1,3-Diphenyl-1H-pyrazole derivatives as a new series of potent PPARγ partial agonists

Pharmacological and computational evaluation of Sapodilla and its constituents for therapeutic potential in hyperactive gastrointestinal disorders

OBJECTIVES

This study was designed to investigate various gastrointestinal effects of Manilkara zapota (Sapodilla), exploring its anti-diarrheal, anti-secretary, anti-spasmodic, anti-ulcer and anti-motility potential.

MATERIALS AND METHODS

Antidiarrheal and anti-secretary activities were investigated using castor oil induced diarrhea and castor oil induced fluid accumulation. Isolated rabbit jejunum tissues (antispasmodic) were employed for in vitro experiments. Antiulcer, antimotility and molecular docking were performed using ethanol-HCl induced ulcer assay, charcoal meal transit time and Auto Doc Vina.

RESULTS

Mz.Cr exhibited protection against castor oil-induced diarrhea (P<0.05 vs. saline group) and dose-dependently inhibited intestinal fluid secretions (P<0.001 vs. castor oil group). Mz.Cr caused relaxation of spontaneous and K⁺ (80 Mm)-induced contractions with EC₅₀ values of 0.11mg/ml (0.08-0.1, n=4) and 0.16 mg/ml (0.09-0.2, n=4) respectively (^* P<0.05^** P<0.01 ^*** P<0.001). It showed protective effect against gastric ulcers induced by ethanol-HCl (P<0.001 vs. saline group). Mz.Cr reduced distance travelled by charcoal meal (P<0.001 vs. saline group). Plant constituents: caffeoylquinic acid and methyl 4-O-galloylchlorogenate showed high binding affinities (E-value≥-6.5 Kcal/mol) against histaminergic H₂ receptors, H⁺/K⁺ ATPase pump and voltage gated L-type calcium channels, while possesses moderate affinities (E-value≥8 Kcal/mol) against histaminergic H₁, muscarinic M₁, M₃ and mu-opioid, whereas lower affinities (E-value≥9.5 Kcal/mol) vs. calmodulin, adrenergic α₁, phosphodiesterase enzyme and dopaminergic D₂ receptors. Lupeol-3-acetate and β-amyrin-3-(3'-dimethyl) butyrate observed weak affinities.

CONCLUSION

In present study, M. zapota is reported to exhibits anti-diarrheal, anti-secretory, anti-spasmodic, anti-motility, anti-ulcer effects and computational binding affinities against gastrointestinal targets.

Computational and Pharmacological Evaluation of Ferrocene-Based Acyl Ureas and Homoleptic Cadmium Carboxylate Derivatives for Anti-diabetic Potential

We investigated possible anti-diabetic effect of ferrocene-based acyl ureas: 4-ferrocenyl aniline (PFA), 1-(4-chlorobenzoyl)-3-(4-ferrocenylphenyl) urea (DPC1), 1-(3-chlorobenzoyl)-3-(4-ferrocenylphenyl) urea (DMC1), 1-(2-chlorobenzoyl)-3-(4-ferrocenylphenyl) urea (DOC1) and homoleptic cadmium carboxylates: bis (diphenylacetato) cadmium (II) (DPAA), bis (4-chlorophenylacetato) cadmium (II) (CPAA), using in silico and in vivo techniques. PFA, DPC1, DMC1, DOC1, DPAA and CPAA exhibited high binding affinities (ACE ≥ −350 Kcal/mol) against targets: aldose reductase, peroxisome proliferator-activated receptor γ, 11β-hydroxysteroid dehydrogenase-1, C-alpha glucosidase and glucokinase, while showed moderate affinities (ACE ≥ −250 Kcal/mol) against N-alpha glucosidase, dipeptidyl peptidase-IV, phosphorylated-Akt, glycogen synthase kinase-3β, fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase, whereas revealed lower affinities (ACE < −250 Kcal/mol) vs. alpha amylase, protein tyrosine phosphatases 1B, glycogen phosphorylase and phosphatidylinositol 3 kinase. In alloxan (300 mg/Kg)-induced diabetic mice, DPAA and DPC1 (1–10 mg/Kg) at day 1, 5, 10, 15, and 20th decreased blood glucose levels, compared to diabetic control group and improved the treated animals body weight. DPAA (10 mg/Kg) and DPC1 (5 mg/Kg) in time-dependent manner (30–120 min.) enhanced tolerance of oral glucose overload in mice. DPAA and DPCI dose-dependently at 1, 5, and 10 mg/Kg decreased glycosylated hemoglobin levels in diabetic animals, as caused by metformin. These results indicate that aforementioned derivatives of ferrocene and cadmium possess anti-diabetic potential.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Synthesis and Pharmacological Activities of Pyrazole Derivatives: A Review

Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.

Hypoglycemic activity of 6-bromoembelin and vilangin in high-fat diet fed-streptozotocin-induced type 2 diabetic rats and molecular docking studies

AIMS

This paper investigates the hypoglycemic activity of two derivatives of embelin (1) viz. 6-bromoembelin (2) and vilangin (3), in high-fat diet - STZ induced diabetic rats.

MAIN METHODS

The effects of 6-bromoembelin (2) and vilangin (3) on insulin resistance, β-cell dysfunction and glucose transport in high-fat diet (HFD) fed-streptozotocin (STZ) (40mg/kg) induced type 2 diabetic rats were evaluated. The binding modes of 6-bromoembelin (2) and vilangin (3) into PPARγ, PI3K, Akt, and GLUT4 were also studied using Autodock 4.2 and ADT 1.5.6 programs.

KEY FINDINGS

At the dose of 30mg/kg, the plasma glucose, plasma insulin and body weight were reduced by both embelin derivatives in diabetic rats. Additionally the altered lipid profiles and hexokinase, glucose-6-phosphatase and fructose-1,6-bisphosphatase levels were brought to normal. Compared to diabetic control group, there was a significant increase in the expression of PPARγ in epididymal adipose tissue. Inhibition of adipogenic activity and mild activation of PPARγ levels in the skeletal muscle and liver were observed. In epididymal adipose tissue, the compounds increased the insulin-mediated glucose uptake through the activation and translocation of GLUT4 in PI3K/p-Akt signaling cascade.

SIGNIFICANCE

The derivatives of embelin such as 6-bromoembelin (2) and vilangin (3) may be useful in the prevention and treatment of obesity-linked type 2 diabetes mellitus.

Breaking the mold: transcription factors in the anucleate platelet and platelet-derived microparticles

Platelets are small anucleate blood cells derived from megakaryocytes. In addition to their pivotal roles in hemostasis, platelets are the smallest, yet most abundant, immune cells and regulate inflammation, immunity, and disease progression. Although platelets lack DNA, and thus no functional transcriptional activities, they are nonetheless rich sources of RNAs, possess an intact spliceosome, and are thus capable of synthesizing proteins. Previously, it was thought that platelet RNAs and translational machinery were remnants from the megakaryocyte. We now know that the initial description of platelets as "cellular fragments" is an antiquated notion, as mounting evidence suggests otherwise. Therefore, it is reasonable to hypothesize that platelet transcription factors are not vestigial remnants from megakaryocytes, but have important, if only partly understood functions. Proteins play multiple cellular roles to minimize energy expenditure for maximum cellular function; thus, the same can be expected for transcription factors. In fact, numerous transcription factors have non-genomic roles, both in platelets and in nucleated cells. Our lab and others have discovered the presence and non-genomic roles of transcription factors in platelets, such as the nuclear factor kappa β (NFκB) family of proteins and peroxisome proliferator-activated receptor gamma (PPARγ). In addition to numerous roles in regulating platelet activation, functional transcription factors can be transferred to vascular and immune cells through platelet microparticles. This method of transcellular delivery of key immune molecules may be a vital mechanism by which platelet transcription factors regulate inflammation and immunity. At the very least, platelets are an ideal model cell to dissect out the non-genomic roles of transcription factors in nucleated cells. There is abundant evidence to suggest that transcription factors in platelets play key roles in regulating inflammatory and hemostatic functions.

Minireview: Challenges and opportunities in development of PPAR agonists

The clinical impact of the fibrate and thiazolidinedione drugs on dyslipidemia and diabetes is driven mainly through activation of two transcription factors, peroxisome proliferator-activated receptors (PPAR)-α and PPAR-γ. However, substantial differences exist in the therapeutic and side-effect profiles of specific drugs. This has been attributed primarily to the complexity of drug-target complexes that involve many coregulatory proteins in the context of specific target gene promoters. Recent data have revealed that some PPAR ligands interact with other non-PPAR targets. Here we review concepts used to develop new agents that preferentially modulate transcriptional complex assembly, target more than one PPAR receptor simultaneously, or act as partial agonists. We highlight newly described on-target mechanisms of PPAR regulation including phosphorylation and nongenomic regulation. We briefly describe the recently discovered non-PPAR protein targets of thiazolidinediones, mitoNEET, and mTOT. Finally, we summarize the contributions of on- and off-target actions to select therapeutic and side effects of PPAR ligands including insulin sensitivity, cardiovascular actions, inflammation, and carcinogenicity.

SAR and Computer-Aided Drug Design Approaches in the Discovery of Peroxisome Proliferator-Activated Receptor γ Activators: A Perspective

Activators of PPARγ, Troglitazone (TGZ), Rosiglitazone (RGZ), and Pioglitazone (PGZ) were introduced for treatment of Type 2 diabetes, but TGZ and RGZ have been withdrawn from the market along with other promising leads due cardiovascular side effects and hepatotoxicity. However, the continuously improving understanding of the structure/function of PPARγ and its interactions with potential ligands maintain the importance of PPARγ as an antidiabetic target. Extensive structure activity relationship (SAR) studies have thus been performed on a variety of structural scaffolds by various research groups. Computer-aided drug discovery (CADD) approaches have also played a vital role in the search and optimization of potential lead compounds. This paper focuses on these approaches adopted for the discovery of PPARγ ligands for the treatment of Type 2 diabetes. Key concepts employed during the discovery phase, classification based on agonistic character, applications of various QSAR, pharmacophore mapping, virtual screening, molecular docking, and molecular dynamics studies are highlighted. Molecular level analysis of the dynamic nature of ligand-receptor interaction is presented for the future design of ligands with better potency and safety profiles. Recently identified mechanism of inhibition of phosphorylation of PPARγ at SER273 by ligands is reviewed as a new strategy to identify novel drug candidates.

Identification of PPARgamma partial agonists of natural origin (I): development of a virtual screening procedure and in vitro validation

Background

Although there are successful examples of the discovery of new PPARγ agonists, it has recently been of great interest to identify new PPARγ partial agonists that do not present the adverse side effects caused by PPARγ full agonists. Consequently, the goal of this work was to design, apply and validate a virtual screening workflow to identify novel PPARγ partial agonists among natural products.

Methodology/Principal Findings

We have developed a virtual screening procedure based on structure-based pharmacophore construction, protein-ligand docking and electrostatic/shape similarity to discover novel scaffolds of PPARγ partial agonists. From an initial set of 89,165 natural products and natural product derivatives, 135 compounds were identified as potential PPARγ partial agonists with good ADME properties. Ten compounds that represent ten new chemical scaffolds for PPARγ partial agonists were selected for in vitro biological testing, but two of them were not assayed due to solubility problems. Five out of the remaining eight compounds were confirmed as PPARγ partial agonists: they bind to PPARγ, do not or only moderately stimulate the transactivation activity of PPARγ, do not induce adipogenesis of preadipocyte cells and stimulate the insulin-induced glucose uptake of adipocytes.

Conclusions/Significance

We have demonstrated that our virtual screening protocol was successful in identifying novel scaffolds for PPARγ partial agonists.

Insulin sensitization via partial agonism of PPARγ and glucose uptake through translocation and activation of GLUT4 in PI3K/p-Akt signaling pathway by embelin in type 2 diabetic rats

BACKGROUND

The present study was aimed at isolating an antidiabetic molecule from a herbal source and assessing its mechanism of action.

METHODS

Embelin, isolated from Embelia ribes Burm. (Myrsinaceae) fruit, was evaluated for its potential to regulate insulin resistance, alter β-cell dysfunction and modulate key markers involved in insulin sensitivity and glucose transport using high-fat diet (HFD) fed-streptozotocin (STZ) (40mg/kg)-induced type 2 diabetic rats. Molecular-dockings were performed to investigate the binding modes of embelin into PPARγ, PI3K, p-Akt and GLUT4 active sites.

RESULTS

Embelin (50mg/kg b wt.) reduced body weight gain, blood glucose and plasma insulin in treated diabetic rats. It further modulated the altered lipid profiles and antioxidant enzymes with cytoprotective action on β-cell. Embelin significantly increased the PPARγ expression in epididymal adipose tissue compared to diabetic control group; it also inhibited adipogenic activity; it mildly activated PPARγ levels in the liver and skeletal muscle. It also regulated insulin mediated glucose uptake in epididymal adipose tissue through translocation and activation of GLUT4 in PI3K/p-Akt signaling cascade. Embelin bound to PPARγ; it disclosed stable binding affinities to the active sites of PI3K, p-Akt and GLUT4.

CONCLUSIONS

These findings show that embelin could improve adipose tissue insulin sensitivity without increasing weight gain, enhance glycemic control, protect β-cell from damage and maintain glucose homeostasis in adipose tissue.

GENERAL SIGNIFICANCE

Embelin can be used in the prevention and treatment of type 2 diabetes mellitus caused due to obesity.

Comparative molecular profiling of the PPARα/γ activator aleglitazar: PPAR selectivity, activity and interaction with cofactors

Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear hormone receptors that control the expression of genes involved in a variety of physiologic processes, through heterodimerization with retinoid X receptor and complex formation with various cofactors. Drugs or treatment regimens that combine the beneficial effects of PPARα and γ agonism present an attractive therapeutic strategy to reduce cardiovascular risk factors. Aleglitazar is a dual PPARα/γ agonist currently in phase III clinical development for the treatment of patients with type 2 diabetes mellitus who recently experienced an acute coronary event. The potency and efficacy of aleglitazar was evaluated in a head-to-head comparison with other PPARα, γ and δ ligands. A comprehensive, 12-concentration dose-response analysis using a cell-based assay showed aleglitazar to be highly potent, with EC(50) values of 5 nM and 9 nM for PPARα and PPARγ, respectively. Cofactor recruitment profiles confirmed that aleglitazar is a potent and balanced activator of PPARα and γ. The efficacy and potency of aleglitazar are discussed in relation to other dual PPARα/γ agonists, in context with the published X-ray crystal structures of both PPARα and γ.