Antidiabetic Effect of Methanolic Extract from Berberis julianae Schneid. via Activation of AMP-Activated Protein Kinase in Type 2 Diabetic Mice

Effects of diazoxide on streptozotocin induced β cell damage via HSP70/HSP90/TLR4/AMPK signaling pathways

I investigated the effects of diazoxide, a mitochondrial potassium channel opener, on streptozotocin (STZ) induced pancreatic β cell damage via the HSP70/HSP90/TLR4/AMPK signaling pathways in vitro. I used the pancreatic β cell line, 1.1B4, to create four groups: control, STZ treated, diazoxide treated, STZ + diazoxide treated. The STZ treated cells were exposed to 20 µM STZ for 2 h with or without 100 µM diazoxide for 24 h. Total antioxidant status (TAS), total oxidant status (TOS), cell viability and mitochondrial membrane potential (MMP) were measured. Expression of ATP-sensitive potassium channel (K_ATP) subunits, heat shock protein-70 (HSP70), heat shock protein-90 (HSP90), toll-like receptor 4 (TLR4), AMP-activated protein kinase (AMPK) and some apoptotic proteins were detected using western blotting. Apoptosis was assessed using TUNEL staining. STZ increased TOS and OSI in the pancreatic β cells; however, diazoxide failed to improve oxidative stress. Also, STZ increased tunnel positive cells in the pancreatic β cells. Diazoxide decreased the tunnel positive cells in the STZ treated β cell. STZ decreased MMP; however, diazoxide did not normalize MMP in the STZ induced β cells. Diazoxide increased the HSP70:HSP90 protein expression ratio. STZ decreased expression of AMPK and subunits of K_ATP channel and increased the expression of caspase-3 and TLR4 protein; diazoxide normalized the expression of all proteins studied. K_ATP channel opening by diazoxide protects pancreatic β cells against STZ toxicity via HSP70/HSP90/TLR4/AMPK signaling.

Neuregulin-1β increases glucose uptake and promotes GLUT4 translocation in palmitate-treated C2C12 myotubes by activating PI3K/AKT signaling pathway

Insulin resistance (IR) is a feature of type 2 diabetes (T2DM) accompanied by reduced glucose uptake and glucose transporter 4 (GLUT4) translocation by skeletal muscle. Neuregulin-1β (NRG-1β) is essential for myogenesis and the regulation of skeletal muscle metabolism. Neuregulin-1β increases insulin sensitivity, promotes glucose uptake and glucose translocation in normal skeletal muscle. Here, we explored whether Neuregulin-1β increased glucose uptake and GLUT4 translocation in palmitate (PA)-treated C2C12 myotubes. After C2C12 myoblasts differentiated into myotubes, we used palmitate to induce cellular insulin resistance. Cells were incubated with or without Neuregulin-1β and glucose uptake was determined using the 2-NBDG assay. The expression level of glucose transporter 4 (GLUT4) was measured via immunofluorescence and Western blotting. MK2206, an inhibitor of AKT, was employed to reveal the important role played by AKT signaling in PA-treated C2C12 myotubes. We then established an animal model with T2DM and evaluated the effects of Neuregulin-1β on body weight and the blood glucose level. The GLUT4 level in the gastrocnemius of T2DM mice was also measured. NRG-1β not only increased glucose uptake by PA-treated myotubes but also promoted GLUT4 translocation to the plasma membrane. The effect of NRG-1β on PA-treated C2C12 myotubes was associated with AKT activation. In T2DM mice, Neuregulin-1β not only improved diabetes-induced weight loss and diabetes-induced hyperglycemia, but also promoted GLUT4 translocation in the gastrocnemius. In summary, Neuregulin-1β increased glucose uptake and promoted translocation of GLUT4 to the plasma membrane in PA-treated C2C12 myotubes by activating the PI3K/AKT signaling pathway.

Type 2 Diabetic Mellitus Inhibits Skin Renewal through Inhibiting WNT-Dependent Lgr5+ Hair Follicle Stem Cell Activation in C57BL/6 Mice

BACKGROUND

Hair follicles are important accessory organs of the skin, and it is important for skin renewal and performs variety of important functions. Diabetes can cause several dermatoses; however, its effect on hair follicles is unclear. The purpose of this study was to investigate the effect of type II diabetes (T2DM) on the hair follicles of mice.

METHODS

Seven-week-old male C57BL/6 littermate mice were divided into two groups. The treatment group was injected with streptozotocin (STZ) to induce T2DM, and the control group was parallelly injected with the same dose of buffer. Seven days after injection, the back is depilated to observe the hair follicle regeneration. Hair follicle regeneration was observed by naked eyes and HE staining. The proliferation of the skin cells was observed by PCNA and K14 staining. The altered genes were screened by RNA sequencing and verified by qRT-PCR. In addition, Lgr5 + GFP/mTmG transgenic mice were used to observe the effect of T2DM on Lgr5 hair follicle stem cells (HFSC). And the expression of WNT4 and WNT8A were measured by Western Blot.

RESULTS

T2DM inhibited hair follicle regeneration. Compared to control mice, T2DM mice had smaller hair follicles, reduced skin thickness, and less expression of PCNA and K14. RNA sequencing showed that the two groups had significant differences in cell cycle and proliferation-related pathways. Compared with the control mice, the mRNA expression of Lgr4, Lgr5, Wnt4, and Wnt8a was decreased in the T2DM group. Moreover, T2DM inhibited the activation of Lgr5 HFSC and the expression of WNT4 and WNT8A.

CONCLUSIONS

T2DM inhibited hair follicle regeneration and skin cells proliferation by inhibiting WNT-dependent Lgr5 HFSC activation. This may be an important reason for the reduction of skin renewal ability and the formation of chronic wounds caused by diabetes. It is important for the treatment of chronic diabetic wounds and the development of tissue engineering.

Phytopharmacology and Clinical Updates of Berberis Species Against Diabetes and Other Metabolic Diseases

The incidences of diabetic mellitus and other metabolic diseases such as hypertension and hyperlipidemia are increasing worldwide; however, the current treatment is not able to control the rapidly increasing trend in diabetes mortality and morbidity. Studies related to the effectiveness of extracts and pure compounds obtained from plants have shown promising responses in preclinical and clinical studies related to these metabolic diseases. Plants belonging to the genus Berberis (Family: Berberidaceae) are widely distributed with nearly 550 species worldwide. Extracts and compounds obtained from Berberis species, especially Berberine alkaloid, showed effectiveness in the management of diabetes and other metabolic diseases. Various pharmacological experiments have been performed to evaluate the effects of Berberis extracts, berberine, and its natural and chemically synthesized derivatives against various cell and animal disease models with promising results. Various clinical trials conducted so far also showed preventive effects of Berberis extracts and berberine against metabolic diseases. The present review focuses on i) research updates on traditional uses, ii) phytopharmacology and clinical studies on Berberis species, and iii) active metabolites in the prevention and treatment of diabetes and other metabolic diseases with a detailed mechanism of action. Furthermore, the review critically analyzes current research gaps in the therapeutic use of Berberis species and berberine and provides future recommendations.

Effect of berberine on the HPA-axis pathway and skeletal muscle GLUT4 in type 2 diabetes mellitus rats

PURPOSE

Activation of the hypothalamus-pituitary-adrenal (HPA) axis pathway is closely related to insulin resistance (IR), glucose, and lipid metabolism disorders in type 2 diabetes mellitus (T2DM). Berberine (BBR) has effect on regulating disorder of glucose and lipid metabolism in T2DM. In fact, activation of the HPA axis pathway is closely related to IR, glucose, and lipid metabolism disorders in T2DM. Here, we investigated whether the therapeutic effect of BBR on T2DM rats is acted through the HPA axis pathway.

METHODS

In this research, we investigated the effects of BBR on the HPA-axis pathway-related indicators and expression of skeletal muscle glucose transporter 4 (GLUT4) in the high-fat diet and streptozotocin-induced T2DM rats, and identify its possible mechanism of improving IR in T2DM.

RESULTS

BBR significantly reduced fasting blood glucose, total cholesterol, and low-density lipoprotein cholesterol in model rats. It also improved the abnormalities of the high-density lipoprotein cholesterol, the insulin resistance index, the insulin sensitivity index, glucagon, and insulin levels. BBR decreased levels of hypothalamic Orexin-A, the OX2R receptor, the corticotropin-releasing hormone, the pituitary and the plasma adrenocorticotropic hormone, as well as serum and urine corticosterone. At the same time, BBR increased mRNA and protein expressions of GLUT4 in skeletal muscles of model rats as well.

CONCLUSION

Those results suggested that BBR can exert inhibition on the HPA-axis and increased skeletal muscle expression of GLUT4 proteins, which may be one of the important mechanisms in BBR to improve IR and regulating glucose and lipid metabolism in T2DM rats.

A SIRT1 agonist reduces cognitive decline in type 2 diabetic rats through antioxidative and anti‑inflammatory mechanisms

Sirtuin 1 (SIRT1) is an NAD+‑dependent protein deacetylase that is involved in cell differentiation, aging, apoptosis, physiological rhythms, metabolic regulation, oxidative stress and numerous other important biological processes. In the present study, the ability of a sirtuin‑1 (SIRT1) agonist, SRT1720, to reduce cognitive decline in type 2 diabetes mellitus (T2DM) was investigated. Streptozotocin‑induced male Sprague‑Dawley rats were used to establish a T2DM model and the protective effect of SRT1720 and its underlying mechanisms were investigated. Body weight and fasting blood glucose (FBG) were recorded and cognitive function was measured with the Morris water maze. Levels of oxidative stress, inflammation, caspase‑3 activity and nuclear factor κB (NF‑κB) mRNA expression were detected with a series of commercial assay kits and reverse transcription‑quantitative polymerase chain reaction, respectively. Western blot analysis was performed to determine the protein expression of NF‑κB, endothelial nitric oxide synthase (eNOS), peroxisome proliferator‑activated receptor γ (PPARγ), AMP‑activated protein kinase (AMPK), heat shock 70 kDa protein (HSP70), SIRT1, nuclear factor erythroid 2‑related factor 2 (Nrf2) and heme oxygenase 1 (HO‑1). The results revealed that SRT1720 significantly increased body weight, decreased FBG, improved cognitive function and reduced the levels of proteins associated with oxidative stress and inflammation damage in T2DM rats. Additionally, SRT1720 significantly decreased NF‑κB p65 mRNA expression and increased eNOS and PPARγ expression. SRT1720 significantly reduced caspase‑3 activity and HSP70 protein expression, and increased p‑AMPK, SIRT1, Nrf2 and HO‑1 protein expression. Collectively, the results indicate that SRT1720 may reduce cognitive decline in T2DM rats through antioxidative and anti‑inflammatory action via NF‑κB and AMPK‑dependent mechanisms.

Ethanolic Extract of Folium Sennae Mediates the Glucose Uptake of L6 Cells by GLUT4 and Ca2

In today’s world, diabetes mellitus (DM) is on the rise, especially type 2 diabetes mellitus (T2DM), which is characterized by insulin resistance. T2DM has high morbidity, and therapies with natural products have attracted much attention in the recent past. In this paper, we aimed to study the hypoglycemic effect and the mechanism of an ethanolic extract of Folium Sennae (FSE) on L6 cells. The glucose uptake of L6 cells was investigated using a glucose assay kit. We studied glucose transporter 4 (GLUT4) expression and AMP-activated protein kinase (AMPK), protein kinase B (PKB/Akt), and protein kinase C (PKC) phosphorylation levels using western blot analysis. GLUT4 trafficking and intracellular Ca²⁺ levels were monitored by laser confocal microscopy in L6 cells stably expressing IRAP-mOrange. GLUT4 fusion with plasma membrane (PM) was observed by myc-GLUT4-mOrange. FSE stimulated glucose uptake; GLUT4 expression and translocation; PM fusion; intracellular Ca²⁺ elevation; and the phosphorylation of AMPK, Akt, and PKC in L6 cells. GLUT4 translocation was weakened by the AMPK inhibitor compound C, PI3K inhibitor Wortmannin, PKC inhibitor Gö6983, G protein inhibitor PTX/Gallein, and PLC inhibitor U73122. Similarly, in addition to PTX/Gallein and U73122, the IP3R inhibitor 2-APB and a 0 mM Ca²⁺-EGTA solution partially inhibited the elevation of intracellular Ca²⁺ levels. BAPTA-AM had a significant inhibitory effect on FSE-mediated GLUT4 activities. In summary, FSE regulates GLUT4 expression and translocation by activating the AMPK, PI3K/Akt, and G protein–PLC–PKC pathways. FSE causes increasing Ca²⁺ concentration to complete the fusion of GLUT4 vesicles with PM, allowing glucose uptake. Therefore, FSE may be a potential drug for improving T2DM.

Mahonia oiwakensis Extract and Its Bioactive Compounds Exert Anti-Inflammatory Activities and VEGF Production Through M2-Macrophagic Polarization and STAT6 Activation

Macrophages play an indispensable role in the host immune defense. Macrophages can undergo polarization into classically (M1) and alternatively (M2) activated macrophages. M1 macrophages activate immune and inflammatory response, while M2 macrophages are involved in tissue remodeling. Mahonia oiwakensis (Mo) is a herbal medicine in Asia used for its anti-inflammatory and analgesic properties; however, the mechanism is unclear. This study analyzed the effect of Mo extracts and its effects on the polarization of both macrophage RAW264.7 cells and mouse splenic macrophages. Water (Mo-W) and EtOH extracts (Mo-E) did not change the viability of RAW264.7 cells, whereas Mo-E inhibited nitric oxide (NO) production. The major compounds, berberine and palmatine, decreased the viability and NO levels of cells. The secretion of inflammatory cytokines CXCL16, IL-6, L-selectin, MCP1, RANTES, and sTNF-R1 was downregulated, whereas the production of vascular endothelial growth factor (VEGF) was upregulated by Mo-E, berberine, and palmatine treatments. Mo-E, berberine, and palmatine stimulated the expression of macrophage CD68 and M2-type CD204 markers, decreased M1-mediated p-STAT1 and NF-κB, and increased M2-mediated p-STAT6 expression. Similar effects on M2 polarization were also observed in splenic macrophages from mice. In conclusion, Mo-E, berberine, and palmatine modulated macrophages through the suppression of M1-mediated inflammation and the recruitment of M2-mediated VEGF secretion and STAT6 expression.

Solid Lipid Nanoparticles of Myricitrin Have Antioxidant and Antidiabetic Effects on Streptozotocin-Nicotinamide-Induced Diabetic Model and Myotube Cell of Male Mouse

Type 2 diabetes mellitus (T2DM) may occur via oxidative stress. Myricitrin is a plant-derived antioxidant, and its solid lipid nanoparticle (SLN) may be more potent. Hence, the present study was conducted to evaluate the effects of myricitrin SLN on streptozotocin-nicotinamide- (STZ-NA-) induced T2DM of the mouse and hyperglycemic myotube. In this experimental study, cold homogenization method was used to prepare SLN. Then, 120 adult male NMRI mice were divided into 7 groups: control, vehicle, diabetes (received STZ 65 mg/kg 15 min after injected NA 120 mg/kg), diabetes + SLN containing myricitrin 1, 3, and 10 mg/kg, and diabetes + metformin. For in vitro study, myoblast (C2C12) cell line was cultured and divided into 6 groups (n = 3): control, hyperglycemia, hyperglycemia + SLN containing myricitrin 1, 3, and, 10 μM, and hyperglycemia + metformin. After the last nanoparticle treatment, plasma samples, pancreas and muscle tissues, and myotubes were taken for experimental assessments. Diabetes increased lipid peroxidation and reduced antioxidant defense along with the hyperglycemia, insulin resistance, and pancreas apoptosis. Hyperglycemia induced oxidative stress, antioxidant impairment, and cellular apoptosis. Myricitrin SLN improved diabetes and hyperglycemia complications in the in vivo and in vitro studies. Therefore, SLN of myricitrin showed antioxidant, antidiabetic, and antiapoptotic effects in the mouse and myotube cells.

Antidiabetic Effect of Tibetan Medicine Tang-Kang-Fu-San in db/db Mice via Activation of PI3K/Akt and AMPK Pathways

This study was to investigate the anti-diabetic effects and molecular mechanisms of Tang-Kang-Fu-San (TKFS), a traditional Tibetan medicine, in treating type 2 diabetes mellitus of spontaneous diabetic db/db mice. Firstly HPLC fingerprint analysis was performed to gain the features of the chemical compositions of TKFS. Next different doses of TKFS (0.5 g/kg, 1.0 g/kg, and 2.0 g/kg) were administrated via oral gavage to db/db mice and their controls for 4 weeks. TKFS significantly lowered hyperglycemia and ameliorated insulin resistance (IR) in db/db mice, indicated by results from multiple tests, including fasting blood glucose test, intraperitoneal insulin and glucose tolerance tests, fasting serum insulin levels and homeostasis model assessment of IR analysis as well as histology of pancreas islets. TKFS also decreased concentrations of serum triglyceride, total and low-density lipoprotein cholesterol, even though it did not change the mouse body weights. Results from western blot and immunohistochemistry analysis indicated that TKFS reversed the down-regulation of p-Akt and p-AMPK, and increased the translocation of Glucose transporter type 4 in skeletal muscles of db/db mice. In all, TKFS had promising benefits in maintaining the glucose homeostasis and reducing IR. The underlying molecular mechanisms are related to promote Akt and AMPK activation and Glucose transporter type 4 translocation in skeletal muscles. Our work showed that multicomponent Tibetan medicine TKFS acted synergistically on multiple molecular targets and signaling pathways to treat type 2 diabetes mellitus.

Antidiabetic activity of perylenequinonoid-rich extract from Shiraia bambusicola in KK-Ay mice with spontaneous type 2 diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Bitter and cold traditional Chinese medicines (TCMs) have been long used to treat diabetes mellitus (DM) based on unique medical theory system since ancient China. As one of bitter and cold TCMs, the stromatas of Shiraia bambusicola have been used for the treatment of DM and exerted clinical effects to a certain extent. However, the corresponding active principles and antidiabetic mechanism of the TCM still remain unknown. Therefore, the aim of the present investigation was to evaluate the potential antidiabetic effect of the active Shiraia bambusicola EtOAc extract (SB-EtOAc) in vitro and in vivo, and elucidate its probable antidiabetic mechanism.

MATERIALS AND METHODS

A LC-PDA-ESIMS protocol was developed to determine the chemical principles of the active EtOAc extract rapidly and unambiguously. The effect of SB-EtOAc on the glucose transporter type 4 (GLUT4) translocation and glucose uptake in L6 cells was examined. SB-EtOAc was orally administration at the dose of 30, 60 and 120mg/kg/d in KK-Ay mice, for 21 days. Body weight, plasma glucose, oral glucose tolerance test, fasted blood glucose levels, oral glucose tolerance test and insulin tolerance test, serum insulin and blood-lipid indexes were measured. GLUT4 on L6 cells membrane and phosphorylation of the AMP-activated protein kinase (p-AMPK) expression in L6 cells were measured. The GLUT4 and p-AMPK expression in KK-Ay mice skeletal muscle were measured. Phosphorylation of the acetyl-CoA carboxylase (p-ACC) and p-AMPK were measured.

RESULTS

In vitro, SB-EtOAc exhibited a strong effect of stimulation on GLUT4 translocation by 3.2 fold in L6 cells compared with basal group, however, the selective AMPK inhibitor compound C can completely inhibit the AMPK pathway and prevent the GLUT4 translocation caused by SB-EtOAc. The further western blotting experiments showed that SB-EtOAc can stimulate AMPK phosphorylation in L6 cells and improve the expression of GLUT4. In vivo, SB-EtOAc can improve the KK-Ay mice insulin resistant and oral glucose tolerance to a certain extent. And the body weight, blood glucose levels and the serum TC, TG, FFA, AST, ALT and LDL-C were significantly reduced and HDL-C were increased after 3 weeks treatment. Mechanistically, phosphorylation of the AMPK and ACC had been improved obviously and the levels of AMPK phosphorylation and GLUT4 had been also enhanced.

CONCLUSION

In vitro, SB-EtOAc exhibited a strong effect of stimulation on GLUT4 translocation and improved significantly the glucose uptake. In vivo, SB-EtOAc significantly improved oral glucose tolerance and the insulin resistant as well as glucolipid metabolism. In this study, SB-EtOAc displayed promising positive antidiabetic activity in vitro and in vivo, partly by modulating AMPK-GLUT4 and AMPK-ACC signaling pathways.

Hypoglycemic Activity and the Potential Mechanism of the Flavonoid Rich Extract from Sophora tonkinensis Gagnep. in KK-Ay Mice

This study investigated the active principles, hypoglycemic activity and potential mechanisms of the flavonoid rich extract from Sophora tonkinensis Gagnep. (ST-EtOAc) in KK-Ay diabetic mice. An off-line semipreparative liquid chromatography-nuclear magnetic resonance (LC-NMR) and liquid chromatography-ultraviolet-electrospray ionization mass spectrometry (LC-UV–ESIMS) protocol was performed to determine 13 flavonoids from ST-EtOAc. ST-EtOAc administrated orally to the KK-Ay mice significantly increased their sensibility to insulin, reduced fasting blood-glucose levels and blood lipid indexes such as triglyceride and cholesterol. Moreover, ST-EtOAc exhibited a strong effect of stimulation on glucose transporter 4 (GLUT4) translocation by 2.7-fold in L6 cells. However, the selective AMP-activated protein kinase (AMPK) inhibitor compound C can completely inhibit the activation of the AMPK pathway and prevent the GLUT4 translocation caused by ST-EtOAc. In vivo, phosphorylation of the AMPK expression in the liver and skeletal muscle was measured. The results showed phosphorylation of the AMPK had been improved and GLUT4 expression had been also enhanced. In this paper, we conclude that, ST-EtOAc seems to have potential beneficial effects on the treatment of type 2 diabetes mellitus with the probable mechanism of stimulating GLUT4 translocation modulated by the AMPK pathway.

Establishment and Characterization of a Newly Established Diabetic Gerbil Line

Objectives

We aimed to selectively breed a spontaneous diabetic gerbil when a sub-line of inbred gerbil showed increased blood glucose levels was found recently. Then we investigated the characteristics including the serum insulin, triglyceride, cholesterol, leptin, adiponectin and explored the underlying molecular mechanism for the diabetic phenotype.

Methods

The spontaneous diabetic line of gerbils was selectively inbreed the sub-line of gerbil by monitoring blood glucose of each animal. The serum insulin, adiponectin, and leptin levels were tested using an ELISA kit. The expression levels of GLUT4, Akt, leptin, adiponectin, and calpain 10 (CAPN10) were tested by western blot and Quantitative Real-time PCR (qPCR) in liver, skeletal muscle, and white adipose.

Results

Our results show that the percentages of animals with FPG≥5.2 (mmol/l), PG2h≥6.8 (mmol/l) and both FPG≥5.2 and PG2h≥6.8 (mmol/l) were increased with the number of breeding generations from F0 (21.33%) to F6 (38.46%). These diabetic gerbils exhibited insulin resistance and leptin resistance as well as decreased adiponectin level in the serum. We also observed decreased expression of adiponectin and increased expression of leptin in the skeletal muscle, respectively.

Conclusions

These results indicate that we have primarily established a spontaneous diabetic gerbil line, and the diabetic phenotypes may have been accounted for by altered expression of leptin and adiponectin.

The 11β-hydroxysteroid dehydrogenase type 1 inhibitor protects against the insulin resistance and hepatic steatosis in db/db mice

Glucocorticoids (GCs) metabolism is regulated by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). When GCs are present in excess, they can impair glucose-dependent insulin sensitivity. We have previously synthesized several curcumin analogues, of which four compounds were selective inhibitors of 11β-HSD1. Here, we present data supporting that the 11β-hydroxysteroid dehydrogenase type 1 inhibitor (H8) inhibits insulin resistance and ameliorates hepatic steatosis in db/db mice. We compared glucose and lipid metabolism in db/db mice with or without administration of H8, which significantly decreased fasting blood glucose levels and protected against insulin resistance and hepatic steatosis compared to when glucose and lipid metabolism were measured following curcumin administration. The hepatic enzyme was reduced significantly in the plasma samples from db/db mice which were treated with H8. Serum corticosterone (active) levels, which are regulated by 11β-HSD1 were reduced when mice received H8. H8 administration suppressed phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6-pase) expression, which are related to gluconeogenesis and enhanced glucose transporter 4 (GLUT4) protein content in liver. Treatment with H8 improved obesity and metabolic disorders, such as insulin resistance and hepatic steatosis by suppressing activity of 11β-HSD1, suggesting that H8 might be a beneficial drug for the treatment of obesity and Type-2 diabetes (T2D).

Antidiabetic effects of flavonoids from Sophora flavescens EtOAc extract in type 2 diabetic KK-ay mice

ETHNOPHARMACOLOGICAL RELEVANCE

Bitter and cold Chinese medicines have been long used for the treatment for diabetes mellitus (DM) for thousands of years in China. The roots of Sophora flavescens Ait., one of bitter and cold Chinese medicines commonly used to remove lung heat have been used to counteract DM and exerted good clinical effects for diabetic patients in some folk hospitals in Fujian province, PR China. However, the corresponding active principles and antidiabetic mechanism of this Traditional Chinese Medicine remain unclear. Therefore, in this study, we aim at chemical profiling of the active principles, validating the potential antidiabetic effects of the active EtOAc extract (SF-EtOAc) in vitro and in vivo, and elucidating its probable antidiabetic mechanism as well as evaluating its acute oral toxicity.

MATERIALS AND METHODS

An off-line semi-preparative LC-NMR and LC-UV-ESI MS protocol was developed to determine the chemical principles of the active EtOAc extract rapidly and unambiguously. The effect of SF-EtOAc on the glucose transporter type 4 (GLUT4) translocation in L6 myotubes was examined. T2DM KK-Ay mice were induced by high-fat diet. SF-EtOAc was orally administration at the dose of 30, 60 and 120 mg/kg/d, for 21 days. Metformin was used as positive control. Body weight, plasma glucose, oral glucose tolerance test, serum insulin and blood-lipid indexes were measured. Phosphorylation of the AMP-activated protein kinase (AMPK) expression in liver was measured.

RESULTS

We found that SF-EtOAc significantly improved oral glucose tolerance, increased serum high density lipoprotein cholesterol (HDL-C) and reduced body weight, blood glucose levels and other related blood-lipid indexes. Mechanistically, SF-EtOAc elevated phosphorylation of AMP-activated protein kinase (AMPK) and stimulated membrane translocation of GLUT4. Moreover, it was unveiled that oral median lethal dose (LD50) of SF-EtOAc was more than 7500 mg/kg, suggesting that SF-EtOAc was practically non-toxic for mice.

CONCLUSIONS

SF-EtOAc improves glucose tolerance, reduces hyperglycemia and resumes insulin levels, at least in part, by activating GLUT4 translocation which may be modulated by AMPK pathway. According to the results of the present study, SF-EtOAc possesses a potent antidiabetic activity and could be used as a safe remedy for the treatment of diabetes.

HPLC-based activity profiling of anti-hepatocellular carcinoma constituents from the Tibetan medicine, Caragana tibetica

During the screening of a traditional Chinese folk herb library against HepG2 and Hep3B cell lines, the EtOAc extract from the Tibetan medicine, Caragana tibetica (CT-EtOAc) exhibited potential anti-hepatocellular carcinoma (anti-HCC) activity. HPLC-based activity profiling was performed for targeted identification of anti-HCC activity from CT-EtOAc by MS-directed purification method. CT-EtOAc was separated by time-based fractionation for further anti-HCC bioassay by a semipreparative HPLC column (150 mm × 10 mm i.d., 5 μm) with a single injection of 5 mg. Bioassay-guided and ESIMS-directed large scale purification was performed with a single injection of 400 mg of CT-EtOAc by peak-based fractionation. A 1.4-mm heavy wall micro NMR tube with z-gradient was used to measure one and two dimensional NMR spectra for the minor or trace amounts of components of the extract. Two active compounds could be elucidated as naringenin chalcone (CT-1) and 3-hydroxy-8, 9-dimethoxypterocarpan (CT-2) relevant to anti-HCC effects for the EtOAc extract of C. tibetica rapidly and unambiguously by this protocol.