Mechanisms and Clinical Application of Tetramethylpyrazine (an Interesting Natural Compound Isolated from Ligusticum Wallichii): Current Status and Perspective

Mercapto-functionalized palygorskite modified the growth of Ligusticum Chuanxiong and restrained the Cd migration in the soil-plant system

Ligusticum Chuanxiong is an essential medicinal and edible plant, but it is highly susceptible to the enrichment of soil Cadmium (Cd), which seriously affects its medical safety. However, the control of Cd uptake by Ligusticum Chuanxiong is little reported. In this study, we reported that a green Mercapto-functionalized palygorskite (MPAL) effectively promoted Ligusticum Chuanxiong growth, and restrained the Cd uptake by Ligusticum Chuanxiong both in the mildly contaminated soil (M-Soil) and severely contaminated soil (S-Soil). The experimental results demonstrated that the application of MPAL significantly increased the biomass and antioxidant enzyme activity of Ligusticum Chuanxiong. In the M-Soil, the Cd content in the roots, stems, and leaves of Ligusticum Chuanxiong decreased markedly by 82.46-86.66%, 64.17-71.73%, and 64.94-76.66%, respectively, after the MPAL treatment. In the S-Soil, MPAL application decreased the Cd content in roots, stems, and leaves by 89.43-98.92%, 24.19-86.22%, and 67.14-77.90%, respectively. Based on Diethylenetriamine Pentaacetic Acid (DTPA) extraction, the immobilization efficiency of MPAL for Cd in soils ranged from 22.01% to 77.04%. Additionally, the HOAc extractable Cd was transformed into reducible and oxidizable fractions. Furthermore, MPAL enhanced the activities of soil alkaline phosphatase, and urease, but decreased sucrase activity. Environmental toxicological analysis indicated that MPAL reduced the potential ecological risk of Cd in the soil. These findings revealed that MPAL can effectively reduce Cd accumulation in Ligusticum Chuanxiong and promote plant growth, suggesting its potential as a viable amendment for remediating Cd-contaminated soils.

Attenuation of biofilm and virulence factors of Pseudomonas aeruginosa by tetramethylpyrazine-gold nanoparticles

Pseudomonas aeruginosa is often identified as the causative agent in nosocomial infections. Their adapted resistance makes them strong towards antimicrobial treatments. They protect and empower their survival behind strong biofilm architecture that works as their armor toward antimicrobial therapy. Additionally, P. aeruginosa generates virulence factors, contributing to chronic infection and recalcitrant phenotypic characteristics. The current study utilizes the benevolence of nanotechnology to develop an alternate technique to control the spreading of P. aeruginosa by limiting its biofilm and virulence development. This study used a natural compound, tetramethylpyrazine, to generate gold nanoparticles. Tetramethylpyrazine-gold nanoparticles (Tet-AuNPs) were presented in spherical shapes, with an average size of 168 ± 52.49 nm and a zeta potential of -12.22 ± 2.06 mV. The minimum inhibition concentration (MIC) of Tet-AuNPs that proved more than 90 % effective in inhibiting P. aeruginosa was 256 μg/mL. Additionally, it also shows antibacterial activities against Staphylococcus aureus (MIC, 256 μg/mL), Streptococcus mutans (MIC, 128 μg/mL), Klebsiella pneumoniae (MIC, 128 μg/mL), Listeria monocytogenes (MIC, 256 μg/mL), and Escherichia coli (MIC, 256 μg/mL). The sub-MIC values of Tet-AuNPs significantly inhibited the early-stage biofilm formation of P. aeruginosa. Moreover, this concentration strongly affected hemolysis, protease activity, and different forms of motilities in P. aeruginosa. Additionally, Tet-AuNPs destroyed the well-established mature biofilm of P. aeruginosa. The expression of genes linked with the biofilm formation and virulence in P. aeruginosa treated with sub-MIC doses of Tet-AuNPs was shown to be significantly suppressed. Gene expression studies support biofilm- and virulence-suppressing effects of Tet-AuNPs at the phenotypic level.

Cocrystallization improves the tabletability of ligustrazine despite a reduction in plasticity

Cocrystallization is an effective method for altering the tableting performance of crystals by modifying their mechanical properties. In this study, cocrystals of ligustrazine (LIG) with malonic acid (MA) and salicylic acid (SA) were investigated to better understand how modifying crystal structure can affect tableting properties. LIG suffered from overcompression at high pressures despite its high plasticity. Both LIG-MA and LIG-SA displayed lower plasticity than LIG, which was confirmed by both an in-die Heckel and energy framework analyses. The LIG-MA cocrystal displayed slightly worse tabletability than LIG, as expected from its lower plasticity. However, LIG-SA surprisingly showed improved tabletability despite its lower plasticity. This was explained by the higher bonding strength of LIG-SA compared with LIG. This work not only provided new examples of tabletability modulation through crystal engineering but also highlighted the risk of failed tabletability predictions based on plasticity alone. Instead, more reliable tabletability predictions of different crystal forms must consider the bonding area - bonding strength interplay.

Targeted reversal of multidrug resistance in ovarian cancer cells using exosome‑encapsulated tetramethylpyrazine

The objective of the present study was to develop exosomes (EXOs) encapsulating tetramethylpyrazine (TMP) for the reversal of drug resistance in ovarian cancer therapy. Human A2780 cells were incubated with TMP for 48 h. Purified TMP‑primed EXOs (EXOs‑TMP) were isolated through ultracentrifugation. The developed EXOs‑TMP were characterized using techniques such as transmission electron microscopy, nanoparticle tracking analysis, Fluorescence microscopy and western blotting. Subsequently, MTT, western blotting and flow cytometry assays were performed to evaluate the biological effects in drug‑resistant A2780T cells. The results demonstrated that the incorporation of TMP into EXOs exhibited an anti‑ovarian cancer effect and markedly enhanced the antitumor efficacy of paclitaxel (PTX). Furthermore, it was identified that the ability of EXO‑TMP to reverse cell resistance was associated with the downregulation of multidrug resistance protein 1, multidrug resistant‑associated protein 1 and glutathione S‑transferase Pi protein expression. Flow cytometry analysis revealed that EXO‑TMP induced apoptosis in drug‑resistant cells and enhanced the apoptotic effect when combined with PTX. EXOs are naturally sourced, exhibit excellent biocompatibility and enable precise drug delivery to target sites, thereby reducing toxic side effects. Overall, EXO‑TMP exhibited direct targeting capabilities towards A2780T cells and effectively reduced their drug resistance. EXOs‑TMP provide a novel and effective drug delivery pathway for reversing drug resistance in ovarian cancer.

The Role of Various Factors in Neural Differentiation of Human Umbilical Cord Mesenchymal Stem Cells with a Special Focus on the Physical Stimulants

Human umbilical cord matrix-derived mesenchymal stem cells (hUCMs) are considered as ideal tools for cell therapy procedures and regenerative medicine. The capacity of these cells to differentiate into neural lineage cells make them potentially important in the treatment of various neurodegenerative diseases. An electronic search was performed in Web of Science, PubMed/MEDLINE, Scopus and Google Scholar databases for articles published from January 1990 to March 2022. This review discusses the current knowledge on the effect of various factors, including physical, chemical and biological stimuli which play a key role in the differentiation of hUCMs into neural and glial cells. Moreover, the currently understood molecular mechanisms involved in the neural differentiation of hUCMs under various environmental stimuli are reviewed. Various stimuli, especially physical stimuli and specifically different light sources, have revealed effects on neural differentiation of mesenchymal stem cells, including hUCMs; however, due to the lack of information about the exact mechanisms, there is still a need to find optimal conditions to promote the differentiation capacity of these cells which in turn can lead to significant progress in the clinical application of hUCMs for the treatment of neurological disorders.

Tetramethylpyrazine promotes axonal remodeling and modulates microglial polarization via JAK2-STAT1/3 and GSK3-NFκB pathways in ischemic stroke

Ischemic stroke results in demyelination that underlies neurological disfunction. Promoting oligodendrogenesis will rescue the injured axons and accelerate remyelination after stroke. Microglia react to ischemia/hypoxia and polarize to M1/M2 phenotypes influencing myelin injury and repair. Tetramethylpyrazine (TMP) has neuroprotective effects in treating cerebrovascular disorders. This study aims to evaluate whether TMP promotes the renovation of damaged brain tissues especially on remyelination and modulates microglia phenotypes following ischemic stroke. Here magnetic resonance imaging (MRI)-diffusion tensor imaging (DTI) and histopathological evaluation are performed to characterize the process of demyelination and remyelination. Immunofluorescence staining is used to prove oligodendrogenesis and microglial polarization. Western blotting is conducted to examine interleukin (IL)-6, IL-10, transforming growth factor β (TGF-β) and Janus protein tyrosine kinase (JAK) 2-signal transducer and activator of transcription (STAT) 1/3-glycogen synthase kinase (GSK) 3-nuclear transcription factor κB (NFκB) signals. Results show TMP alleviates the injury of axons and myelin sheath, increases NG2+, Ki67+/NG2+, CNPase+, Ki67+/CNPase+, Iba1+/Arg-1+ cells and decreases Iba1+ and Iba1+/CD16+ cells in periinfarctions of rats. Particularly, TMP downregulates IL-6 and upregulates IL-10 and TGF-β expressions, besides, enhances JAK2-STAT3 and suppresses STAT1-GSK3-NFκB activation in middle cerebral artery occlusion (MCAo) rats. Then we demonstrate that TMP reverses M1/M2 phenotype via JAK2-STAT1/3 and GSK3-NFκB pathways in lipopolysaccharide (LPS) plus interferon-γ (IFN-γ)-stimulated BV2 microglia. Blocking JAK2 with AG490 counteracts TMP's facilitation on M2 polarization of microglia. This study warrants the promising therapy for stroke with TMP treatment.

Optimization of Molasses and Soybean Meal Content to Enhance Tetramethylpyrazine Yield by Bacillus sp. TTMP20

Microbial fermentation for the production of tetramethylpyrazine (TTMP) is considered to be the most promising method, and the development of a cheap fermentation substrate is of great importance for large-scale TTMP production. In this study, inexpensive by-products from the food industry, i.e., molasses and soybean meal (instead of glucose and tryptone), were used as substrates for TTMP fermentation. The pretreatment of soybean meal was explored in order to achieve a better fermentation effect. The contents of each component in the fermentation medium were optimized by central composite design (CCD). The optimum contents were as follows: 72.5 g/L of molasses, 37.4 g/L of diammonium hydrogen phosphate (DAP), 53.4 g/L of soybean meal, and 5 g/L of yeast powder. The software predicted a maximum TTMP yield of 1469.03 mg/L, and the actual TTMP yield was 1328.95 mg/L for the validation experiment in the optimum medium. Under the optimum conditions (72.5 g/L of molasses, 37.4 g/L of DAP, 53.4 g/L of soybean meal, and 5 g/L of yeast powder), the actual maximum TTMP yield (1328.95 mg/L) in this study was much higher than the TTMP yield (895.13 mg/L) under the conditions (150 g/L of molasses, 30 g/L of DAP, 30 g/L of tryptone, and 10 g/L of yeast powder) of our previous study published in Molecules. In this study, the TTMP yield improved by 48.46%, with decreased molasses (more than half), decreased yeast powder (half) and by-product soybean meal instead of tryptone compared to our previous study. In summary, the cheaper fermentation medium had a higher TTMP yield in this study, which improves the application potential of Bacillus sp. TTMP20.

Tetramethylpyrazine contributes to the neuroprotection in a rodent epileptic model of pentylenetetrazole-induced kindling

OBJECTIVES

In this study, tetramethylpyrazine (TMP) was evaluated for its therapeutic potential as an alternative therapy for epileptogenesis and its associated comorbidities in rats.

METHODS

The sub-convulsant dose of pentylenetetrazole (PTZ) (35 mg/kg, intraperitoneally) was injected on alternative days to produce kindling for 32 days and observed for seizure score percent of kindled animals in each group. After kindling, the animals were evaluated in models of anxiety, memory and predictive of depression. The neuroprotective effect of TMP was assessed by estimating the biochemical parameters in the cortex and hippocampus of the brain. Histopathological alterations were also observed in the cortex and hippocampus (CA1, CA3 and DG).

KEY FINDINGS

The administration of TMP reduced the seizure score and percentage of kindled animals dose-dependently. Furthermore, TMP significantly improved the behavioural parameters measured in the predictive models of depression but not in the anxiety and cognitive performances of the animals. The oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations in the brain induced by PTZ were significantly mitigated by administering the TMP high dose of 60 mg/kg.

CONCLUSION

In conclusion, the TMP attenuated the depression behaviour in the PTZ-induced kindled rats, and reduced the oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations of the brain.

HMGB1-induced activation of ER stress contributes to pulmonary artery hypertension in vitro and in vivo

BACKGROUND

HMGB1 and ER stress have been considered to participate in the progression of pulmonary artery hypertension (PAH). However, the molecular mechanism underlying HMGB1 and ER stress in PAH remains unclear. This study aims to explore whether HMGB1 induces pulmonary artery smooth muscle cells (PASMCs) functions and pulmonary artery remodeling through ER stress activation.

METHODS

Primary cultured PASMCs and monocrotaline (MCT)-induced PAH rats were applied in this study. Cell proliferation and migration were determined by CCK-8, EdU and transwell assay. Western blotting was conducted to detect the protein levels of protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor-4 (ATF4), seven in absentia homolog 2 (SIAH2) and homeodomain interacting protein kinase 2 (HIPK2). Hemodynamic measurements, immunohistochemistry staining, hematoxylin and eosin staining were used to evaluate the development of PAH. The ultrastructure of ER was observed by transmission electron microscopy.

RESULTS

In primary cultured PASMCs, HMGB1 reduced HIPK2 expression through upregulation of ER stress-related proteins (PERK and ATF4) and subsequently increased SIAH2 expression, which ultimately led to PASMC proliferation and migration. In MCT-induced PAH rats, interfering with HMGB1 by glycyrrhizin, suppression of ER stress by 4-phenylbutyric acid or targeting SIAH2 by vitamin K3 attenuated the development of PAH. Additionally, tetramethylpyrazine (TMP), as a component of traditional Chinese herbal medicine, reversed hemodynamic deterioration and vascular remodeling by targeting PERK/ATF4/SIAH2/HIPK2 axis.

CONCLUSIONS

The present study provides a novel insight to understand the pathogenesis of PAH and suggests that targeting HMGB1/PERK/ATF4/SIAH2/HIPK2 cascade might have potential therapeutic value for the prevention and treatment of PAH.

Potential therapeutic effects of Chinese meteria medica in mitigating drug-induced acute kidney injury

Drug-induced acute kidney injury (DI-AKI) is one of the leading causes of kidney injury, is associated with high mortality and morbidity, and limits the clinical use of certain therapeutic or diagnostic agents, such as antineoplastic drugs, antibiotics, immunosuppressants, non-steroidal anti-inflammatory drugs, and contrast media. In recent years, numerous studies have shown that many Chinese meteria medica, metabolites derived from botanical drugs, and Chinese medicinal formulas confer protective effects against DI-AKI by targeting a variety of cellular or molecular mechanisms, such as oxidative stress, inflammatory, cell necrosis, apoptosis, and autophagy. This review summarizes the research status of common DI-AKI with Chinese meteria medica interventions, including cisplatin, gentamicin, contrast agents, methotrexate, and acetaminophen. At the same time, this review introduces the metabolites with application prospects represented by ginseng saponins, tetramethylpyrazine, panax notoginseng saponins, and curcumin. Overall, this review provides a reference for the development of promising nephroprotectants.

An ongoing journey of chalcone analogues as single and multi-target ligands in the field of Alzheimer's disease: A review with structural aspects

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disorder with progressive dementia and cognitive impairment. AD poses severe health challenge in elderly people and become one of the leading causes of death worldwide. It possesses complex pathophysiology with several hypotheses (cholinergic hypothesis, amyloid hypothesis, tau hypothesis, oxidative stress, mitochondrial dysfunction etc.). Several attempts have been made for the management of multifactorial AD. Acetylcholinesterase is the only target has been widely explored in the management of AD to the date. The current review set forth the chalcone based natural, semi-synthetic and synthetic compounds in the search of potential anti-Alzheimer's agents. The main highlights of current review emphasizes on chalcone target different enzymes and pathways like Acetylcholinesterase, β-secretase (BACE1), tau proteins, MAO, free radicals, Advanced glycation end Products (AGEs) etc. and their structure activity relationships contributing in the inhibition of above mentioned various targets of AD.

Tetramethylpyrazine Attenuates Oxygen-glucose Deprivation-induced Neuronal Damage through Inhibition of the HIF-1α/BNIP3 Pathway: From Network Pharmacological Finding to Experimental Validation

AIMS

A network pharmacological analysis combined with experimental validation was used to investigate the neuroprotective mechanism of the natural product Tetramethylpyrazine(TMP).

BACKGROUND

Protecting neurons is critical for acute ischemic stroke treatment. Tetramethylpyrazine is a bioactive component extracted from Chuanxiong. The neuroprotective potential of TMP has been reported, but a systematic analysis of its mechanism has not been performed.

OBJECTIVE

Based on the hints of network pharmacology and bioinformatics analysis, the mechanism by which TMP alleviates oxygen-glucose deprivation-induced neuronal damage through inhibition of the HIF-1α/BNIP3 pathway was verified.

METHOD

In this study, we initially used network pharmacology and bioinformatics analyses to elucidate the mechanisms involved in TMP's predictive targets on a system level. The HIF-1α/BNIP3 pathway mediating the cellular response to hypoxia and apoptosis was considered worthy of focus in the bioinformatic analysis. An oxygen-glucose deprivation (OGD)-induced PC12 cell injury model was established for functional and mechanical validation. Cell viability, lactate dehydrogenase leakage, intracellular reactive oxygen species, percentage of apoptotic cells, and Caspase-3 activity were determined to assess the TMP's protective effects. Transfection with siRNA/HIF-1α or pcDNA/HIF-1α plasmids to silence or overexpress hypoxia-inducible factor 1α(HIF-1α). The role of HIF-1α in OGD-injured cells was observed first. After that, TMP's regulation of the HIF-1α/BNIP3 pathway was investigated. The pcDNA3.1/HIF-1α-positive plasmids were applied in rescue experiments.

RESULT

The results showed that TMP dose-dependently attenuated OGD-induced cell injury. The expression levels of HIF-1α, BNIP3, and the Bax/Bcl-2 increased significantly with increasing OGD duration. Overexpression of HIF-1α decreased cell viability, increased BNIP3 expression, and Bax/Bcl-2 ratio; siRNA-HIF-1α showed the opposite effect. TMP treatment suppressed HIF-1α, BNIP3 expression, and the Bax/Bcl-2 ratio and was reversed by HIF-1α overexpression.

CONCLUSION

Our study shows that TMP protects OGD-damaged PC12 cells by inhibiting the HIF-1α/BNIP3 pathway, which provides new insights into the mechanism of TMP and its neuroprotective potential.

Ligustrazine mitigates chronic venous disease-induced pain hyperalgesia through desensitization of inflammation-associated TRPA1 activity in DRG

ETHNOPHARMACOLOGICAL RELEVANCE

Ligustrazine, an important active ingredient extracted from Ligusticum chuanxiong hort, has been widely used to cure cardiovascular diseases and exerts an analgesic effect.

AIMS OF THIS STUDY

The aim of this study is to investigate whether ligustrazine mitigates chronic venous disease (CVeD)-induced pain and to explore its underlying mechanisms.

MATERIALS AND METHODS

A mouse model of CVeD was established by vein ligature. Ligustrazine was administered intraperitoneally to CVeD mice for a single injection (20 mg/kg, 100 mg/kg, and 200 mg/kg) or once a day for three weeks (100 mg/kg and 200 mg/kg), and TRPA1 overexpressed HEK 293 cells were treated with ligustrazine (600 μM) in the presence of mustard oil (100 μM) for 2 min. Patch clamp and calcium imaging were used to measure the inhibitory response of ligustrazine on DRG neurons and TRPA1 transfected HEK293 cells.

RESULTS

The present results showed that mice receiving vein ligature surgery exhibited obvious pain hypersensitivity to mechanical, cold and thermal stimuli, whereas ligustrazine significantly reversed the pain hyperalgesia in CVeD mice. Furthermore, ligustrazine desensitized transient receptor potential ankyrin 1 (TRPA1) activity in the dorsal root ganglion (DRG) neurons, resulting in suppressing the DRG neuronal excitability in the CVeD mice. However, ligustrazine could not directly inhibit the response of TRPA1 transfected HEK293 cells to mustard oil. Strikingly, ligustrazine restricted the macrophage infiltration and decreased the mRNA levels of Interleukin-1β (IL-1β) and NOD-like receptor protein 3 (NLRP3) in the DRG neurons of the CVeD mice.

CONCLUSIONS

The present study provided evidence that ligustrazine alleviated pain hypersensitivity to mechanical, cold and thermal stimuli in CVeD mice. Ligustrazine could weaken the activity of TRPA1 in the DRG to mitigate CVeD-induced pain hyperalgesia mainly through inhibition of inflammation. Our findings identify that ligustrazine may be a new therapeutic agent for the treatment of CVeD-induced pain.

Tetramethylpyrazine protects neural stem cells against sevoflurane-induced toxicity through Akt/GSK-3β pathway

Sevoflurane, a commonly used anesthetic, has been found to cause neural stem cell (NSC) injury, thereby contributing to neurocognitive impairment following general anesthesia. Tetramethylpyrazine (TMP), one of the most widely used medicinal compounds isolated from a traditional Chinese herb, possess neuroprotective activity. However, its effect on sevoflurane-induced NSC injury remains unclear. NSCs were pretreated with indicated concentrations of TMP for 2 h and then exposed to sevoflurane for 6 h. Cell injury was measured using lactate dehydrogenase (LDH) release assay. Cell viability and proliferation were detected by cell counting kit-8 (CCK-8) assay and 5-bromo-2'-deoxyuridine (BrdU) labeling, respectively. Apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The levels of cleaved caspase-3, phosphorylated protein kinase B (Akt) and phosphorylated glycogen synthase kinase-3β (GSK-3β) were detected by western blotting. Our results showed exposure to sevoflurane decreased the viability and proliferation of NSCs, while TMP preserved NSC viability and proliferation after sevoflurane exposure. In addition, the expression of cleaved caspase-3 and TUNEL positive cells were markedly decreased in TMP-treated NSCs compared with the control. Furthermore, pretreatment with TMP significantly increased the levels of phosphorylated Akt and GSK-3β in sevoflurane-injured NSCs. However, an upstream inhibitor of Akt, LY294002 abolished the protective of TMP on the cell viability of NSCs. In conclusion, these findings indicate that TMP protects NSCs from sevoflurane-induced toxicity through Akt/GSK-3β pathway.

Tetramethylpyrazine: A review on its mechanisms and functions

Ligusticum chuanxiong Hort (known as Chuanxiong in China, CX) is one of the most widely used and long-standing medicinal herbs in China. Tetramethylpyrazine (TMP) is an alkaloid and one of the active components of CX. Over the past few decades, TMP has been proven to possess several pharmacological properties. It has been used to treat a variety of diseases with excellent therapeutic effects. Here, the pharmacological characteristics and molecular mechanism of TMP in recent years are reviewed, with an emphasis on the signal-regulation mechanism of TMP. This review shows that TMP has many physiological functions, including anti-oxidant, anti-inflammatory, and anti-apoptosis properties; autophagy regulation; vasodilation; angiogenesis regulation; mitochondrial damage suppression; endothelial protection; reduction of proliferation and migration of vascular smooth muscle cells; and neuroprotection. At present, TMP is used in treating cardiovascular, nervous, and digestive system conditions, cancer, and other conditions and has achieved good curative effects. The therapeutic mechanism of TMP involves multiple targets, multiple pathways, and bidirectional regulation. TMP is, thus, a promising drug with great research potential.

Magnetic Resonance Imaging Investigation of Neuroplasticity After Ischemic Stroke in Tetramethylpyrazine-Treated Rats

Ischemic stroke elicits white matter injury typically signed by axonal disintegration and demyelination; thus, the development of white matter reorganization is needed. 2,3,5,6-Tetramethylpyrazine (TMP) is widely used to treat ischemic stroke. This study was aimed to investigate whether TMP could protect the white matter and promote axonal repair after cerebral ischemia. Male Sprague–Dawley rats were subjected to permanent middle cerebral artery occlusion (MCAO) and treated with TMP (10, 20, 40 mg/kg) intraperitoneally for 14 days. The motor function related to gait was evaluated by the gait analysis system. Multiparametric magnetic resonance imaging (MRI) was conducted to noninvasively identify gray-white matter structural integrity, axonal reorganization, and cerebral blood flow (CBF), followed by histological analysis. The expressions of axonal growth-associated protein 43 (GAP-43), synaptophysin (SYN), axonal growth-inhibitory signals, and guidance factors were measured by Western blot. Our results showed TMP reduced infarct volume, relieved gray-white matter damage, promoted axonal remodeling, and restored CBF along the peri-infarct cortex, external capsule, and internal capsule. These MRI findings were confirmed by histopathological data. Moreover, motor function, especially gait impairment, was improved by TMP treatment. Notably, TMP upregulated GAP-43 and SYN and enhanced axonal guidance cues such as Netrin-1/DCC and Slit-2/Robo-1 but downregulated intrinsic growth-inhibitory signals NogoA/NgR/RhoA/ROCK-2. Taken together, our data indicated that TMP facilitated poststroke axonal remodeling and motor functional recovery. Moreover, our findings suggested that TMP restored local CBF, augmented guidance cues, and restrained intrinsic growth-inhibitory signals, all of which might improve the intracerebral microenvironment of ischemic areas and then benefit white matter remodeling.

Tetramethylpyrazine Improves Monocrotaline-Induced Pulmonary Hypertension through the ROS/iNOS/PKG-1 Axis

Background

Tetramethylpyrazine (TMP), a potent anti-free radical and anti-inflammations substance, has been demonstrated to possess a direct vessel relaxation property. This study aimed to evaluate the effect of TMP treatment in pulmonary hypertension (PH) and test the hypothesis that TMP prevents or reverses the process of PH.

Methods

Rats (n = 36) injected with 50 mg/kg of monocrotaline (MCT) subcutaneously 4 weeks to develop PH were then randomized to TMP (5 mg/kg per day) for another 4 weeks. Hemodynamics was evaluated via the right ventricle. Pulmonary vessels structural remodeling and inflammation were examined by histologic and transmission electron microscopy observation. The expression of inducible nitric oxide synthase (iNOS) and cGMP-dependent protein kinases 1 (PKG-1) was detected by immunohistochemical staining and Western blot. Generation of reactive oxygen species (ROS) and antioxidation species was measured by biochemical analyses.

Results

MCT increased PH and right ventricle hypertrophy. TMP alleviated pulmonary arterial pressure elevation, leukocyte infiltration, and structural remodeling of pulmonary arterials induced by MCT successfully. TMP treatment significantly increased the PKG-1 expression and suppressed the iNOS expression. The activity of superoxide dismutase (SOD), glutathione peroxidase (GSH), and catalase (CAT) was significantly higher than control group, while malondialdehyde (MDA) levels were lower compared with MCT group.

Conclusion

TMP can suppress established MCT-induced PH through the ROS/iNOS/PKG axis. The underlying mechanisms may be associated with its anti-inflammatory, antioxidant, and antiproliferative properties in pulmonary arterial.

Tetramethylpyrazine Alleviates Endothelial Glycocalyx Degradation and Promotes Glycocalyx Restoration via TLR4/NF-κB/HPSE1 Signaling Pathway During Inflammation

Tetramethylpyrazine (TMP), a Chinese traditional herbal extraction widely used in treating cardiovascular diseases, could attenuate vascular endothelial injuries, but the underlying mechanism remains incomprehensive. Vascular glycocalyx coating on the endothelium would be damaged and caused endothelial dysfunction in the inflammatory microenvironment, which was the initial factor of morbidity of many vascular diseases, such as atherosclerosis (AS). Here, we thoroughly investigated the molecular mechanism of TMP on vascular endothelial glycocalyx in the LPS-induced inflammatory model both in vitro and in vivo. Results showed that pretreatment with TMP significantly inhibited glycocalyx degradation and monocytes adhesion to the endothelial process. Moreover, TMP pretreatment inhibited the expression of HPSE1 (a major degrading enzyme of endothelial glycocalyx), Toll-like receptor 4 (TLR4), and the translocation of nuclear factor kappa B p65 (NF-κB p65). We were utilized withTLR4 siRNA, NF-κB inhibitor, and HPSE1 overexpression analysis confirmed TMP's protection on endothelial glycocalyx injury, which further contributed to the monocyte-endothelial adhesion process. It was indicated that TMP might suppress glycocalyx degradation through TLR4/NF-κB/HPSE1 signaling pathway. Taken together, our results enriched the occurrence molecular mechanism of glycocalyx shedding and molecular regulation mechanism of TMP in protecting integrity of the glycocalyx structure during inflammation. As TMP is currently used in clinical applications, it may be considered a novel strategy against atherosclerosis through its ability to protect endothelial glycocalyx.

Tetramethylpyrazine: An Active Ingredient of Chinese Herbal Medicine With Therapeutic Potential in Acute Kidney Injury and Renal Fibrosis

As an increasing public health concern worldwide, acute kidney injury (AKI) is characterized by rapid deterioration of kidney function. Although continuous renal replacement therapy (CRRT) could be used to treat severe AKI, effective drug treatment methods for AKI are largely lacking. Tetramethylpyrazine (TMP) is an active ingredient of Chinese herb Ligusticum wallichii (Chuan Xiong) with antioxidant and anti-inflammatory functions. In recent years, more and more clinical and experimental studies suggest that TMP might effectively prevent AKI. The present article reviews the potential mechanisms of TMP against AKI. Through search and review, a total of 23 studies were finally included. Our results indicate that the undergoing mechanisms of TMP preventing AKI are mainly related to reducing oxidative stress injury, inhibiting inflammation, preventing apoptosis of intrinsic renal cells, and regulating autophagy. Meanwhile, given that AKI and chronic kidney disease (CKD) are very tightly linked by each other, and AKI is also an important inducement of CKD, we thus summarized the potential of TMP impeding the progression of CKD through anti-renal fibrosis.

Efficacy of Ligustrazine Injection as Adjunctive Therapy in Treating Acute Cerebral Infarction: A Systematic Review and Meta-Analysis

Background: Ligustrazine injection has been widely used as adjunctive therapy in the treatment of acute cerebral infarction (ACI) during the past decades in China, but its clinical efficacy is not yet well confirmed. This study aims to evaluate the efficacy of ligustrazine injection as adjunctive therapy for ACI.

Methods: Databases including China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), PubMed, Medline, Google Scholar, Chinese Biomedical Literature Database, Cochrane Library, Embase, Sino-Med, Wanfang Database, and Chinese Science Citation Database were systematically searched for the published randomized controlled trials (RCTs) on ligustrazine injection in the treatment of ACI until November 2020. Meta-analysis was performed on the primary outcome measure (i.e., clinical effective rate) and the secondary outcome measure [i.e., neurological deficit score (NDS), fibrinogen, low shear blood viscosity (LBV), and high shear blood viscosity (HBV)]. The quality of the included RCTs was assessed according to the M scoring system (the refined Jadad scale). Sensitivity analysis and subgroup analysis were conducted according to the methodological quality, years of publication, and sample size.

Results: Nineteen RCTs, containing 2022 patients, were included in this study. Meta-analysis indicated that ligustrazine injection combined with Western medicine could achieve a better effect in the treatment of ACI than using Western medicine alone in terms of clinical effective rate (RR = 1.24; 95% CI, 1.19–1.29), NDS (MD = −3.88; 95%CI, −4.51 to −3.61), fibrinogen (MD = −0.59; 95% CI, −0.76 to −0.42), LBV (MD = −2.11; 95% CI, −3.16 to −1.06), and HBV (MD = −0.88; 95% CI, −1.20 to −0.55).

Conclusions: This research indicated that ligustrazine injection as adjunctive therapy seemed to be more effective than using western medicine alone in treating ACI. However, more evidence is required to confirm the efficacy of ligustrazine injection due to the low methodological quality of the included RCTs.

Natural ingredients from Chinese materia medica for pulmonary hypertension

Pulmonary hypertension (PH) is a severe pathophysiological condition characterized by pulmonary artery remodeling and continuous increases in pulmonary artery pressure, which may eventually develop to right heart failure and death. Although newly discovered and incredible treatment strategies in recent years have improved the prognosis of PH, limited types of effective and economical drugs for PH still makes it as a life-threatening disease. Some drugs from Chinese materia medica (CMM) have been traditionally applied in the treatment of lung diseases. Accumulating evidence suggests active pharmaceutical ingredients (APIs) derived from those medicines brings promising future for the prevention and treatment of PH. In this review, we summarized the pharmacological effects of APIs derived from CMM which are potent in treating PH, so as to provide new thoughts for initial drug discovery and identification of potential therapeutic strategies in alternative medicine for PH.

Tetramethylpyrazine alleviates endoplasmic reticulum stress‑activated apoptosis and related inflammation in chondrocytes

Excessive apoptosis of chondrocytes and degradation of the extracellular matrix (ECM) contribute to the typical pathological characteristics of osteoarthritis (OA). Various studies have reported that tetramethylpyrazine (TMP) protects against multiple disorders by inhibiting inflammation and oxidative stress. The present study investigated the effects of TMP on chondrocytes and evaluated the associated mechanisms. To determine the effect of TMP on OA and the underlying mechanisms, chondrocytes were incubated with TMP and IL-1β or thapsigargin (TG) Western blotting assays were performed to examine the expression levels of endoplasmic reticulum (ER) stress proteins, and TUNEL staining, fluorescence immunostaining and reverse transcription-quantitative PCR were used to determine the apoptosis levels, and catabolic and inflammatory factors. It was found that TMP protected chondrocytes by suppressing IL-1β-induced expression of glucose-regulated protein 78 (GRP78) and CHOP (an apoptotic protein). TMP regulated the TG-mediated upregulated expression of GRP78 and CHOP in the chondrocytes of rats, as well as markedly suppressed levels of ER stress-triggered inflammatory cytokines (TNF-α and IL-6). Furthermore, TMP modulated TG-induced changes in ECM catabolic metabolism in rat chondrocytes. Collectively, TMP alleviated ER-stress-activated apoptosis and related inflammation in chondrocytes, indicating that it has therapeutic potential for the treatment of OA.

Danshen-Chuanxiongqin Injection attenuates cerebral ischemic stroke by inhibiting neuroinflammation via the TLR2/ TLR4-MyD88-NF-κB Pathway in tMCAO mice

Danshen-Chuanxiongqin Injection (DCI) is a commonly used traditional Chinese medicine for the treatment of cerebral ischemic stroke in China. However, its underlying mechanisms remain completely understood. The current study was designed to explore the protective mechanisms of DCI against cerebral ischemic stroke through integrating whole-transcriptome sequencing coupled with network pharmacology analysis. First, using a mouse model of cerebral ischemic stroke by transient middle cerebral artery occlusion (tMCAO), we found that DCI (4.10 mL·kg^-1) significantly alleviated cerebral ischemic infarction, neurological deficits, and the pathological injury of hippocampal and cortical neurons in mice. Next, the whole-transcriptome sequencing was performed on brain tissues. The cerebral ischemia disease (CID) network was constructed by integrating transcriptome sequencing data and cerebrovascular disease-related genes. The results showed CID network was imbalanced due to tMCAO, but a recovery regulation was observed after DCI treatment. Pathway analysis of the key genes with recovery efficiency showed that the neuroinflammation signaling pathway was highly enriched, while the TLR2/TLR4-MyD88-NF-κB pathway was predicted to be affected. Consistently, the in vivo validation experiments confirmed that DCI exhibited protective effects against cerebral ischemic stroke by inhibiting neuroinflammation via the TLR2/TLR4-MyD88-NF-κB pathway. More interestingly, DCI markedly suppressed the neutrophils infiltrated into the brain parenchyma via the choroid plexus route and showed anti-neuroinflammation effects. In conclusion, our results provide dependable evidence that inhibiting neuroinflammation via the TLR2/TLR4-MyD88-NF-κB pathway is the main mechanism of DCI against cerebral ischemic stroke in mice.

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.

Intra-Articular Injection of a Nanosuspension of Tetramethylpyrazine Dihydroxynaphthalenate for Stronger and Longer-Lasting Effects Against Osteoarthritis

Tetramethylpyrazine (TMP), isolated from the rhizome of the traditional Chinese medicinal plant Chuanxiong (Ligusticum wallichii Franchat) shows therapeutic efficacy against osteoarthritis. After intra-articular injection, the retention time of TMP in the joint cavity is short, which limits its treatment effect. To avoid this problem, the present study explored the preparation of a TMP nanosuspension (TMP-NS) based on hydrophobic ion pairing. TMP-NS showed a particle size of approximately 588 nm and, after intra-articular injection in rats, it had longer retention in the articular cavity, higher TMP concentrations in joints, and greater anti-osteoarthritic efficacy than TMP solution. TMP-NS didn't cause significant inflammation at the joint. These results suggest that TMP-NS may strengthen and prolong the therapeutic efficacy of TMP against osteoarthritis without systemic toxicity.

Tetramethylpyrazine Improves Cognitive Function of Alzheimer's Disease Mice by Regulating SSTR4 Ubiquitination

Purpose

Many researches have investigated the functions of tetramethylpyrazine (TMP) in Alzheimer's disease (AD). This study aimed to discuss the underlying mechanism of TMP in AD mice.

Methods

TMP (200 mg/kg) was administered to 6-month-old APP/PS1 transgenic mice, and behavioral changes and hippocampal nerve injury in AD mice were detected. Apoptosis and autophagy-related protein levels were detected. Changes in gene expression before and after TMP treatment were compared using transcriptome sequencing. The effects of Cullin 4B (CUL4B) overexpression and somatostatin receptor 4 (SSTR4) silencing on AD symptoms and SSTR4 ubiquitination in APP/PS1 mice were observed. SH-SY5Y and PC12 cells were treated with 25 μmol/L Aβ_25-35 and TMP to observe cell viability, apoptosis, and autophagy. Cell viability and apoptosis were measured again after treatment with proteasome inhibitor MG132 or lysosomal inhibitor 3-mA.

Results

TMP treatment improved the behavioral cognition of APP/PS1 mice and improved the neuronal apoptosis and damage in brain tissue. CUL4B was significantly upregulated in APP/PS1 mouse brain tissue, and SSRT4 protein was downregulated, and the levels of CUL4B and SSRT4 were negatively correlated. TMP treatment downregulated CUL4B, inhibited SSRT4 ubiquitination and upregulated SSRT4 protein level in APP/PS1 mouse brain tissue, while CUL4B overexpression or SSRT4 silencing reversed the effect of TMP. TMP and MG132 improved the decreased activity, increased apoptosis and increased SSRT4 protein in SH-SY5Y and PC12 cells treated with Aβ_25-35, but not 3-mA. CUL4B overexpression promoted the ubiquitination of SSTR4 in cells, which partially reversed the effect of TMP.

Conclusion

TMP could improve the cognitive ability of AD mice by inhibiting CUL4B expression and the ubiquitination degradation of SSTR, and alleviating neuronal apoptosis and injury. This study may offer a new therapeutic option for AD treatment.

Tetramethylpyrazine supplementation improves performance, digestion, blood and immune state of broilers exposure to oxidative stress

This study aimed to investigate the effect of dietary tetramethylpyrazine (TMP) on the growth performance, nutrient digestion, blood parameters and immunity of broilers under oxidative stress. Five treatments included negative control, positive control with lipopolysaccharide induction and TMP addition at 50, 100 and 150 mg/kg of diet using 600 male Arbor Acres broiler chicks. Results showed that during 1-14 days of age, body weight gain and feed efficiency in the positive control were worsened (p < .05) compared with the negative control, while with incremental TMP doses from 0 to 150 mg/kg there were linear and quadratic increases (p < .001) in body weight gain and a linear decrease in feed/gain (p = .001). During 12-14 days of age, with incremental TMP doses, crude protein digestibility was linearly increased (p = .001), and gross energy utilization was linearly and quadratically changed (p < .001). At 14 days of age, the TMP beneficially regulated digestive enzymes, blood parameters and immunoglobulins, showing linear and quadratic responses (p ≤ .008) on trypsin, lipase, glutamic pyruvic transaminase, glucose, lipoproteins, albumin, immunoglobulins (M, Y), interleukin 6 and interferon α, and only linear changes (p ≤ .030) on amylase, glutamic oxaloacetic transaminase, immunoglobulin A and interleukin 2. Most parameters in TMP groups reached to the levels of negative control and the effects of TMP at 100 or 150 mg/kg were more pronounced on body weight gain, crude protein digestibility, trypsin and glutamic pyruvic transaminase. It is concluded that TMP can be used as a feed additive capable of improving growth, blood parameter and immunity of broiler chicks under oxidative stress.

Tetramethylpyrazine Alleviates Behavioral and Psychological Symptoms of Dementia Through Facilitating Hippocampal Synaptic Plasticity in Rats With Chronic Cerebral Hypoperfusion

Behavioral and psychological symptoms of dementia (BPSD) ubiquitously disturb all patients with dementia at some point in the disease course. Although a plethora of non-pharmacological and pharmacological methods targeting the relief BPSD have been developed, the therapeutic effect is still far from ideal. Here, a rat BPSD model combining the physiological changes with mental insults was successfully established. Meanwhile, our results indicated that TMP attenuated anxious behavior using an elevated plus maze (EPM) test, ameliorated recognitive ability and sociability through a novel object recognition test (NORT) and social interaction test (SIT), and improved learning and memory impairments via a Barnes maze in rats with bilateral common carotid arteries occlusion (BCCAO) plus chronic restraint stress (CRS). Given that hippocampus chronic cerebral hypoperfusion (CCH) always causes damage to the hippocampus, and the majority of cognitive impairments, behaviors, and stress responses are associated with pathology in the hippocampus including anxiety and depression, we paid attention to investigate the role of the hippocampus in BPSD. Our results indicated that Tetramethylpyrazine (TMP) attenuated anxiety and ameliorated recognitive ability, sociability, learning, and memory impairments due to alleviating dendritic and spine deficits, and upregulating the expression of synapse-related proteins (including PSD95, SYN, GAP43, SYP) in the hippocampus. We also found that the underlying mechanism was that TMP could activate the TrkB/ERK/CREB signaling pathway to promote synaptic remodeling in vivo and in vitro. Mechanically, the present study enlarges the therapeutic scope of TMP in neurodegenerative disorders and provides basic knowledge and feasible candidates for treating BPSD, particularly for vascular dementia.

Neuroprotective Effect for Cerebral Ischemia by Natural Products: A Review

Natural products have a significant role in the prevention of disease and boosting of health in humans and animals. Stroke is a disease with high prevalence and incidence, the pathogenesis is a complex cascade reaction. In recent years, it’s reported that a vast number of natural products have demonstrated beneficial effects on stroke worldwide. Natural products have been discovered to modulate activities with multiple targets and signaling pathways to exert neuroprotection via direct or indirect effects on enzymes, such as kinases, regulatory receptors, and proteins. This review provides a comprehensive summary of the established pharmacological effects and multiple target mechanisms of natural products for cerebral ischemic injury in vitro and in vivo preclinical models, and their potential neuro-therapeutic applications. In addition, the biological activity of natural products is closely related to their structure, and the structure-activity relationship of most natural products in neuroprotection is lacking, which should be further explored in future. Overall, we stress on natural products for their role in neuroprotection, and this wide band of pharmacological or biological activities has made them suitable candidates for the treatment of stroke.

Vinegar/Tetramethylpyrazine Induces Nutritional Preconditioning Protecting the Myocardium Mediated by VDAC1

Vinegar is good for health. Tetramethylpyrazine (TMP) is the main component of its flavor, quality, and function. We hypothesized that vinegar/TMP pretreatment could induce myocardial protection of "nutritional preconditioning (NPC)" by low-dose, long-term supplementation and alleviate the myocardial injury caused by anoxia/reoxygenation (A/R). To test this hypothesis, TMP content in vinegar was detected by HPLC; A/R injury model was prepared by an isolated mouse heart and rat cardiomyocyte to evaluate the myocardial protection and mechanism of vinegar/TMP pretreatment by many enzymatic or functional, or cellular and molecular biological indexes. Our results showed that vinegar contained TMP, and its content was in direct proportion to storage time. Vinegar/TMP pretreatment could improve hemodynamic parameters, decrease lactate dehydrogenase (LDH) and creatine phosphokinase activities, and reduce infarct size and apoptosis in the isolated hearts of mice with A/R injury. Similarly, vinegar/TMP pretreatment could increase cell viability, decrease LDH activity, and decrease apoptosis against A/R injury of cardiomyocytes. Vinegar/TMP pretreatment could also maintain the mitochondrial function of A/R-injured cardiomyocytes, including improving oxygen consumption rate and extracellular acidification rate, reducing reactive oxygen species generation, mitochondrial membrane potential loss, mitochondrial permeability transition pore openness, and cytochrome c releasing. However, the protective effects of vinegar/TMP pretreatment were accompanied by the downregulation of VDAC1 expression in the myocardium and reversed by pAD/VDAC1, an adenovirus that upregulates VDAC1 expression. In conclusion, this study is the first to demonstrate that vinegar/TMP pretreatment could induce myocardial protection of NPC due to downregulating VDAC1 expression, inhibiting oxidative stress, and preventing mitochondrial dysfunction; that is, VDAC1 is their target, and the mitochondria are their target organelles. TMP is one of the most important myocardial protective substances in vinegar.

The Tetramethylpyrazine Derivative Statmp-151: A Novel Small Molecule Stat3 Inhibitor With Promising Activity Against Breast Cancer

Breast cancer is the most common malignancy in women and is a molecularly heterogeneous disease. Signal transducer and activator of transcription 3 (Stat3) is overexpressed and hyperactivated in a variety of human tumours, including breast cancer, thus representing a promising target for breast cancer treatment. In the present study, we evaluated the activities of a novel Stat3 inhibitor named Statmp-151 in the human breast cancer cell lines MCF-7 and MDA-MB-231 and the murine mammary carcinoma cell line 4T1. The in vitro results showed that Statmp-151 inhibited the proliferation of breast cancer cell lines in a dose- and time-dependent manner and suppressed the phosphorylation of Stat3 in a dose-dependent manner. Flow cytometry (FCM) assays revealed that Statmp-151 affected mitochondrial membrane potential and reactive oxygen species (ROS) production. Furthermore, Statmp-151 inhibited cell migration, as shown by analysis of the matrix metalloproteinases MMP2 and MMP9. Finally, in a 4T1 tumour-bearing mouse model, intraperitoneal injection of 30 mg/kg/day Statmp-151 significantly suppressed the growth of tumours without obvious toxicity. These results indicated that Statmp-151 might be a potential candidate for the treatment of breast cancer.

Tetramethylpyrazine Ameliorates Peritoneal Angiogenesis by Regulating VEGF/Hippo/YAP Signaling

Angiogenesis of human peritoneal vascular endothelial cells (HPVECs), linked to vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) signaling, is a complication of peritoneal fibrosis (PF). Hippo/YAP signaling interacts with VEGF/VEGFR2 signaling, but the effect on peritoneal angiogenesis and PF has not been studied. We tested VEGF/Hippo/YAP inhibition by tetramethylpyrazine (TMP) in PF mice and HPVECs. This treatment ameliorated peritoneal dialysis (PD)–induced angiogenesis and PF. In mice, PF was associated with upregulation of VEGF, and TMP ameliorated submesothelial fibrosis, perivascular bleeding, and Collagen I abundance. In HPVECs, angiogenesis occurred due to human peritoneal mesothelial cells (HPMCs)–conditioned medium, and TMP alleviated HPVECs migration, tube formation, and YAP nuclear translocation. YAP knockdown PF mouse and HPVEC models were established to further confirm our finding. YAP deletion attenuated the PD-induced or VEGF-induced increase in angiogenesis and PF. The amount of CYR61 and CTGF was significantly less in the YAP knockdown group. To study the possibility that TMP could benefit angiogenesis, we measured the HPVECs migration and tube formation and found that both were sharply increased in YAP overexpression; TMP treatment partly abolished these increases. As well, the amount of VEGFR localized in the trans-Golgi network was lower by double immunofluorescence; VEGFR and its downstream signaling pathways including p-ERK, p-P38, and p-Akt were more in HPVECs with YAP overexpression. Overall, TMP treatment ameliorated angiogenesis, PF, and peritoneum injury. These changes were accompanied by inhibition of VEGF/Hippo/YAP.

Diffusion kurtosis imaging to evaluate the effect and mechanism of tetramethylpyrazine on cognitive impairment induced by lipopolysaccharide in rats

Using diffusion kurtosis imaging (DKI) to evaluate the brain changes, the therapeutic effect and mechanism of tetramethylpyrazine in rats with dementia induced by lipopolysaccharide. Thirty-six male Sprague-Dawley rats were randomly divided into control group and five groups pretreated with sham operation, lipopolysaccharide(150ug) and three doses of tetramethylpyrazine(5, 10, and 20 mg/mL respectively). The Morris water maze test was used to evaluate cognitive ability. DKI and histology were performed. Low-dose of tetramethylpyrazine pretreated rats showed lower escape latency(6th day: 15.92seconds(s) vs. 5.11 s, P = 0.001), spent more time in the target quadrant(15.67 s vs. 29.83 s, P = 0.009) and crossed the platform area more frequently(3.50 vs. 9.17, P = 0.001) than rats in the LPS-treated group. Compared to sham group, the fractional anisotropy (FA), axial diffusion (Da), mean kurtosis (MK), and axial kurtosis (Ka) values in the cortex of lipopolysaccharide group were lower (P = 0.021,0.003,0.003,0.001,respectively).The MK, Ka, Kr, and FA values in the hippocampus of the lipopolysaccharide group were higher (P = 0.01, 0.026,0.007,0.003,respectively),while MD and Da values were lower (P = 0.045,0.044, respectively). Tetramethylpyrazine-pretreated rats showed higher values of FA, MD, Da, MK, and Ka in the cortex, lower MK, Ka, Kr, and FA values and higher MD,Da values in the hippocampus than the lipopolysaccharide group. Histologically, prominent inflammatory cells infiltration in the brain parenchyma of lipopolysaccharide group were observed, while groups pretreated using tetramethylpyrazine were alleviated. Tetramethylpyrazine can improve cognitive dysfunction induced by lipopolysaccharide. DKI can sensitively detect microstructure integrity of brain parenchyma in a non-invasive manner.

Potential Effects of Nutraceuticals in Retinopathy of Prematurity

Retinopathy of prematurity (ROP), the most common cause of childhood blindness, is a hypoxia-induced eye disease characterized by retinal neovascularization. In the normal retina, a well-organized vascular network provides oxygen and nutrients as energy sources to maintain a normal visual function; however, it is disrupted when pathological angiogenesis is induced in ROP patients. Under hypoxia, inadequate oxygen and energy supply lead to oxidative stress and stimulate neovasculature formation as well as affecting the function of photoreceptors. In order to meet the metabolic needs in the developing retina, protection against abnormal vascular formation is one way to manage ROP. Although current treatments provide beneficial effects in reducing the severity of ROP, these invasive therapies may also induce life-long consequences such as systemic structural and functional complications as well as neurodevelopment disruption in the developing infants. Nutritional supplements for the newborns are a novel concept for restoring energy supply by protecting the retinal vasculature and may lead to better ROP management. Nutraceuticals are provided in a non-invasive manner without the developmental side effects associated with current treatments. These nutraceuticals have been investigated through various in vitro and in vivo methods and are indicated to protect retinal vasculature. Here, we reviewed and discussed how the use of these nutraceuticals may be beneficial in ROP prevention and management.

Interphotoreceptor Retinoid-Binding Protein (IRBP) in Retinal Health and Disease

Interphotoreceptor retinoid-binding protein (IRBP), also known as retinol binding protein 3 (RBP3), is a lipophilic glycoprotein specifically secreted by photoreceptors. Enriched in the interphotoreceptor matrix (IPM) and recycled by the retinal pigment epithelium (RPE), IRBP is essential for the vision of all vertebrates as it facilitates the transfer of retinoids in the visual cycle. It also helps to transport lipids between the RPE and photoreceptors. The thiol-dependent antioxidant activity of IRBP maintains the delicate redox balance in the normal retina. Thus, its dysfunction is suspected to play a role in many retinal diseases. We have reviewed here the latest research on IRBP in both retinal health and disease, including the function and regulation of IRBP under retinal stress in both animal models and the human retina. We have also explored the therapeutic potential of targeting IRBP in retinal diseases. Although some technical barriers remain, it is possible that manipulating the expression of IRBP in the retina will rescue or prevent photoreceptor degeneration in many retinal diseases.

Targeted Drugs for Treatment of Pulmonary Arterial Hypertension: Past, Present, and Future Perspectives

Pulmonary arterial hypertension (PAH) is a devastating disease that can lead to right ventricular failure and premature death. Although approved drugs have been shown to be safe and effective, PAH remains a severe clinical condition, and the long-term survival of patients with PAH is still suboptimal. Thus, potential therapeutic targets and new agents to treat PAH are urgently needed. In recent years, a variety of related pathways and potential therapeutic targets have been found, which brings new hope for PAH therapy. In this perspective, not only are the marketed drugs used to treat PAH summarized but also the recently developed novel pharmaceutical therapies currently in clinical trials are discussed. Furthermore, the advances in natural products as potential treatment for PAH are also updated.

Tetramethylpyrazine Ameliorates Lipopolysaccharide-Induced Sepsis in Rats via Protecting Blood-Brain Barrier, Impairing Inflammation and Nitrous Oxide Systems

The aim of this study was to assess the underlying impact of Tetramethylpyrazine (TMP), which is the main activity compound of Ligusticum chuanxiong Hort, on the blood–brain barrier, inflammatory and nitrous oxide systems in a rat model of lipopolysaccharide (LPS)-induced sepsis. The SD rats were divided into control group, LPS treatment group, and LPS + TMP treatment group. TMP administered by tail vein injection. The mortality of experimental rats was recorded during the experiment. Rats were sacrificed after 14 days. Peripheral blood was collected and the expression levels of inflammatory factors TNF-α, IL-1β, and IL-6 were detected by ELISA. The integrity of blood-brain barrier was detected by sodium fluorescein staining. Lung and brain tissues were taken to detect the infiltration of immune cells. Immunohistochemistry was performed to detect the expression of tight junctions related proteins and oxidative stress-related proteins. The results showed that TMP treatment for 14 days significantly decreased the weight loss and increased the survival rate of the septic rats significantly. TMP decreased the infiltration of inflammatory cells and alleviated the sepsis-induced damage in both the lung and brain tissues. The inflammatory cytokines TNF-α, IL-1β, and IL-6, were significantly decreased post-TMP treatment. Histopathological analysis with sodium fluorescein staining density showed that TMP had a protective effect on the basal lamina and cerebral cortex. Also, TMP significantly increased expression of the tight junction-related proteins claudin-5 and occludin in the brain tissue and increased the expression of the ZO-1, Occludin, and Claudin-5 genes, indicating alleviated the degree of blood–brain barrier destruction. Furthermore, immunohistochemistry (IHC) and immunoblotting confirmed that TMP could inhibit the indicators of the nitrous oxide system, iNOS and eNOS; in addition, TMP significantly decreased the levels of MDA and NO. The findings showed that TMP treatment during sepsis was associated with the protection of the blood–brain barrier and the suppression of inflammatory reactions and the nitrous oxide system. This study reveals a promising protective role of TMP in septic encephalopathy and may suggest a therapeutic approach for fighting the deadly disease of sepsis in the clinic.

A comprehensive review of natural products to fight liver fibrosis: Alkaloids, terpenoids, glycosides, coumarins and other compounds

The discovery of drugs to treat liver fibrosis has long been a challenge over the past decades due to its complicated pathogenesis. As a primary approach for drug development, natural products account for 30% of clinical drugs used for disease treatment. Therefore, natural products are increasingly important for their medicinal value in liver fibrosis therapy. In this part of the review, special focus is placed on the effect and mechanism of natural compounds, including alkaloids, terpenoids, glycosides, coumarins and others. A total of 36 kinds of natural compounds demonstrate significant antifibrotic effects in various liver fibrosis models in vivo and in hepatic stellate cells (HSCs) in vitro. Revealing the mechanism will provide further basis for clinical conversion, as well as accelerate drug discovery. The mechanism was further summarized with the finding of network regulation by several natural products, such as oxymatrine, paeoniflorin, ginsenoside Rg1 and taurine. Moreover, there are still improvements needed in investigating clinical efficacy, determining mechanisms, and combining applications, as well as semisynthesis and modification. Therefore, natural products area promising resource for agents that protect against liver fibrosis.

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.).

Recruitment of Mesenchymal Stem Cells to Damaged Sites by Plant-Derived Components

Mesenchymal stem cells (MSCs) are capable of differentiating into a limited number of diverse cells and secrete regenerative factors that contribute to the repair of damaged tissue. In response to signals emitted by tissue damage, MSCs migrate from the bone marrow and area surrounding blood vessels within tissues into the circulating blood, and accumulate at the site of damage. Hence, MSC transplantation therapy is beginning to be applied to the treatment of various intractable human diseases. Recent medicinal plants studies have shown that plant-derived components can activate cell functions. For example, several plant-derived components activate cell signaling pathways, such as phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK), enhance expression of the CXCL12/CXCR4 axis, stimulate extracellular matrix remodeling, and consequently, promote cell migration of MSCs. Moreover, plant-derived components have been shown to promote recruitment of MSCs to damaged tissues and enhance healing in disease models, potentially advancing their therapeutic use. This article provides a comprehensive review of several plant-derived components that activate MSC migration and homing to damaged sites to promote tissue repair.

Tetramethylpyrazine attenuates endotoxin-induced retinal inflammation by inhibiting microglial activation via the TLR4/NF-κB signalling pathway

Ocular inflammation is a common pathological condition of a series of retinal degenerative diseases. Tetramethylpyrazine (TMP), a Chinese herbal extraction, is widely used in the treatment of several ocular diseases in Eastern countries. However, the exact mechanisms correlating the vision protective effects of TMP have not been elucidated. Thus, this study aimed to investigate TMP's molecular targets in anti-inflammatory activity in endotoxin lipopolysaccharide (LPS)-induced retinal inflammation both in vitro and in vivo. The primary cultured retinal microglial cells were pretreated with TMP and then activated by LPS. We found pretreatment with TMP significantly inhibited LPS-induced upregulation of CD68, a marker of mononuclear microglia activation. The morphological changes induced by LPS were also inhibited by the TMP pretreatment. Moreover, Toll like receptor 4 (TLR4), phosphorylation of inhibitor of NF-κB alpha (p-IκB-α) and the translocation of nuclear factor kappa B p65 (NF-κB p65) were significantly downregulated in retinal microglial cells with TMP pretreatment, which indicated that TMP might suppress LPS-induced retinal microglial activation through TLR4/NF-κB signalling pathway. And these results were confirmed in vivo. Pretreatment with TMP inhibited microglial activation, migration and regeneration, especially in ganglion cell layer (GCL). In addition to the inhibition of TLR4, TMP significantly inhibited the translocation of NF-κB p-65 to the nucleus in vivo. The downstream genes of NF-κB, such as the pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), were significantly downregulated by TMP pretreatment in the retina. Accordingly, the increased expression of cleaved caspase-3 and the decreased ratio of B-cell lymphoma-2 (Bcl-2) to Bcl-2 associated X Protein (Bax) were significantly attenuated by TMP. TUNEL assay also demonstrated that TMP exerted neuroprotective effects in the retina. Therefore, this study elucidated a novel mechanism that TMP inhibits retinal inflammation by inhibiting microglial activation via a TLR4/NF-κB signalling pathway.

Protective effect and possible mechanisms of ligustrazine isolated from Ligusticum wallichii on nephropathy in rats with diabetes: A preclinical systematic review and meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Ligusticum wallichii has been used to treat renal diseases for thousands of years in China. Ligustrazine (Lig) is the active ingredient of Ligusticum wallichii that possesses a variety of biological activities against kidney disease.

AIM OF THE STUDY

The purpose of this review is to further evaluate whether the supplementation with Lig has an effect on improving renal pathology, renal function indexes and blood glucose levels in animal model of diabetic nephropathy (DN). Potential mechanisms of Lig for DN as well as the existing problems regarding the modeling method and limitations in this area of research were also summarized.

MATERIALS AND METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) checklist was used to organize the search of eight databases from inception to June 2019. We used Cochrane Collaboration's 10-item checklist and Rev-Man 5.3 software to analyze the data as well as risk of bias.

RESULTS

The study quality scores ranged from 2 to 6 points with an average of 4.471. Compared with the control group, Lig significantly improved pathological changes of kidney including glomeruli and tubules, and induced significant decreases in levels of blood urea nitrogen, serum creatinine, 24-h urinary albumin and HbA1c, as well as increasing creatinine clearance rates. In subgroup analysis, the groups of high-dose STZ (≥60 mg/kg) and longer period of Lig treatment (>8 w) showed better results than those of the control group. No difference was seen between the high (>150 mg/kg, QD) and low (≤150 mg/kg, QD) dose of Lig treatment groups.

CONCLUSION

Lig exerts renoprotective functions in an animal model of DN mediated by antioxidant action, inhibition of apoptosis, anti-inflammatory action, reduction of renal fibrosis, reduction of the proliferation of mesangial cells, inhibition of endotheliosis, inhibition of atherosclerosis and promotion of renal autophagy. The positive conclusion should be treated cautiously because of various methodological flaws. Further studies are recommended according to ARRIVE guidelines. The method of modeling with high-dose STZ should be avoided and improved STZ modeling schemes are recommended. Considering the large dosage range of Lig used clinically and in animals, the future studies on the basis of animal renal histology are urgently needed to determine the optimal dosages to delay histological changes. Nevertheless, together, our findings suggest that Lig is a renoprotective candidate drug for treatment of DN.

Tetramethylpyrazine alleviates iron overload damage in vascular endothelium via upregulating DDAHII expression

Iron overload causes vascular endothelium damage. It has been thought to relate excessive reactive oxygen species (ROS) generation. Tetramethylpyrazine (TMP), an active ingredient of Ligusticum chuanxiong Hort, protects various cells by inhibiting oxidative stress and cascade reaction of apoptosis. However, whether TMP can increase DDAHII activity and expression against endothelial cell damage induced by iron overload, and the protective mechanism has not been elucidated. In this study, 50 μM iron dextran and 25 μM TMP were used to co-treat HUVECs for 48 h. TMP could increase cell viability and decrease LDH activity, enhance DDAHII expression and activity, p-eNOS/eNOS ratio, NO content, and reduce ADMA level. TMP also showed a strong antioxidant activity with inhibited ROS generation and oxidative stress. Moreover, TMP attenuated mitochondrial membrane potential loss, inhibited mitochondrial permeability transition pore openness, and decreased apoptosis induced by iron overload. While mentioned above, the protective effects of TMP were abolished with the addition of pAD/DDAHII-shRNA. The effects of TMP against iron overload were similar to the positive control groups, L-arginine, a competitive substrate of ADMA, or edaravone, free radical scavenger. These results signify that TMP alleviated iron overload damage in vascular endothelium via ROS/ADMA/ DDAHII/eNOS/NO pathway.

Phytochemical drug candidates for the modulation of peroxisome proliferator-activated receptor γ in inflammatory bowel diseases

Plant-based compounds or phytochemicals such as alkaloids, glycosides, flavonoids, volatile oils, tannins, resins, and polyphenols have been used extensively in traditional medicine for centuries and more recently in Western alternative medicine. Extensive evidence suggests that consumption of dietary polyphenolic compounds lowers the risk of inflammatory diseases. The anti-inflammatory properties of several phytochemicals are mediated through ligand-inducible peroxisome proliferator-activated receptors (PPARs), particularly the PPARγ transcription factor. Inflammatory bowel disease (IBD) is represented by ulcerative colitis, which occurs in the mucosa of the colon and rectum, and Crohn's disease (CD) that can involve any segment of gastrointestinal tract. Because of the lack of cost-effective pharmaceutical treatment options, many IBD patients seek and use alternative and unconventional therapies to alleviate their symptoms. PPARγ plays a role in the inhibition of inflammatory cytokine expression and activation of anti-inflammatory immune cells. The phytochemicals reported here are ligands that activate PPARγ, which in turn modulates inflammatory responses. PPARγ is highly expressed in the gut making it a potential therapeutic target for IBDs. This review summarizes the effects of the currently published phytochemicals that modulate the PPARγ pathway and reduce or eliminate colonic inflammation.