Cytotoxicity to macrophages of tetrandrine, an antisilicosis alkaloid, accompanied by an overproduction of prostaglandins

Inhalation of Tetrandrine-hydroxypropyl-β-cyclodextrin Inclusion Complexes for Pulmonary Fibrosis Treatment

Pulmonary fibrosis (PF) is a kind of interstitial lung disease with the features of progressive and often fatal dyspnea. Tetrandrine (TET) is the major active constituent of Chinese herbal Stephania tetrandra S. Moore, which has already applied clinically to treat rheumatism, lung cancer, and silicosis. In this work, a tetrandrine-hydroxypropyl-β-cyclodextrin inclusion compound (TET-HP-β-CD) was developed for the treatment of pulmonary fibrosis via inhalation administration. TET-HP-β-CD was prepared by the freeze-drying method and identified using the cascade impactor, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectrum (FT-IR). A bleomycin-induced pulmonary fibrosis rat model was used to assess the effects of inhaled TET and TET-HP-β-CD. Animal survival, hydroxyproline content in the lungs, and lung histology were detected. The results showed that inhalation of TET-HP-β-CD alleviated inflammation and fibrosis, limited the accumulation of hydroxyproline in the lungs, regulated protein expression in PF development, and improved postoperative survival. Moreover, nebulized delivery of TET-HP-β-CD accumulated chiefly in the lungs and limited systemic distribution compared with intravenous administration. The present results indicated that inhalation of TET-HP-β-CD is an attractive candidate for the treatment of pulmonary fibrosis.

Self-Nanoemulsifying Drug Delivery System of Tetrandrine for Improved Bioavailability: Physicochemical Characterization and Pharmacokinetic Study

The main purpose of this study was to investigate the potential of self-nanoemulsified drug delivery system (SNEDDS) to improve the oral bioavailability of tetrandrine (Tet). SNEDDS was developed by using rational blends of excipients with good solubilizing ability for Tet which was selected based on solubility studies. Further ternary phase diagram was constructed to determine the self-emulsifying region. The optimal formulation with the best self-nanoemulsified and solubilization ability consisted of 40% (w/w) oleic acid as oil, 15% (w/w) SPC and 30% (w/w) Cremophor RH-40 as surfactant, and 15% (w/w) PEG₄₀₀ as cosurfactant. The average droplet size and zeta-potential of the optimal Tet SNEDDS were 19.75±0.37 nm and 1.87±0.26 mv, respectively. The dissolute rate of Tet SNEDDS in various dissolution media was remarkably faster than Tet commercial tablet. Moreover, in vivo pharmacokinetic study results show that significant increase (p≤ 0.05) in the peak concentration (Cmax) and the area under the curve (AUC) of Tet was observed after the oral administration of Tet SNEDDS and the absorption of Tet from SNEDDS resulted in approximately 2.33-fold increase in oral bioavailability compared with the commercial tablet. Our research suggests that the prepared Tet SNEDDS could be a good candidate for improved the dissolution and oral bioavailability of Tet.

Antimicrobial and Anti-Inflammatory Effects of Ethanol Extract of Corylopsis coreana Uyeki Flos

Background:

Corylopsis coreana Uyeki (Hamamelidaceae) is a medicinal plant cultivated in Northeast Asia. Previously, we have reported that an ethanol extract of Corylopsis coreana Uyeki flos (ECCF) contains four active compounds with antioxidant activity.

Objective:

The aim of this study was to investigate the antimicrobial spectrum against infectious bacteria and anti-inflammatory effect of ECCF in a mouse model of acute local inflammation.

Materials and Methods:

In vitro antimicrobial susceptibility was evaluated using standard plate assay technique. Antimicrobial activities (minimum inhibitory concentration, MIC; μg/mL) were determined with the serial dilution method. In vivo anti-inflammatory activity was studied using a mouse model of carrageenan-induced air pouch inflammation.

Results:

The ECCF showed antimicrobial activities against general bacteria and drug-resistant bacteria including Staphylococcus aureus, Micrococcus luteus ATCC 9341, Mycrobacterium smegmatis ATCC 9341, Mycrobacterium smegmatis ATCC 9341, Salmonella typhimrium KCTC 1925, and nine methicillin-resistant Staphylococcus aureus strains, with MIC values ranging from 250 to 1000 μg/mL. In in vivo mouse model, inflammatory morphologic changes observed in the air pouch membrane were restored to its normal condition by the ECCF treatment. Moreover, the ECCF significantly reduced exudate volumes, protein contents, inflammatory cell counts, and pro-inflammatory cytokine levels in the exudates recovered from air pouches of the mouse model. Flavonoids in the ECCF were found to contain bergenin, quercitrin, and quercetin with reported anti-inflammatory activity via suppressing tumor necrosis factor-α production.

Conclusion:

To the best of our knowledge, this is the first report to demonstrate the antimicrobial and anti-inflammatory activities of ECCF. Our results suggest that the ECCF might potentially serve as an alternative or complementary medicine for treating inflammatory diseases caused by microbial infection.

SUMMARY

ECCF showed antimicrobial activity against infectious bacteria and multidrug-resistant strains.

ECCF exhibited anti-inflammatory activity in a carrageenan-induced air pouch mouse model.

ECCF contained several active constituents such as bergenin, quercitrin, and quercetin.

Abbreviations used:Corylopsis coreana CCF: Uyeki flos, ECCF: ethanol extract of CCF

Crystalline silica incubated in ascorbic acid acquires a higher cytotoxic potential

Quartz incubated in an aqueous solution of ascorbic acid is partially dissolved and the potential to generate hydroxyl radicals from hydrogen peroxide is enhanced. In order to investigate whether the surface activation triggered by the treatment with ascorbic acid would also involve an enhancement in cell toxicity, a murine macrophage cell line (RAW 264.7) was exposed to untreated and ascorbic acid-treated quartz. Ascorbic acid pretreated quartz was more toxic than untreated quartz and all cells died within 24 hours after exposure. Tetrandrine (a Chinese drug employed to retard or reverse fibrotic lesions of silicosis in humans) partially reduced cell toxicity generated by ascorbic acid pretreated quartz.

The inhibitory activity of cocoa phenolic extract against pro-inflammatory mediators secretion induced by lipopolysaccharide in RAW 264.7 cells

Cocoa is a rich source of polyphenols that has been traditionally used as the treatment of several types of inflammation related disease. The response to inflammation comprises the consecutive release of mediators and the enlistment of circulating leukocytes, such as macrophages. Currently, Cocoa-derived polyphenolics have shown anti-inflammatory effects in vivo, but the therapeutic benefits in vitro remain unclear. Therefore, in this study, the effect of cocoa polyphenolic extract (CPE) on RAW 264.7 macrophage cells sensitized by lipopolysaccharide as in vitro inflammatory model was investigated. The anti-inflammatory activity of CPE was assessed by measuring its ability to inhibit the pro-inflammatory enzyme 5-lipoxygenase (5-LOX) and the pro-inflammatory mediators prostaglandin E₂ (PGE₂), reactive oxygen species (ROS), nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α). The results show that CPE significantly inhibits 5-LOX activity (p < 0.01). In addition, CPE dose-dependently suppressed the production of PGE₂, ROS, NO and TNF-α in RAW 264.7 cells. These data suggest that CPE may be used for the treatment of inflammation and it’s related-diseases.

Tetrandrine is a potent cell autophagy agonist via activated intracellular reactive oxygen species

Background

Autophagy is an evolutionarily conserved cellular process that involves the lysosomal degradation of proteins and organelles and the recycling of cellular components to ensure cellular survival under external or internal stress. Numerous data has indicated that autophagy can be successfully targeted for the treatment of multiple cancers. We have previously demonstrated that tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent antitumor effects when used either alone or in combination with other drugs.

Results

In the present study, we showed that tetrandrine is a broad-spectrum potent autophagy agonist. Although low-dose tetrandrine treatment does not affect cell viability, it can potently induce autophagy in a variety of cell lines, including cancerous cells and nontumorigenic cells. The autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ), effectively blocked tetrandrine-induced autophagy. Moreover, tetrandrine significantly triggered the induction of mitophagy. The underlying mechanisms are associated with the tetrandrine-induced production of intracellular reactive oxygen species (ROS), which plays a critical role in tetrandrine-induced autophagy.

Conclusions

Here, we report that tetrandrine is a potent cell autophagy agonist and may have a wide range of applications in the fields of antitumor therapy and basic scientific research.

c-Jun NH2-terminal kinase-induced proteasomal degradation of c-FLIPL/S and Bcl2 sensitize prostate cancer cells to Fas- and mitochondria-mediated apoptosis by tetrandrine

Tetrandrine, a constituent of Chinese herb Stephania tetrandra, causes cell death in prostate cancer, but the molecular mechanisms leading to apoptosis is not known. Here we demonstrated that tetrandrine selectively inhibits the growth of prostate cancer PC3 and DU145 cells compared to normal prostate epithelial PWR-1E cells. Tetrandrine-induced cell death in prostate cancer cells is caused by reactive oxygen species (ROS)-mediated activation of c-Jun NH2-terminal kinase (JNK1/2). JNK1/2-mediated proteasomal degradation of c-FLIPL/S and Bcl2 proteins are key events in the sensitization of prostate cancer cells to Fas- and mitochondria-mediated apoptosis by tetrandrine. Tetrandrine-induced JNK1/2 activation caused the translocation of Bax to mitochondria by disrupting its association with Bcl2 which was accompanied by collapse of mitochondrial membrane potential (MMP), cytosolic release of cytochrome c and Smac, and apoptotic cell death. Additionally, tetrandrine-induced JNK1/2 activation increased the phosphorylation of Bcl2 at Ser70 and facilitated its degradation via the ubiquitin-mediated proteasomal pathway. In parallel, tetrandrine-mediated ROS generation also caused the induction of ligand-independent Fas-mediated apoptosis by activating procaspase-8 and Bid cleavage. Inhibition of procaspase-8 activation attenuated the cleavage of Bid, loss of MMP and caspase-3 activation suggest that tetrandrine-induced Fas-mediated apoptosis is associated with the mitochondrial pathway. Furthermore, most of the signaling effects of tetrandrine on apoptosis were significantly attenuated in the presence of antioxidant N-acetyl-l-cysteine, thereby confirming the involvement of ROS in these events. In conclusion, the results of the present study indicate that tetrandrine-induced apoptosis in prostate cancer cells is initiated by ROS generation and that both intrinsic and extrinsic pathway contributes to cell death.

Tetrandrine induces mitochondria-mediated apoptosis in human gastric cancer BGC-823 cells

Tetrandrine, a bis-benzylisoquinoline alkaloid isolated from the dried root of Hang-Fang-Chi (Stephaniatetrandra S. Moore), has been reported to possess anti-cancer effects on many tumors. In this study, we investigated tetrandrine-induced apoptosis on human gastric cancer BGC-823 cells in vitro and in vivo. The results showed that tetrandrine significantly inhibited cell viability in a dose- and time-dependent manner and induced apoptosis. It increased the apoptosis; upregulation of Bax, Bak, and Bad; and downregulation of Bcl-2 and Bcl-xl in BGC-823 cells. Moreover, tetrandrine increased the activation of caspase-3 and -9, release of cytochrome c, and upregulation of apaf-1, suggesting that tetrandrine-induced apoptosis was related to the mitochondrial pathway. Meanwhile, pretreatment with the pan-caspase inhibitor z-VAD-fmk in BGC-823 cells reduced tetrandrine-induced apoptosis by blocking activation of caspases. Furthermore, tetrandrine effectively inhibited tumor growth via apoptosis induction, which was verified by immunohistochemical analysis in a nude mouse xenograft model. Taken together, we concluded that tetrandrine significantly inhibited the proliferation of gastric cancer BGC-823 cells through mitochondria-dependent apoptosis, which may play a promising role in gastric cancer therapy.

Autophagy-related gene 7 (ATG7) and reactive oxygen species/extracellular signal-regulated kinase regulate tetrandrine-induced autophagy in human hepatocellular carcinoma

Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent antitumor effects and has the potential to be used as a cancer chemotherapeutic agent. We previously reported that high concentrations of tetrandrine induce apoptosis in liver cancer cells. Here, we found that in human hepatocellular carcinoma (HCC) cells, a low dose of tetrandrine (5 μm) induced the expression of LC3-II, resulted in the formation of acidic autophagolysosome vacuoles (AVOs), and caused a punctate fluorescence pattern with the GFP-LC3 protein, which all are markers for cellular autophagy. Tetrandrine induced the production of intracellular reactive oxygen species (ROS), and treatment with ROS scavengers significantly abrogated the tetrandrine-induced autophagy. These results suggest that the generation of ROS plays an important role in promoting tetrandrine-induced autophagy. Tetrandrine-induced mitochondrial dysfunction resulted in ROS accumulation and autophagy. ROS generation activated the ERK MAP kinase, and the ERK signaling pathway at least partially contributed to tetrandrine-induced autophagy in HCC cells. Moreover, we found that tetrandrine transcriptionally regulated the expression of autophagy related gene 7 (ATG7), which promoted tetrandrine-induced autophagy. In addition to in vitro studies, similar results were also observed in vivo, where tetrandrine caused the accumulation of ROS and induced cell autophagy in a tumor xenograft model. Interestingly, tetrandrine treatment also induced autophagy in a ROS-dependent manner in C. elegans muscle cells. Therefore, these findings suggest that tetrandrine is a potent autophagy agonist and may be a promising clinical chemotherapeutic agent.

Synergistic anti-inflammatory effects of Laminaria japonica fucoidan and Cistanche tubulosa extract

The anti-inflammatory effects of fuciodan and Cistanche tubulosa (CT) extract were investigated in vitro macrophage culture system and in vivo carrageenan-induced air pouch inflammation model. CT extract inhibited nitric oxide production from activated RAW 264.7 macrophage cells, while fucoidan was inactive. In vivo air pouch inflammation model, carrageenan-induced vascular exudation and increased nitric oxide and prostaglandin E₂ concentrations in the exudates were synergistically suppressed by co-administration of fucoidan or CT extract. Moreover, tissue inflammation was substantially attenuated by the combinational therapy. However, there was no synergistic effect against the inflammatory cell infiltration, although fucoidan and CT extract each markedly reduced the cell numbers. Therefore, it is suggested that fucoidan blocks infiltration of inflammatory cells, while CT extract inhibits activation of the cells, and that their combinational treatment could be a promising candidate for the relief of various types of inflammation.

Enhancement of radiosensitivity and the potential mechanism on human esophageal carcinoma cells by tetrandrine

The purposes of this study were to test the effect of tetrandrine, alone or combined with radiation, on human esophageal cancer cell line TE1 (TE1 cells) and investigate the potential antitumor mechanism. Human esophageal cancer cell line TE1 was tested by methyl thiazolyl tetrazolium assay for cell proliferation, colony-forming assay for cell radiosensitivity, flow cytometry assay for cell cycle distribution, and western blot assay for cell cycle protein expression. When treated alone, tetrandrine had a time- and concentration-dependent cytotoxic effect on TE1 cells. The dose-enhancement ratio for combined tetrandrine and radiation was markedly increased when compared with tetrandrine alone. Further, expression of cyclin B1 protein increased after addition of tetrandrine when compared with radiation only. Radiation-induced G2 arrest was abrogated with treatment of tetrandrine. In conclusion, tetrandrine can enhance the radiosensitivity of TE1 cells and this may involve relief of radiation-induced G2/M arrest in TE1 cells.

Characterisation of the anti-inflammatory and antinociceptive activities and the mechanism of the action of Lippia gracilis essential oil

ETHNOPHARMACOLOGICAL RELEVANCE

The species Lippia gracilis Schauer, known in Brazil as "Alecrim-da-chapada", is popularly used in folk medicine to treat cough, bronchitis, nasal congestion, and headache.

MATERIALS AND METHODS

Lippia gracilis essential oil (EO; 10, 30, and 100mg/kg, p.o.) and the reference drugs morphine (5mg/kg, p.o.) and acetylsalicylic acid (ASA; 200mg/kg, p.o.) were evaluated using models for analgesia (acetic acid-induced contortion, formalin-induced licking, and hot plate) or inflammation (formalin-induced licking response and subcutaneous air pouch model). To elucidate the antinociceptive mechanism of action, animals were pre-treated with naloxone (opioid receptor antagonist; 1mg/kg, i.p.), atropine (cholinergic antagonist; 1mg/kg, i.p.) or l-nitro arginine methyl ester (L-NAME; 3mg/kg, i.p.) 30 min prior to oral administration of EO.

RESULTS

EO significantly inhibited the number of writhings in acetic acid-induced contortions and the time that the animal spent licking the formalin-injected paw (second phase). All doses of EO increased the baseline and the area under the curve in the hot plate model. The administration of naloxone did not reverse the antinociceptive effect of EO in the acetic acid-induced contortion and formalin-induced licking models. L-NAME and atropine significantly reversed the effect of EO in the models of contortion, formalin, and hot plate. EO also inhibited the inflammatory process induced by subcutaneous carrageenan injection, reducing cell migration, exudate volume, extravased protein, and inflammatory mediators (nitric oxide, prostaglandin E2, TNF-α, and IFN-γ) produced in the pouch.

CONCLUSIONS

Our results indicate that the essential oil from Lippia gracilis produces an antinociceptive effect that could be potentially mediated by cholinergic receptors and the nitric oxide pathway. Our data also suggest that the anti-inflammatory activity caused by EO exposure occurs through inhibition of nitric oxide and PGE2 production.

Characterisation of the anti-inflammatory and antinociceptive activities of the Hyptis pectinata (L.) Poit essential oil

AIM OF THE STUDY

Hyptis pectinata Poit (Lamiaceae) is grown in the northeastern regions of Brazil and is popularly known as "sambacaitá" or "canudinho". It is extensively used in folk medicine to treat inflammatory conditions, bacterial infections, pain, and cancer.

MATERIALS AND METHODS

Hyptis pectinata essential oil (EO, 10, 30, and 100mg/kg, p.o.) and the reference drugs morphine (5mg/kg, p.o.) and acetylsalicylic acid (ASA, 200mg/kg, p.o.) were evaluated using models for analgesia (acetic acid-induced contortions and hot plate) or inflammation (formalin-induced licking response and the subcutaneous air-pouch model). To elucidate the EO's mechanism of action, animals were pre-treated with the opioid receptor antagonist naloxone (1mg/kg, i.p.), the cholinergic antagonist atropine (1mg/kg, i.p.), or l-nitro arginine methyl ester (l-NAME, 3mg/kg, i.p.) 30 min prior to the oral administration of the EO.

RESULTS

The EO significantly inhibited the number of writhings and the time the animals spent licking their formalin-injected paws (second phase). The EO, at doses of 30 and 100mg/kg, increased baseline measurements and area under the curve measurements in the hot plate model, respectively. The administration of naloxone reversed the antinociceptive effect of the EO in the hot plate model. l-NAME significantly reversed the effects of the EO in the contortions and hot plate models. Atropine completely reversed the antinociceptive activity of the EO in all models. Additionally, the EO inhibited the inflammatory process induced by subcutaneous carrageenan injection by reducing cell migration, exudate volume, protein concentration, and inflammatory mediators (nitric oxide, prostaglandin E2, IL-6, and TNF-α) produced in the pouch.

CONCLUSIONS

Our results indicate that the Hyptis pectinata essential oil exhibits antinociceptive effects, likely mediated by opioid and cholinergic receptors, and anti-inflammatory activity through the inhibition of nitric oxide and PGE2 production.

Tetrandrine induces apoptosis by activating reactive oxygen species and repressing Akt activity in human hepatocellular carcinoma

Tetrandrine, a bisbenzylisoquinoline alkaloid component of broadly used traditional Chinese medicine, has antitumor effects against some cancers. In our study, we investigated the effects of tetrandrine on the human hepatocellular carcinoma (HCC) in vitro and in vivo. The results showed that tetrandrine effectively induced apoptosis of liver cancer cell in a dose- and time-dependent manner accompanied by alteration of cell morphology, chromatin fragmentation and caspase activation. Tetrandrine treatment also induced intracellular accumulation of reactive oxygen species (ROS), and ROS scavengers (LNAC and GSH) completely blocked the effects of tetrandrine-induced apoptosis, suggesting that the generation of ROS plays an important role in tetrandrine-induced apoptosis. Although the activities of JNK and ERK were inhibited significantly by tetrandrine treatment, JNK and ERK are not involved in the tetrandrine-induced apoptosis. In contrast, Akt activity was found to be closely related to tetrandrine-induced apoptosis. The data demonstrated that Akt activity inhibitor LY294002 synergistically promoted tetrandrine-induced apoptosis of HCC, whereas ectopic expression of Akt contrastly abrogated partial of the tetrandrine-induced apoptosis. These data suggest that Akt signal is the downstream event of ROS generation in the tetrandrine-induced HCC cell apoptosis. Moreover, the results of xenograft in nude mice were consistent with that of the in vitro studies. Therefore, our data suggest that tetrandrine may be a promising agent for the treatment of HCC as a regulator of ROS/Akt pathway.

The genus Stephania (Menispermaceae): chemical and pharmacological perspectives

The plants of the genus Stephania (Menispermaceae) are widely distributed, and have long been used in folk medicine for the treatment of various ailments such as asthma, tuberculosis, dysentery, hyperglycemia, malaria, cancer and fever. Over 150 alkaloids together with flavonoids, lignans, steroids, terpenoids and coumarins have been identified in the genus, and many of these have been evaluated for biological activity. This review presents comprehensive information on the chemistry and pharmacology of the genus together with the traditional uses of many of its plants. In addition, this review discusses the structure-activity relationship of different compounds as well as recent developments and the scope for future research in this aspect.

Ethanol extract of Angelica gigas inhibits croton oil-induced inflammation by suppressing the cyclooxygenase - prostaglandin pathway

The anti-inflammatory effects of an ethanol extract of Angelica gigas (EAG) were investigated in vitro and in vivo using croton oil-induced inflammation models. Croton oil (20 microg/mL) up-regulated mRNA expression of cyclooxygenase (COX)-I and COX-II in the macrophage cell line, RAW 264.7, resulting in the release of high concentrations of prostaglandin E(2) (PGE(2)). EAG (1 approximately 10 microg/mL) markedly suppressed croton oil-induced COX-II mRNA expression and PGE(2) production. Application of croton oil (5% in acetone) to mouse ears caused severe local erythema, edema and vascular leakage, which were significantly attenuated by oral pre-treatment with EAG (50 approximately 500 mg/kg). Croton oil dramatically increased blood levels of interleukin (IL)-6 and PGE(2) without affecting tumor-necrosis factor (TNF)-alpha and nitric oxide (NO) levels. EAG pre-treatment remarkably lowered IL-6 and PGE(2), but did not alter TNF-alpha or NO concentrations. These results indicate that EAG attenuates inflammatory responses in part by blocking the COX - PGE(2) pathway. Therefore, EAG could be a promising candidate for the treatment of inflammatory diseases.

Anti-inflammatory effects of an ethanol extract of Angelica gigas in a Carrageenan-air pouch inflammation model

Anti-inflammatory effects of an ethanol extract of Angelica gigas (EAG; 50, 160, or 500 mg/kg) were investigated in a carrageenan-induced air pouch inflammation model. Injection of 1 ml of carrageenan (1%) into mouse air pouches markedly increased the exudate volume and exudate albumin concentration, which were significantly attenuated by oral pretreatment with EAG. EAG also markedly reduced carrageenan-induced infiltrations of neutrophils, monocytes, and lymphocytes, but did not influence eosinophils or basophils. Carrageenan dramatically increased levels of tumor necrosis factor-alpha and interleukin-6, which might be derived from the infiltrated cells. It also elevated nitric oxide, and slightly increased prostaglandin E(2). EAG pretreatment significantly lowered tumor necrosis factor-alpha and nitric oxide, but did not alter interleukin-6 or prostaglandin E(2) levels. These results indicate that EAG attenuates some inflammatory responses by blocking the tumor necrosis factor-alpha-nitric oxide pathway, and that EAG could be a promising anti-inflammatory drug candidate for inflammatory diseases.

Synergistic effect of ERK inhibition on tetrandrine-induced apoptosis in A549 human lung carcinoma cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to have anti-tumor activity in various malignant neoplasms. However, the precise mechanism by which TET inhibits tumor cell growth remains to be elucidated. The present studies were performed to characterize the potential effects of TET on phosphoinositide 3-kinase/Akt and extracellular signal-regulated kinase (ERK) pathways since these signaling pathways are known to be responsible for cell growth and survival. TET suppressed cell proliferation and induced apoptosis in A549 human lung carcinoma cells. TET treatment resulted in a down-regulation of Akt and ERK phosphorylation in both time-/concentration-dependent manners. The inhibition of ERK using PD98059 synergistically enhanced the TET-induced apoptosis of A549 cells whereas the inhibition of Akt using LY294002 had a less significant effect. Taken together, our results suggest that TET: i) selectively inhibits the proliferation of lung cancer cells by blocking Akt activation and ii) increases apoptosis by inhibiting ERK. The treatment of lung cancers with TET may enhance the efficacy of chemotherapy and radiotherapy and increase the apoptotic potential of lung cancer cells.

Tetrandrine suppresses tumor growth and angiogenesis of gliomas in rats

Tetrandrine, a bisbenzylisoquinoline alkaloid, has antitumor effects against some cancers, but its effects on gliomas are unknown. In this study, we investigated the effects of tetrandrine on the growth and angiogenesis of rat RT-2 gliomas. We treated RT-2 glioma cells with tetrandrine and then measured cytotoxicity, apoptosis and expression of vascular endothelial growth factor (VEGF). We also examined the cytotoxic effect of tetrandrine on the ECV304 human umbilical vein endothelial cells and the effects of tetrandrine on the in vivo angiogenesis. Tumor size and animal survival were followed in tetrandrine-treated rats with subcutaneous or intracerebral gliomas. Expression of CD31 in tetrandrine-treated gliomas was followed to study its effect on glioma-induced angiogenesis. Tetrandrine had cytotoxic effects and induced apoptosis of glioma cells in a concentration- and time-dependent manner. Tetrandrine also inhibited the expression of VEGF in glioma cells, induced cytotoxicity effect on the ECV304 cells and suppressed the in vivo angiogenesis. Tetrandrine (150 mg/kg/day) had significant antitumor effects on subcutaneous tumors and led to slower tumor growth rate, longer animal survival time and higher animal survival (p < 0.05). Tetrandrine also affected intracerebral tumors and prolonged animal survival (p < 0.05) without affecting survival rate. Immunohistochemical analyses showed that the subcutaneous gliomas from tetrandrine-treated rats had fewer microvessel densities than control rats (p = 0.01). The results demonstrate that tetrandrine is cytotoxic to RT-2 glioma cells, has antitumor effects on subcutaneous and intracerebral gliomas, and inhibits angiogenesis in subcutaneous gliomas. Tetrandrine has potential as a treatment for gliomas.

Differential effects of triptolide and tetrandrine on activation of COX-2, NF-kappaB, and AP-1 and virus production in dengue virus-infected human lung cells

Most virus infections induce cycloxygenase-2 (COX-2) expression and subsequent prostaglandin E₂ (PGE₂) production in cells, an inflammatory response that might be detrimental to virus replication and pathogenesis. This response in dengue virus infection remains to be elucidated. Triptolide and tetrandrine, compounds derived from two commonly used Chinese herbs, both demonstrate anti-inflammatory and immunosuppressive effects partly through modulation of COX-2 expression and, hence, may have antiviral effects. In this study, we examined, firstly, the immune response to dengue virus infection with respect to COX-2 expression and PGE₂ production in human lung cells (A549), liver cells (HepG2) and dendritic cells. Secondly, we assessed the potential antiviral effects of triptolide and tetrandrine on dengue virus infection vis-à-vis expression of COX-2, PGE₂, transcription factors, as well as virus production. We found that dengue virus infection enhanced COX-2 expression and PGE₂ production in A549 cells, similarly to the response in dendritic cells, but not in HepG2 cells. In dengue virus-infected A549 cells, nuclear factor κB (NF-κB) and activator protein 1 (AP-1) were also activated, and both were dose-dependently inhibited by triptolide (0.5–4 ng/ml). Tetrandrine (1–10 μM) had no similar immunosuppressive effects and, moreover, at higher concentrations, enhanced NF-κB and AP-1 activity, COX-2 expression and PGE₂ production. However, unexpectedly, tetrandrine, but not triptolide, dose-dependently suppressed dengue virus production in A549 cells, independent of PGE₂ level. Our findings imply that triptolide and tetrandrine may attenuate dengue virus infection in human lung cells, but through distinct pathways.

A comparative study of grape seed extract and vitamin E effects on silica-induced pulmonary fibrosis in rats

Due to the production of reactive oxygen species (ROS), oxidative stress has been implicated in the pathogenesis of silica-induced lung fibrosis. So it is hypothesized that grape seed extract (GSE) or vitamin E (Vit E) as antioxidants may ameliorate some symptoms of the disease. Male Wistar albino rats were divided into 7 groups: rats in group I instilled intratracheally (IT) with a single dose of silica suspension (50mg/rat) as positive control (PC). Treatment groups (II-IV) received Vit E (20 IU/kg/day), GSE (150 mg/kg/day), or Vit E+GSE simultaneously orally 1 day after instillation of silica. Groups V and VI were given oral GSE or Vit E after instillation of the equivalent volume of saline (IT) as controls for GSE or Vit E. Rats of group VII only instilled saline (IT) as negative control. After 90 days animals were sacrificed and plasma-malondialdehyde (p-MDA) and lung tissue hydroxyproline (HP) were quantified. The lungs were also investigated for histopathological changes. The mean concentrations of p-MDA and HP in studied groups (I-VII) were 1.95, 2.77, 0.72, 0.81, 0.64, 0.94, 1.02 micromolMDA/L(plasma) and 28.476, 27.85, 22.83, 22.64, 15.40, 18.31, 18.51 mgHP/g(tissue), respectively. Silica caused a significant increase in HP content of lungs and MDA levels in the plasma except in GSE-treated groups (III and IV). According to the results of this study GSE could reduce the fibrogenic effect of silica. However; no synergistic effect was observed after co-administration of GSE and Vit E.

Tetrandrine Inhibits Proinflammatory Cytokines, iNOS and COX-2 Expression in Human Monocytic Cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid isolated from the dried root of hang-fang-chi (Stephania tetrandra S. Moore), is traditionally used in China for treating inflammation, hypertension and silicosis. In this study, our aim was to examine the anti-inflammatory mechanism of TET through measuring the inducible nitric oxide synthase (iNOS), cyclooxygenase-1, and -2 (COX-1 and COX-2) expression, cytokines (TNF-alpha, IL-4 and IL-8) formation, nitric oxide (NO) release and prostaglandin E2 (PGE2) generation in lipopolysaccharide (LPS)-induced human monocytic (THP-1) cells. Results showed that TET remarkably suppressed the LPS (1 microg/ml) induction of NO release and PGE2 generation. It also significantly attenuated the LPS-induced transcription of proinflammatory cytokines (TNF-alpha, IL-4 and IL-8) in a dose-dependent manner. Furthermore, TET at 100 microM significantly blocked the LPS induction of iNOS and COX-2 expression, but not the COX-1. Taken together, these results suggest that TET exerts anti-inflammatory effects probably through the suppression of COX-2 and iNOS expression.

Tetrandrine and thapsigargin release arachidonic acid from cells in culture and stimulate prostacyclin production in rat liver cells, but may do so by different pathways

Background

Tetrandrine inhibits tumor cell proliferation and demonstrates chemoprevention in cancer models. Speculation on the association between its effects on K⁺ and Ca²⁺ channels and cancer chemoprevention has been made. Thapsigargin also affects K⁺ and Ca²⁺ conductance. Thapsigargin, however, is a weak tumor promoter in the two-stage model of mouse skin carcinogenesis, yet it can induce apoptosis in androgen-independent prostatic cancer cells. I have postulated that arachidonic acid release from cells in culture is associated with cancer chemoprevention. The effects of tetrandrine and thapsigargin on arachidonic acid release from human colon carcinoma and rat liver cells and prostacyclin production by rat liver cells are compared in the current studies.

Results

Tetrandrine and thapsigargin stimulate arachidonic acid release from human colon carcinoma and rat liver cells and prostacyclin production in rat liver cells. The stimulation by tetrandrine is not affected by incubation with actinomycin D, 100 mM KCl, the [Ca²⁺]_i chelator, 1,2-bis (o-amino-5-fluorophenoxy) ethane-N,N,N',N',-tetraacetic acid tetraacetoxymethylester (BAPTA/AM) or in the absence of extracellular Ca²⁺. In contrast, stimulation by thapsigargin is inhibited by incubation with actinomycin D, 100 mM KCl, BAPTA/AM or in the absence of extracellular Ca²⁺.

Conclusion

Both tetrandrine and thapsigargin stimulate arachidonic acid release, but based on the different results obtained in the presence of actinomycin D, the [Ca²⁺]_i chelator, 100 mM KCl and in the absence of extracellular Ca²⁺, the mechanisms leading to this release and pathways leading to apoptosis and/or cancer chemoprevention may be different. Stimulations by tetrandrine may be mediated by activation of a secretory phospholipase A₂, whereas thapsigargin's stimulations may be mediated by the cytoplasmic Ca²⁺-dependent phospholipase A₂.

Total assignment and structure in solution of tetrandrine by NMR spectroscopy and molecular modelling

High-resolution 1- and 2D NMR spectra of tetrandrine and molecular modelling were employed to characterise its structure in solution. Complete and unambiguous assignment of all proton and carbon resonance signals is reported. Scalar couplings were determined from dihedral angles with the Karplus equation. Inter-proton distances were evaluated from NOE correlation peaks. Comparison of simulated and X-ray conformations of tetrandrine reveals only small differences.

Tetrandrine-induced apoptosis is mediated by activation of caspases and PKC-δ in U937 cells

Tetrandrine, which is isolated from Chinese herb Stephania tetrandrae, possesses anti-inflammatory, immunosuppressive, and cytoprotective properties. Though it was previously shown that tetrandrine causes a G1 blockade and apoptosis in various cell types, however, the mechanism by which tetrandrine initiates apoptosis remains poorly understood. In present study, we investigated the mechanisms of apoptosis induced by tetrandrine in U937 leukemia cells. Tetrandrine inhibited U937 cell growth by inducing apoptosis. After treatment of U937 cells with tetrandrine (10microM) for 24h, alteration of cell morphology, chromatin fragmentation, cytochrome c release, and caspase activation were observed. Tetrandrine also induced early oxidative stress, which resulted in activation of JNK, but not ERK and p38 MAPK. A broad-spectrum caspase inhibitor and antioxidants significantly blocked tetrandrine-induced caspase-3 activation. However, inhibition of the JNK activity with SP600125 did not block tetrandrine-induced apoptosis. Tetrandrine-induced apoptosis of U937 cells also required activity of PKC-delta, because pretreatment with a specific PKC-delta inhibitor greatly blocked tetrandrine-induced caspase-3 activation. In addition, the apoptotic response to tetrandrine was significantly attenuated in dominant-negative PKC-delta transfected MCF-7 cells, suggesting that PKC-delta plays an important role in tetrandrine-induced apoptosis and can induce caspase activation. These results suggest that tetrandrine induces oxidative stress, JNK activation, and caspase activation. However, JNK activation by ROS is not involved in the tetrandrine-induced apoptosis. In addition, tetrandrine induces caspase-dependent generation of a catalytically active fragment of PKC-delta, and this fragment also appears to play a role in the activation of caspases.

Atractylodes japonica Suppresses Lipopolysaccharide-Stimulated Expressions of Inducible Nitric Oxide Synthase and Cyclooxygenase-2 in RAW 264.7 Macrophages

Atractylodes japonica has traditionally been used for the treatment of pain and arthritis. The effect of Atractylodes japonica against lipopolysaccharide-induced inflammation was investigated using reverse transcription-polymerase chain reaction (RT-PCR), nitric oxide detection, and prostaglandin E2 (PGE2) immunoassay in mouse RAW 264.7 macrophages. The aqueous extract of Atractylodes japonica suppressed nitric oxide production and PGE2 synthesis by inhibition of the lipopolysaccharide-stimulated enhancement of inducible nitric oxide synthase and cyclooxygenase-2 mRNAs expressions in RAW 264.7 macrophages. These results suggest that Atractylodes japonica exerts anti-inflammatory and analgesic effects probably by suppression of the inducible nitric oxide synthase and cyclooxygenase-2 expressions.

Warifteine and milonine, alkaloids isolated from Cissampelos sympodialis Eichl: cytotoxicity on rat hepatocyte culture and in V79 cells

Two alkaloids were isolated from the leaves of Cissampelos sympodialis; a bisbenzylisoquinoline compound named warifteine and a novel 8,14-dihydromorphinandienone alkaloid named milonine. The cytotoxic effects of these alkaloids were assayed in cultured hepatocytes and V79 fibroblasts. Three independent endpoint assays for cytotoxicity in vitro were used: the nucleic acid content (NAC), tetrazolium reduction (MTT) and neutral red uptake (NRU). Milonine was less toxic than warifteine in both cell cultures. The IC50 values determined in the three different viability assays were around 100 and 400 microM after milonine treatment of V79 cells or hepatocytes. IC50 values ranging from 10 to 35 microM were obtained for warifteine in the viability tests evaluated in V79 cells and hepatocytes. Due to the similar cytotoxic effects detected on V79 cells and hepatocytes, probably warifteine and milonine induced toxic effects independent to the cytochrome P450. This hypothesis was corroborated by the results where Cimetidine (1.0 mM), a traditional cytochrome P450 inhibitor, did not protect the cells from the toxic action of warifteine or milonine. In conclusion, these alkaloids merit further investigations as potential novel pharmacological agents although milonine was less toxic than warifteine in the cells models investigated.

Tetrandrine cytotoxicity and its dual effect on oxidative stress-induced apoptosis through modulating cellular redox states in Neuro 2a mouse neuroblastoma cells

Tetrandrine (TET), a plant alkaloid, is known primarily as a non-selective Ca(2+) channel blocker. On the contrary to the cytoprotective effect on ischemia/reperfusion injury, TET has also been reported to cause cytotoxicity. In this study, we wished to understand the apparently disparate effects of this potential drug and thus investigated molecular mechanisms on proliferation and apoptosis and its effect on oxidative stress-induced apoptosis in Neuro 2a mouse neuroblastoma cells. We showed that TET, at high concentrations, induced cell cycle arrest and apoptosis through oxidative stress with following observations. Firstly, 10 microM TET elevated the reactive oxygen species (ROS) level and accordingly depleted glutathione (GSH) content. Secondly, pretreatment with antioxidants (NAC or GSH) protected cells from TET-induced apoptosis. We also demonstrated that treatment with 10 microM TET caused not only induction of p53, p21(waf1), and Bax, but also nuclear translocation of p53 and hypo-phosphorylation of pRb concurrently. Our important finding is that the concentration-dependent dual effect of TET, either inhibiting or promoting cell death induced by H(2)O(2) was observed, probably through regulating redox balance, which was well reflected on the GSH content in each condition. Besides, inhibition of Ca(2+) influx protected cells from H(2)O(2)-induced apoptosis even in the presence of 10 microM TET. Taken together, our data suggest that TET regulation of cellular redox states may play a major role in its dual action of cytotoxicity and cytoprotection.

Plant alkaloid tetrandrine and its analog block CD28-costimulated activities of human peripheral blood T cells: potential immunosuppressants in transplantation immunology

BACKGROUND

T lymphocyte activation mediated by CD28 costimulation plays a critical role in graft rejection. Plant alkaloid tetrandrine, purified from a Chinese antirheumatic herb, is a potent immunosuppressant. Here, we examined its effects on several CD28-costimulated T-cell activities. In addition, such effects were readily compared with the effects of three tetrandrine analogs.

METHODS

T lymphocytes were purified from whole blood by negative selection. The stimuli that mimic CD28 costimulation included both anti-CD3 + anti-CD28 monoclonal antibody and PMA+anti-CD28 monoclonal antibody. The determination of CD28-costimulated cell proliferation was performed by tritium uptake, cytokine production by ELISA, cell surface interleukin 2Ra and CD69 expression by flow cytometry, and mixed leukocyte reaction by tritium uptake. Drug cytotoxicity was determined by trypan blue exclusion, propidium iodide staining, and MTT colorimetric assays.

RESULTS

Tetrandrine inhibited CD28-costimulated T-cell proliferation and cytokine production through a mechanism different from that of cyclosporine. In addition, tetrandrine down-regulated both T helper 1 and T helper 2 cytokine production in CD4+ and CD8+ T-cell subpopulations. By examining cytokine production and T-cell activation marker expression, we further demonstrated that, among tetrandrine and its analogs tested, dauricine was the most potent suppressor of CD28-costimulated T-cell activities. Furthermore, the different immunosuppressive activities of these compounds were not associated with their cytotoxic capacities. Finally, the unparalleled inhibitory potency of dauricine on both mixed leukocyte reaction and CD28-costimulated T-cell proliferation suggests that dauricine preferentially targeted CD28-costimulated T-cell activities.

CONCLUSIONS

This is the first report to show that tetrandrine and its analogs potently inhibited both PMA+CD28-costimulated and CD3 + CD28-costimulated activation of human peripheral blood T cells. Based upon their structural similarity and different immunosuppressive potency, these in vitro data also provide very useful information for further identification and development of more potent and less toxic immunosuppressants to achieve transplantation success.

Liposomes, micelles and microemulsions as new delivery systems for cytotoxic alkaloids

This review describes the design and performance of specialized delivery systems, such as liposomes, micellar solutions and microemulsions, for the administration of cytotoxic alkaloids. Special attention is directed towards three types of compound, Vinca, Camptotheca and Taxus alkaloids, which have been previously indicated as of promise as antitumour agents but which still present serious drawbacks. In this respect, this review analyses different delivery strategies that are able to substantially improve the therapeutic applicability of such antitumour drugs.

Plant alkaloid tetrandrine downregulates protein kinase C-dependent signaling pathway in T cells

Tetrandrine, a purified traditional Chinese medicinal herb that acts as an immunosuppressant and a Ca2+ channel blocker, has been clinically used to treat patients with arthritis, silicosis and hypertension. Since T cells play a critical role as autoreactive and pathogenic population in autoimmune diseases, in this study, we examined the immunosuppressive effect of tetrandrine on human peripheral blood T cells. We showed that tetrandrine inhibited phorbol 12-myristate 13-acetate (PMA) + ionomycin-induced T cell proliferation, interleukin-2 secretion and the expression of the T cell activation antigen, CD71. Further investigation of the molecular mechanism demonstrated that tetrandrine inhibited the expression of the protein kinase C-dependent interleukin-2 receptor alpha chain and CD69 but not the expression of the Ca2+-dependent CD40 ligand and CD69. Interestingly, when tetrandrine and cyclosporin A were added together, significant synergism in the suppression of T cell activation was observed. Moreover, of the several tetrandrine analogues studied, hernandezine was the most potent inhibitor of protein kinase C signaling events. These results also suggest that the protein kinase C-inhibitory capacity of tetrandrine and its analogues may not be associated with their function as Ca2+ channel blockers. Lastly, we showed that, within therapeutic concentrations, tetrandrine and its analogues could induce cellular apoptosis, which is defective in autoimmune diseases. In conclusion, our findings provide novel information about the molecular mechanism of the immunosuppressive effect of tetrandrine and its analogues in human peripheral blood T cells.

The role of prostaglandin E2 and nitric oxide in cell death in J774 murine macrophages

We investigated the role of prostaglandin E2 (PGE2) and its interactions with nitric oxide (NO) on cell death and NO-mediated cytotoxicity in the murine macrophage cell line J774. Stimulation of the J774 cells with lipopolysaccharide together with interferon-gamma resulted in a dose-dependent cytotoxicity and production of PGE2 and NO, measured as nitrite. Our results showed a linear correlation between PGE2 release and cytotoxicity. The cyclooxygenase (COX) inhibitor indomethacin completely inhibited PGE2 biosynthesis, without affecting NO production or cell death. This supports previous reports suggesting that overproduction of endogenous PGE2 is mainly the consequence of cell death and does not cause it. In contrast, the NO synthase inhibitor N(omega)-monomethyl-L-arginine (L-NMMA) gave a significant, though incomplete suppression of NO release and cell death. This points to the presence of other cytotoxic factors besides NO. To evaluate the toxic effect solely due to NO, macrophages were exposed to the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP). Incubation with SNAP also resulted in a concentration-dependent cell injury and PGE2 production. When exogenously added, PGE2 protected against SNAP-mediated cytotoxicity and simultaneously increased PGE2 release into the medium, without inducing COX-2. The cytoprotection and the stimulation of PGE2 release were both reversed by indomethacin. In conclusion, PGE2 biosynthesis may represent a mechanism by which inflammatory macrophages protect themselves against the cytotoxic effects of NO.