Quercetin exerts anti-tumor immune mechanism by regulating IL-6/JAK2/STAT3 signaling pathway to deplete Treg cells.

Breast cancer is still the leading cause of death among women worldwide. Due to the lack of effective drug targets, triple-negative breast cancer has a worse prognosis and higher mortality compared with other types of breast cancer, and chemotherapy is still the main treatment for triple-negative breast cancer at present. Quercetin (QUE) is a flavonoid compound found in a variety of fruits and vegetables. The mechanism of QUE has been extensively studied, such as prostate cancer, colon cancer, ovarian cancer, etc. However, the anti-tumor immune mechanism of QUE in triple-negative breast cancer remains unclear. Therefore, we assessed the anti-tumor immune effects of QUE on triple-negative breast cancer using both 4T1 cells and a xenograft mouse model of 4T1 cells. In vitro, we examined the inhibitory effects of QUE on 4T1 cells and its molecular mechanisms through MTT, Transwell, ELISA, and Western blotting. In vivo, by establishing a xenograft mouse model, we utilized flow cytometry, immunohistochemistry, ELISA, and Western blotting to evaluate the anti-tumor immune effects of QUE on triple-negative breast cancer. The results indicate that QUE inhibits the proliferation, migration, and invasion of 4T1 cells, concurrently significantly suppressing the IL-6/JAK2/STAT3 signaling pathway. Furthermore, it depletes Treg cell content in 4T1 xenograft mice, thereby improving the tumor immune microenvironment and promoting the cytotoxicity of relevant tumor immune cells. These findings suggest that QUE may serve as a potential adjuvant for immune therapy in triple-negative breast cancer.

Apigenin promotes apoptosis of 4T1 cells through PI3K/AKT/Nrf2 pathway and improves tumor immune microenvironment in vivo.

The 2022 US Cancer Statistics show that breast cancer is one of the most common cancers in women. Epidemiology has shown that adding flavonoids to the diet inhibits cancers that arise in particular women, such as cervical cancer, ovarian cancer, and breast cancer. Although there have been research reports on apigenin (API) and breast cancer, its anti-tumor effect and potential mechanism on breast cancer have not yet been clarified. Therefore, in this study, we used 4T1 cells and a 4T1 xenograft tumor mouse model to investigate the antitumor effect of API on breast cancer and its underlying mechanism. In vitro, we used MTT, transwell, staining, and western blotting to investigate the inhibitory effect of apigenin on 4T1 and the underlying molecular mechanism. In vivo by establishing a xenograft tumor model, using immunohistochemistry, and flow cytometry to study the inhibitory effect of apigenin on solid breast tumors and its effect on the tumor immune microenvironment. The results showed that API can induce breast cancer cell apoptosis through the PI3K/AKT/Nrf2 pathway and can improve the tumor immune microenvironment in mice with breast tumors, thereby inhibiting the growth of breast cancer. Thus, API may be a promising agent for breast cancer treatment.

Potentially inappropriate medication among older patients with diabetic kidney disease.

Objective: Potentially inappropriate medications (PIM) contribute to poor outcomes in older patients, making it a widespread health problem. The study explored the occurrence and risk factors of PIM in older diabetic kidney disease (DKD) patients during hospitalization and investigated whether polypharmacy was associated with it. Methods: Retrospective analysis of the patients ≥ 65 years old diagnosed with DKD from July to December 2020; the PIM was evaluated according to the American Beers Criteria (2019). Factors with statistical significance in univariate analysis were included in Logistic multivariate analysis to explore the potential risk factors related to PIM. Results: Included 186 patients, 65.6% of patients had PIM, and 300 items were confirmed. The highest incidence of PIM was 41.7% for drugs that should be carefully used by the older, followed by 35.3% that should be avoided during hospitalization. The incidence of PIM related to diseases or symptoms, drug interactions to avoid, and drugs to avoid or reduce dose for renal insufficiency patients were 6.3%, 4.0% and 12.7%, respectively. The medications with a high incidence of PIM were diuretics (35.0%), benzodiazepines (10.7%) and peripheral ɑ1 blockers (8.7%). Compared with hospitalization, there were 26% of patients had increased PIM at discharge. Multivariate Logistic regression analysis showed that polypharmacy during hospitalization was an independent risk factor for PIM, OR = 4.471 (95% CI: 2.378, 8.406). Conclusion: The incidence of PIM in hospitalized older DKD patients is high; we should pay more attention to the problem of polypharmacy in these patients. Pharmacists identifying the subtypes and risk factors for PIM may facilitate risk reduction for older DKD patients.

Drug-Related Problems in Bariatric Surgery: a Retrospective Study.

BACKGROUND: With the rapid increase of bariatric surgery worldwide, drug-related problems (DRPs) in this area seem to be rising. This study aimed to investigate the incidence and characteristics of DRPs in patients undergoing bariatric surgery. METHODS: Medication records for patients who underwent bariatric surgery were analysed retrospectively between January 2019 and December 2020 in our center. We classified and analysed DRPs using the Pharmaceutical Care Network Europe classification (PCNE version 9.0). Rating severity of these DRPs was based on the National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) classification. Continuous variables were analysed by Student's t-test, and categorical variables were compared using the chi-square test. One-way ANOVA was used to compare the numbers of DRPs. RESULTS: Totally 347 patients were reviewed, and 760 DRPs were identified with an average of 2.19 ± 1.36 DRPs for each patient. The most common DRPs were problems related to perioperative antibiotics accounting for 29.47%, 25.62% and 14.34% for hepatoprotection and proton-pump inhibitors (PPI), respectively. The leading causes of DRPs were inappropriate medications for antibiotics, hepatoprotection, ancillary drugs and PPI. 89.34% of the DRPs were rated at severity categories B-D (which means potential adverse reactions that may occur), whereas 10.66% were rated as categories E-H. There were relations between DRPs and older (32.22 ± 9.29 vs. 29.11 ± 6.53 years), fewer concomitant surgeries (1.89 ± 1.25 vs. 2.99 ± 1.31), longer postoperative fasting time (PFT) (1.18 ± 0.55 vs. 1.06 ± 0.24 days) and more comorbidities (6.71 ± 2.63 vs. 5.23 ± 1.46) (P < 0.05). CONCLUSIONS: The incidence of DRPs in the perioperative period of bariatric surgery is high. Patients with fewer concomitant surgeries and longer PFT are prone to DRPs. It is necessary for clinical pharmacists to participate in medication monitoring and reviewing to facilitate enhanced recovery after bariatric surgery.

A network pharmacology-based approach to explore the therapeutic potential of Sceletium tortuosum in the treatment of neurodegenerative disorders.

Sceletium tortuosum (SCT) has been utilized medicinally by indigenous Koi-San people purportedly for mood elevation. SCT extracts are reported to be neuroprotective and have efficacy in improving cognition. However, it is still unclear which of the pharmacological mechanisms of SCT contribute to the therapeutic potential for neurodegenerative disorders. Hence, this study investigated two aspects-firstly, the abilities of neuroprotective sub-fractions from SCT on scavenging radicals, inhibiting some usual targets relevant to Alzheimer's disease (AD) or Parkinson's disease (PD), and secondly utilizing the network pharmacology related methods to search probable mechanisms using Surflex-Dock program to show the key targets and corresponding SCT constituents. The results indicated sub-fractions from SCT could scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, inhibit acetylcholinesterase (AChE), monoamine oxidase type B (MAO-B) and N-methyl-D-aspartic acid receptor (NMDAR). Furthermore, the results of gene ontology and docking analyses indicated the key targets involved in the probable treatment of AD or PD might be AChE, MAO-B, NMDAR subunit2B (GluN2B-NMDAR), adenosine A2A receptor and cannabinoid receptor 2, and the corresponding constituents in Sceletium tortuosum might be N-trans-feruloyl-3-methyldopamine, dihydrojoubertiamine and other mesembrine type alkaloids. In summary, this study has provided new evidence for the therapeutic potential of SCT in the treatment of AD or PD, as well as the key targets and notable constituents in SCT. Therefore, we propose SCT could be a natural chemical resource for lead compounds in the treatment of neurodegenerative disorders.

Andrographolide Derivative AL-1 Ameliorates LPS-induced Acute Lung Injury by Inhibiting NLRP3 Inflammasome and Lung Permeability.

BACKGROUND: Acute lung injury (ALI) is a serious respiratory disease with a high mortality rate, and there is an urgent need for a more effective treatment strategy. Andrographolide derivative AL-1 has been identified to possess anti-inflammatory activity. However, whether it could reduce LPS-induced lung injury in mice through inhibiting NLRP3 inflammasome activation and protecting lung permeability has not yet been elucidated. In the present research, we investigated the protective effect of AL-1 on ALI mice and demonstrated the potential mechanisms. METHODS: Male Balb/c mice were anesthetized with isoflurane, and ALI mice were induced by intratracheal instillation of LPS. The mice were euthanized after LPS administration for 12 h, then bronchoalveolar lavage fluid (BALF) and lung tissues were collected. The levels of inflammatory factors were measured by ELISA assay, and HE staining and lung injury scoring were used to evaluate the pathological changes in the pulmonary tissues. Immunohistochemistry and immunofluorescence examination were conducted to detect the expression levels of related proteins. Western blot was performed to measure the levels of NLRP3 inflammasome and tight junction proteins. RESULTS: The study indicated that AL-1 effectively alleviated lung injury by reduction of proinflammatory cytokine levels, MPO activity, lung W/D ratio, and total protein levels. Furthermore, AL-1 improved pathological changes in lung tissue and significantly reduced the infiltration of inflammatory cells. Administration with AL-1 markedly inhibited the expression of NLRP3, ASC, Caspase-1, IL-1ß, gasdermin D (GSDMD), and VCAM-1 but increased the expression of ZO-1, Occludin, JAM-A, and Claudin-1. CONCLUSION: Taken together, these results demonstrated that AL-1 ameliorated pulmonary damage by inhibiting the activation of the NLRP3 inflammasome pathway and restoring TJ protein expression.

Preventive effect of tetramethylpyrazine on nitroglycerin-tolerance in rats by improving oxidative stress and ribosome homeostasis.

Nitroglycerin (NTG) is recommended as the first-line drug in angina pectoris though its prolonged use impacts nitroglycerin tolerance. In this study, we investigated the preventive effect of Tetramethylpyrazine (TMP), a famous Chinese medicine used for cardiovascular diseases, on NTG-induced tolerance and further explained the underlying mechanism of its action. The results revealed that pretreatment of TMP improved NTG-induced tolerance in vitro thoracic aorta rings and in rats. Proteomic analysis showed oxidative stress and ribosome proteins dyshomeostasis in NTG-tolerance vessels. TMP attenuated the oxidative stress by enhancing the protein expression of ALDH2, Nrf2 and HO-1. In addition, TMP recovered the down-regulated expression of RpL10a induced by nitroglycerin. Therefore, TMP could prevent nitroglycerin tolerance in rats, which may be mediated by up-regulation of ALDH2 and Nrf2/HO-1 signaling pathway and involved in the restoration of ribosome homeostasis. These findings indicate the potential of TMP as a promising medicine for preventing the development of nitroglycerin-induced tolerance.

Dexrazoxane Alleviated Doxorubicin-Induced Nephropathy in Rats.

INTRODUCTION: Doxorubicin (DOX), an anthracycline antitumor agent, has been widely used against various solid tumors and hematological malignancies. However, the clinical application of DOX is restricted by its multiple organ toxicity including nephrotoxicity. This study investigated the protective effects and mechanisms of dexrazoxane (DZR) against DOX-induced nephropathy in rats. METHODS: Male Sprague Dawley rats received 2.5 mg/kg DOX once a week for 5 consecutive weeks. 24-h urinary protein and renal function injury biomarkers were determined to evaluate the renal function. Histopathological changes and glomerulosclerosis were examined by hematoxylin and eosin and periodic acid-Schiff staining. The change of renal ultrastructure in the DOX-induced rats was observed by the electron microscopy. The renal apoptosis was detected by TUNEL staining and measured the protein expression of Caspase-3, Bcl-2, and Bax. Renal interstitial fibrosis was determined by Masson staining and immunohistochemistry examination. The levels of vimentin, alpha-smooth muscle actin (α-SMA), and transforming growth factor ß (TGF-ß) in kidney tissue were detected by Western blot. RESULTS: DZR pretreatment markedly raised the survival rate and improved the renal dysfunction in DOX-treated rats. DZR ameliorated DOX-induced histopathological lesion of glomerular and tubular and apoptosis. DZR restored the oxidant/antioxidant balance via regulating the levels of MDA, SOD, and TAC. DZR reduced DOX-induced collagen IV deposition and renal interstitial fibrosis and downregulated the fibrosis-related protein expressions of vimentin, α-SMA, and TGF-ß1. CONCLUSION: Our results suggest DZR exerted its protective effects against DOX-induced nephropathy through inhibition of lipid peroxidation, apoptosis, and fibrosis.

Danshensu derivative ADTM ameliorates CCl4­induced acute liver injury in mice through inhibiting oxidative stress and apoptosis.

Previous studies reported a novel danshensu derivative (R)-(3,5,6-Trimethylpyrazinyl) methyl-2-acetoxy-3-(3,4-diacetoxyphenyl) propanoate (ADTM), which conferred cardioprotective, neuroprotective and anti-thrombotic effects. Here we aim to investigate the hepatoprotective effect of ADTM on acute liver injury caused by carbon tetrachloride (CCl4) and the underlying molecular mechanisms. ADTM (30 and 60 mg/kg) was given to mice by gavage for two weeks. At the last day mice were injected with 0.3% CCl4, 10 mL/kg, ip for 24 h. Clinical and histological chemistry assays were performed to assess liver injury. Moreover, hepatic oxidative stress and apoptosis related markers were determined by western blotting. As a result, ADTM significantly protected against CCl4-induced liver injury by the decrease of elevated serum transaminases and liver index, and the attenuation of histopathological changes in mice. In addition, ADTM remarkably alleviated hepatic oxidative stress (MDA contents and SOD activity) and apoptosis. Further studies revealed that ADTM significantly inhibited the CCl4-induced upregulation of Bax/Bcl-2, increased the CCl4-induced decrease of AKT phosphorylation and inhibited the expression level of NF-κB p65 in CCl4-intoxicated mice. These findings suggest that ADTM possesses the potential protective effects against CCl4-induced liver injury in mice by exerting antioxidative stress and antiapoptosis.

A novel danshensu/tetramethypyrazine derivative attenuates oxidative stress-induced autophagy injury via the AMPK-mTOR-Ulk1 signaling pathway in cardiomyocytes.

Myocardial ischemia/reperfusion injury (MIRI) is an inevitable and unsolved clinical problem in the treatment of ischemic heart diseases. Compound DT-010 is a novel danshensu/tetramethylpyrazine derivative and was examined as a candidate for treating MIRI. In the present study, MTT, lactate dehydrogenase assay and Hoechst staining data indicated that DT-010 attenuated tert-butylhydroperoxide (t-BHP)-induced oxidative damage by increasing cell survival, reducing cell damage and decreasing apoptosis in H9c2 cardiomyocytes. Autophagy was assessed by western blotting for microtubule-associated protein 1A/1B-light chain 3 (LC3-II and LC3-I) expression, acridine orange and monodansylcadaverine staining for autophagosome formation and the monomeric red fluorescent protein-green fluorescent protein-LC3 assay for autophagic flow. t-BHP-induced cell damage was aggravated by the autophagy agonist rapamycin and alleviated by the autophagy blocker hydroxy-chloroquine, suggesting that autophagy was involved in t-BHP-induced cardiomyocyte injury. DT-010 pretreatment significantly prevented t-BHP-induced cell damage, which was partially but significantly abolished by rapamycin and significantly improved by hydroxy-chloroquine treatment. DT-010 treatment inhibited t-BHP-induced autophagy in H9c2 cells, reduced phosphorylation of 5'-AMP-activated protein kinase (AMPK) and promoted the phosphorylation of mTOR and unc-51 like autophagy activating kinase 1 (Ulk1). To conclude, DT-010 can serve as a potential candidate for myocardial ischemia-reperfusion injury therapy. The cardioprotective effects of DT-010 could be partially attributed to its inhibition of autophagy via the AMPK-mTOR-Ulk1 signaling pathway.

Andrographolide derivative AL-1 reduces intestinal permeability in dextran sulfate sodium (DSS)-induced mice colitis model.

AIMS: This study was to assess whether andrographolide derivative (AL-1) could restore mucosal homeostasis and regulate tight junctions through MLCK-dependent pathway in DSS-induced colitis mice. MAIN METHODS: Colitis mice model was induced by daily administration of 2.5% DSS for seven days. The therapeutic effect was determined by evaluating the histopathological changes and the pro-inflammatory cytokine level. In addition, the effects of AL-1 on tight junctions were examined by immunohistochemistry and Western blot. The expressions of factors in MLCK-dependent pathway were evaluated by immunofluorescence and Western blot. KEY FINDINGS: AL-1 protected the intestinal barrier function in DSS-induced colitis mice. These protective effects were achieved by maintaining the normal mucus secretion and preserving tight junctions via suppression of the MLCK-dependent pathway. SIGNIFICANCE: AL-1 could prevent the increase in the DSS-induced intestinal permeability. These data indicated that AL-1 could be a promising agent for UC treatment.

A Danshensu-Tetramethylpyrazine Conjugate DT-010 Overcomes Multidrug Resistance in Human Breast Cancer.

Background: We previously demonstrated that a Danshensu-Tetramethylpyrazine conjugate DT-010 enhanced anticancer effect of doxorubicin (Dox) in Dox-sensitive human breast cancer cells, and protected against Dox-induced cardiotoxicity. This work was designed to see whether DT-010 overcomes Dox resistance in resistant human breast cancer cells. Methods: The effects of DT-010, Dox or their combination on cell viability of Dox-resistant human breast cancer MCF-7/ADR cells were conducted using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was examined by flow cytometry after Annexin V-FITC/PI co-staining. Dox accumulation in MCF-7/ADR cells was detected by flow cytometry and fluorescence microscopy. A fluorometric multidrug resistance (MDR) assay kit was used to evaluate the effect of DT-010 on MDR transporter activity. P-glycoprotein (P-gp) expression and activity were analyzed by Western blot and rhodamine 123 (Rh123) efflux assay, respectively. The effects of DT-010 on glycolysis and mitochondrial stress were detected using an Extracellular Flux Analyzer. A Succinate Dehydrogenase Activity Assay kit was used to measure mitochondrial complex II activity. Results: At non-cytotoxic concentrations, DT-010 in combination with Dox led to a significant growth inhibition of MCF-7/ADR cells, suggesting a synergy between DT-010 and Dox to reverse Dox resistance. DT-010 restored Dox-mediated apoptosis and p53 induction in MCF-7/ADR cells. DT-010 increased Dox accumulation in MCF-7/ADR cells via inhibiting P-gp activity, but without changing P-gp expression. Further studies showed that DT-010 significantly inhibited glycolysis and mitochondrial function of MCF-7/ADR cells. Mitochondrial complex II activity was inhibited by DT-010 or DT-010/Dox combination, but not by Dox. The DT-010-mediated suppression of metabolic process may render cells more vulnerable to Dox treatment and thus result in enhanced efficacy. Conclusions: The results indicate that DT-010 overcomes Dox resistance in human breast cancer cells through a dual action via simultaneously inhibiting P-gp-mediated drug efflux and influencing metabolic process.

The novel N-methyl-d-aspartate receptor antagonist MN-08 ameliorates lipopolysaccharide-induced acute lung injury in mice.

Acute lung injury (ALI) is a clinically severe respiratory disorder, and effective therapy is urgently needed. MN-08, a novel synthetic N-methyl-d-aspartate receptor (NMDAR) antagonist, was investigated for its effect on lipopolysaccharide (LPS)-induced ALI. In vitro, the protective effect of MN-08 on inflammatory response, oxidative stress, and tight junctions (TJs) structure was explored in LPS-induced RAW 264.7 cells and A549 cells. MN-08 markedly decreased (p < 0.001) the levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and reactive oxygen species (ROS), whereas it moderately upregulated (p < 0.05) heme oxygenase (HO)-1 protein expression in LPS-induced RAW 264.7 cells. Moreover, MN-08 significantly inhibited (p < 0.001) cell apoptosis and improved (p < 0.001) protein expression of TJs in LPS-induced A549 cells. In vivo, the therapeutic effect of MN-08 was evaluated in the LPS-induced ALI model through intratracheal instillation in BALB/c mice. MN-08 administration dramatically attenuated (p < 0.001) pulmonary pathological changes and reduced (p < 0.001) the levels of glutamate, myeloperoxidase (MPO), malondialdehyde (MDA), and number of cells in BALF, whereas it increased (p < 0.05) superoxide dismutase (SOD) and glutathione (GSH) activities in ALI mice. Furthermore, MN-08 markedly blocked the mitogen-activated protein kinases (MAPKs)/nuclear translocation of nuclear factor-κB (NF-κB) signaling pathways in RAW 264.7 cells and lung tissues. These results indicate that MN-08 exhibits lung protection in an LPS-induced ALI model via anti-inflammatory and anti-oxidative activities.

A novel agent attenuates cardiotoxicity and improves antitumor activity of doxorubicin in breast cancer cells.

Doxorubicin (Dox) is a well-known chemotherapeutic agent used in the treatment of various cancers. However, Dox-induced cardiotoxicity limits its further clinical use. We have previously reported a small molecular named biotin-conjugated ADTM analog (BAA) that exhibits cytoprotective effects against oxidative stress-induced cell injury in cardiomyoblast H9c2 cells. Here, the protective effects of BAA, indexed by attenuation of the cardiotoxicity induced by Dox as well as synergistic antitumor activity that increases the chemotherapeutic efficacy of Dox were investigated. Our results demonstrated that BAA significantly ameliorated Dox-induced toxicity in the H9c2 cells and zebrafish models. In addition, BAA attenuated Dox-induced endoplasmic reticulum (ER) stress in H9c2 cells. An ER stress inhibitor, 4-phenylbutyric acid, reversed the protective effect of BAA in H9c2 cells. In contrast, in human breast tumor MDA-MB-231 cells, BAA significantly enhanced Dox-induced cytotoxicity through upregulating Dox-induced ER stress response. Taken together, our findings indicate that Dox combined with BAA can significantly enhance its antitumor activity in breast cancer cells and reduce its cardiotoxicity, at least in part, by mediating ER stress activation.

Miconazole stimulates post-ischemic neurogenesis and promotes functional restoration in rats.

Miconazole, a frequently used antifungal drug, has been identified with new functions to promote oligodendrocyte progenitor cells differentiation and to enhance remyelination. However, the neuroregenerative and therapeutic benefit of miconazole on ischemic stroke model have not been tested. In the present study, the effects of miconazole on a rat model of transient middle cerebral artery occlusion were evaluated. Rats received miconazole (10 mg/kg) or saline by intravenous administration for 7 days after stroke. A battery of neurobehavioral assessments, including rotarod test, open-field test, neurological severity score and novel object recognition task were evaluated. The results revealed a significant functional improvement in miconazole-treated rats compared with vehicle-treated control. Animals were sacrificed at 7 and 28 days after stroke. Double immunofluorescence staining for NeuN+/BrdU+, DCX+/BrdU+ and Nestin+/BrdU+ cells indicated miconazole significantly promoted neurogenesis. Western blotting analysis revealed miconazole upregulated the protein expression of brain derived neurotrophic factor, myocyte enhancer factor 2D, synaptophysin, and postsynaptic density protein 95, while downregulated the expression of cyclin-dependent kinase 5. Taken together, miconazole promoted functional recovery on ischemic stroke model via stimulating post-ischemic neurogenesis.

A Novel Tetramethylpyrazine Derivative Protects Against Glutamate-Induced Cytotoxicity Through PGC1α/Nrf2 and PI3K/Akt Signaling Pathways.

Glutamate-induced excitotoxicity is one of the main causes of neuronal cell death in stroke. Compound 22a has been previously reported as a promising neuroprotective compound derived from tetramethylpyrazine, which is a widely used active ingredient of traditional Chinese medicine Chuanxiong (Ligusticum wallichii Franchat). Compound 22a can protect neurons from oxidative stress-induced PC12 cell death and alleviates the infarct areas and brain edema in a rat permanent middle cerebral artery occlusion model. In the current work, we further investigated the neuroprotective effects and underlying mechanisms of compound 22a against glutamate-induced excitotoxicity in primary culture of rat cerebellar granule neurons (CGNs). We found that pretreatment with compound 22a prevented glutamate-induced neuronal damage by maintaining mitochondrial membrane potential and attenuating cellular apoptosis. Compound 22a could also enhance peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) transcriptional activity and induce nuclear accumulation of Nrf2 in PC12 cells. Accordingly, pretreatment with compound 22a reversed the glutamate-induced down-regulation of expression of the proteins PGC1α, transcriptional factor NF-E2-related factor 2 (Nrf2), and hemooxygenase 1 (HO-1). In addition, compound 22a increased the phosphorylation of phosphoinositide 3-kinase (p-PI3K), phosphorylated protein kinase B (p-Akt), and glycogen synthase kinase 3ß (p-GSK3ß). Meanwhile, the small interfering RNA-mediated silencing of PGC1α expression and selective inhibitors targeting PI3K/Akt (LY294002 and Akt-iv) could significantly attenuate the neuroprotective effect of compound 22a. Taken together, compound 22a protected against glutamate-induced CGN injury possibly in part through regulation of PGC1α/Nrf2 and PI3K/Akt pathways.

A Novel Tetramethylpyrazine Derivative Prophylactically Protects against Glutamate-Induced Excitotoxicity in Primary Neurons through the Blockage of N-Methyl-D-aspartate Receptor.

The over-activation of NMDA receptor via the excessive glutamate is believed to one of the most causal factors associated with Alzheimer's disease (AD), a progressive neurodegenerative brain disorder. Molecules that could protect against glutamate-induced neurotoxicity may hold therapeutic values for treating AD. Herein, the neuroprotective mechanisms of dimeric DT-010, a novel derivative of naturally occurring danshensu and tetramethylpyrazine, were investigated using primary rat cerebellar granule neurons (CGNs) and hippocampal neurons. It was found that DT-010 (3-30 µM) markedly prevented excitotoxicity of CGNs caused by glutamate, as evidenced by the promotion of neuronal viability as well as the reversal of abnormal morphological changes. While its parent molecules did not show any protective effects even when their concentration reached 50 µM. Additionally, DT-010 almost fully blocked intracellular accumulation of reactive oxygen species caused by glutamate and exogenous oxidative stimulus. Moreover, Western blot results demonstrated that DT-010 remarkably attenuated the inhibition of pro-survival PI3K/Akt/GSK3ß pathway caused by glutamate. Ca2+ imaging with Fluo-4 fluorescence analysis further revealed that DT-010 greatly declined glutamate-induced increase in intracellular Ca2+. Most importantly, with the use of whole-cell patch clamp electrophysiology, DT-010 directly inhibited NMDA-activated whole-cell currents in primary hippocampal neurons. Molecular docking simulation analysis further revealed a possible binding mode that inhibited NMDA receptor at the ion channel, showing that DT-010 favorably binds to Asn602 of NMDA receptor via arene hydrogen bond. These results suggest that DT-010 could be served as a novel NMDA receptor antagonist and protect against glutamate-induced excitotoxicity from blocking the upstream NMDA receptors to the subsequent Ca2+ influx and to the downstream GSK3ß cascade.

Neuroprotective Effect and Mechanism of Action of Tetramethylpyrazine Nitrone for Ischemic Stroke Therapy.

Our previous studies demonstrated that the multifunctional agent TBN, a derivative of tetramethylpyrazine armed with a nitrone moiety, displayed high therapeutic efficacy in experimental ischemic stroke models. However, its molecular mechanisms of action underlying the neuroprotective effect need further exploration. In the present study, we found that TBN had significant activities scavenging free radicals such as ·OH, O 2·- and ONOO-, inhibiting Ca2+ overload, maintaining mitochondrial function and preventing neuronal damage in primary cortical cultures. Further, TBN was effective in reducing brain infarction and ameliorating impairment of behavioral functions in the permanent middle cerebral artery occlusion (p-MCAo) rat model. TBN down-regulated the expression of pro-apoptotic factors Bax, while up-regulated the expression of anti-apoptotic factor Bcl-2 and increased the expression of pro-survival factors including p-Akt and p-GSK3ß in the peri-infarct cortex of p-MCAo rats. In addition, LY-294002 (a PI3K inhibitor) and MK2206 (an Akt inhibitor) significantly blocked the protective effect of TBN against OGD-induced death of cortical neurons. Taken together, the multifunctional mechanisms including scavenging free radicals, blocking calcium overload, maintaining mitochondrial function and activating the PI3K/Akt/p-GSK3ß cell survival pathway were possibly involved in the neuroprotective effects of TBN, making it a promising clinical candidate for the treatment of ischemic stroke.