The plasma glucose lowering action of tetrandrine in streptozotocin-induced diabetic rats

Alkaloids in genus stephania (Menispermaceae): A comprehensive review of its ethnopharmacology, phytochemistry, pharmacology and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Approximately 60 species of the genus Stephania (Menispermaceae) are distributed worldwide. Among these, 39 species are located in South and Southwest China; in particular, these plants are rich in alkaloids and were used in traditional Chinese medicine (TCM) against numerous ailments.

AIM OF THIS REVIEW

The purpose of this study was to provide organized information on the ethnopharmacological uses as well as the phytochemical, pharmacological, and toxicological evaluation of the alkaloids derived from plant species included in the genus Stephania. In addition, we aimed to provide comprehensive basic knowledge on the medicinal properties of these plants and establish meaningful guidelines for further research.

MATERIALS AND METHODS

Information related to the Stephania genus was collected from scientific databases, such as Web of Science, PubMed, Baidu Scholar, and China Academic Journals (CNKI), within the last 20 years on phytochemistry, pharmacology, and toxicology of the plants in genus Stephania. Furthermore, information was obtained from the Pharmacopoeia of the People's Republic of China. Chinese Pharmacopoeia and Flora of China.

RESULTS

Plant species belonging to the genus Stephania have been mentioned as traditional remedies and various alkaloidal compounds have been identified and isolated, including aporphine, proaporphine, morphinane, hasubanane, protoberberine, benzylisoquinoline, and bisbenzylisoquinoline and among others. The isolated alkaloidal compounds reportedly exhibited promising pharmacological properties, such as antimicrobial, antiviral, antitumor, antioxidant, antihyperglycemic, anti-inflammatory, antinociceptive, anti-multidrug resistance, neuroprotective, and cardioprotective activities.

CONCLUSIONS

The genus Stephania is widely used in TCM. The ethnopharmacological uses, phytochemistry, and pharmacology of the Stephania sp. Described in this review demonstrated that these plants contain numerous alkaloids and active constituents and display myriad pharmacological activities. Typically, research on the plants' pharmacological activity focuses on parts of the plants and the associated compounds. However, many Stephania species have rarely been studied, and the ethnomedicinal potential of those discovered has not been scientifically evaluated and needs to be further elucidated. Furthermore, quality control and toxicology studies are warranted in the future.

An overview on the chemistry, pharmacology and anticancer properties of tetrandrine and fangchinoline (alkaloids) from Stephania tetrandra roots

Tetrandrine (TET) and fangchinoline (FAN) are dominant bisbenzylisoquinoline (BBIQ) alkaloids from the roots of Stephania tetrandra of the family Menispermaceae. BBIQ alkaloids comprise two benzylisoquinoline units linked by oxygen bridges. The molecular structures of TET and FAN are exactly the same, except that TET has a methoxy (-OCH₃) group, while FAN has a hydroxyl (-OH) group at C7. In this overview, the current knowledge on the chemistry, pharmacology and anticancer properties of TET and FAN have been updated. The focus is on colon and breast cancer cells, because they are most susceptible to TET and FAN, respectively. Against colon cancer cells, TET inhibits cell proliferation and tumor growth by inducing apoptosis and G1 cell cycle arrest, and suppresses adhesion, migration and invasion of cells. Against breast cancer cells, FAN inhibits cell proliferation by inducing apoptosis, G1-phase cell cycle arrest and inhibits cell migration. The processes involve various molecular mechanisms and signaling pathways. Some insights on the ability of TET and FAN to reverse multi-drug resistance in cancer cells and suggestions for future research are provided.

Bioassay guided fractionation of Cyclea peltata using in vitro RAW 264.7 cell culture, antioxidant assays and isolation of bioactive compound tetrandrine

BACKGROUND

Cyclea peltata is one of the herbs mentioned in ancient scriptures of Ayurveda and is used in different types of Ayurvedic gritham preparations. Moreover, in traditional/tribal medicine C. peltata is used as digestive, anti-inflammatory, diuretic and to treat jaundice, digestive disorders, etc. OBJECTIVE: Activity guided fractionation of C. peltata and in correlation with the levels of bioactive compound tetrandrine.

MATERIALS AND METHODS

Preliminary phytochemical screening, estimation of total alkaloid content, preparation of different extracts of C. peltata (crude extract CP, hexane extract HCP, chloroform extract CCP, methanol extract MCP, alkaloid fraction ACP). In vitro anti-inflammatory studies using RAW 264.7 cells and in vitro antioxidant assays of the different extracts of C. peltata. HPTLC estimation of tetrandrine (TET) was carried out using solvent system toluene: ethyl acetate: diethylamine (7.2: 2: 0.8) and isolation of TET from ACP.

RESULTS

Preliminary phytochemical studies of C. peltata showed the presence of alkaloid content in all extracts. Whereas, saponins, steroids and terpenoids were detected in CP and CCP. ACP and TET showed significant in vitro anti-inflammatory and antioxidant activity when compared to other extracts. ACP and TET (100 μg/ml) treatment significantly inhibited the mRNA expression of iNOS, COX-2, TNF-α in LPS treated RAW 264.7 cells. HPTLC estimation of bioactive compound tetrandrine was highest in ACP-228.4 μg/mg followed by CP-29.62 μg/mg, CCP-23.46 μg/mg, MCP-18.82 μg/mg and HCP-1.25 μg/mg. TET has been isolated from ACP.

CONCLUSION

The results of the present in vitro assays revealed that the alkaloid fraction (ACP) is the most active fraction when compared to other extracts and has a positive correlation with the levels of bioactive compound tetrandrine.

A critical review: traditional uses, phytochemistry, pharmacology and toxicology of Stephania tetrandra S. Moore (Fen Fang Ji)

ABSTRACT

Stephania tetrandra S. Moore (S. tetrandra) is distributed widely in tropical and subtropical regions of Asia and Africa. The root of this plant is known in Chinese as "Fen Fang Ji". It is commonly used in traditional Chinese medicine to treat arthralgia caused by rheumatism, wet beriberi, dysuria, eczema and inflamed sores. Although promising reports have been published on the various chemical constituents and activities of S. tetrandra, no review comprehensively summarizes its traditional uses, phytochemistry, pharmacology and toxicology. Therefore, the review aims to provide a critical and comprehensive evaluation of the traditional use, phytochemistry, pharmacological properties, pharmacokinetics and toxicology of S. tetrandra in China, and meaningful guidelines for future investigations.

Tetrandrine inhibits differentiation of proinflammatory subsets of T helper cells but spares de novo differentiation of iTreg cells

Tetrandrine (TET) is an anti-inflammatory compound isolated from Chinese herb Stephania tetrandra S. Moore. It was reported recently that the differentiation of Th17 cells was inhibited, while the generation of induced Treg cells (iTregs) was promoted, by TET treatment. We therefore carefully examined the effect of TET on the differentiation of four major subsets of T helper cells. The results showed that in vitro treatment with TET potently inhibited the differentiation of Th1, Th2 and Th17 cells. Administration of LPS resulted in a mixed Th1, Th2 and Th17 responses in normal mice, and such effect of LPS was inhibited by in vivo TET treatment as well. In contrast, TET did not promote or inhibit the in vitro generation of iTregs from naïve CD4⁺CD25^-Foxp3/gfp^- T cells. Furthermore, spontaneous and rapamycin-induced conversion of naïve CD4⁺CD25^-Foxp3/gfp^- T cells into Foxp3-expressing iTregs in congenic mice was not affected by TET treatment. Thus, TET had the capacity to inhibit the differentiation of proinflammatory Th1, Th2 and Th17 cells, while sparing the generation of Tregs. As a Treg-friendly and broad spectrum anti-inflammatory agent, the molecular mechanism and the therapeutic potential of TET in various human inflammatory diseases should be further studied.

Tetrandrine has anti-adipogenic effect on 3T3-L1 preadipocytes through the reduced expression and/or phosphorylation levels of C/EBP-α, PPAR-γ, FAS, perilipin A, and STAT-3

Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra S. Moore and has been shown to possess anti-inflammatory and anti-cancerous activities. In this study, the effect of tetrandrine on adipogenesis in 3T3-L1 preadipocytes was investigated. Tetrandrine at 10 μM concentration strongly inhibited lipid accumulation and triglyceride (TG) synthesis during the differentiation of 3T3-L1 preadipocytes into adipocytes. On mechanistic levels, tetrandrine reduced not only the expressions of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A but also the phosphorylation levels of signal transducer and activator of transcription-3 (STAT-3) during 3T3-L1 adipocyte differentiation. Tetrandrine also reduced the mRNA expression of leptin, but not adiponectin, during 3T3-L1 adipocyte differentiation. Collectively, these findings show that tetrandrine has strong anti-adipogenic effect on 3T3-L1 preadipocytes and the effect is largely attributable to the reduced expression and/or phosphorylation levels of C/EBP-α, PPAR-γ, FAS, perilipin A, and STAT-3.

Tetrandrine--A molecule of wide bioactivity

Stephania tetrandra and other related species of Menispermaceae form the major source of the bisbenzylisoquinoline alkaloid - tetrandrine. The plant is extensively referenced in the Chinese Pharmacopoeia for its use in the Chinese medicinal system as an analgesic and diuretic agent and also in the treatment of hypertension and various other ailments, including asthma, tuberculosis, dysentery, hyperglycemia, malaria, cancer and fever. Tetrandrine, well-known to act as a calcium channel blocker, has been tested in clinical trials and found effective against silicosis, hypertension, inflammation and lung cancer without any toxicity. Recently, the efficacy of tetrandrine was tested against Mycobaterium tuberculosis, Candida albicans, Plasmodium falciparum and Ebola virus. Tetrandrine's pharmacological property has been proved to be through its action on different signalling pathways like reactive oxygen species, enhanced autophagic flux, reversal of multi drug resistance, caspase pathway, cell cycle arrest and by modification of calcium channels. The present review summarises current knowledge on the synthesis, distribution, extraction, structural elucidation, pharmacological properties and the mechanism of action of tetrandrine. Future perspectives in the clinical use of tetrandrine as a drug are also considered.

Ameliorative effect of alkaloid extract of Cyclea peltata (Poir.) Hook. f. & Thoms. roots (ACP) on APAP/CCl4 induced liver toxicity in Wistar rats and in vitro free radical scavenging property

OBJECTIVE

To evaluate the hepatoprotective and antioxidant properties of alkaloid extract of Cyclea peltata (C. peltata) against paracetamol/carbon tetra chloride induced liver damage in Wistar rats.

METHODS

In vivo paracetamol/carbon tetrachloride induced liver damage in Wistar rats, in vitro free radical scavenging studies, HPTLC estimation of tetrandrine and direct analysis in real time- mass spectrometry of alkaloid extract of C. peltata were used for the validation.

RESULTS

The results showed that pretreatment with alkaloid extract of C. peltata caused significant reduction of serum glutamate pyruvate transaminase, serum glutamate oxaloacetate transaminase, serum alkaline phosphatase, serum cholesterol, liver malondialdehyde levels. The reduced glutathione, catalase, superoxide dismutase levels in liver were increased with alkaloid extract of C. peltata treatment. These results were almost comparable to silymarin and normal control. Histopathological studies also substantiated the biochemical findings. The in vitro hydroxyl, superoxide and DPPH scavenging study of alkaloid extract of C. peltata showed significant free radical scavenging property.

CONCLUSIONS

The hepatoprotective property of alkaloid extract of C. peltata against paracetamol/carbon tetrachloride may be due the synergistic action of alkaloids especially tetrandrine, fangchinoline through free radical scavenging and thus preventing oxidative stress.

Diabetes is an inflammatory disease: evidence from traditional Chinese medicines

Diabetes is usually associated with inflammation. Inflammation contributes to the development of diabetes. Traditional Chinese medicines (TCM) play an important role in lowering blood glucose and controlling inflammation. Many studies show that TCM with hypoglycaemic effects, for example Radix Astragali, Radix Rehmanniae, Radix Trichosanthis, Panax Ginseng, Fructus Schisandrae, Radix Ophiopogonis, Rhizoma Anemarrhenae, Radix Puerariae, Fructus Lycii, Poria, Rhizoma Coptidis, Rhizoma Dioscoreae, Rhizoma Polygonati, Radix Salviae Miltiorrhizae, Radix Glycyrrhizae, Semen Trigonellae, Momordica charantia, Allium sativum, Opuntia stricta, Aloe vera, Cortex Cinnamomi, Rhizoma Curcumae Longae, and so on, have nearly independent anti-inflammatory action. Antihyperglycaemic compounds, for example berberine, puerarin, quercetin, ferulic acid, astragaloside IV, curcumin, epigallocatechin gallate, resveratrol, tetrandrine, glycyrrhizin, emodin and baicalin, used in TCM also have anti-inflammatory effects. These studies suggest that TCM might exert hypoglycaemic effects that are partly mediated by the anti-inflammatory mechanisms. However, small amounts of TCM with potent anti-inflammatory action does not have any hypoglycaemic effect. This indirectly indicates that diabetes may be a low-grade inflammatory disease and potent regulation of inflammatory mediators may not be required. Studies of TCM add new evidences, which indicate that diabetes may be an inflammatory disease and slight or moderate inhibition of inflammation might be useful to prevent the development of diabetes. Through this review, we aim to develop more perspectives to indicate that diabetes may be an inflammatory disease and diverse TCM may share a common antidiabetic property: anti-inflammatory action. Further studies should focus on and validate inflammation-regulating targets of TCM that may be involved in inhibiting the development of diabetes.

Role of nitric oxide in the brain during lipopolysaccharide-evoked systemic inflammation

Although the inducible isoform of nitric oxide synthase (iNOS) is a well-established source of nitric oxide (NO*) during inflammation of the central nervous system (CNS), little is known about the involvement of constitutive isoforms of NOS (cNOS) in the inflammatory process. The aim of this study was to compare the responses of the expression and activity of iNOS and the two cNOS isoforms, neuronal and endothelial (nNOS and eNOS, respectively), in the brain to systemic inflammation and their roles in the cascade of events leading to degeneration and apoptosis. A systemic inflammatory response in C57BL/6 mice was induced by intraperitoneal injection of lipopolysaccharide [LPS; 1 mg/kg body weight (b.w.)]. The relative roles of the NOS isoforms were evaluated after injection of NG-nitro-L-arginine (NNLA; 30 mg/kg b.w.), which preferentially inhibits cNOS, or 1400W (5 mg/kg b.w.), an inhibitor of iNOS. Biochemical and morphological alterations were analyzed up to 48 hr after administration of LPS. Systemic LPS administration evoked significant ultrastructural alterations in brain capillary vessels, neuropils, and intracellular organelles of neurons, astrocytes, and microglia. Apoptotic/autophagic processes occurred in many neurons of the substantia nigra (SN), which coincided with exclusive enhancement of iNOS expression and activity in this brain region. Moreover, inhibitors of both iNOS and cNOS prevented LPS-evoked release of apoptosis-inducing factor (AIF) from SN mitochondria. Collectively, the results indicate that synthesis of NO* by both the inducible and constitutive NOS isoforms contribute to the activation of apoptotic pathways in the brain during systemic inflammation.

Antiproliferative and apoptotic effects of tetrandrine on different human hepatoma cell lines

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid isolated from the dried root of Hang-Fang-Chi (Stephania tetrandra S. Moore), is well known to possess activities including antioxidant, anti-inflammation, anti-fibrotic and anticancer. It is used clinically to treat hypertension and silicosis. In the present study, the anti-proliferative and apoptotic effects of TET were evaluated on three different hepatoma cell lines, namely Hep G2, PLC/PRF/5 and Hep 3B. Using XTT assay, results showed that the IC50 values of TET were 4.35 microM for Hep G2, 9.44 microM for PLC/PRF/5 and 10.41 microM for Hep 3B cells. The CC50 of TET against BNL-CL.2 mouse normal liver cells was 31.12 microM. Interestingly, TET exhibited a lower IC50 value and better selectivity against Hep G2 and PLC/PRF/5 cells than cisplatin. Microscopic observation study, DNA fragmentation assay and flow cytometric analysis further supported apoptotic effect of TET on both PLC/PRF/5 and Hep 3B cells. The cell cycle of PLC/PRF/5 treated with TET appeared to arrest at G2/M phase in a dose-dependent manner, whereas no effect was noted on the cell cycle of Hep 3B cells. The present study concludes that TET exhibited anti-proliferative effect on Hep G2, PLC/PRF/5 and Hep 3B cells in a dose-dependent manner. TET also possesses a lower IC50 and better SI value than cisplatin against Hep G2 and PLC/PRF/5 cells. The effect of TET on cell cycle progression was found to vary with the type of hepatoma cells, suggesting the genetic make-up of the cells play an important role in the response to drug treatment.

Oxidative variables in the rat brain after sepsis induced by cecal ligation and perforation

OBJECTIVE

The underlying mechanisms of the changes in mental status, septic encephalopathy, and long-term cognitive symptoms in sepsis survivors have only been defined in part. The present study was undertaken to assess different variables of oxidative stress in several brain structures after cecal ligation and perforation in the rat.

DESIGN

Prospective animal study.

SETTING

Animal basic science laboratory.

SUBJECTS

Male Wistar rats, weighing 250-350 g.

INTERVENTIONS

Rats were subjected to cecal ligation and perforation (sepsis group) with saline resuscitation (at 50 mL/kg immediately and 12 hrs after cecal ligation and perforation) or sham operation (control group).

MEASUREMENTS AND MAIN RESULTS

Oxidative damage, assessed by the thiobarbituric acid reactive species and the protein carbonyl assays, occurred early (after 6 hrs) in the course of sepsis development in the hippocampus, cerebellum, and cortex. At longer times after sepsis induction (12-96 hrs), there was no evidence of oxidative damage in all analyzed structures. Except for the striatum, earlier in sepsis development (6 hrs) we demonstrated an increase in superoxide dismutase activity without a proportional increase in catalase activity with a consequent increase in the relation of superoxide dismutase/catalase. The balance between these enzymes was restored in the studied structures 12-96 hrs after sepsis induction.

CONCLUSIONS

The short-term oxidative damage demonstrated here could participate in the development of central nervous system symptoms during sepsis development, or even septic encephalopathy. The alterations in the superoxide dismutase/catalase relation were temporally related to the occurrence or not of oxidative damage in the central nervous system.

Inhibition of intestinal glucose uptake by aporphines and secoaporphines

The effects of aporphines and secoaporphines on glucose uptake by isolated intestinal brush-border membrane vesicles (BBMV) or basolateral membrane vesicles (BLMV) and glucose absorption during in situ intestinal perfusion were studied. Of the tested compounds, N-allylsecoboldine was the most potent glucose uptake inhibitor, with IC50 values of 159 microM and 121 microM, respectively, for uptake by BBMV and BLMV. While thaliporphine competitively inhibited glucose uptake by both membrane preparations, inhibition by N-allylsecoboldine was competitive using BBMV and noncompetitive using BLMV. In addition, N-allylsecoboldine significantly reduced both glucose absorption during in situ intestinal perfusion and blood glucose levels in the oral glucose tolerance test. The results demonstrate that levels of both aporphines and secoaporphines achievable by oral administration have an inhibitory effect on intestinal glucose uptake and suggest that the hypoglycemic effects of these compounds merit attention.

Effect of Tetrandrine on Calcium-Dependent Tumour Necrosis Factor-alpha Production in Glia-Neurone Mixed Cultures

Tumour necrosis factor-alpha is believed to have a deleterious role in the pathophysiology of brain injury. Tetrandrine has protective effect on neuronal cells, however, the mechanisms involved in its action have not been clearly established. The aim of this study was to investigate the role of tetrandrine on calcium-dependent tumour necrosis factor-alpha production in glia-neurone mixed cultures. Glia-neurone mixed cultures were treated by addition of Ca2+ regulating agents for a period of 6 hr. Tetrandrine or/and TMB-8 were added 30 min. before the stimulation. The supernatant tumour necrosis factor-alpha levels were quantified by enzyme-linked immunosorbent assay. Exposure of lipopolysaccharide 10 and 100 ng/ml caused significant increase in tumour necrosis factor-alpha production respectively, with no alteration in cultures treated with 1 ng/ml lipopolysaccharide. Glia-neurone mixed cultures exhibited a marked elevation in tumour necrosis factor-alpha production after exposure to CaCl2, KCl, thapsigargin, BHQ and norepinephrine in the presence of lipopolysaccharide at 1 ng/ml respectively. Tetrandrine 0.3, 1, and 3 microM concentration-dependently reduced tumour necrosis factor-alpha production evoked by CaCl2 or KCl. Tetrandrine preincubation had no significant effect on the response to Ca2+-ATPase inhibitor thapsigargin or BHQ. Norepinephrine-induced tumour necrosis factor-alpha production was significantly reduced by tetrandrine and almost abolished by combination of tetrandrine and intracellular Ca2+ release inhibitor TMB-8. These results suggested that tetrandrine at a concentration of 0.3, 1, or 3 microM inhibited tumour necrosis factor-alpha production induced by Ca2+ entry in glia-neurone mixed cultures.

Mediation of Endogenous beta-endorphin by Tetrandrine to Lower Plasma Glucose in Streptozotocin-induced Diabetic Rats

The role of beta-endorphin in the plasma glucose-lowering action of tetrandrine in streptozotocin-induced diabetic rats (STZ-diabetic rats) was investigated. The plasma glucose concentration was assessed by the glucose oxidase method. The enzyme-linked immunosorbent assay was used to determine the plasma level of beta-endorphin-like immunoreactivity (BER). The mRNA levels of glucose transporter subtype 4 (GLUT4) in soleus muscle and phosphoenolpyruvate carboxykinase (PEPCK) in the liver of STZ-diabetic rats were detected by Northern blotting analysis. The expressed protein of GLUT4 or PEPCK was characterized by Western blotting analysis. Tetrandrine dose-dependently increased plasma BER in a manner parallel to the decrease of plasma glucose in STZ-diabetic rats. Moreover, the plasma glucose-lowering effect of tetrandrine was inhibited by naloxone and naloxonazine at doses sufficient to block opioid μ-receptors. Further, tetrandrine failed to produce plasma glucose-lowering action in opioid μ-receptor knockout diabetic mice. Bilateral adrenalectomy eliminated the plasma glucose-lowering effect and plasma BER-elevating effect of tetrandrine in STZ-diabetic rats. Both effects were abolished by treatment with hexamethonium or pentolinium at doses sufficient to block nicotinic receptors. Tetrandrine enhanced BER release directly from the isolated adrenal medulla of STZ-diabetic rats and this action was abolished by the blockade of nicotinic receptors. Repeated intravenous administration of tetrandrine (1.0 mg/kg) to STZ-diabetic rats for 3 days resulted in an increase in the mRNA and protein levels of the GLUT4 in soleus muscle, in addition to the lowering of plasma glucose. Similar treatment with tetrandrine reversed the elevated mRNA and protein levels of PEPCK in the liver of STZ-diabetic rats. The obtained results suggest that tetrandrine may induce the activation of nicotinic receptors in adrenal medulla to enhance the secretion of beta-endorphin, which could stimulate opioid μ-receptors to increase glucose utilization or/and reduce hepatic gluconeogenesis to lower plasma glucose levels in STZ-diabetic rats.