Sudeep Gautam

Identification of novel PTP1B inhibitors by pharmacophore based virtual screening, scaffold hopping and docking.

Design and synthesis of protein tyrosine phosphatases-1B (PTP1B) inhibitors are important for the drugs targeted to treat diabetes and obesity. The pharmacophore modeling, docking and scaffold hopping techniques have been applied to discover the novel PTP1B inhibitors. The ten prioritized compounds (115-119, 120-121, 127, 130-131) from the library of 86 compounds were synthesized and found positive in the micro molar range for PTP1B in-vitro inhibitory assays as compared to Suramin (IC50 9.5 μM). Among these five active compounds (115-119) were tested in STZ-s induced diabetic rat model and the most active compound 115 in this test, was further tested in C57BL/KsJ-db/db mice where it significantly improved OGTT along with the fasting and random blood glucose level. The treatment by the compound 115 significantly improved the insulin resistance and insulin signaling by restoring the insulin level and normalizing the serum lipid profile. Compound 115 also augmented the insulin action by modulating the expression of genes involved in insulin signaling like IRS 1-2, PI3K, PTPN1, Akt2, AMPK and PPAR-α. Western blot analysis of both skeletal muscle and liver demonstrated that proteins and intermediate enzymes of insulin signaling were also increased as compared to control group. The compound 115 was also investigated for anti-adipogenic effect on 3T3L-1 cells. The compound 115 inhibited MDI induced lipid accumulation in a dose-dependent manner. The oral bioavailability of compound 115 was ∼10.29% after 30 mg/kg oral dosing assessed in rat.

Aegeline from Aegle marmelos stimulates glucose transport via Akt and Rac1 signaling, and contributes to a cytoskeletal rearrangement through PI3K/Rac1.

Aegeline is an alkaloidal-amide, isolated from the leaves of Aegle marmelos and have shown antihyperglycemic as well as antidyslipidemic activities in the validated animal models of type 2 diabetes mellitus. Here we delineate, aegeline enhanced GLUT4 translocation mediated 2-deoxy-glucose uptake in both time and concentration-dependent manner. 2-deoxy-glucose uptake was completely stymied by the transport inhibitors (wortmannin and genistein) in C2C12 myotubes. Pharmacological inhibition of Akt (also known as protein kinase B) and Ras-related C3 botulinum toxin substrate 1 (Rac1) suggest that both Akt and Rac1 operate aegeline-stimulated glucose transport via distinct parallel pathways. Moreover, aegeline activates p21 protein-activated kinase 1 (PAK1) and cofilin (an actin polymerization regulator). Rac1 inhibitor (Rac1 inhib II) and PAK1 inhibitor (IPA-3) completely blocked aegeline-induced phosphorylation of cofilin and p21 protein-activated kinase 1 (PAK1). In summary, these findings suggest that aegeline stimulates the glucose transport through Akt and Rac1 dependent distinct parallel pathways and have cytoskeletal roles via stimulation of the PI3-kinase-Rac1-PAK1-cofilin pathway in the skeletal muscle cells. Therefore, multiple targets of aegeline in the improvement of insulin sensitivity of the skeletal muscle cells may be suggested.

Bioactivity-guided chemical analysis of Melia azedarach L. (Meliaceae), displaying antidiabetic activity.

One new Euphane-type triterpenoid 3β-hydroxytirucalla-5, 24-dien-21-oic acid (1), and ten known compounds (2-11) were isolated from Melia azedarach L. through bioassay-guided chemical analysis. The structures of the isolated compounds were established by means of 1D and 2D NMR spectroscopic ((1)H, (13)C, DEPT, COSY, HSQC and HMBC) and MS spectral analyses. All the fractions and isolated pure compounds were evaluated for antidiabetic activity by determining their inhibitory effects on PTP-1B enzyme as well as glucose uptake stimulation in C2Cl2 myoblasts cells. Compounds 4 and 7 showed significant in vitro PTP-1B inhibitory activity with 69.2 and 66.8% inhibition at 10 μg/ml concentrations respectively.

4-Hydroxyisoleucine improves insulin resistance by promoting mitochondrial biogenesis and act through AMPK and Akt dependent pathway.

4-Hydroxyisoleucine (4-HIL) is an unusual amino acid isolated from fenugreek seeds (Trigonella foenum graecum L). Various studies have shown that it acts as an antidiabetic agent yet its mechanism of action is not clear. We therefore investigated the effect 4-HIL on the high fructose diet fed streptozotocin induced diabetic rats and L6 myotubes. 4-HIL (50 mg/kg) has improved blood lipid profile, glucose tolerance and insulin sensitivity in a diabetic rat model. It has increased the glucose uptake in L6 myotubes in AMPK-dependent manner and upregulated the expression of genes (PGC-1α, PGC-1β, CPT 1 and CPT 2), which have role in mitochondrial biogenesis and energy metabolism in the liver, skeletal muscles as well as in L6 myotubes. Interestingly, it also increased the AMPK and Akt expression along with their phosphorylated forms in the liver and muscle tissues of treated animals. Altogether we concluded that 4-HIL acts to improve insulin resistance by promoting mitochondrial biogenesis in high fructose diet fed STZ induced diabetic rats.

Nymphaea rubra Ameliorates TNF-α-Induced Insulin Resistance via Suppression of c-Jun NH2-Terminal Kinase and Nuclear Factor-κB in the Rat Skeletal Muscle Cells

In this work, we demonstrated insulin signaling and the anti-inflammatory effects by the chloroform fraction of ethanolic extract of Nymphaea rubra flowers in TNF-α-induced insulin resistance in the rat skeletal muscle cell line (L6 myotubes) to dissect out its anti-hyperglycemic mechanism. N. rubra enhances the GLUT4-mediated glucose transport in a dose dependent manner and also increases the tyrosine phosphorylation of both IR-β and IRS-1, and the IRS-1 associated PI-3 kinase activity in TNF-α-treated L6 myotubes. Moreover, N. rubra decreases Ser307 phosphorylation of IRS-1 by the suppression of JNK and NF-κB activation. In conclusion, N. rubra reverses the insulin resistance by the inhibition of c-Jun NH2-Terminal Kinase and Nuclear-κB.

4-Hydroxyisoleucine attenuates the inflammation-mediated insulin resistance by the activation of AMPK and suppression of SOCS-3 coimmunoprecipitation with both the IR-β subunit as well as IRS-1

It is known that 4-hydroxyisoleucine (4-HIL) from seeds of Trigonella foenum-graecum has beneficial effects on low-grade inflammation; therefore, the insulin signaling as well as the anti-inflammatory effects of 4-HIL in TNF-α-induced insulin resistance in C2C12 myotubes was studied with an aim to dissect out the mechanism(s) of the inflammation-mediated insulin resistance. TNF-α suppressed insulin-stimulated glucose transport rate and increased Ser-307 phosphorylation of insulin receptor substrate-1 (IRS-1). However, the treatment of 4-hydroxyisoleucine enhanced insulin-stimulated glucose transport rate via the activation of AMP-activated protein kinase (AMPK) in a dose-dependent manner. 4-HIL also increases the tyrosine phosphorylation of both IR-β and IRS-1. Moreover, coimmunoprecipitation (Co-IP) of insulin receptor-β (IR-β) subunit with IRS-1 was found to be increased by 4-hydroxyisoleucine. Concentration of SOCS-3 protein and coimmunoprecipitation of SOCS-3 protein with both the IR-β subunit as well as IRS-1 was found to be decreased by 4-HIL. We conclude that the 4-hydroxyisoleucine reverses the insulin resistance by the activation of AMPK and suppression of SOCS-3 coimmunoprecipitation with both the IR-β subunit as well as IRS-1.

A collagen domain–derived short adiponectin peptide activates APPL1 and AMPK signaling pathways and improves glucose and fatty acid metabolisms

Adiponectin is a fat tissue–derived adipokine with beneficial effects against diabetes, cardiovascular diseases, and cancer. Accordingly, adiponectin-mimetic molecules possess significant pharmacological potential. Oligomeric states of adiponectin appear to determine its biological activity. We identified a highly conserved, 13-residue segment (ADP-1) from adiponectins collagen domain, which comprises GXXG motifs and has one asparagine and two histidine residues that assist in oligomeric protein assembly. We therefore hypothesized that ADP-1 promotes oligomeric assembly and thereby mediates potential metabolic effects. We observed here that ADP-1 is stable in human serum and oligomerizes in aqueous environments. We also found that ADP-1 activates AMP-activated protein kinase (AMPK) in an adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1)-dependent pathway and stimulates glucose uptake in rat skeletal muscle cells (L6 myotubes). ADP-1–induced glucose transport coincided with ADP-1–induced biosynthesis of glucose transporter 4 and its translocation to the plasma membrane. ADP-1 induced an interaction between APPL1 and the small GTPase Rab5, resulting in AMPK phosphorylation, in turn leading to phosphorylation of p38 mitogen-activated protein kinase (MAPK), acetyl-CoA carboxylase, and peroxisome proliferator–activated receptor α. Similar to adiponectin, ADP-1 increased the expression of the adiponectin receptor 1 (AdipoR1) gene. Of note, ADP-1 decreased blood glucose levels and enhanced insulin production in pancreatic β cells in db/db mice. Further, ADP-1 beneficially affected lipid metabolism by enhancing lipid globule formation in mouse 3T3-L1 adipocytes. To our knowledge, this is the first report on identification of a short peptide from adiponectin with positive effects on glucose or fatty acid metabolism.

Chalcone-Based Aryloxypropanolamine as a Potential Antidiabetic and Antidyslipidaemic Agent

Poonam Shukla, Mavurapu Satyanarayana, Prem C. Verma, Jaya Tiwari, Atma P. Dwivedi, Rohit Srivastava, Neha Rehuja, Swayam P. Srivastava, Sudeep Gautam, Akhilesh K. Tamrakar, Anil K. Dwivedi, Hari N. Kushwaha, Nagsen Gautam, Shio K. Singh, Mukesh Srivastava, Chandishwar Nath, Ram Raghubir, Arvind K. Srivastava and Ram Pratap* Division of Medicinal and Process Chemistry, Division of Biochemistry, Division of Pharmaceutics, Division of Pharmacokinetics and Pharmaco-dynamics, Division of Biometry and Statistics, Division of Toxicology and Division of Pharmacology, CSIR-Central Drug Research Institute, Sector-10 Jankipuram Extension, Sitapur Road, Lucknow 226 031, India

Antidiabetic Potential of Potentilla fulgens Roots in Validated Animal Models of Diabetes

The present study was undertaken to investigate the antidiabetic potential of tap roots of Potentilla fulgens in streptozotocin induced diabetic rat models. The crude powder, ethanolic, ethanolic: aqueous and aqueous extracts of tap roots were administered to normoglycemic- and streptozotocin (STZ)-induced diabetic rats in a single dose study. The ethanolic extract showed significant improvement in oral glucose tolerance and antihyperglycemic effect on sucrose loaded normal rats and STZ-induced diabetic rats. Of the isolated aqueous, n-butanol, chloroform and n-hexane soluble fractions of the active ethanolic extract of the roots, the aqueous fraction (100 mg/kg body weight) showed significant blood glucose lowering effect on STZ-induced diabetic rats. In a multiple dose study, aqueous fraction of ethanolic extract of P. fulgens roots significantly improved the body weight, percent glycated hemoglobin (%HbA1c), fasting blood glucose, oral glucose tolerance (OGTT), serum insulin, lipid profile, liver and kidney parameters in STZ-induced diabetic rats. The aqueous fraction also showed marked improvement in OGTT and serum insulin level in neonatal STZ-induced diabetic rats for 30 consecutive days. The aqueous fraction of the roots also inhibited the activity of alpha (α)-glucosidase enzyme in a dose dependent manner. In conclusion, the finding suggested that an aqueous fraction of tap roots of P. fulgens possessed potential antidiabetic activity.