Drug discovery approaches targeting the incretin pathway

An Update on Dipeptidyl Peptidase-IV Inhibiting Peptides

Diabetes is a chronic metabolic disorder. According to the International Diabetes Federation, about 537 million people are living with diabetes. The two types of diabetes are type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), among which the population affected by T2DM is relatively higher. A major reason for T2DM is that insulin stimulation is hampered due to the inactivation of incretin hormones. Dipeptidyl peptidase-IV (DPP-IV) is a serine protease that is directly involved in the inactivation of incretin hormones, e.g., glucagon-like peptide-1 (GLP-1). Therefore, the inhibition of DPP-IV can be a promising method for managing T2DM, in addition to other enzyme inhibition strategies, such as inhibition of α-amylase and α -glucosidase. Currently, about 12 different gliptin drugs are available in the market that inhibit DPP-IV in a dose-dependent manner. Instead of gliptins, 'peptides' can also be employed as an alternative and promising way to inhibit DPP-IV. Peptide inhibitors of DPP-IV have been identified from various plants and animals. Chemically synthesized peptides have also been experimented for inhibiting DPP-IV. Most peptides have been analysed by biochemical assays, whereas some in vitro assays have also been reported. Molecular docking analysis has been applied to comprehend the mechanism of inhibition. In this review, certain aspects of natural as well as synthetic peptides are described that have been proven to inhibit DPP-IV.

Incretins as a Potential Treatment Option for Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a metabolic disease affecting an increasing number of pregnant women around the world. It is not only associated with numerous perinatal complications but also has long-term consequences impacting maternal health and fetal development. To prevent them, it is important to keep glucose levels under control. As much as 15-30% of GDM patients will require treatment with insulin, metformin, or glyburide. With that in mind, it is crucial to keep searching for novel and improved pharmacotherapies. Nowadays, there are ongoing studies investigating the use of other groups of drugs that have proven successful in the treatment of T2DM. Glucagon-like peptide-1 (GLP-1) receptor agonist and dipeptidyl peptidase-4 (DPP-4) inhibitor are among the drugs targeting the incretin system and are currently receiving significant attention. The aim of our review is to demonstrate the potential of these medications in treating GDM and preventing its later complications. It seems that both groups may be successful in the GDM management used alone or as an addition to better-known drugs, including metformin and glyburide. However, more clinical trials are needed to confirm their importance in GDM treatment and to demonstrate effective therapeutic strategies.

Review of pharmaceutical and therapeutic approaches for type 2 diabetes and related disorders

One of the essential diseases that are increasing in the world is type 2 diabetes (T2D), which many people around the world live with this disease. Various studies have revealed that insulin resistance, lessened insulin production has been associated with T2D, and they also show that this disease can have a genetic origin and is associated with different genes such as KCNQ1, PPAR-γ, calpain-10, ADIPOR2, TCF7L2 that can be utilized as a therapeutic target. Different therapeutic approaches and strategies such as exercise and diet, pharmacological approaches, and utilization of nanoparticles in drug delivery and gene therapy can be effective in the treatment and control of T2D. Glucagon-like peptide 1 (GLP-1) and sodium glucose cotransporter-2 (SGLT2) have both been considered as drug classes in the treatment of T2D and T2D-related diseases such as cardiovascular disease and renal disease, and have considerable influences such as diminished cardiovascular mortality in individuals with T2D, ameliorate postprandial glycaemia, ameliorate fasting glycaemia, and diminish body weight on disease treatment and improvement process. In the present review article, we have made an attempt to explore the risk factors, Genes, and diseases associated with T2D, therapeutic approaches in T2D, the influences of drugs such as Dapagliflozin, Metformin, Acarbose, Januvia (Sitagliptin), and Ertugliflozin on T2D in clinical trials and animal model studies. Research in clinical trials has promising results that support the role of these drug approaches in T2D prophylaxis and ameliorate safety even though additional clinical research is still obligatory.

A Novel Metric to Quantify the Effect of Pathway Enrichment Evaluation With Respect to Biomedical Text-Mined Terms: Development and Feasibility Study

BACKGROUND

Natural language processing has long been applied in various applications for biomedical knowledge inference and discovery. Enrichment analysis based on named entity recognition is a classic application for inferring enriched associations in terms of specific biomedical entities such as gene, chemical, and mutation.

OBJECTIVE

The aim of this study was to investigate the effect of pathway enrichment evaluation with respect to biomedical text-mining results and to develop a novel metric to quantify the effect.

METHODS

Four biomedical text mining methods were selected to represent natural language processing methods on drug-related gene mining. Subsequently, a pathway enrichment experiment was performed by using the mined genes, and a series of inverse pathway frequency (IPF) metrics was proposed accordingly to evaluate the effect of pathway enrichment. Thereafter, 7 IPF metrics and traditional P value metrics were compared in simulation experiments to test the robustness of the proposed metrics.

RESULTS

IPF metrics were evaluated in a case study of rapamycin-related gene set. By applying the best IPF metrics in a pathway enrichment simulation test, a novel discovery of drug efficacy of rapamycin for breast cancer was replicated from the data chosen prior to the year 2000. Our findings show the effectiveness of the best IPF metric in support of knowledge discovery in new drug use. Further, the mechanism underlying the drug-disease association was visualized by Cytoscape.

CONCLUSIONS

The results of this study suggest the effectiveness of the proposed IPF metrics in pathway enrichment evaluation as well as its application in drug use discovery.

Therapies for the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes and Dyslipidemia

Cardiovascular disease (CVD) is the leading cause of death worldwide and is the clinical manifestation of the atherosclerosis. Elevated LDL-cholesterol levels are the first line of therapy but the increasing prevalence in type 2 diabetes mellitus (T2DM) has positioned the cardiometabolic risk as the most relevant parameter for treatment. Therefore, the control of this risk, characterized by dyslipidemia, hypertension, obesity, and insulin resistance, has become a major goal in many experimental and clinical studies in the context of CVD. In the present review, we summarized experimental studies and clinical trials of recent anti-diabetic and lipid-lowering therapies targeted to reduce CVD. Specifically, incretin-based therapies, sodium-glucose co-transporter 2 inhibitors, and proprotein convertase subtilisin kexin 9 inactivating therapies are described. Moreover, the novel molecular mechanisms explaining the CVD protection of the drugs reviewed here indicate major effects on vascular cells, inflammatory cells, and cardiomyocytes, beyond their expected anti-diabetic and lipid-lowering control. The revealed key mechanism is a prevention of acute cardiovascular events by restraining atherosclerosis at early stages, with decreased leukocyte adhesion, recruitment, and foam cell formation, and increased plaque stability and diminished necrotic core in advanced plaques. These emergent cardiometabolic therapies have a promising future to reduce CVD burden.

Prominent and emerging anti-diabetic molecular targets

Diabetes is on the rise across the globe affecting more than 463 million people and crucially increasing morbidities of diabetes-associated diseases. Urgent and immense actions are needed to improve diabetes prevention and treatment. Regarding the correlation of diabetes with many associated diseases, inhibition of the disease progression is more crucial than controlling symptoms. Currently, anti-diabetic drugs are accompanied by undesirable side-effects and target confined types of biomolecules. Thus, extensive research is demanding to identify novel disease mechanisms and molecular targets as probable candidates for effective treatment of diabetes. This review discusses the conventional molecule targets that have been applied for their therapeutic rationale in treatment of diabetes. Further, the emerging and prospective molecular targets for the future focus of library screenings are presented.

Cryo-EM as a powerful tool for drug discovery

The recent revolution in cryo-EM has produced an explosion of structures at near-atomic or better resolution. This has allowed cryo-EM structures to provide visualization of bound small-molecule ligands in the macromolecules, and these new structures have provided unprecedented insights into the molecular mechanisms of complex biochemical processes. They have also had a profound impact on drug discovery, defining the binding modes and mechanisms of action of well-known drugs as well as driving the design and development of new compounds. This review will summarize and highlight some of these structures. Most excitingly, the latest cryo-EM technology has produced structures at 1.2 Å resolution, further solidifying cryo-EM as a powerful tool for drug discovery. Therefore, cryo-EM will play an ever-increasing role in drug discovery in the coming years.

Pyrazole Incorporated New Thiosemicarbazones: Design, Synthesis and Investigation of DPP-4 Inhibitory Effects

Dipeptidyl peptidase-4 (DPP-4) inhibition has been recognized as a promising approach to develop safe and potent antidiabetic agents for the management of type 2 diabetes. In this context, new thiosemicarbazones (2a-o) were prepared efficiently by the reaction of aromatic aldehydes with 4-[4-(1H-pyrazol-1-yl)phenyl]thiosemicarbazide (1), which was obtained via the reaction of 4-(1H-pyrazol-1-yl)phenyl isothiocyanate with hydrazine hydrate. Compounds 2a-o were evaluated for their DPP-4 inhibitory effects based on a convenient fluorescence-based assay. 4-[4-(1H-pyrazol-1-yl)phenyl]-1-(4-bromobenzylidene)thiosemicarbazide (2f) was identified as the most effective DPP-4 inhibitor in this series with an IC₅₀ value of 1.266 ± 0.264 nM when compared with sitagliptin (IC₅₀ = 4.380 ± 0.319 nM). MTT test was carried out to assess the cytotoxic effects of compounds 2a-o on NIH/3T3 mouse embryonic fibroblast (normal) cell line. According to cytotoxicity assay, compound 2f showed cytotoxicity towards NIH/3T3 cell line with an IC₅₀ value higher than 500 µM pointing out its favourable safety profile. Molecular docking studies indicated that compound 2f presented π-π interactions with Arg358 and Tyr666 via pyrazole scaffold and 4-bromophenyl substituent, respectively. Overall, in vitro and in silico studies put emphasis on that compound 2f attracts a great notice as a drug-like DPP-4 inhibitor for further antidiabetic research.

Structural optimization of pyrazolo[1,5-a]pyrimidine derivatives as potent and highly selective DPP-4 inhibitors

Our previous discovery of pyrazolo [1,5-a]pyrimidin-7(4H)-one scaffold-based DPP-4 inhibitors yielded two potent compounds b2 (IC₅₀ = 79 nM) and d1 (IC₅₀ = 49 nM) but characterized by cytotoxicity. Herein, with scaffold hopping and fragment-based drug design strategies, highly potent and selective pyrazolo [1,5-a]pyrimidine DPP-4 inhibitors were found featured by reduced or diminished cytotoxicity. Specifically, c24 (IC₅₀ = 2 nM) exhibits a 25 to 40-fold increase of inhibitory activity respect to those of b2 and d1, respectively, 2-fold from Alogliptin (IC₅₀ = 4 nM), and remarkable selectivity over DPP-8 and DPP-9 (>2000 fold). Further docking studies confirmed that the pyrazolo [1,5-a]pyrimidine core interacts with the S1 pocket whereas its substituted aromatic ring interacts with the sub-S1 pocket. The interactive mode in this case resembles that of Alogliptin and Trelagliptin. Further in vivo IPGTT assays in diabetic mice demonstrated that c24 effectively reduces glucose excursion by 48% at the dose of 10 mg/kg, suggesting that c24 is worthy of further development as a potent anti-diabetes agent.