Discovery of potent, selective, and orally bioavailable quinoline-based dipeptidyl peptidase IV inhibitors targeting Lys554

Discovery of imeglimin-inspired novel 1,3,5-triazine derivatives as antidiabetic agents in streptozotocin-induced diabetes in Wistar rats via inhibition of DPP-4

Novel 1,3,5-triazine derivatives bearing oxazine have been synthesized and tested for their ability to inhibit a panel of dipeptidyl peptidase (DPP)-4, 8, and 9 enzymes. In a comparative inhibitory assay, the molecules showed potent inhibition of DPP-4 ranging from IC50 of 4.2 ± 0.30-260.5 ± 0.42 nM, with no activity against DPP-8 and DPP-9. Among the tested series, compound 8c demonstrated the strongest DPP-4 inhibitory activity with an IC50 of 4.2 ± 0.30 nM. It also showed the greatest binding affinity during docking studies with DPP-4 with a docking score of -8.956 and a glide energy of -78.546 kcal mol-1 and was found oriented in the S1 and S2 pockets of the DPP-4 active site, which is composed of the catalytic triad Ser 630, Asp 710, and His 740. The in vivo pharmacological assay revealed that compound 8c in a dose-dependent manner improved the insulin level, body weight, antioxidants, and HDL, and reduced the levels of blood glucose, LDL, and VLDL in streptozotocin-induced diabetes in Wistar rats. Our study demonstrated the discovery and development of novel 1,3,5-triazine derivatives bearing oxazine as a novel class of anti-diabetic agents via inhibition of DPP-4.

Discovery of novel 1,3,5-triazine derivatives as an antidiabetic agent in Wistar rats via inhibition of DPP-4

Aim: To develop imeglimin-inspired novel 1,3,5-triazine derivatives as antidiabetic agents. Materials & methods: These derivatives were synthesized and tested against DPP enzymes. Compound 8c was tested for in vivo antidiabetic activity in streptozotocin-induced diabetes in Wistar rats by estimating various biochemical parameters. Docking experiments were also performed. Results: Compound 8c was identified as a selective and potent DPP-4 inhibitor. It was proficiently docked into the catalytic triad of Ser 630, Asp 710 and His740 in S1 and S2 pockets of DPP-4. In experimental animals, it also showed dose-dependent improvement in blood glucose, blood insulin, bodyweight, lipid profile and kidney and liver antioxidant profiles. Conclusion: This study demonstrated the discovery of imeglimin-inspired novel 1,3,5-triazines as a potent antidiabetic agent.

A review upon medicinal perspective and designing rationale of DPP-4 inhibitors

Type 2 Diabetes Mellitus (T2DM) is one of the highly prevalence disorder and increasing day by day worldwidely. T2DM is a metabolic disorder, which is characterized by deficiency in insulin or resistance to insulin and thus increases the glucose levels in the blood. Various approaches are there to treat diabetes but still there is no cure for this disease. DPP-4 inhibitor is a privileged target in the field of drug discovery and provides various opportunities in exploring this target for development of molecules as antidiabetic agents. DPP-4 acts by inhibiting the incretin action and thus decreases the level of blood glucose by imparting minimal side effects. Sitagliptin, vildagliptin, linagliptin etc. are the different DPP-4 based drugs approved throughout the world for the treatment of diabetes mellitus. Cyanopyrrolidines, triazolopiperazine amide, pyrrolidines are basic core nucleus present in various DPP-4 inhibitors and has potential effects. In the past few years, researchers had applied various approaches to synthesize potent DPP-4 inhibitors as antidiabetic agent without side effects like weight gain, cardiovascular risks, retinopathy etc. This review will also emphasize the recent strategies and rationale utilized by researchers for the development of DPP-4 inhibitors. This review also reveals about the various other approaches like molecular modelling, ligand based drug designing, high throughput screening etc. are used by the various research group for the development of potential DPP-4 inhibitors.

Cobalt-Catalyzed C-H Activation/Annulation of Benzamides with Fluorine-Containing Alkynes: A Route to 3- and 4-Fluoroalkylated Isoquinolinones

The C-H activation/annulation reaction of various benzamides with fluoroalkylated alkynes in the presence of a Co(acac)₂·2H₂O catalyst proceeded very smoothly to give the corresponding 3- and 4-fluoroalkylated isoquinolinones in excellent yields with approximately 70% regioselectivities. These regioisomers could be successfully separated and obtained in pure form. Major or minor regioisomers were determined as 4- or 3-fluoroalkylated isoquinolinones, respectively, based on X-ray crystallographic analyses.

Drug discovery approaches targeting the incretin pathway

Incretin pathway plays an important role in the development of diabetes medications. Interventions in DPP-4 and GLP-1 receptor have shown remarkable efficacy in experimental and clinical studies and imperatively become one of the most promising therapeutic approaches in the T2DM drug discovery pipeline. Herein, we analyzed the actionmechanismsof DPP-4 and GLP-1 receptor targeting the incretin pathway in T2DM treatment. We gave an insight into the structural requirements for the potent DPP-4 inhibitors and revealed a classification of DPP-4 inhibitors by stressing on the binding modes of these ligands to the enzyme. We then reviewed the drug discovery strategies for the development of peptide and non-peptide GLP-1 receptor agonists (GLP-1 RAs). Furthermore, the drug design strategies for DPP-4 inhibitors and GLP-1R agonists were detailed accurately. This review might provide an efficient evidence for the highly potent and selective DPP-4 inhibitors and the GLP-1 RAs, as novel medicines for patients suffering from T2DM.

Integrated Protocol to Design Potential Inhibitors of Dipeptidyl Peptidase- 4 (DPP-4)

BACKGROUND

A strategy for the treatment of type II diabetes mellitus is the inhibition of the enzyme known as dipeptidyl peptidase-4 (DPP-4).

AIMS

This study aims to investigate the main interactions between DPP-4 and a set of inhibitors, as well as proposing potential candidates to inhibit this enzyme.

METHODS

We performed molecular docking studies followed by the construction and validation of CoMFA and CoMSIA models. The information provided from these models was used to aid in the search for new candidates to inhibit DPP-4 and the design of new bioactive ligands from structural modifications in the most active molecule of the studied series.

RESULTS

We were able to propose a set of analogues with biological activity predicted by the CoMFA and CoMSIA models, suggesting that our protocol can be used to guide the design of new DPP-4 inhibitors as drug candidates to treat diabetes.

CONCLUSION

Once the integration of the techniques mentioned in this article was effective, our strategy can be applied to design possible new DPP-4 inhibitors as candidates to treat diabetes.

Benzo[4,5]thieno[2,3-d]pyrimidine phthalimide derivative, one of the rare noncompetitive inhibitors of dipeptidyl peptidase-4

A small library of benzo[4,5]thieno[2,3-d]pyrimidine phthalimide and amine derivatives was evaluated for inhibitory activity against dipeptidyl peptidase-4 (DPP-4). The phthalimide derivatives exhibited better activity than the amine precursors, with 2-(2-(3-chlorobenzyl)-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4-yl)isoindoline-1,3-dione (compound 14) as the most effective inhibitor (IC₅₀  = 34.17 ± 5.11 μM). The five most potent selected inhibitors did not show cytotoxicity to a greater extent on Caco-2 cells, even at a concentration of 250 μM. Compound 14 is considered as a novel representative of the rare noncompetitive DPP-4 inhibitors. Molecular docking and dynamics simulation indicated the importance of the Tyr547, Lys554, and Trp629 residues of DPP-4 in the formation of the enzyme-inhibitor complex. These observations could be potentially utilized for the rational design and optimization of novel (structurally similar, with phthalimide moiety, or different) noncompetitive DPP-4 inhibitors, which are anyway rare, but favorable in terms of the saturation of substrate competition.

Synthesis of Flubromazepam Positional Isomers for Forensic Analysis

Designer benzodiazepines have recently appeared in many forensic cases as legal alternatives to federally scheduled drugs such as diazepam (Valium) and alprazolam (Xanax). Though current forensic instrumental techniques are often sufficient for identifying novel psychoactive substances, they may not readily differentiate between potential positional isomers. Additionally, characterization data for positional isomers of known designer benzodiazepines are widely nonexistent. In this study, flubromazepam, a recognized designer benzodiazepine since 2012, was targeted for synthesis and characterization due to its potential for federal scheduling and current legal status within the United States. A practical synthetic method was developed to prepare purified reference materials for each positional isomer of flubromazepam in which the positions of the bromine and fluorine substituents were varied. Possible isomers (9 of the 12) were successfully prepared and used for further analysis.

Emergence of promising novel DPP-4 inhibitory heterocycles as anti-diabetic agents: A review

Diabetes has turned out to be an epidemic in the recent years all over the world, and today it has become a burden on the healthcare system. Over the years, with technological advancements, different classes of antidiabetic medications have emerged, like sulfonylureas, biguanides, alpha-glucosidase inhibitors, and thiazolidinediones, but these are often loaded with serious aftermaths like hypoglycemia, weight gain, cardiovascular and renal issues. Dipeptidyl peptidase-4 (DPP-4) inhibition is an exciting and new approach in the treatment of type-2 diabetes. DPP-4 inhibitors or "gliptins" are weight neutral, pose lesser risk of hypoglycemia, and provide a long-term post-meal glycemic control. In this review, an attempt has been made to investigate novel potential compounds that can be added to the existing list of anti-diabetic drugs.

Activity and selectivity cliffs for DPP-IV inhibitors: Lessons we can learn from SAR studies and their application to virtual screening

The inhibition of dipeptidyl peptidase-IV (DPP-IV) has emerged over the last decade as one of the most effective treatments for type 2 diabetes mellitus, and consequently (a) 11 DPP-IV inhibitors have been on the market since 2006 (three in 2015), and (b) 74 noncovalent complexes involving human DPP-IV and drug-like inhibitors are available at the Protein Data Bank (PDB). The present review aims to (a) explain the most important activity cliffs for DPP-IV noncovalent inhibition according to the binding site structure of DPP-IV, (b) explain the most important selectivity cliffs for DPP-IV noncovalent inhibition in comparison with other related enzymes (i.e., DPP8 and DPP9), and (c) use the information deriving from this activity/selectivity cliff analysis to suggest how virtual screening protocols might be improved to favor the early identification of potent and selective DPP-IV inhibitors in molecular databases (because they have not succeeded in identifying selective DPP-IV inhibitors with IC₅₀ ≤ 100 nM). All these goals are achieved with the help of available homology models for DPP8 and DPP9 and an analysis of the structure-activity studies used to develop the noncovalent inhibitors that form part of some of the complexes with human DPP-IV available at the PDB.

Design of potent dipeptidyl peptidase IV (DPP-4) inhibitors by employing a strategy to form a salt bridge with Lys554

We report a design strategy to obtain potent DPP-4 inhibitors by incorporating salt bridge formation with Lys554 in the S1' pocket. By applying the strategy to the previously identified templates, quinoline 4 and pyridines 16a, 16b, and 17 have been identified as subnanomolar or nanomolar inhibitors of human DPP-4. Docking studies suggested that a hydrophobic interaction with Tyr547 as well as the salt bridge interaction is important for the extremely high potency. The design strategy would be useful to explore a novel design for DPP-4 inhibitors having a distinct structure with a unique binding mode.

Molecular docking studies and 2D analyses of DPP-4 inhibitors as candidates in the treatment of diabetes

Dipeptidyl peptidase-4 (DPP-4) is an important biological target related to the treatment of diabetes as DPP-4 inhibitors can lead to an increase in the insulin levels and a prolonged activity of glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP), being effective in glycemic control. Thus, this study analyses the main molecular interactions between DPP-4 and a series of bioactive ligands. The methodology used here employed molecular modeling methods, such as HQSAR (Hologram Quantitative Structure-Activity) analyses and molecular docking, with the aim of understanding the main structural features of the compound series that are essential for the biological activity. Analyses of the main interactions in the active site of DPP-4, in particular, the contribution of the hydroxyl coordination between Tyr547 and Ser630 by the water molecule, which is described in the literature as important for the coordinated interactions in the active site, were performed. Significant correlation coefficients of the best 2D model (r(2) = 0.942 and q(2) = 0.836) were obtained, indicating the predictive power of this model for untested compounds. Therefore, the final model constructed in this study, along with the information from the contribution maps, could be useful in the design of novel DPP-4 ligands with improved activity.

Pharmacophore modeling and molecular docking studies of acridines as potential DPP-IV inhibitors

Inhibition of dipeptidyl peptidase-IV (DPP-IV) prevents the inactivation of gastric inhibitory polypeptide (GIP) and glucagon-like peptide–1 (GLP-1). This increases circulating levels of active GLP-1 and GIP and stimulates insulin secretion, which results in lowering of glucose levels and improvement of the glycemic control in patients with type 2 diabetes. In this study, pharmacophore modeling and docking experiments were carried out and a series of eight novel 2-ethoxy-6,9-disubstituted acridines (13, 15, and 17a–17f) have been designed and synthesized. Then, these compounds were evaluated for their ability to inhibit DPP-IV. Most of the synthesized compounds were proven to have anti-DPP-IV activity where compound 17b displayed the best activity of 43.8% inhibition at 30 μmol/L concentration. Results of this work might be helpful for further optimization to develop more potent DPP-IV inhibitors.

Recent approaches to medicinal chemistry and therapeutic potential of dipeptidyl peptidase-4 (DPP-4) inhibitors

Dipeptidyl peptidase-4 (DPP-4) is one of the widely explored novel targets for Type 2 diabetes mellitus (T2DM) currently. Research has been focused on the strategy to preserve the endogenous glucagon like peptide (GLP)-1 activity by inhibiting the DPP-4 action. The DPP-4 inhibitors are weight neutral, well tolerated and give better glycaemic control over a longer duration of time compared to existing conventional therapies. The journey of DPP-4 inhibitors in the market started from the launch of sitagliptin in 2006 to latest drug teneligliptin in 2012. This review is mainly focusing on the recent medicinal aspects and advancements in the designing of DPP-4 inhibitors with the therapeutic potential of DPP-4 as a target to convey more clarity in the diffused data.