CD36 gene deletion reduces muscle insulin sensitivity in mice by up-regulating PTP1B expression / 南方医科大学学报

OBJECTIVE@#To investigate the effect CD36 deficiency on muscle insulin signaling in mice fed a normal-fat diet and explore the possible mechanism.@*METHODS@#Wild-type (WT) mice and systemic CD36 knockout (CD36-/-) mice with normal feeding for 14 weeks (n=12) were subjected to insulin tolerance test (ITT) after intraperitoneal injection with insulin (1 U/kg). Real-time PCR was used to detect the mRNA expressions of insulin receptor (IR), insulin receptor substrate 1/2 (IRS1/2) and protein tyrosine phosphatase 1B (PTP1B), and Western blotting was performed to detect the protein expressions of AKT, IR, IRS1/2 and PTP1B in the muscle tissues of the mice. Tyrosine phosphorylation of IR and IRS1 and histone acetylation of PTP1B promoter in muscle tissues were detected using co-immunoprecipitation (Co-IP) and chromatin immunoprecipitation (ChIP), respectively.@*RESULTS@#CD36-/- mice showed significantly lowered insulin sensitivity with obviously decreased area under the insulin tolerance curve in comparison with the WT mice (P < 0.05). CD36-/- mice also had significantly higher serum insulin concentration and HOMA-IR than WT mice (P < 0.05). Western blotting showed that the p-AKT/AKT ratio in the muscle tissues was significantly decreased in CD36-/- mice as compared with the WT mice (P < 0.01). No significant differences were found in mRNA and protein levels of IR, IRS1 and IRS2 in the muscle tissues between WT and CD36-/- mice (P>0.05). In the muscle tissue of CD36-/- mice, tyrosine phosphorylation levels of IR and IRS1 were significantly decreased (P < 0.05), and the mRNA and protein levels of PTP1B (P < 0.05) and histone acetylation level of PTP1B promoters (P < 0.01) were significantly increased as compared with those in the WT mice. Intraperitoneal injection of claramine, a PTP1B inhibitor, effectively improved the impairment of insulin sensitivity in CD36-/- mice.@*CONCLUSION@#CD36 is essential for maintaining muscle insulin sensitivity under physiological conditions, and CD36 gene deletion in mice causes impaired insulin sensitivity by up-regulating muscle PTP1B expression, which results in detyrosine phosphorylation of IR and IRS1.

Análisis de asociación entre polimorfismos (rs941798 y rs914458) del gen PTPN1 y diabetes tipo 2 en familias de Lima-Perú / Analysis of the association between PTPN1 gene polymorphisms (rs941798 and rs914458) and type 2 diabetes in families from Lima ­ Peru

Objetivo: Analizar la asociación de los polimorfismos de un solo nucleótido (SNP) rs941798 y rs914458 del gen PTPN1 con la diabetes tipo 2 en familias peruanas de Lima. Materiales y métodos: Veintitrés tríos familiares fueron captados en el Hospital Nacional Arzobispo Loayza. Se extrajeron muestras de sangre periférica para obtener el ADN y luego las frecuencias alélicas y genotípicas de los SNP. La genotipificación de los SNP se realizó mediante secuenciación. El análisis de asociación basado en familias entre los SNP y la diabetes tipo 2 se realizó con el programa FBAT. Resultados: Se observaron los 3 genotipos posibles para cada SNP, rs941798 (A>G) y rs914458 (G>C). Las pruebas de asociación basada en familias a nivel alélico mostraron al alelo A del SNP rs941798 asociado a la diabetes tipo 2 (p = 0.023) bajo uno de los modelos evaluados; no obstante, tras la corrección de Bonferroni para comparaciones múltiples, esta asociación se perdió. No se evidenció asociación entre los SNP y la enfermedad en ningún nivel (alélico, genotípico o haplotípico). Conclusiones: No se encontraron evidencias de asociación significativa entre los SNP rs941798 y rs914458 del gen PTPN1 con la DT2 en familias peruanas de Lima, en ninguno de los niveles estudiados (alélico, genotípico y haplotípico).

Objective: To analyze the association that PTPN1 gene single nucleotide polymorphisms (SNPs) rs941798 and rs914458 have with type 2 diabetes in Peruvian families from Lima. Materials and methods: Twenty-three (23) families consisting of three members each were recruited at the Hospital Nacional Arzobispo Loayza. Peripheral blood samples were collected to obtain the DNA, and then the allele and genotype frequencies of the SNPs. SNP genotyping was performed using the sequencing method. The family-based analysis of the association between SNPs and type 2 diabetes was conducted using the family-based association test (FBAT) program. Results: Three (3) possible genotypes were observed for each SNP, i.e. rs941798 (A>G) and rs914458 (G>C). In one of the assessed models, the family-based association tests showed at the allele level that allele A of SNP rs941798 is associated with type 2 diabetes (p = 0.023). However, after using the Bonferroni correction for multiple comparisons, this association was lost. No association was demonstrated between the SNPs and the disease at any level (allele, genotype or haplotype). Conclusions: No evidence of significant association was found between PTPN1 gene SNPs rs941798 and rs914458 and type 2 diabetes at the studied levels (allele, genotype or haplotype) in Peruvian families from Lima.

Flavonoids with PTP1B inhibition from Broussonetia papyrifera / 中国中药杂志

Eleven flavonoids were isolated from the twigs of Broussonetia papyrifera by column chromatography over silica gel,ODS,MCI gel,and Sephadex LH-20,as well as RP-HPLC.Their structures were identified by spectroscopic methods including NMR,MS,UV,and IR as broupapyrin A(1),5,7,3',4'-tetrahydroxy-3-methoxy-8-geranylflavone(2),8-prenylquercetin-3-methyl ether(3),broussonol D(4),broussoflavonol B(5),uralenol(6),broussonol E(7),8-(1,1-dimethylallyl)-5'-(3-methylbut-2-enyl)-3',4',5,7-tetrahydroxyflanvonol(8),broussoflavonol E(9),4,2',4'-trihydroxychalcone(10),and butein(11).Compound 1 is a new isoprenylated flavonol.Compounds 3,6,10,and 11 were obtained from the genus Broussonetia for the first time,and 4 and 7 were firstly discovered in B.papyrifera.Compounds 1-5 and 7-9 showed significant inhibitory effects on PTP1 B with IC50 values ranging from(0.83±0.30) to(4.66±0.83) μmol·L-1.

Protein tyrosine phosphatase 1B inhibitory activities of ursane-type triterpenes from Chinese raspberry, fruits of Rubus chingii / 中国天然药物

Protein tyrosine phosphatase 1B (PTP1B) has led to an intense interest in developing its inhibitors as anti-diabetes, anti-obesity and anti-cancer agents. The fruits of Rubus chingii (Chinese raspberry) were used as a kind of dietary traditional Chinese medicine. The methanolic extract of R. chingii fruits exhibited significant PTP1B inhibitory activity. Further bioactivity-guided fractionation resulted in the isolation of three PTP1B inhibitory ursane-type triterpenes: ursolic acid (1), 2-oxopomolic acid (2), and 2α, 19α-dihydroxy-3-oxo-urs-12-en-28-oic acid (3). Kinetics analyses revealed that 1 was a non-competitive PTP1B inhibitor, and 2 and 3 were mixed type PTP1B inhibitors. Compounds 1-3 and structurally related triterpenes (4-8) were further analyzed the structure-activity relationship, and were evaluated the inhibitory selectivity against four homologous protein tyrosine phosphatases (TCPTP, VHR, SHP-1 and SHP-2). Molecular docking simulations were also carried out, and the result indicated that 1, 3-acetoxy-urs-12-ene-28-oic acid (5), and pomolic acid-3β-acetate (6) bound at the allosteric site including α3, α6, and α7 helix of PTP1B.

Protein tyrosine phosphatase 1B is a mediator of cyclic ADP ribose-induced Ca²⁺ signaling in ventricular myocytes

Cyclic ADP-ribose (cADPR) releases Ca²⁺ from ryanodine receptor (RyR)-sensitive calcium pools in various cell types. In cardiac myocytes, the physiological levels of cADPR transiently increase the amplitude and frequency of Ca²⁺ (that is, a rapid increase and decrease of calcium within one second) during the cardiac action potential. In this study, we demonstrated that cADPR levels higher than physiological levels induce a slow and gradual increase in the resting intracellular Ca²⁺ ([Ca²⁺](i)) level over 10 min by inhibiting the sarcoendoplasmic reticulum Ca²⁺ ATPase (SERCA). Higher cADPR levels mediate the tyrosine-dephosphorylation of α-actin by protein tyrosine phosphatase 1B (PTP1B) present in the endoplasmic reticulum. The tyrosine dephosphorylation of α-actin dissociates phospholamban, the key regulator of SERCA, from α-actin and results in SERCA inhibition. The disruption of the integrity of α-actin by cytochalasin B and the inhibition of α-actin tyrosine dephosphorylation by a PTP1B inhibitor block cADPR-mediated Ca²⁺ increase. Our results suggest that levels of cADPR that are relatively higher than normal physiological levels modify calcium homeostasis through the dephosphorylation of α-actin by PTB1B and the subsequent inhibition of SERCA in cardiac myocytes.

The effects of compound CX09040 on the inhibition of PTP1B and protection of pancreatic β cells / 药学学报

To investigate the effects of 2-(4-methoxycarbonyl-2-tetradecyloxyphenyl)carbamoylbenzoic acid (CX09040) on protecting pancreatic β cells, the β cell dysfunction model mice were induced by injection of alloxan into the caudal vein of ICR mice, and were treated with compound CX09040. Liraglutide was used as the positive control drug. The amount and the size of islets observed in pathological sections were calculated to evaluate the β cell mass; the glucose stimulated insulin secretion (GSIS) test was applied to estimate the β cell secretary function; the oral glucose tolerance test (OGTT) was taken to observe the glucose metabolism in mice; the expressions of protein in pancreas were detected by Western blotting. The effects on the target protein tyrosine phosphatase 1B (PTP1B) were assessed by the PTP1B activities of both recombinant protein and the intracellular enzyme, and by the PTP1B expression in the pancreas of mice, separately. As the results, with the treatment of CX09040 in alloxan-induced β cell dysfunction mice, the islet amount (P<0.05) and size (P<0.05) increased significantly, the changes of serum insulin in GSIS (P<0.01) and the values of acute insulin response (AIR, P<0.01) were enhanced, compared to those in model group; the impaired glucose tolerance was also ameliorated by CX09040 with the decrease of the values of area under curve (AUC, P<0.01). The activation of the signaling pathways related to β cell proliferation was enhanced by increasing the levels of p-Akt/Akt (P<0.01), p-FoxO1/FoxOl (P<0.001) and PDX-1 (P<0.01). The effects of CX09040 on PTP1B were observed by inhibiting the recombinant hPTP1B activity with IC50 value of 2.78x 10(-7) mol.L-1, reducing the intracellular PTP1B activity of 72.8% (P<0.001), suppressing the PTP1B expression (P<0.001) and up-regulating p-IRβ/IRβ (P<0.01) in pancreas of the β cell dysfunction mice, separately. In conclusion, compound CX09040 showed significant protection effects against the dysfunction of β cell of mice by enlarging the pancreatic β cell mass and increasing the glucose-induced insulin secretion; its major mechanism may be the inhibition on target PTP1B and the succedent up-regulation of β cell proliferation.

Análisis de asociación genética entre el SNP RS914458 del gen proteína tirosina fosfatasa no receptor tipo 1 (ptpn1) y diabetes tipo 2 en población peruana / Genetic association analysis between SNP rs914458 of protein tyrosine phosphatase, non-receptor type 1(ptpn1) gene and Type 2 Diabetes in Peruvian Population

Evaluar la posible asociación entre el SNP rs914458 (C>G) del gen PTPN1con la DM2 en una población de la zona urbana de Lima - Perú. Material y Métodos: El estudio incluyó un total de 216 personas de la zona urbana de Lima correspondientes a un grupo control (n = 123) y un grupo de pacientes diagnosticados con diabetes tipo 2 provenientes del Hospital A. Loayza (n = 93). La genotipificación del SNP se llevó a cabo mediante PCR y con un secuenciador ABI PRISM 310. El análisis de asociación se llevó a cabo con el uso de la herramienta web SNPStats para realizar cinco modelos de regresión logística. El efecto de la asociación genética se estableció con el valor de OR. Resultados: La frecuencia del MAF (alelo G) fue de 0.22 en el grupo de controles y en el grupo de pacientes. Ninguno de los modelos de regresión muestra valores de OR (considerando los CI) por encima o por debajo del valor de referencia. Conclusión: No se encontró asociación genética significativa entre el SNP rs914458 del gen PTPN1 y la DM2 para la población de la zona urbana de Lima - Perú...

Objective: Evaluate the association between SNP rs914458 (C>G) of PTPN1 gene with T2DM in a population from the urban area of Lima - Peru. Material and Methods: This study included a total of 216 subjects from the urban area of Lima. The number of subjects in control group was 123, and 93 patients diagnosed with type 2 diabetes from Hospital A. Loayza. SNP genotyping was performed by PCR and sequencing using ABI PRISM 310 DNA sequencer. The association analysis was carried out using the web tool SNPStats and five logistic regression models were performed. The effect of genetic association was established with the OR. Results: The frequency of MAF (allele G) was 0.22 in both control and patient groups. The OR values were not different from the reference values considering the respective confidence interval. Conclusion: No significant association was found between the SNP rs914458 and the PTPN1 gene with T2DM for the urban population of Lima - Peru...

Beneficial effects of Ginkgo biloba extract on insulin signaling cascade, dyslipidemia, and body adiposity of diet-induced obese rats

Ginkgo biloba extract (GbE) has been indicated as an efficient medicine for the treatment of diabetes mellitus type 2. It remains unclear if its effects are due to an improvement of the insulin signaling cascade, especially in obese subjects. The aim of the present study was to evaluate the effect of GbE on insulin tolerance, food intake, body adiposity, lipid profile, fasting insulin, and muscle levels of insulin receptor substrate 1 (IRS-1), protein tyrosine phosphatase 1B (PTP-1B), and protein kinase B (Akt), as well as Akt phosphorylation, in diet-induced obese rats. Rats were fed with a high-fat diet (HFD) or a normal fat diet (NFD) for 8 weeks. After that, the HFD group was divided into two groups: rats gavaged with a saline vehicle (HFD+V), and rats gavaged with 500 mg/kg of GbE diluted in the saline vehicle (HFD+Gb). NFD rats were gavaged with the saline vehicle only. At the end of the treatment, the rats were anesthetized, insulin was injected into the portal vein, and after 90s, the gastrocnemius muscle was removed. The quantification of IRS-1, Akt, and Akt phosphorylation was performed using Western blotting. Serum levels of fasting insulin and glucose, triacylglycerols and total cholesterol, and LDL and HDL fractions were measured. An insulin tolerance test was also performed. Ingestion of a hyperlipidic diet promoted loss of insulin sensitivity and also resulted in a significant increase in body adiposity, plasma triacylglycerol, and glucose levels. In addition, GbE treatment significantly reduced food intake and body adiposity while it protected against hyperglycemia and dyslipidemia in diet-induced obesity rats. It also enhanced insulin sensitivity in comparison to HFD+V rats, while it restored insulin-induced Akt phosphorylation, increased IRS-1, and reduced PTP-1B levels in gastrocnemius muscle. The present findings suggest that G. biloba might be efficient in preventing and treating obesity-induced insulin signaling impairment.

Inhibitory effect of Persea americana Mill leaf aqueous extract and itsfractions on PTP1B as therapeutic target for type 2 diabetes / Efecto inhibidor del extracto acuoso de hojas de Persea americana Mill y sus fracciones sobre PTP1Bcomo diana terapéutica para la diabetes tipo 2

Persea Americana Mill (Lauraceae), is a popular plant in Cuba due to its nutritional and medicinal properties. The fruit of the plant is commonly known as avocado. The leaves of Persea americana Mill have been popularly used in the treatment of diabetes incountries in Latin America and Africa. The present study is aimed to explore one of the underlying mechanisms that mediate the antidiabeticefficacy of Persea americana Mill. The aqueous extract from the leaves of the plant and its fractions were evaluated on the inhibitory activity of the protein tyrosine phosphatase 1B (PTP1B) as target of type 2 diabetes. The results revealed that aqueous extract from Pamericana inhibited the enzymatic activity of PTP1B in an extract concentration dependent manner, resulting mainly active the most polarfraction. The present research demonstrated that aqueous extract from P americana and polar fraction (PaF10) have promissory antidiabetic properties mediated by PTP1B, which is a relevant mechanism involved on insulin resistance in type 2 diabetes.

Persea americana Mill. (Lauraceae), es una planta popular en Cuba, debido a sus propiedades nutricionales y medicinales. El fruto de la planta se conoce comúnmente como aguacate. En la etnomedicina las hojas de Persea americana Mill. se han utilizadopopularmente en el tratamiento de la diabetes en varios países en Latinoamérica y África. El presente estudio tuvo el objetivo de explorar laeficacia antidiabética y el mecanismo subyacente, de las hojas de Persea americana. El extracto acuoso de las hojas de la planta y sus fracciones, se evaluaron en un blanco terapéutico de interés en la de diabetes tipo 2: actividad enzimática de la proteína tirosina fosfatasa 1B (PTP1B). Los resultados revelaron que el extracto acuoso de P americana inhibe la actividad enzimática de la enzima PTP1B en una manera dependiente de la concentración, resultando más activa la fracción de mayor polaridad. La presente investigación demostró que elextracto acuoso de P americana y su fracción polar (PaF10), poseen efecto antidiabético promisorio, debido al efecto inhibitorio de PTP1B, mecanismo relevante en la insulino resistencia en la diabetes tipo2.

Expression change of SH2B1, SOCS3, PTP1B and NPY in mice hypothalamus and its relation with obesity / 中南大学学报(医学版)

OBJECTIVE@#To investigate the expression pattern of adapter protein with a Src-homology 2 domain (SH2B1), the suppressor of cytokine signaling-3 (SOCS3), protein-tyrosine phosphatase 1B (PTP1B) and neturopetide Y (NPY) in obese and normal mice hypothalamus and its relation with serum leptin and insulin levels.@*METHODS@#The obesity animal model was prepared with healthy C57/bl6 mice. Lee's index and Homeostasis model assessment-insulin resistance (HOMA-IR) were calculated. The mRNA levels of SH2B1, SOCS3, PTP1B and NPY were measured by fluorescent quantitation RT-PCR. The SH2B1 and NPY protein expressions were detected by Western blot.@*RESULTS@#Compared with the normal mice of the same age, SH2B1 mRNA expression in the obese mice hypothalamus decreased. SOCS3 and PTP1B mRNA expression increased. Western blot showed that SH2B1 protein expression decreased, while NPY protein expression increased in the obese mice. Linear correlation analysis showed that the serum leptin and fasting insulin levels were negatively correlated with SH2B1mRNA expression and positively correlated with SOCS3 and PTP1B mRNA expression.@*CONCLUSION@#SH2B1, SOCS3, PTP1B and NPY are key factors for obesity development.

Chromium-containing traditional Chinese medicine, Tianmai Xiaoke Tablet improves blood glucose through activating insulin-signaling pathway and inhibiting PTP1B and PCK2 in diabetic rats / 中西医结合学报

<p><b>OBJECTIVE</b>Chromium is an essential mineral that is thought to be necessary for normal glucose homeostasis. Numerous studies give evidence that chromium picolinate can modulate blood glucose and insulin resistance. The main ingredient of Tianmai Xiaoke (TMXK) Tablet is chromium picolinate. In China, TMXK Tablet is used to treat type 2 diabetes. This study investigated the effect of TMXK on glucose metabolism in diabetic rats to explore possible underlying molecular mechanisms for its action.</p><p><b>METHODS</b>Diabetes was induced in rats by feeding a high-fat diet and subcutaneously injection with a single dose of streptozotocin (50 mg/kg, tail vein). One week after streptozotocin-injection, model rats were divided into diabetic group, low dose of TMXK group and high dose of TMXK group. Eight normal rats were used as normal control. After 8 weeks of treatment, skeletal muscle was obtained and was analyzed using Roche NimbleGen mRNA array and quantitative polymerase chain reaction (qPCR). Fasting blood glucose, oral glucose tolerance test and homeostasis model assessment of insulin resistance (HOMA-IR) index were also measured.</p><p><b>RESULTS</b>The authors found that the administration of TMXK Tablet can reduce the fasting blood glucose and fasting insulin level and HOMA-IR index. The authors also found that 2 223 genes from skeletal muscle of the high-dose TMXK group had significant changes in expression (1 752 increased, 471 decreased). Based on Kyoto encyclopedia of genes and genomes pathway analysis, the most three significant pathways were "insulin signaling pathway", "glycolysis/gluconeogenesis" and "citrate cycle (TCA)". qPCR showed that relative levels of forkhead box O3 (FoxO3), phosphoenolpyruvate carboxykinase 2 (Pck2), and protein tyrosine phosphatase 1B (Ptp1b) were significantly decreased in the high-dose TMXK group, while v-akt murine thymoma viral oncogene homolog 1 (Akt1) and insulin receptor substrate 2 (Irs2) were increased.</p><p><b>CONCLUSION</b>Our data show that TMXK Tablet reduces fasting glucose level and improves insulin resistance in diabetic rats. The mechanism may be linked to the inactivation of PTP1B and PCK enzymes, or through intracellular pathways, such as the insulin signaling pathway.</p>

SAR of benzoyl sulfathiazole derivatives as PTP1B inhibitors / 药学学报

Protein tyrosine phosphatase (PTP) 1B is a potential target for the treatment of diabetes and obesity. We have previously identified the benzoyl sulfathiazole derivative II as a non-competitive PTP1B inhibitor with in vivo insulin sensitizing effects. Preliminary SAR study on this compound series has been carried out herein, and thirteen new compounds have been designed and synthesized. Among them, compound 10 exhibited potent inhibition against human recombinant PTP1B with the IC50 value of 3.97 micromol x L(-1), and is comparable to that of compound II.

Design, synthesis and evaluation of malonic acid-based PTP1B inhibitors / 药学学报

Protein tyrosine phosphatase (PTP) 1B is a potential target for the treatment of diabetes and obesity. Phosphotyrosine (pTyr) is the substrate for PTP1B dephosphorylation. Malonic acid moiety was used herein as a mimic of the phosphate group in pTyr, and novel malonic acid derivatives 1-7 were designed, synthesized and evaluated as PTP1B inhibitors. Results from enzymatic assays indicated that compounds 3 and 4 exhibited potent inhibition against human recombinant PTP1B with IC50 values of 7.66 and 1.88 micromol x L(-1), respectively.

Investigation of a compound, compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on metabolic syndrome treatment I--improving insulin resistance / 中国中药杂志

To investigate the effects of a compound (FF16), compatibility of Rhodiola crenulata, Cordyceps militaris, and Rheum palmatum, on insulin resistance. The results showed that FF16 significantly improved the insulin sensitivity through decreasing AUC values in insulin tolerance tests by 24.1%, 38.5%; reducing the levels of serum insulin by 46.0%, 30.4%, of HOMA-IR by 52.4%, 81.2%; and reversing the lower GIR values by 119.3%, 202.4% in IRF mice and KKAy mice, respectively. In addition, in KKAy mice, the value of whole body insulin sensitivity index (ISWBI) was enhanced by 1.0 times, the abilities of the insulin-induced glucose uptake in liver, adipose and skeletal muscle were enhanced by 1.5, 2.8 and 2.2 times, respectively, in FF16-treated mice comparing with those in model mice. The recombinant human protein tyrosine phosphatase 1B (PTP1B) activity was inhibited by FF16 in vitro with the IC50 value of 0.225 mg x L(-1). The increased PTP1B expression in the liver was also reversed by 45.8% with the administration of FF16 in IRF mice. In conclusion, FF16 could improve insulin resistance by inhibiting the activity of PTP1B.

High-throughput screening of human soluble protein tyrosine phosphatase 1B inhibitors / 药学学报

To screen potential human soluble protein tyrosine phosphatase 1B (PTP1B) inhibitors, a high-throughput screening (HTS) model in 384-well microplate with total volume of 50 microL was established. Recombinant PTP1B was cloned and expressed in E. coli. with its specific substrate 4-nitrophenyl phosphate disodium salt hexahydrate (PNPP). The HTS model was based on enzyme reaction rate with enhanced sensitivity and specificity (Z' = 0.78). A total of 24,240 samples were screened, among them 80 samples with inhibition greater than 70% were selected for further rescreening. Finally, six compounds with high inhibitory activity were identified, whose IC50 values were 21.58, 18.39, 15.37, 11.92, 37.27, and 36.61 microg x mL(-1), separately. The results indicated that the method was stable, sensitive, reproducible and also suitable for high-throughput screening.

Phenolic acid derivatives from Bauhinia glauca subsp. pernervosa / 药学学报

To study the chemical constituents of Bauhinia glauca subsp. pernervosa, eleven phenolic acids were isolated from a 95% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, ODS, MCI, Sephadex LH-20, and semi-preparative HPLC. By spectroscopic techniques including 1H NMR, 13C NMR, 2D NMR, and HR-ESI-MS, these compounds were identified as isopropyl O-beta-(6'-O-galloyl)-glucopyranoside (1), ethyl O-beta-(6'-O-galloyl)-glucopyranoside (2), 3, 4, 5-trimethoxyphenyl-(6'-O-galloyl)-O-beta-D-glucopyranoside (3), 3, 4, 5-trimethoxyphenyl-beta-D-glucopyranoside (4), gallic acid (5), methyl gallate (6), ethyl gallate (7), protocatechuic acid (8), 3, 5-dimethoxy-4-hydroxybenzoic acid (9), erigeside C (10) and glucosyringic acid (11). Among them, compound 1 is a new polyhydroxyl compound; compounds 2, 10, and 11 were isolated from the genus Bauhinia for the first time, and the other compounds were isolated from the plant for the first time. Compounds 6 and 8 showed significant protein tyrosine phosphatase1B (PTP1B) inhibitory activity in vitro with the IC50 values of 72.3 and 54.1 micromol x L(-1), respectively.

Study on the mechanism of action of total flavonoids of Litsea coreana for reducing blood glucose level in rat with type 2 diabetes mellitus / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the possible mechanism of total flavonoids of Litsea coreana (TFLC) on reducing blood glucose level in rat with type 2 diabetes mellitus (T2DM).</p><p><b>METHODS</b>Male SD rats of T2DM allocated in two groups were treated with 400 mg/kg TFLC or metformin respectively via gastrogavage for 6 weeks. Blood routine biochemical indices in rats were measured; pathology of rats' liver was examined with HE stain under transmission electron microscopy; levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in liver homogenate were determined, and the expression of protein tyrosine phosphatase 1B (PTP1B) in liver was detected using RT-PCR at the terminal of the experiment.</p><p><b>RESULTS</b>Biochemical measuring showed that the glucose tolerance of rats after treatment was markedly improved in both groups. Meantime, levels of fast blood glucose (FBG), glycohemoglobin (HbA1c), fast blood insulin (FINS), free fatty acid (FFA), total cholesterol (TC), triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C), as well as MDA level in liver were decreased, while levels of high density lipoprotein-cholesterol (HDL-C) in blood and SOD in liver were significantly increased in both groups after treatment, showing insignificant difference between two treatment groups. Light microscopic examination showed markedly fatty degeneration of liver, and electron microscopic examination found mitochondria swelling and endoplasmic reticulum breakage in liver of T2DM rats, but these changes were ameliorated to some extent after treatment. The elevated PTP1B expression in liver of T2DM rats was decreased in the TFLC treated group, but unchanged in the metformin treated group.</p><p><b>CONCLUSION</b>TFLC can significantly decrease the blood levels of glucose and lipid and ameliorate oxidation stress in liver; its mechanism of action in improving insulin resistance might be related with its suppression on PTP1B expression in rat's liver to enhance the insulin signaling pathway.</p>

Research progress of several protein tyrosine phosphatases in diabetes / 生理学报

Diabetes mellitus is caused by deficiency of insulin secretion from the pancreatic islet beta cells and/or insulin resistance in liver, muscle and adipocytes, resulting in glucose intolerance and hyperglycemia. Several protein tyrosine phosphatases, such as PTP1B (PTPN1), TCPTP (PTPN2), LYP (PTPN22), PTPIA-2, PTPMEG2 (PTPN9) or OSTPTP are involved in insulin signaling pathway, insulin secretion and autoreactive attack to pancreatic beta cells. Genetic mutation or overexpression of these phosphotases has been found to cause or increase the risk of diabetes mellitus. Some population with high risk for type 2 diabetes has overexpressed PTP1B, a prototypical tyrosine phosphatase which down-regulates insulin and leptin signal transduction. Animal PTP1B knockout model and PTP1B specific inhibitor cellular studies indicate PTP1B may serve as a therapeutic target for type 2 diabetes. TCPTP shares more than 70% sequence identity with PTP1B in their catalytic domain. TCPTP dephosphorylates tyrosine phosphorylated substrates overlapping with PTP1B but also has its own distinct dephosphorylation sites and functions. Recent research indicates TCPTP may have role in type 1 diabetes via dysregultaion of cytokine-mediated immune responses or pancreatic beta cell apoptosis. The tyrosine phosphatase LYP, which down-regulates LCK activity in T cell response, can become mutated as R620W which is highly correlated to type 1 diabetes. LYP R620W may be a gain of function mutation which suppresses TCR signaling. Patients bearing the R620W mutant have impaired T cell responses and increased populations of (CD45RO+CD45RA-) CD4+ T cells. A detailed elucidation of mechanism of R620W in type 1 diabetes and specific LYP inhibitor development will help characterize LYP R620W as a therapeutic target. A receptor tyrosine phosphatase, PTPIA-2/beta is a major autoantigen of type 1 diabetes. A diagnosis kit identifying PTPIA-2/beta autoantibodies is valuable in early detection and prevention of type 1 diabetes. In addition, other phosphatase like OSTPTP and PTPMEG2 are involved in type 2 diabetes via regulation of insulin production, beta cell growth or insulin signaling. Research into understanding the mechanism of these tyrosine phosphatases in diabetes, such as their precise functions in the regulation of insulin secretion, the insulin response and the immune response will strengthen our knowledge of diabetes pathophysiology which may result in new diagnostic and therapeutic strategies for diabetes.

Preliminary exploration of inhibitory activities of Salvia species on PTP1B / 药学学报

An in vitro screening model was applied to test the inhibitory activities of 17 Salvia species on protein tyrosine phosphatase 1B (PTP1B). Root methanol extracts from wild-collected Salvia species were analyzed using this model. Most of the samples tested showed positive activities on human PTP1B. The inhibition rates of Salvia crude extracts varied from 9.76% to 100% at 30 microg x mL(-1), with the most convincing effects coming from Salvia evansiana and Salvia castanea. HPLC analysis revealed seven components shared by Salvia samples could be related to the inhibitory activities.

Synthesis and preliminary evaluation of antidiabetic activity of 4-(3-(4-bromophenyl)-3-oxo-1-arylpropylamino)-N-(5-methylisoxazol-3-yl)benzenesulfonamide / 药学学报

Diabetes mellitus is a common metabolic disease with a high and growing prevalence affecting 4% of the population worldwide, the development of safe and effective therapeutic drug is the major thrust for chemists and pharmacists. To search for active antidiabetic lead compound, we designed and synthesized some novel beta-amino ketone derivatives containing sulfamethoxazole moiety directly through Mannich reaction of sulfamethoxazole, 4-bromoacetophenone and some aromatic aldehydes catalyzed by concentrated hydogen chloride or iodine in the solution of ethanol at 24-40 degrees C with convenient operation, mild reaction condition and satisfactory yield (32%-90%). Their chemical structures were characterized by 1H NMR, 13C NMR, MS and HR-MS. Biological activity tests showed that, in the range of low concentration (5-10 microg x mL(-1)), these title compounds to a certain degree possess protein tyrosine phosphatase 1B (PTP1B) inhibitory activity and a-glucosidase inhibitory activity, moreover, some could activate peroxisome proliferator-activated receptor response element (PPRE) moderately. The PPRE agonist activities of seven compounds are almost 40% of that of Pioglitazone (the positive control), compound 12 shows the strongest activity (66.35%) among them. Thus, it was found that some of 4-(3-(4-bromophenyl)-3-oxo-1-arylpropylamino)-N-(5-methyl-isoxazol-3-yl) benzenesulfonamide containing sulfamethoxazole moiety exhibited antidiabetic activity for the first time.