectively reduce BBB permeability, which may be closely associated with the enhanced splenic anti-inflammatory effects activated by nAChRa7 stimulation, and potentially improve cognitive recovery concerning spatial learning and memory.

A Novel Danshensu-Tetramethylpyrazine Conjugate DT-010 Provides Cardioprotection through the PGC-1α/Nrf2/HO-1 Pathway

In this study, we investigated the cardioprotective mechanisms of action of DT-010, a novel danshensu-tetramethylpyrazine conjugate. DT-010 significantly preserved cell viability and suppressed cell apoptosis in H9c2 cells injured by tert-butylhydroperoxide (t-BHP), iodoacetic acid (IAA) and hypoxia-reoxygenation. In addition, DT-010 pre-treatment reduced the intracellular level of free radicals including superoxide anion (·O₂^-), hydroxyl radical (·OH) and peroxynitrite anion (ONOO^-) after t-BHP exposure. Moreover, DT-010 up-regulated the protein expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) and nuclear factor-E2-related factor 2 (Nrf2) as well as mitochondrial transcription factor A (Tfam) and heme oxygenase-1 (HO-1) in H9c2 cells. DT-010 also triggered Nrf2 nuclear translocation. In a rat myocardial ischemia-reperfusion model, DT-010 significantly alleviated myocardial infarction. The results indicated that DT-010 may be a promising candidate for the treatment of cardiovascular diseases, particularly myocardial ischemia and reperfusion injury.

Synthesis and protective effect of new ligustrazine-vanillic acid derivatives against CoCl2-induced neurotoxicity in differentiated PC12 cells

Ligustrazine-vanillic acid derivatives had been reported to exhibit promising neuroprotective activities. In our continuous effort to develop new ligustrazine derivatives with neuroprotective effects, we attempted the synthesis of several ligustrazine-vanillic acid amide derivatives and screened their protective effect on the injured PC12 cells damaged by CoCl₂. The results showed that most of the newly synthesized derivatives exhibited higher activity than ligustrazine, of which, compound VA-06 displayed the highest potency with EC₅₀ values of 17.39 ± 1.34 μM. Structure-activity relationships were briefly discussed.Graphical abstractNew series of ligustrazine-vanillic acid amide derivatives were synthesized and evaluated for their protective effect on the injured PC₁₂ cells damaged by CoCl₂. VA-06 was found to be the most active one.

Vascular Contributions to Cognitive Impairment and Treatments with Traditional Chinese Medicine

The prevalence of cognitive impairment and dementia caused by cerebrovascular disease is likely to increase with the global aging population. Vascular contributions to cognitive impairment and dementia (VCID) is a wide spectrum term used to include a diverse heterogeneous group of cognitive syndromes with vascular factors regardless of the cause of pathogenesis. VCID ranges from mild cognitive impairment to full-blown dementia with vascular dementia (VaD) as the most severe stage. It is further complexed by the coexistence of other forms of dementia such as Alzheimer's disease (AD). Recent researches in the functions of the neurovascular unit (NVU) suggest that dysfunction of the NVU might be the cause of primary vascular events in the brain that leads to further neurodegeneration. In this review, we have briefly summarized various forms of VCID. There is currently no standard therapy for VCID or dementia. Given the fact that Traditional Chinese Medicine (TCM) has gained popularity worldwide, we also reviewed recent scientific and clinical findings on various antidementia TCM for the treatment of VCID, including Salvia miltiorrhiza, Huperzia serrata, Ligusticum chuanxiong, Ginkgo biloba, Panax ginseng, and also TCM formula Sailuotong capsule (SLT) and Fufangdanshen tablets (FFDS).

Tetramethylpyrazine nitrone, a multifunctional neuroprotective agent for ischemic stroke therapy

TBN, a novel tetramethylpyrazine derivative armed with a powerful free radical-scavenging nitrone moiety, has been reported to reduce cerebral infarction in rats through multi-functional mechanisms of action. Here we study the therapeutic effects of TBN on non-human primate model of stroke. Thirty male Cynomolgus macaques were subjected to stroke with 4 hours ischemia and then reperfusion. TBN were injected intravenously at 3 or 6 hours after the onset of ischemia. Cerebral infarction was examined by magnetic resonance imaging at 1 and 4 weeks post ischemia. Neurological severity scores were evaluated during 4 weeks observation. At the end of experiment, protein markers associated with the stroke injury and TBN treatment were screened by quantitative proteomics. We found that TBN readily penetrated the blood brain barrier and reached effective therapeutic concentration after intravenous administration. It significantly reduced brain infarction and modestly preserved the neurological function of stroke-affected arm. TBN suppressed over-expression of neuroinflammatory marker vimentin and decreased the numbers of GFAP-positive cells, while reversed down-regulation of myelination-associated protein 2', 3'-cyclic-nucleotide 3'-phosphodiesterase and increased the numbers of NeuN-positive cells in the ipsilateral peri-infarct area. TBN may serve as a promising new clinical candidate for the treatment of ischemic stroke.

Design, Synthesis, and Biological Evaluation of Novel Tetramethylpyrazine Derivatives as Potential Neuroprotective Agents

Oxidative stress plays a crucial role in neurological diseases, resulting in excessive production of reactive oxygen species, mitochondrial dysfunction and cell death. In this work, we designed and synthesized a series of tetramethylpyrazine (TMP) derivatives and investigated their abilities for scavenging free radicals and preventing against oxidative stress-induced neuronal damage in vitro. Among them, compound 22a, consisted of TMP, caffeic acid and a nitrone group, showed potent radical-scavenging activity. Compound 22a had broad neuroprotective effects, including rescuing iodoacetic acid-induced neuronal loss, preventing from tert-butylhydroperoxide (t-BHP)-induced neuronal injury. Compound 22a exerted its neuroprotective effect against t-BHP injury via activation of the phosphatidyl inositol 3-kinase (PI3K)/Akt signaling pathway. Furthermore, in a rat model of permanent middle cerebral artery occlusion, compound 22a significantly improved neurological deficits, and alleviated the infarct area and brain edema. In conclusion, our results suggest that compound 22a could be a potential neuroprotective agent for the treatment of neurological disease, particularly ischemic stroke.

Ligustrazine monomer against cerebral ischemia/reperfusion injury

Ligustrazine (2,3,5,6-tetramethylpyrazine) is a major active ingredient of the Szechwan lovage rhizome and is extensively used in treatment of ischemic cerebrovascular disease. The mechanism of action of ligustrazine use against ischemic cerebrovascular diseases remains unclear at present. This study summarizes its protective effect, the optimum time window of administration, and the most effective mode of administration for clinical treatment of cerebral ischemia/reperfusion injury. We examine the effects of ligustrazine on suppressing excitatory amino acid release, promoting migration, differentiation and proliferation of endogenous neural stem cells. We also looked at its effects on angiogenesis and how it inhibits thrombosis, the inflammatory response, and apoptosis after cerebral ischemia. We consider that ligustrazine gives noticeable protection from cerebral ischemia/reperfusion injury. The time window of ligustrazine administration is limited. The protective effect and time window of a series of derivative monomers of ligustrazine such as 2-[(1,1-dimethylethyl)oxidoimino]methyl]-3,5,6-trimethylpyrazine, CXC137 and CXC195 after cerebral ischemia were better than ligustrazine.

Attenuation of Streptomycin Ototoxicity by Tetramethylpyrazine in Guinea Pig Cochlea

Objective

Tetramethylpyrazine has been suggested to have a therapeutic effect on impaired hearing that is induced by aminoglycoside antibiotics. However, its effectiveness on streptomycin ototoxicity and its cellular mechanisms are relatively unknown. Here we investigate the protective effect of tetramethylpyrazine on streptomycin-induced ototoxicity in guinea pig cochlea.

Study Design

Prospective randomized laboratory study.

Setting

Hearing Research Laboratory of China Medical University.

Subjects and Methods

Adult guinea pigs were randomized to 4 groups. Hearing sensitivity of guinea pigs was tested by auditory brainstem response measurements before streptomycin exposure and again 10 days later. The cochlear tissues were prepared for electron microscopy and immunohistochemical staining of heat shock protein 70 (HSP70). The effect of tetramethylpyrazine on streptomycin-induced activation of caspase-3 was evaluated by Western blotting.

Results

Co-therapy with tetramethylpyrazine reduced a profound streptomycin-induced auditory threshold shift compared with streptomycin treatment alone ( P = .0002 or P = .00008). Tetramethylpyrazine also attenuated the structural disruption in streptomycin-treated outer hair cells and marginal cells of vascular stria by transmission electronic microscopy and scanning electronic microscopy, respectively. Moreover, tetramethylpyrazine decreased the streptomycin-stimulated expressions of HSP70 and caspase-3. The correlation analysis demonstrated that HSP70 expression had a positive correlation with auditory brainstem response thresholds (|R| = 0.6-0.9, P = .0073 or P = .0169).

Conclusions

Our data suggest that the protective effect of tetramethylpyrazine on hearing function is associated with the reduction of stress response and inhibition of apoptosis. Tetramethylpyrazine may have therapeutic potential for patients with ototoxicity diseases.

The combination of astragalus membranaceus and ligustrazine ameliorates micro-haemorrhage by maintaining blood-brain barrier integrity in cerebrally ischaemic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Haemorrhagic transformation is an asymptomatic event that frequently occurs after following ischaemic stroke, particularly when pharmaceutical thrombolysis is used. However, the mechanism responsible for haemorrhagic transformation remains unknown, and therapeutics have not been identified. In this study, we administered a combination of astragalus membranaceus and ligustrazine to rats with cerebral ischaemia that had undergone thrombolysis. We analysed the effect of this combination on the attenuation of haemorrhagic transformation and the maintenance of blood-brain barrier integrity.

METHODS

A rat model of focal cerebral ischaemia was induced with autologous blood clot injections. Thrombolysis was performed via the intravenous injection of rt-PA. Astragalus membranaceus, ligustrazine or a combination of Astragalus membranaceus and ligustrazine was administered immediately after the clot injection. The cerebral infarct area, neurological deficits, blood-brain barrier integrity, and cerebral haemorrhage status were determined after 3, 6 and 24h of ischaemia. The ultrastructure of the blood-brain barrier was examined with a transmission electron microscope. The expression of tight junction proteins, including claudin-1, claudin-5, occludin, and zonula occludens-1, and matrix metallopeptidase-9 activation was further evaluated in terms of their roles in the protective effects of the combination drug on the integrity of the blood-brain barrier.

RESULTS

Ischaemia-induced Evans blue leakage and cerebral haemorrhage were markedly reduced in the combination drug-treated rats compared to the rats treated with either astragalus membranaceus or ligustrazine alone (p<0.05). The disruption of the ultrastructure of the blood-brain barrier and the neurological deficits were ameliorated by the combination treatment (p<0.05). The reductions in the expression of laudin-1, claudin-5, occludin, and ZO-1 were smaller in the rats that received the combination treatment. In addition, MMP-9 activity was suppressed in the combination-treated rats compared to the controls (p<0.05).

CONCLUSIONS

Treatment with a combination of astragalus membranaceus and ligustrazine alleviated ischaemia-induced micro-haemorrhage transformation by maintaining the integrity of the blood-brain barrier.

The novel tetramethylpyrazine bis-nitrone (TN-2) protects against MPTP/MPP+-induced neurotoxicity via inhibition of mitochondrial-dependent apoptosis

Mitochondrial-dependent apoptosis plays an important role in the degeneration of dopaminergic neurons in Parkinson's disease (PD). Methyl-4-phenyl-1,2,3,6-tetra- hydropyridine (MPTP), the most widely used neurotoxin to simulate PD, is converted to 1-methyl-4-phenylpyridinium (MPP(+)) in vivo. MPP(+) induces excessive intracellular reactive oxygen species (ROS), leading to mitochondrial-dependent apoptosis via sequentially opening mitochondria permeability transition pore (mPTP) to release cytochrome c from mitochondria into cytoplasm and activate pro-apoptotic caspase proteins. We have previously synthesized 2,5-[[(1,1-dimethylethyl)oxidoimino]methyl]-3,6-trimethylpyrazine (TN-2), a novel derivative of the Chinese herb medicine tetramethylpyrazine (TMP). TN-2 is armed with two powerful free radical-scavenging nitrone moieties. TN-2 significantly reversed the loss of dopaminergic neurons in the substantia nigra and the decrease in dopamine level in the striatum induced by MPTP in mice. TN-2 ameliorated the MPTP-induced decrease of brain superoxide dismutase activity and glutathione concentration and increase of brain malondialdehyde. In addition, TN-2 inhibited MPP(+)-induced neuronal damage/apoptosis in primary cerebellum granular neurons (CGNs) and SH-SY5Y cells. TN-2 decreased excessive intracellular ROS, prevented the loss of mitochondrial membrane potential, blocked the release of mitochondrial cytochrome c and inhibited the activation of caspase-3 and caspase-9. Moreover, TN-2 treatment increased the mRNA expression of mitochondrial biogenesis factors peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1 (PGC- 1α and β) and mitochondrial transcription factor A (Tfam) in SH-SY5Y cells and CGNs. These results suggest that TN-2 protects dopaminergic neurons against MPTP/MPP(+)-induced neurotoxicity via the inhibition of mitochondrial-dependent apoptosis and possibly via the activation of mitochondrial biogenesis, indicating that TN-2 is a potential new treatment for PD.

Tetramethylpyrazine, a natural alkaloid, attenuates pro-inflammatory mediators induced by amyloid β and interferon-γ in rat brain microglia

Neuroinflammation has been consistently reported as a pathological hallmark of Alzheimer׳s disease and other neurodegenerative diseases. Microglial cells are activated by diverse pathological stimuli and play key roles in development of neuroinflammation. Amyloid β peptide (Aβ), the major constituent of amyloid plaques in Alzheimer׳s brain, is known to activate cultured microglial cells to produce increased amounts of proinflammatory and neurotoxic factors. Tetramethylpyrazine (TMP) is the main bioactive alkaloid isolated from Ligusticum chuanxiong. TMP has multiple pharmacological activities, including anti-oxidant, anti-inflammatory, and anti-cancer effects. Neuroprotective potential of TMP has been demonstrated in animal models of neuropathologies. However, the efficacy of this compound for controlling Aβ-related neuropathology has not been explored yet. We examined the efficacy of TMP in the repression of inflammatory response in cultured microglial cells stimulated with Aβ25-35 in the presence of interferon (IFN)-γ. TMP significantly inhibited the Aβ25-35 and IFN-γ-stimulated productions of nitric oxide, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, monocyte chemoattractant protein-1, and intracellular reactive oxygen species from primary microglial cells. TMP also effectively reduced Aβ25-35 and IFN-γ-elicited NF-κB activation. In organotypic hippocampal slice cultures (OHSCs), TMP significantly blocked Aβ25-35-induced reactive oxygen species generation and phosphorylation of Akt. Furthermore, TMP also inhibited Aβ1-42-induced TNF-α and IL-1β production in primary microglial cells and neuronal death in OHSCs. These results suggest that TMP provide a possible therapeutic approach for alleviating the inflammatory progression of Alzheimer׳s disease.

Tetramethylpyrazine promotes the proliferation and migration of brain endothelial cells

The aim of the present study was to investigate the role of tetramethylpyrazine (TMP), one of the alkaloids isolated from the Chinese herb Chuanxiong, on the proliferation and migration of brain endothelial cells. A different dosage of TMP was employed to stimulate the mouse microvascular cell line bEnd.3 in vitro. TMP at lower concentrations (0.25 ng/ml), however not at high concentrations (100 ng/ml) could promote the proliferation and migration of endothelial cells, which was further enhanced if combined with soluble Fas ligand (sFasL). TMP alone, or combined with sFasL, increased the autocrine signaling of vascular endothelial growth factor (VEGF) by endothelial cells and TMP improved the expression of Fas on endothelial cells, which may explain the effect of the sFasL. These results provide insight into the underlying mechanisms of the effects of TMP on stroke and other vascular diseases.

Herbal medicines for ischemic stroke: combating inflammation as therapeutic targets

Stroke is a debilitating disease for which limited therapeutic approaches are available currently. Thus, there is an urgent need for developing novel therapies for stroke. Astrocytes, endothelial cells and pericytes constitute a neurovascular network for metabolic requirement of neurons. During ischemic stroke, these cells contribute to post-ischemic inflammation at multiple stages of ischemic cascades. Upon ischemia onset, activated resident microglia and astrocytes, and infiltrated immune cells release multiple inflammation factors including cytokines, chemokines, enzymes, free radicals and other small molecules, not only inducing brain damage but affecting brain repair. Recent progress indicates that anti-inflammation is an important therapeutic strategy for stroke. Given a long history with direct experience in the treatment of human subjects, Traditional Chinese Medicine and its related natural compounds are recognized as important sources for drug discovery. Last decade, a great progress has been made to identify active compounds from herbal medicines with the properties of modulating post-ischemic inflammation for neuroprotection. Herein, we discuss the inflammatory pathway in early stage and secondary response to injured tissues after stroke from initial artery occlusion to brain repair, and review the active ingredients from natural products with anti-inflammation and neuroprotection effects as therapeutic agents for ischemic stroke. Further studies on the post-ischemic inflammatory mechanisms and corresponding drug candidates from herbal medicine may lead to the development of novel therapeutic strategies in stroke treatment.

Neuroprotection in stroke: past, present, and future

Stroke is a devastating medical condition, killing millions of people each year and causing serious injury to many more. Despite advances in treatment, there is still little that can be done to prevent stroke-related brain damage. The concept of neuroprotection is a source of considerable interest in the search for novel therapies that have the potential to preserve brain tissue and improve overall outcome. Key points of intervention have been identified in many of the processes that are the source of damage to the brain after stroke, and numerous treatment strategies designed to exploit them have been developed. In this review, potential targets of neuroprotection in stroke are discussed, as well as the various treatments that have been targeted against them. In addition, a summary of recent progress in clinical trials of neuroprotective agents in stroke is provided.

Intravenous administration of tetramethylpyrazine reduces intestinal ischemia-reperfusion injury in rats

Intestinal ischemia-reperfusion injury (IIRI) is a life-threatening condition requiring prompt medical intervention. Tetramethylpyrazine (TMP) is a biologically active alkaloid isolated from Ligusticum wallichii. Previously, it was shown that TMP causes vasodilatation and inhibition of platelet aggregation as well as exhibits significant antioxidant effects. Therefore, the aim of the present study was to evaluate possible therapeutic effects of TMP in the prevention of IIRI. Wistar rats (n = 80) were randomly divided into eight experimental groups and subjected to a 1 h occlusion of cranial mesenteric artery followed by 0, 1, 12, and 24 h period of reperfusion. Thirty minutes before the IIRI animals received either TMP (30 mg/kg, i.v.) or identical volume of saline. In addition, a control group of 10 animals was not exposed to IIRI. Intestine morphology was evaluated by using histopathological injury index examination (HII), goblet and Paneth cells quantification as well as by applying immunofluorescent methods such as InSitu TUNEL and caspase-3 positivity assessment. Here we showed that preconditioning with TMP prior IIRI decreases the grade of injury. Significant reduction of HII was detected in TMP pretreated groups after 0, 1, and 12 h of reperfusion where injury reduction up to 75% was found. Lower histopathological damage in preconditioned groups was accompanied with increased number of secretory epithelial cells and decreased number of apoptotic cells. These results demonstrate the protective effect of TMP on the small intestine mucosa, suggesting administration of TMP as a molecule for pharmacological intervention against IIRI.