A novel AMPK activator, WS070117, improves lipid metabolism discords in hamsters and HepG2 cells

2', 3', 5'-tri-O-acetyl-N6-(3-hydroxyphenyl) adenosine alleviates diet-induced hyperlipidemia by modulating intestinal gene expression profiles and metabolic pathway

There is a growing body of evidence suggesting that the composition of intestinal flora plays a significant role in regulating lipid metabolism. 2', 3', 5'-tri-O-acetyl-N6-(3-hydroxyphenyl) adenosine (IMMH007) is a new candidate compound for regulating blood cholesterol and other lipids. In this study, we conducted metagenomic and metabolomic analyses on samples from high-fat diet-fed (HFD) hamsters treated with IMMH007. Our findings revealed that IMM-H007 reversed the imbalance of gut microbiota caused by a high-fat diet. Additionally, it activated adiponectin receptor and pantothenate and CoA biosynthesis pathway-related genes, which are known to regulate lipid and glucose metabolism. Furthermore, IMM-H007 promotes cholesterol metabolism by reducing the abundance of genes and species associated with 7α-dehydroxylation and bile salt hydrolase (BSH). Metabolomics and pharmacological studies have shown that IMM-H007 effectively improved glucose and lipid metabolism disorders caused by HFD, reduced the aggregation of secondary bile acids (SBAs), significantly increased the content of hyodeoxycholic acid (HDCA), and also activated the expression of VDR in the small intestine. As a result, there was a reduction in the leakage of diamine oxidase (DAO) into the bloodstream in hamsters, accompanied by an upregulation of ZO-1 expression in the small intestine. The results suggested that IMM-H007 regulated glucose and lipid metabolism, promoted cholesterol metabolism through activating the expression of VDR, inhibiting inflammatory and improving the permeability of the intestinal barrier. Thus, our study provides new understanding of how IMM-H007 interacts with intestinal function, microbiota, and relevant targets, shedding light on its mechanism of action.

Paradoxical reduction of plasma lipids and atherosclerosis in mice with adenine-induced chronic kidney disease and hypercholesterolemia

Background

Atherosclerotic cardiovascular disease is prevalent among patients with chronic kidney disease (CKD). In this study, we initially aimed to test whether vascular calcification associated with CKD can worsen atherosclerosis. However, a paradoxical finding emerged from attempting to test this hypothesis in a mouse model of adenine-induced CKD.

Methods

We combined adenine-induced CKD and diet-induced atherosclerosis in mice with a mutation in the low-density lipoprotein receptor gene. In the first study, mice were co-treated with 0.2% adenine in a western diet for 8 weeks to induce CKD and atherosclerosis simultaneously. In the second study, mice were pre-treated with adenine in a regular diet for 8 weeks, followed by a western diet for another 8 weeks.

Results

Co-treatment with adenine and a western diet resulted in a reduction of plasma triglycerides and cholesterol, liver lipid contents, and atherosclerosis in co-treated mice when compared with the western-only group, despite a fully penetrant CKD phenotype developed in response to adenine. In the two-step model, renal tubulointerstitial damage and polyuria persisted after the discontinuation of adenine in the adenine-pre-treated mice. The mice, however, had similar plasma triglycerides, cholesterol, liver lipid contents, and aortic root atherosclerosis after being fed a western diet, irrespective of adenine pre-treatment. Unexpectedly, adenine pre-treated mice consumed twice the calories from the diet as those not pre-treated without showing an increase in body weight.

Conclusion

The adenine-induced CKD model does not recapitulate accelerated atherosclerosis, limiting its use in pre-clinical studies. The results indicate that excessive adenine intake impacts lipid metabolism.

IMM-H007 attenuates isoprenaline-induced cardiac fibrosis through targeting TGFβ1 signaling pathway

Upon chronic stress, β-adrenergic receptor activation induces cardiac fibrosis and leads to heart failure. The small molecule compound IMM-H007 has demonstrated protective effects in cardiovascular diseases via activation of AMP-activated protein kinase (AMPK). This study aimed to investigate IMM-H007 effects on cardiac fibrosis induced by β-adrenergic receptor activation. Because adenosine analogs also exert AMPK-independent effects, we assessed AMPK-dependent and -independent IMM-H007 effects in murine models of cardiac fibrosis. Continual subcutaneous injection of isoprenaline for 7 days caused cardiac fibrosis and cardiac dysfunction in mice in vivo. IMM-H007 attenuated isoprenaline-induced cardiac fibrosis, diastolic dysfunction, α-smooth muscle actin expression, and collagen I deposition in both wild-type and AMPKα2-/- mice. Moreover, IMM-H007 inhibited transforming growth factor β1 (TGFβ1) expression in wild-type, but not AMPKα2-/- mice. By contrast, IMM-H007 inhibited Smad2/3 signaling downstream of TGFβ1 in both wild-type and AMPKα2-/- mice. Surface plasmon resonance and molecular docking experiments showed that IMM-H007 directly interacts with TGFβ1, inhibits its binding to TGFβ type II receptors, and downregulates the Smad2/3 signaling pathway downstream of TGFβ1. These findings suggest that IMM-H007 inhibits isoprenaline-induced cardiac fibrosis via both AMPKα2-dependent and -independent mechanisms. IMM-H007 may be useful as a novel TGFβ1 antagonist.

Soyasapogenol C from Fermented Soybean (Glycine Max) Acting as a Novel AMPK/PPARα Dual Activator Ameliorates Hepatic Steatosis: A Novel SANDA Methodology

(1) Background: Soyasapogenol C (SSC), a derivative of soyasapogenol B (SSB), is specifically found high in many fermented soybean (Glycine max) products, including Cheonggukjang (in Korean). However, the biological activities for preventing and treating hepatic steatosis, and the precise underlying mechanisms of SSC, remain to be explored. (2) Methods: A novel SANDA (structural screening, ADMET prediction, network pharmacology, docking validation, and activity evaluation) methodology was used to examine whether SSC exerts hepatoprotective effects in silico and in vitro. (3) Results: SSC had better ADMET characteristics and a higher binding affinity with predicted targets chosen from network pathway analysis than SSB. SSC induced the phosphorylation of AMP-activated protein kinase (AMPK) and stimulated the nuclear translocation of peroxisome proliferator-activated receptor alpha (PPARα), further enhancing PPAR response element (PPRE) binding activity in HepG2 cells. Concurrently, SSC significantly inhibited triglyceride accumulation, which was associated with the suppression of lipogenesis genes and the enhancement of fatty acid oxidation gene expression in HepG2 cells. (4) Conclusions: Soyasapogenol C, discovered using a novel SANDA methodology from fermented soybean, is a novel AMPK/PPARα dual activator that is effective against hepatic steatosis. Dietary supplementation with soyasapogenol C may prevent the development of hepatic steatosis and other diseases associated with fat accumulation in the liver.

Drug repurposing for hyperlipidemia associated disorders: An integrative network biology and machine learning approach

Hyperlipidemia causes diseases like cardiovascular disease, cancer, Type II Diabetes and Alzheimer's disease. Drugs that specifically target HL associated diseases are required for treatment. 34 KEGG pathways targeted by lipid lowering drugs were used to construct a directed protein-protein interaction network and driver nodes were determined using CytoCtrlAnalyser plugin of Cytoscape 3.6. The involvement of driver nodes of HL in other diseases was verified using GWAS. The central nodes of the network and 34 overrepresented pathways had a critical role in Hyperlipidemia. The PI3K-AKT signalling pathway, non-essentiality, non-centrality and approved drug target status were the predominant features of the driver nodes. Next, a Random Forest classifier was trained on 1445 molecular descriptors calculated using PaDEL for 50 approved lipid lowering and 84 lipid raising drugs as the positive and negative training set respectively. The classifier showed average accuracy of 76.8 % during 5-fold cross validation with AUC of 0.79 ± 0.06 for the ROC curve. The classifier was applied to select molecules with favourable properties for lipid lowering from the 130 approved drugs interacting with the identified driver nodes. We have integrated diverse network data and machine learning to predict repurposing of nine drugs for treatment of HL associated diseases.

Lactobacillus Strains Alleviated Hyperlipidemia and Liver Steatosis in Aging Rats via Activation of AMPK

In this study, we hypothesized that different strains of Lactobacillus can alleviate hyperlipidemia and liver steatosis via activation of 5′ adenosine monophosphate-activated protein kinase (AMPK), an enzyme that is involved in cellular energy homeostasis, in aged rats. Male rats were fed with a high-fat diet (HFD) and injected with D-galactose daily over 12 weeks to induce aging. Treatments included (n = 6) (i) normal diet (ND), (ii) HFD, (iii) HFD-statin (lovastatin 2 mg/kg/day), (iv) HFD-Lactobacillus fermentum DR9 (10 log CFU/day), (v) HFD-Lactobacillus plantarum DR7 (10 log CFU/day), and (vi) HFD-Lactobacillus reuteri 8513d (10 log CFU/day). Rats administered with statin, DR9, and 8513d reduced serum total cholesterol levels after eight weeks (p < 0.05), while the administration of DR7 reduced serum triglycerides level after 12 weeks (p < 0.05) as compared to the HFD control. A more prominent effect was observed from the administration of DR7, where positive effects were observed, ranging from hepatic gene expressions to liver histology as compared to the control (p < 0.05); downregulation of hepatic lipid synthesis and β-oxidation gene stearoyl-CoA desaturase 1 (SCD1), upregulation of hepatic sterol excretion genes of ATP-binding cassette subfamily G member 5 and 8 (ABCG5 and ABCG8), lesser degree of liver steatosis, and upregulation of hepatic energy metabolisms genes AMPKα1 and AMPKα2. Taken altogether, this study illustrated that the administration of selected Lactobacillus strains led to improved lipid profiles via activation of energy and lipid metabolisms, suggesting the potentials of Lactobacillus as a promising natural intervention for alleviation of cardiovascular and liver diseases.

Comparative analysis of stimulation and binding characteristics of adenosine analogs to AMP-activated protein kinase

To compare the stimulation and binding characteristics of adenosine analogs including AMP, IMM-H007, and M1, to AMPK, and to explore the potential mechanism underlying the regulation effect of adenosine analogs on AMPK activity, [γ-³²P]ATP assay, circular dichroism experiments and molecular docking test were performed. We found that the interactions with Thr86, Thr88, and His150 in site 1 are probably the reason why the affinities of IMM-H007, M1, and adenosine are comparable but their allosteric activation on AMPK varies greatly, partly interpreting the mechanism of AMPK activity regulated by adenosine analogs.

Comprehensive characterization of in vitro and in vivo metabolites of 2',3',5'‑tri‑O‑acetyl‑N6‑(3‑hydroxyphenyl) adenosine and study of the metabolites distribution in rats by combined methods of HPLC-DAD, off-line cryoNMR, and HPLC-QTOFMS

The compound 2',3',5'‑tri‑O‑acetyl‑N₆‑(3‑hydroxyphenyl) adenosine (also known as IMM-H007) is a new adenosine analogue that displays anti-hyperlipidaemic activity in many preliminary studies. To clarify its biotransformation process, in vitro and in vivo metabolic patterns of IMM-H007 in rat liver microsomes (RLMs), urine, feces, serum, and various tissues were investigated using high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD), off-line cryogenically cooled probe nuclear magnetic resonance (cryoNMR), and high-performance liquid chromatography quadrupole TOF MS (HPLC-QTOFMS) measurements. A total of 21 metabolites were detected and identified based on accurate mass measurements, diagnostic product ions, and 1D and 2D NMR data. All of the 21 metabolites were detected in vivo besides the 7 ones (LM1-3, LM4a-b, LM5, LM6 (M8)) in vitro. Among them, eight metabolites were phase I metabolites composed of the hydrolysis products LM1-3, LM4a, LM4b, LM5 and M7-8, and hydrolysis and hydroxylation products M6. Others were phase II metabolites including glucuronidation products M2, M4, M9, M11a-c, and M12a-c; and sulfation products M3, M5, and M10. Notably, 14 metabolites (LM1-3, LM4a-b, LM5, M9-10, M11a-c, M12a-c) were unreported before and the distribution of IMM-H007 and its all metabolites was reported for the first time. The results revealed IMM-H007 was metabolized mainly in the small intestine and serum, kidney, stomach, small and large intestines were important samples for metabolites presence. This work improves understanding of the metabolism, distribution, and excretion of IMM-H007, and demonstrates the HPLC/HPLC-MS/off-line cryoNMR approach can be applied for detection and identification of metabolites in complex biological matrices.

AMP-activated protein kinase agonist N6-(3-hydroxyphenyl)adenosine protects against fulminant hepatitis by suppressing inflammation and apoptosis

Both AMP-activated protein kinase (AMPK) agonist and inhibitor have been reported to protect against fulminant hepatitis, implying that AMPK may play a complicated role in the development of fulminant hepatitis. In this study, we exploited whether the novel AMPK agonist N₆-(3-hydroxyphenyl)adenosine (named as M1) exerted protective effects on fulminant hepatitis and whether its beneficial effects were AMPK-dependent. Results showed that intraperitoneal injection of M1 improved liver function, ameliorated liver injury and finally raised the survival rate in d-galactosamine/lipopolysaccharide (GalN/LPS)-treated mice. These beneficial effects of M1 may attribute to the suppression of pro-inflammatory cytokines production and the prevention of hepatocyte apoptosis. Furthermore, M1 pretreatment mitigated LPS-stimulated TLR4 expression and NFκB activation in murine peritoneal macrophages and prevented actinomycin D (Act D)/tumor necrosis factor α (TNFα)-induced apoptosis by promoting protective autophagy in primary hepatocytes. Additionally, M1-induced AMPK activation was responsible both for its anti-inflammatory action in macrophages and for its anti-apoptotic action in hepatocytes. To our surprise, compared with the control AMPKα1^lox/lox/AMPKα2^lox/lox mice, liver-specific AMPKα1 knockout (AMPKα1_LS^−/−) mice were more sensitive to GalN/LPS administration but not AMPKα2_LS^−/−mice, and the beneficial effects of M1 on acute liver failure and the production of pro-inflammatory factors were dampened in AMPKα1_LS^−/− mice. Therefore, our study may prove that M1 could be a promising therapeutic agent for fulminant hepatitis, and targeting AMPK may be useful therapeutically in the control of LPS-induced hepatotoxicity.

IMM-H007, a new therapeutic candidate for nonalcoholic fatty liver disease, improves hepatic steatosis in hamsters fed a high-fat diet

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease in humans, is characterized by the accumulation of triacylglycerols (TGs) in hepatocytes. We tested whether 2′,3′,5′‐tri‐acetyl‐N6‐(3‐hydroxylaniline) adenosine (IMM‐H007) can eliminate hepatic steatosis in hamsters fed a high‐fat diet (HFD), as a model of NAFLD. Compared with HFD‐only controls, IMM‐H007 treatment significantly lowered serum levels of TG, total cholesterol, and free fatty acids (FFAs) in hamsters fed the HFD, with a prominent decrease in levels of serum transaminases and fasting insulin, without affecting fasting glucose levels. Moreover, ¹H‐MRI and histopathological analyses revealed that hepatic lipid accumulation and fibrosis were improved by IMM‐H007 treatment. These changes were accompanied by improvement of insulin resistance and oxidative stress, and attenuation of inflammation. IMM‐H007 reduced expression of proteins involved in uptake of hepatic fatty acids and lipogenesis, and increased very low density lipoprotein secretion and expression of proteins responsible for fatty acid oxidation and autophagy. In studies in vivo, IMM‐H007 inhibited fatty acid import into hepatocytes and liver lipogenesis, and concomitantly stimulated fatty acid oxidation, autophagy, and export of hepatic lipids. These data suggest that IMM‐H007 resolves hepatic steatosis in HFD‐fed hamsters by the regulation of lipid metabolism. Thus, IMM‐H007 has therapeutic potential for NAFLD.

Tangshen formula attenuates hepatic steatosis by inhibiting hepatic lipogenesis and augmenting fatty acid oxidation in db/db mice

Tangshen formula (TSF), a well-prescribed traditional Chinese formula, has been used in the treatment of diabetic nephropathy. However, whether TSF ameliorates dyslipidemia and liver injury associated with diabetes remains unclear. In this study, we examined the effects of TSF on lipid profiles and hepatic steatosis in db/db mice. For this purpose, 8‑week-old db/db mice were treated with TSF or saline for 12 weeks via gavage and db/m mice were used as controls. Body weight and blood glucose levels were monitored weekly and bi-weekly, respectively. Blood samples were obtained for the analysis of lipids and enzymes related to hepatic function, and liver tissues were analyzed by histology, immunohistochemistry and molecular examination. The results revealed that TSF markedly reduced body weight, liver index [liver/body weight (LW/BW)] and improved lipid profiles, hepatic function and steatosis in db/db mice. TSF induced the phosphoralation of AMP-activated protein kinase and inhibited the activity of sterol regulatory element-binding protein 1 together with the inhibition of the expression of genes involved in de novo lipogenesis (DNL) and gluconeogenesis, such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), stearoyl CoA desaturase 1 (SCD1), glucose-6-phosphatase (G6pc) and phosphoenolpyruvate carboxykinase 1 (Pck1). Additionally, the silent mating type information regulation 2 homolog 1 (Sirt1)/peroxisome proliferator-activated receptor α (PPARα)/malonyl-CoA decarboxylase (MLYCD) cascade was potently activated by TSF in the liver and skeletal muscle of db/db mice, which led to enhanced fatty acid oxidation. These findings demonstrated that TSF attenuated hepatic fat accumulation and steatosis in db/db mice by inhibiting lipogenesis and augmenting fatty acid oxidation.

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.

Simultaneous quantification of 2',3',5'-tri-O-acetyl-N6-(3-hydroxylaniline)adenosine and its principal metabolites in hamster blood by LC-MS/MS and its application in pharmacokinetics study

2',3',5'-Tri-O-acetyl-N6-(3-hydroxylaniline)adenosine (IMM-H007, once called WS070117) is being developed as a novel anti-hyperlipidemia agent for its high efficacy and low toxicity. In this study, a sensitive and specific liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was established for the simultaneous quantification of IMM-H007 and its two major metabolites (3S,4R,5R)-2-(hydroxymethyl)-5-(6-((3-hydroxyphenyl)amino)-9H-purin-9-yl)tetrahdrofuran-3,4-diol (M1) and ((2R,3S,4R,5R)-3,4-dihydroxy-5-(6-((3-hydroxyphenyl)amino)-9H-purin-9-yl)tetrahydrofuran-2-yl)methyl dihydrogen phosphate (MP) in hamster blood. An analogue of IMM-H007, WS070119 was used as the internal standard. Blood samples were prepared by a simple protein precipitation with acetonitrile. The chromatographic separation was performed on a ReproSil-Pur 120C18 column (3μm, 2mm×100mm) with a gradient mobile phase of methanol/water containing 0.1% formic acid (v/v) in a flow rate of 0.2mL/min. Detection was carried out on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization (ESI) in positive ion selective reaction monitoring (SRM) mode. The monitored transitions were 486.2→228.1 for IMM-H007, 360.0→228.0 for M1, 440.0→228.0 for MP and 374.1→242.0 for the internal standard, respectively. Satisfactory linearity was obtained for the analytes over the range of 1-500ng/mL for IMM-H007, 2-1000ng/mL for M1 and 10-5000ng/mL for MP. The lower limits of the quantification (LLOQs) were 1ng/mL for IMM-H007, 2ng/mL for M1 and 10ng/mL for MP. The intra-day and inter-day precisions (RSD, %) of the analytes were within 14.2%, and the accuracy (RE, %) ranged from -9.4% to 10.7%. The average recoveries of the analytes were more than 80.0%. The analytes were proved to be stable during given storage, preparation, and analytic procedures. The method was successfully applied to the pharmacokinetic study in hamsters after oral administration of IMM-H007.

The Synthesis of the Metabolites of 2',3',5'-Tri-O-acetyl-N₆-(3-hydroxyphenyl) Adenosine (WS070117)

Seven metabolites of 2′,3′,5′-tri-O-acetyl-N₆-(3-hydroxyphenyl) adenosine (WS070117) were synthesized by deacetylation, hydrolysis, cyclization, sulfonylation and glycosylation reactions, respectively. All these compounds, which could be useful as material standards for metabolic research, were characterized by NMR and HPLC-MS (ESI) analyses.

AMP-activated protein kinase attenuates oxLDL uptake in macrophages through PP2A/NF-κB/LOX-1 pathway

The differentiation of macrophages into lipid-laden foam cells is a hallmark in early-stage atherosclerosis. The developmental role of adenosine monophosphate-activated protein kinase (AMPK) in a transformation of foam cells, especially in macrophage cholesterol uptake that remains undetermined. Here we demonstrate that AMPK activation in response to IMM-H007 or AICAR resulted in a decrease in macrophage cholesterol uptake and thus inhibited foam cell formation in macrophages mediated by oxidized low-density lipoprotein (oxLDL). This functional change was caused by a downregulation of mRNA and protein expression of LOX-1 but not other scavenger receptors, including scavenger receptor-A (SR-A), CD36 and scavenger receptor-BI (SR-BI). The expression of LOX-1 was regulated by AMPK activation induced decreased phosphorylation of nuclear transcription factor NF-κB, since siRNA interference or dominant negative AMPK overexpression significantly promotes Ser536 dephosphorylation of NF-κB p65 and thus increases LOX-1 expression. Moreover, pharmacological AMPK activation was shown to promote protein phosphatase 2A (PP2A) activity and the specific PP2A inhibitor, okadaic acid, could prevent the effects of IMM-H007 or AICAR on NF-κB and LOX-1. In vivo, pharmacological AMPK activation reduced the lesion size of atherosclerosis and the expression of LOX-1 in aortas in apolipoprotein E-deficient mice. Our current findings suggest a novel mechanism of LOX-1 regulation by AMPK to attenuate macrophage oxLDL uptake and atherosclerosis.

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.

Structure Elucidation of the Metabolites of 2', 3', 5'-Tri-O-Acetyl-N6-(3-Hydroxyphenyl) Adenosine in Rat Urine by HPLC-DAD, ESI-MS and Off-Line Microprobe NMR

2', 3', 5'-Tri-O-acetyl-N6-(3-hydroxyphenyl) adenosine (also known as WS070117) is a new adenosine analog that displays anti-hyperlipidemic activity both in vitro and in vivo experiments as shown in many preliminary studies. Due to its new structure, little is known about the metabolism of WS070117. Hence, the in vivo metabolites of WS070117 in rat urine following oral administration were investigated. Identification of the metabolites was conducted using the combination of high-performance liquid chromatography (HPLC) coupled with diode array detector (DAD), ion trap electrospray ionization-mass spectrometry (ESI-MS), and off-line microprobe nuclear magnetic resonance (NMR) measurements. Seven metabolites were obtained as pure compounds at the sub-milligram to milligram levels. Results of structure elucidation unambiguously revealed that the phase I metabolite, N6-(3-hydroxyphenyl) adenosine (M8), was a hydrolysate of WS070117 by hydrolysis on the three ester groups. N6-(3-hydr-oxyphenyl) adenine (M7), also one of the phase I metabolites, was the derivative of M8 by the loss of ribofuranose. In addition to two phase I metabolites, there were five phase II metabolites of WS070117 found in rat urine. 8-hydroxy-N6-(3-hydroxy-phenyl) adenosine (M6) was the product of M7 by hydrolysis at position 8. The other four were elucidated to be N6-(3-O-β-D-glucuronyphenyl) adenine (M2), N8-hydroxy-N6-(3-O-sulfophenyl) adenine (M3), N6-(3-O-β-D-glucuronyphenyl) adenosine (M4), and N6-(3-O- sulfophenyl) adenosine (M5). Phase II metabolic pathways were proven to consist of hydroxylation, glucuronidation and sulfation. This study provides new and valuable information on the metabolism of WS070117, and also demonstrates the HPLC/MS/off-line microprobe NMR approach as a robust means for rapid identification of metabolites.

Chlorogenic acid-enriched extract from Eucommia ulmoides leaves inhibits hepatic lipid accumulation through regulation of cholesterol metabolism in HepG2 cells

CONTEXT

Eucommia ulmoides Oliver (Eucommiaceae) leaf exhibits beneficial lipid-lowering and anti-obesity effects. However, the mechanisms remain unknown.

OBJECTIVE

The objective of this study is to investigate the lipid-lowering effects of chlorogenic acid (CGA)-enriched extract from this plant (CAEF) in human hepatoma HepG2 cells, focusing on cholesterol metabolism.

MATERIALS AND METHODS

HepG2 cells were treated with CAEF (10, 20, 25, 40, 60, and 80 mg/L), CGA (0.3, 3, 30, 300, and 600 μmol/L), and simvastatin (0.1, 1, 10, 50, and 100 μmol/L) for 24 or 48 h. The cytotoxicity, Oil red O staining, total cholesterol, and triacylglycerol in supernatants were determined. The mRNA expression of genes involved in cholesterol metabolism was determined with RT-PCR. The protein expression of HMG-CoA reductase (HMGCR) was examined by immunocytochemistry and western-blot.

RESULTS

The IC50 values were 59.2 mg/L for CAEF, 335.9 μmol/L for CGA, and 10.5 μmol/L for simvastatin. By treating cells with CAEF (25 mg/L), CGA (30 μmol/L), or simvastatin (10 μmol/L) for 48 h, the efflux of total cholesterol and triacylglycerol was increased (CAEF, 4.06- and 31.00-folds; CGA, 2.94- and 2.17-folds; and simvastatin, 3.94- and 24.67-folds), and the cellular lipid droplets were reduced in Oil red O staining. CAEF and CGA increased mRNA expression of ABCA1, CYP7A1, and AMPKα2, while CAEF and simvastatin decreased SREBP2. However, their effects on LXRα mRNA expression were variable. Importantly, all drugs significantly inhibited protein expression of HMGCR at mRNA and protein levels.

DISCUSSION AND CONCLUSION

CAEF is a promising dietary supplement to prevent obesity and dyslipidemia and the effects appear to be due, at least in part, to regulating cholesterol metabolism through inhibition of HMGCR in HepG2 cells.

Inhibition of AMP Kinase by the Protein Phosphatase 2A Heterotrimer, PP2APpp2r2d

AMP kinase is a heterotrimeric serine/threonine protein kinase that regulates a number of metabolic processes, including lipid biosynthesis and metabolism. AMP kinase activity is regulated by phosphorylation, and the kinases involved have been uncovered. The particular phosphatases counteracting these kinases remain elusive. Here we discovered that the protein phosphatase 2A heterotrimer, PP2A(Ppp2r2d), regulates the phosphorylation state of AMP kinase by dephosphorylating Thr-172, a residue that activates kinase activity when phosphorylated. Co-immunoprecipitation and co-localization studies indicated that PP2A(Ppp2r2d) directly interacted with AMP kinase. PP2A(Ppp2r2d) dephosphorylated Thr-172 in rat aortic and human vascular smooth muscle cells. A positive correlation existed between decreased phosphorylation, decreased acetyl-CoA carboxylase Acc1 phosphorylation, and sterol response element-binding protein 1c-dependent gene expression. PP2A(Ppp2r2d) protein expression was up-regulated in the aortas of mice fed a high fat diet, and the increased expression correlated with increased blood lipid levels. Finally, we found that the aortas of mice fed a high fat diet had decreased AMP kinase Thr-172 phosphorylation, and contained an Ampk-PP2A(Ppp2r2d) complex. Thus, PP2A(Ppp2r2d) may antagonize the aortic AMP kinase activity necessary for maintaining normal aortic lipid metabolism. Inhibiting PP2A(Ppp2r2d) or activating AMP kinase represents a potential pharmacological treatment for many lipid-related diseases.

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

We have investigated the antidiabetic effect and mechanism of methanolic extract of Berberis julianae Schneid. (BJSME) in STZ induced Type 2 diabetes mellitus mice. T2DM mice were induced by high fat diet and low dose streptozotocin (STZ). BJSME was orally administrated at the doses of 60, 120, and 240 mg/kg/d, for 21 days. Metformin was used as positive control drug. Food intake, body weight, plasma glucose, oral glucose tolerance test, insulin tolerance test, insulin, and blood-lipid content were measured. The effects of BJSME on the glucose transporter 4 (GLUT4) translocation in L6 myotubes and the GLUT4 protein expression in skeletal muscle as well as phosphorylation of the AMP-activated protein kinase (AMPK) in liver and muscle were examined. In vitro and in vivo results indicate that BJSME increased GLUT4 translocation by 1.8-fold and BJSME significantly improved the oral glucose tolerance and low density lipoprotein cholesterol (LDL-C) of serum and reduced body weight, glucose, and other related blood-lipid contents. The BJSME treatment also stimulated the phosphorylation of AMPK. Thus, BJSME seems to possess promising beneficial effects for the treatment of T2DM with the possible mechanism via stimulating AMPK activity.

Activators of AMPK: not just for Type II diabetes

Recent discoveries of AMPK activators point to the large number of therapeutic candidates that can be transformed to successful designs of novel drugs. AMPK is a universal energy sensor and influences almost all physiological processes in the cells. Thus, regulation of the cellular energy metabolism can be achieved in selective tissues via the artificial activation of AMPK by small molecules. Recently, special attention has been given to direct activators of AMPK that are regulated by several nonspecific upstream factors. The direct activation of AMPK, by definition, should lead to more specific biological activities and as a result minimize possible side effects.

AMP-activated protein kinase activators in diabetic ulcers: from animal studies to Phase II drugs under investigation

INTRODUCTION

Diagnosed cases of diabetes have gradually increased year by year, and research on diabetes mellitus (DM) has attracted greater attention from the medical profession. Diabetic ulcers present persistent pain and the risk of bacterial infection. However, no promising treatment methods have been found. As a regulator of cellular energy balance, 5' adenosine monophosphate-activated protein kinase (AMPK) has been suggested as a drug target for DM, including such drugs as metformin.

AREAS COVERED

This review summarizes the current research and clinical trials of AMPK activators on diabetic wound healing and diabetic ulcers. Furthermore, it discusses the feasibility of AMPK activators in the treatment of diabetic wounds.

EXPERT OPINION

Animal studies have demonstrated that AMPK activators are a potential treatment for diabetic ulcers. AMPK activators alleviate tissue inflammation and promote re-epithelialization in diabetic wounds. However, due to the complicated pathological mechanism of diabetic foot ulcers, AMPK activators should be combined with other approaches. The new strategies for combination therapy with AMPK activator may provide a therapeutic advantage for patients with diabetic ulcers.

The inhibition of oleic acid induced hepatic lipogenesis and the promotion of lipolysis by caffeic acid via up-regulation of AMP-activated kinase

BACKGROUND

Caffeic acid (CA) can inhibit toxin-induced liver injury. In this study, CA is assessed for its lipid lowering potential when oleic acid is used to induce non-alcoholic fatty liver disease in human HepG2 cells.

RESULTS

The results showed that both the triglyceride and cholesterol content are decreased in the HepG2 cells by using the enzymatic colorimetric method. CA enhances the phosphorylation of AMP-activated protein kinase (AMPK) and its primary downstream targeting enzyme, acetyl-CoA carboxylase. CA down-regulates the lipogenesis gene expression of sterol regulatory element-binding protein-1 and its target genes, fatty acid synthase in the presence of oleic acid. In addition, CA significantly decreases cholesterol and triglyceride production via inhibition the expression of both 3-hydroxy-3-methyglutary coenzyme A reductase and glycerol-3-phosphate acyltransferase. These effects are eliminated by pretreatment with compound C, an AMPK inhibitor.

CONCLUSIONS

These results demonstrate that CA inhibits oleic acid induced hepatic lipogenesis and the promotion of lipolysis via up-regulation of AMP-activated kinase.

Antidiabetic effect of total flavonoids from Sanguis draxonis in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Sanguis draxonis (SD) is a kind of red resin obtained from the wood of Dracaena cochinchinensis (Lour.) S. C. Chen (Dracaena cochinchinensis). It is a Chinese traditional herb that is prescribed for the handling of diabetic disorders, which is also supported by an array of scientific studies published in recent years. Although chemical constituents of this plant material have also been previously evaluated (Tang et al., 1995; Wei et al., 1998), it still remains poorly understood which constituent is the major contributor to its antidiabetic activities. Moreover, very little is known about the molecular mechanisms underlying antidiabetic activities of SD. Flavonoids exist at a high level in SD. The aim of this study is to evaluate the antidiabetic effects of total flavonoids from SD (SDF) in type 2 Diabetes mellitus (T2DM) rats.

MATERIALS AND METHODS

T2DM rats were induced by 4 weeks high-fat diet and a singular injection of streptozotocin (STZ) (35mg/kg). Then T2DM rats were treated with SDF for 21 days, using normal saline as the negative control. For comparison, a standard antidiabetic drug, metformin (200mg/kg), was used as a positive control. Three weeks later, relative biochemical indexes were determined and histopathological examinations were performed to assess the antidiabetic activities of SDF.

RESULTS

SDF not only exhibited a significant hypoglycemic activity, but also alleviated dyslipidemia, tissue steatosis, and oxidative stress associated with T2DM. Moreover, considerable pancreatic islet protecting effects could be observed after SDF treatment. Further investigations revealed a potential anti-inflammation activity of SDF by determining serum levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP).

CONCLUSIONS

This study demonstrates both hypoglycemic and hypolipidemic effects of SDF in T2DM rats, suggesting that flavonoids are the major active ingredients accounting for the antidiabetic activity of SD. Alleviating chronic inflammation responses and protecting pancreatic islets are possible mechanisms involved in the antidiabetic activity of SDF.

Alternanthera sessilis Red Ethyl Acetate Fraction Exhibits Antidiabetic Potential on Obese Type 2 Diabetic Rats

The antidiabetic potential of Alternanthera sessilis Red was investigated using the obese type 2 diabetic rats induced by high fat diet and streptozotocin. Three fractions (hexane, ethyl acetate, and water) were obtained from the crude ethanol extract of Alternanthera sessilis Red. Alternanthera sessilis Red ethyl acetate fraction (ASEAF) was found to possess the most potent antihyperglycemic effect through oral glucose tolerance test. The ASEAF was subsequently given to the diabetic rats for two weeks. It was found that two-week administration of ASEAF reduces the fasting blood glucose level, triglyceride level, and free fatty acid level of the rats. ASEAF-treated diabetic rats showed higher pancreatic insulin content and pancreatic total superoxide dismutase activity compared to the untreated diabetic rats. Also, the insulin sensitivity indexes suggested that ASEAF ameliorates the insulin resistant state of the diabetic rats. In conclusion, ASEAF could be developed into a potential antidiabetic agent for the management of type 2 diabetes.

Triacetyl-3-hydroxyphenyladenosine, a derivative of cordycepin, attenuates atherosclerosis in apolipoprotein E-knockout mice

The cholesterol-modulating, immune-regulating and anti-inflammatory properties of cordycepin are well documented. Here we examined the effects of triacetyl-3-hydroxyphenyladenosine (THPA), a derivative of cordycepin, on the development of atherosclerosis (AS) in apolipoprotein E-knockout (apoE-/-) mice. The atherosclerotic lesion formation displayed by the oil red O staining-positive area was reduced significantly in either the aortic root section or the whole aorta en face in THPA-administrated apoE-/- mice. Plasma analysis by enzymatic method or enzyme-linked immunosorbent assay (ELISA) showed that high-density lipoprotein-cholesterol (HDL-C) was decreased, whereas apolipoprotein A-I (apoA-I) levels were markedly increased by THPA. In addition, ELISA and spectrophotometric measurement showed that plasma levels of tumor necrosis factor-α, interleukin-1 and malondialdehyde were decreased in mice treated with THPA. Realtime polymerase chain reaction detection disclosed that the expression of several transporters involved in reverse cholesterol transport was induced by THPA, and the expression of hepatic ABCA1 and apoA-I, which play roles in the maturation of HDL-C, was also elevated in the THPA-treated groups. Moreover, THPA enhanced the expression of endothelial nitric oxide synthase (NOS), and reduced the expression of inducible NOS and lectin-like oxidized LDL receptor-1 in the aorta, suggesting that THPA can exert endothelial protection effects. In addition, the expression or activation of several proinflammatory factors in the aorta was suppressed by THPA. In conclusion, our results reveal the inhibitory effects of THPA on AS in apoE-/- mice.

Beneficial metabolic effects of 2',3',5'-tri-acetyl-N6- (3-hydroxylaniline) adenosine in the liver and plasma of hyperlipidemic hamsters

Background

Pharmaceutical research of hyperlipidemia has been commonly pursued using traditional approaches. However, unbiased metabonomics attempts to explore the metabolic signature of hyperlipidemia in a high-throughput manner to understand pathophysiology of the disease process.

Methodology/Principal Findings

As a new way, we performed ¹H NMR-based metabonomics to evaluate the beneficial effects of 2′,3′,5′-tri-acetyl-N₆- (3-hydroxylaniline) adenosine (WS070117) on plasma and liver from hyperlipidemic Syrian golden hamsters. Both plasma and liver profiles provided a clearer distinction between the control and hyperlipidemic hamsters. Compared to control animals, hyperlipidemic hamsters showed a higher content of lipids (triglyceride and cholesterol), lactate and alanine together with a lower content of choline-containing compounds (e.g., phosphocholine, phosphatidylcholine, and glycerophosphocholine) and betaine. As a result, metabonomics-based findings such as the PCA and OPLS-DA plotting of metabolic state and analysis of potential biomarkers in plasma and liver correlated well to the assessment of biochemical assays, Oil Red O staining and in vivo ultrasonographic imaging suggesting that WS070117 was able to regulate lipid content and displayed more beneficial effects on plasma and liver than simvastatin.

Conclusions/Significance

This work demonstrates the promise of applying ¹H NMR metabonomics to evaluate the beneficial effects of WS070117 which may be a good drug candidate for hyperlipidemia.

Antidiabetic effect of total saponins from Entada phaseoloides (L.) Merr. in type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

The seed of Entada phaseoloides (L.) Merr. (Entada phaseoloides) has been long used as an effective herb for the treatment of Diabetes mellitus by Dai people, one of the Chinese ethnic minorities. Saponin is an abundant type of secondary metabolic products in the seed of this plant. The aim of this study is to evaluate the potential therapeutic effects of total saponins from Entada phaseoloides (TSEP) in experimental type 2 Diabetes mellitus (T2DM) rats.

MATERIALS AND METHODS

T2DM rats were induced by high-fat diet and low-dose streptozotocin (STZ). Then different oral doses of TSEP (25, 50 and 100 mg/kg) were administrated to T2DM rats for 21 days. For comparison, a standard antidiabetic drug, metformin (200 mg/kg), was used as a positive control drug. Then the relative biochemical analysis and histopathological examination were made to evaluate the antidiabetic effect of TSEP.

RESULTS

TSEP dramatically reduced fasted blood glucose and serum insulin levels and alleviates hyperglycemia associated oxidative stress in T2DM rats. Moreover, a significantly hypolipidemic effect and an improvement in tissue steatosis could be observed after TSEP administration. Further investigations revealed a possible anti-inflammation effect of TSEP by examining serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP). The effects of TSEP exhibited a dose-dependent manner and were comparable to metformin.

CONCLUSION

Our present study demonstrates both hypoglycemic and hypolipidemic activities of TSEP in T2DM rats, which support its antidiabetic property. This work also implies a possibility that TSEP exerts its therapeutic effect through repressing chronic inflammation responses.

Cyanidin-3-O-β-glucoside regulates fatty acid metabolism via an AMP-activated protein kinase-dependent signaling pathway in human HepG2 cells

BACKGROUND

Hepatic metabolic derangements are key components in the development of fatty liver disease. AMP-activated protein kinase (AMPK) plays a central role in controlling hepatic lipid metabolism through modulating the downstream acetyl CoA carboxylase (ACC) and carnitine palmitoyl transferase 1 (CPT-1) pathway. In this study, cyanidin-3-O-β-glucoside (Cy-3-g), a typical anthocyanin pigment was used to examine its effects on AMPK activation and fatty acid metabolism in human HepG2 hepatocytes.

RESULTS

Anthocyanin Cy-3-g increased cellular AMPK activity in a calmodulin kinase kinase dependent manner. Furthermore, Cy-3-g substantially induced AMPK downstream target ACC phosphorylation and inactivation, and then decreased malonyl CoA contents, leading to stimulation of CPT-1 expression and significant increase of fatty acid oxidation in HepG2 cells. These effects of Cy-3-g are largely abolished by pharmacological and genetic inhibition of AMPK.

CONCLUSION

This study demonstrates that Cy-3-g regulates hepatic lipid homeostasis via an AMPK-dependent signaling pathway. Targeting AMPK activation by anthocyanin may represent a promising approach for the prevention and treatment of obesity-related nonalcoholic fatty liver disease.