The structure-activity relationship between peroxisome proliferator-activated receptor gamma agonism and the antihyperglycemic activity of thiazolidinediones

A comprehensive review of small-molecule drugs for the treatment of type 2 diabetes mellitus: Synthetic approaches and clinical applications

Type 2 diabetes mellitus (T2DM) is a long-term metabolic disorder characterized by the body's resistance to insulin and inadequate production of insulin. Small molecule drugs to treat T2DM mainly control blood sugar levels by improving insulin sensitivity, increasing insulin secretion, or reducing liver glycogen production. With the deepening of research on the pathogenesis of diabetes, many drugs with new targets and mechanisms of action have been discovered. The targets of the drugs for T2DM are mainly dipeptidyl peptidase IV inhibitors (DPP4), sodium/glucose cotransporter 2 inhibitors (SGLT2), sulfonylurea receptor modulators (SUR), peroxisome proliferator-activated receptor γ agonists (PPARγ), etc. We are of the opinion that acquiring a comprehensive comprehension of the synthetic procedures employed in drug molecule production will serve as a source of inventive and pragmatic inspiration for the advancement of novel, more potent, and feasible synthetic methodologies. This review aims to outline the clinical applications and synthetic routes of some representative drugs to treat T2DM, which will drive the discovery of new, more effective T2DM drugs.

Legionella pneumophila usurps host cell lipids for vacuole expansion and bacterial growth

Vacuolar pathogens reside in membrane-bound compartments within host cells. Maintaining the integrity of this compartment is paramount to bacterial survival and replication as it protects against certain host surveillance mechanisms that function to eradicate invading pathogens. Preserving this compartment during bacterial replication requires expansion of the vacuole membrane to accommodate the increasing number of bacteria, and yet, how this is accomplished remains largely unknown. Here, we show that the vacuolar pathogen Legionella pneumophila exploits multiple sources of host cell fatty acids, including inducing host cell fatty acid scavenging pathways, in order to promote expansion of the replication vacuole and bacteria growth. Conversely, when exogenous lipids are limited, the decrease in host lipid availability restricts expansion of the replication vacuole membrane, resulting in a higher density of bacteria within the vacuole. Modifying the architecture of the vacuole prioritizes bacterial growth by allowing the greatest number of bacteria to remain protected by the vacuole membrane despite limited resources for its expansion. However, this trade-off is not without risk, as it can lead to vacuole destabilization, which is detrimental to the pathogen. However, when host lipid resources become extremely scarce, for example by inhibiting host lipid scavenging, de novo biosynthetic pathways, and/or diverting host fatty acids to storage compartments, bacterial replication becomes severely impaired, indicating that host cell fatty acid availability also directly regulates L. pneumophila growth. Collectively, these data demonstrate dual roles for host cell fatty acids in replication vacuole expansion and bacterial proliferation, revealing the central functions for these molecules and their metabolic pathways in L. pneumophila pathogenesis.

Assessment of the risk of imidaclothiz to the dominant aphid parasitoid Binodoxys communis (Hymenoptera: Braconidae)

The neonicotinoid of imidaclothiz insecticide with low resistance and high efficiency, has great potential for application in pest control in specifically cotton field. In this systematically evaluate the effects of sublethal doses of imidaclothiz (LC10: 11.48 mg/L; LC30: 28.03 mg/L) on the biology, transcriptome, and microbiome of Binodoxys communis, the predominant primary parasitic natural enemy of aphids. The findings indicated that imidaclothiz has significant deleterious effects on the survival rate, parasitic rate, and survival time of B. communis. Additionally, there was a marked reduction in the survival rate and survival time of the F1 generation, that is, the negative effect of imidaclothiz on B. communis was continuous and trans-generational. Transcriptome analysis revealed that imidaclothiz treatment elicited alterations in the expression of genes associated with energy and detoxification metabolism. In addition, 16S rRNA analysis revealed a significant increase in the relative abundance of Rhodococcus and Pantoea, which are associated with detoxification metabolism, due to imidaclothiz exposure. These findings provide evidence that B. communis may regulate gene expression in conjunction with symbiotic bacteria to enhance adaptation to imidaclothiz. Finally, this study precise evaluation of imidaclothiz's potential risk to B. communis and provides crucial theoretical support for increasing the assessment of imidaclothiz in integrated pest management.

Microsecond MD Simulations to Explore the Structural and Energetic Differences between the Human RXRα-PPARγ vs. RXRα-PPARγ-DNA

The heterodimeric complex between retinoic X receptor alpha (RXRα) and peroxisome proliferator-activated receptor gamma (PPARγ) is one of the most important and predominant regulatory systems, controlling lipid metabolism by binding to specific DNA promoter regions. X-ray and molecular dynamics (MD) simulations have revealed the average conformation adopted by the RXRα-PPARγ heterodimer bound to DNA, providing information about how multiple domains communicate to regulate receptor properties. However, knowledge of the energetic basis of the protein-ligand and protein-protein interactions is still lacking. Here we explore the structural and energetic mechanism of RXRα-PPARγ heterodimer bound or unbound to DNA and forming complex with co-crystallized ligands (rosiglitazone and 9-cis-retinoic acid) through microsecond MD simulations, molecular mechanics generalized Born surface area binding free energy calculations, principal component analysis, the free energy landscape, and correlated motion analysis. Our results suggest that DNA binding alters correlated motions and conformational mobility within RXRα–PPARγ system that impact the dimerization and the binding affinity on both receptors. Intradomain correlated motions denotes a stronger correlation map for RXRα-PPARγ-DNA than RXRα-PPARγ, involving residues at the ligand binding site. In addition, our results also corroborated the greater role of PPARγ in regulation of the free and bound DNA state.

TF-DUBTACs Stabilize Tumor Suppressor Transcription Factors

Targeted protein degradation approaches have been widely used for degrading oncogenic proteins, providing a potentially promising therapeutic strategy for cancer treatment. However, approaches to targeting tumor suppressor proteins are very limited, and only a few agonists have been developed to date. Here, we report the development of a platform termed TF-DUBTAC, which links a DNA oligonucleotide to a covalent ligand of the deubiquitinase OTUB1 via a click reaction, to selectively stabilize tumor suppressor transcription factors. We developed three series of TF-DUBTACs, namely, FOXO-DUBTAC, p53-DUBTAC, and IRF-DUBTAC, which stabilize FOXO3A, p53, and IRF3 in cells, respectively, in an OTUB1-dependent manner. These results suggest that TF-DUBTAC is a generalizable platform to achieve selective stabilization of tumor suppressor transcription factors as a therapeutic means to suppress tumorigenesis.

Identification of novel and potential PPARγ stimulators as repurposed drugs for MCAO associated brain degeneration

Peroxisome proliferator-activated receptor-gamma (PPARγ) has been shown to have therapeutic promise in the treatment of ischemic stroke and is supported by several studies. To identify possible PPARγ activators, the current study used an in silico technique in conjunction with molecular simulations and in vivo validation. FDA-approved drugs were evaluated using molecular docking to determine their affinity for PPARγ. The findings of molecular simulations support the repurposing of rabeprazole and ethambutol for the treatment of ischemic stroke. Adult Sprague Dawley rats were subjected to transient middle cerebral artery occlusion (t-MCAO). Five groups were made as a sham-operated, t-MCAO group, rabeprazole +t-MCAO, ethambutol +t-MCAO, and pioglitazone +t-MCAO. The neuroprotective effects of these drugs were evaluated using the neurological deficit score and the infarct area. The inflammatory mediators and signaling transduction proteins were quantified using Western blotting, ELISA, and immunohistochemistry. The repurposed drugs mitigated cerebral ischemic injury by PPARγ mediated downregulation of nods like receptor protein 3 inflammasomes (NLRP3), tumor necrosis factor-alpha (TNF-α), cyclooxygenase 2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-kB), and c-Jun N-terminal kinase (p-JNK). Our data demonstrated that rabeprazole and ethambutol have neuroprotective potential via modulating the cytoprotective stress response, increasing cellular survival, and balancing homeostatic processes, and so may be suitable for future research in stroke therapy.

Antidiabetic potential of seaweed and their bioactive compounds: a review of developments in last decade

Diabetes Mellitus is a public health problem worldwide due to high morbidity and mortality rate associated with it. Diabetes can be managed by synthetic hypoglycemic drugs, although their persistent uses have several side effects. Hence, there is a paradigm shift toward the use of natural products having antidiabetic potential. Seaweeds, large marine benthic algae, are an affluent source of various bioactive compounds, including phytochemicals and antioxidants thus exhibiting various health promoting properties. Seaweed extracts and its bioactive compounds have antidiabetic potential as they inhibit carbohydrate hydrolyzing enzymes in vitro and exhibit blood glucose lowering effect in random and post prandial blood glucose tests in vivo. In addition, they have been associated with reduced weight gain in animals probably by decreasing mRNA expression of pro-inflammatory cytokines with concomitant increase in mRNA expression levels of anti-inflammatory cytokines. Their beneficial effect has been seen in serum and hepatic lipid profile and antioxidant enzymes indicating the protective role of seaweeds against free radicals mediated oxidative stress induced hyperglycemia and associated hyperlipidemia. However, the detailed and in-depth studies of seaweeds as whole, their bioactive isolates and their extracts need to be explored further for their health benefits and wide application in food, nutraceutical and pharmaceutical industries.

Synthesis and biological evaluation of thiazolidinedione derivatives with high ligand efficiency to P. aeruginosa PhzS

The thiazolidinone ring is found in compounds that have widespan biology activity and there is mechanism-based evidence that compounds bearing this moiety inhibit P. aeruginosa PhzS (PaPzhS), a key enzyme in the biosynthesis of the virulence factor named pyocyanin. Ten novel thiazolidinone derivatives were synthesised and screened against PaPhzS, using two orthogonal assays. The biological results provided by these and 28 other compounds, whose synthesis had been described, suggest that the dihydroquinazoline ring, found in the previous hit (A- Kd = 18 µM and LE = 0.20), is not required for PaPzhS inhibition, but unsubstituted nitrogen at the thiazolidinone ring is. The molecular simplification approach, pursued in this work, afforded an optimised lead compound (13- 5-(2,4-dimethoxyphenyl)thiazolidine-2,4-dione) with 10-fold improvement in affinity (Kd= 1.68 µM) and more than 100% increase in LE (0.45), which follows the same inhibition mode as the original hit compound (competitive to NADH).Executive summaryPhzS is a key enzyme in the pyocyanin biosynthesis pathway in P. aeruginosa.Orthogonal assays (TSA and FITC) show that fragment-like thiazolidinedione derivatives bind to PaPhzS with one-digit micromolar affinity.Fragment-like thiazolidinedione derivatives bind to the cofactor (NADH) binding site in PaPhzS.The molecular simplification optimised the ligand efficiency and affinity of the lead compound.

Targeting Nuclear Receptors in Neurodegeneration and Neuroinflammation

Nuclear receptors, also known as ligand-activated transcription factors, regulate gene expression upon ligand signals and present as attractive therapeutic targets especially in chronic diseases. Despite the therapeutic relevance of some nuclear receptors in various pathologies, their potential in neurodegeneration and neuroinflammation is insufficiently established. This perspective gathers preclinical and clinical data for a potential role of individual nuclear receptors as future targets in Alzheimer's disease, Parkinson's disease, and multiple sclerosis, and concomitantly evaluates the level of medicinal chemistry targeting these proteins. Considerable evidence suggests the high promise of ligand-activated transcription factors to counteract neurodegenerative diseases with a particularly high potential of several orphan nuclear receptors. However, potent tools are lacking for orphan receptors, and limited central nervous system exposure or insufficient selectivity also compromises the suitability of well-studied nuclear receptor ligands for functional studies. Medicinal chemistry efforts are needed to develop dedicated high-quality tool compounds for the therapeutic validation of nuclear receptors in neurodegenerative pathologies.

Benzosuberene-sulfone analogues synthesis from Cedrus deodara oil and their therapeutic evaluation by computational analysis to treat type 2 diabetes

Benzosuberene-sulfone (BSS) analogues have been semi-synthesized following green approaches from himachalenes, which has been extracted from essential oil of Cedrus deodara. In this process, benzosuberene in presence of different aryl or alkyl sodium sulfinates, I₂ and potassium persulfate (K₂S₂O₈) in acetonitrile-water solvent conditions gave BSS-analogues at room temperature. Under this reaction, a facile endocyclic β-H elimination has been noticed for BSS-analogues synthesis instead of vinyl sulfones and the reason may be due to its specific structure and electronic environment. The BSS-compounds were obtained with moderate to excellent yields under mild conditions. All the compounds were computationally subjected to drug likeliness and toxicity prediction studies. Further, the synthesized molecules were evaluated under in-silico studies for their binding affinity towards the native Peroxisome Proliferator-Activated Receptor Gamma (PPARG), and two PPARG mutants (R357A and V290M). Both the mutant forms of PPARG are deficient in eliciting a response to treatment with full and partial agonists. Our computational studies suggested that the molecule 3q performed better than the standard drug (Rosiglitazone) in all three protein structures. This implies that our suggested molecule could act as a more potent antagonist to native PPARG and could also be developed to treat type-2 diabetes patients with R357A and V290M mutations, which didn't elicit any response to currently available drugs in the market.

The Effects of Major Mushroom Bioactive Compounds on Mechanisms That Control Blood Glucose Level

Diabetes mellitus is a life-threatening multifactorial metabolic disorder characterized by high level of glucose in the blood. Diabetes and its chronic complications have a significant impact on human life, health systems, and countries' economies. Currently, there are many commercial hypoglycemic drugs that are effective in controlling hyperglycemia but with several serious side-effects and without a sufficient capacity to significantly alter the course of diabetic complications. Over many centuries mushrooms and their bioactive compounds have been used in the treatment of diabetes mellitus, especially polysaccharides and terpenoids derived from various mushroom species. This review summarizes the effects of these main mushroom secondary metabolites on diabetes and underlying molecular mechanisms responsible for lowering blood glucose. In vivo and in vitro data revealed that treatment with mushroom polysaccharides displayed an anti-hyperglycemic effect by inhibiting glucose absorption efficacy, enhancing pancreatic β-cell mass, and increasing insulin-signaling pathways. Mushroom terpenoids act as inhibitors of α-glucosidase and as insulin sensitizers through activation of PPARγ in order to reduce hyperglycemia in animal models of diabetes. In conclusion, mushroom polysaccharides and terpenoids can effectively ameliorate hyperglycemia by various mechanisms and can be used as supportive candidates for prevention and control of diabetes in the future.

Activation of peroxisome proliferator-activated receptor γ reduces alcohol drinking and seeking by modulating multiple mesocorticolimbic regions in rats

Peroxisome proliferator-activated receptor γ (PPARγ) is an intracellular transcription factor whose signaling activation by the selective agonist pioglitazone reduces alcohol drinking and alcohol-seeking behavior in rats. The present study utilized the two-bottle choice and operant self-administration procedures to investigate neuroanatomical substrates that mediate the effects of PPARγ agonism on alcohol drinking and seeking in msP rats. Bilateral infusions of pioglitazone (0, 5, and 10 μg/μl) in the rostromedial tegmental nucleus (RMTg) decreased voluntary alcohol drinking and alcohol self-administration. Microinjections of pioglitazone in the ventral tegmental area (VTA), central amygdala (CeA), and nucleus accumbens (NAc) shell had no such effect. Notably, water, food, and saccharin consumption was unaltered by either treatment. The yohimbine-induced reinstatement of alcohol seeking was prevented by infusions of pioglitazone (0, 2.5, 5, and 10 μg/μl) in the CeA, VTA, and RMTg but not in the NAc shell. These results emphasize the involvement of mesocorticolimbic circuitries in mediating the effects of PPARγ agonists on alcohol drinking and seeking. These results will facilitate future studies that investigate the pathophysiological role of PPARγ in alcohol use disorder and help clarify the mechanisms by which the activation of this receptor decreases the motivation for drinking.

Retinoic acid receptor γ is a therapeutically targetable driver of growth and survival in prostate cancer

BACKGROUND

Prostate cancer (PC) tissue contains all-trans retinoic acid (ATRA) at a very low level (10-9 M), at least an order of magnitude lower than in adjacent normal healthy prostate cells or benign prostate hyperplasia. When this is coupled with deregulated expression of the intracellular lipid-binding proteins FABP5 and CRABP2 that is frequently found in PC, this is likely to result in the preferential delivery of ATRA to oncogenic PPARβ/δ rather than retinoic acid receptors (RARs). There are three isotypes of RARs (RARα, RARβ, and RARγ) and recent studies have revealed discrete physiological roles. For example, RARα and RARγ promote differentiation and self-renewal, respectively, which are critical for proper hematopoiesis.

AIMS

We have previously shown that ATRA stimulates transactivation of RARγ at sub-nanomolar concentrations (EC50 0.24 nM), whereas an 80-fold higher concentration was required for RARα-mediated transactivation (EC50 19.3 nM). Additionally, we have shown that RAR pan-antagonists inhibit the growth of PC cells (at 16-34 nM). These findings, together with the low level of ATRA in PC, led us to hypothesize that RARγ plays a role in PC pathogenesis and that RARγ-selective antagonism may be an effective treatment.

METHODS AND RESULTS

We found that concentrations of 10-9 M and below of ATRA promoted survival/proliferation and opposed adipogenic differentiation of human PC cell lines by a mechanism that involves RARγ. We also found that a RARγ-selective antagonist (AGN205728) potently induced mitochondria-dependent, but caspase-independent, cell death in PC cell lines. Furthermore, AGN205728 demonstrated synergism in killing PC cells in combination with cytotoxic chemotherapeutic agents.

CONCLUSION

We suggest that the use of RARγ-selective antagonists may be effective in PC (and potentially other cancers), either as a single agent or in combination with cytotoxic chemotherapy.

Management of pediatric differentiated thyroid cancer: An overview for the pediatric oncologist

Differentiated thyroid cancer (DTC) is the most common childhood thyroid malignancy. The standard of care for pediatric DTC is total thyroidectomy followed by radioactive iodine (RAI) treatment when indicated. Molecular changes and potential therapeutic targets have been recently described in pediatric thyroid cancer. Pediatric oncologists are increasingly involved in the evaluation of thyroid nodules in childhood cancer survivors and in the management of advanced thyroid cancer. In 2015, the American Thyroid Association published management guidelines for children with DTC. We provide an overview of the current standard of care and highlight available targeted therapies for progressive or RAI refractory DTC.

Virtual Screening and In Silico Simulation Analysis for Rapid and Efficient Identification of Novel Natural GPR40 Agonist

Background:

Diabetes is the foremost health problem worldwide predisposing to increased mortality and morbidity. The available synthetic drugs have serious side effects and thus, emphasize further need to develop effective medication therapy. GPR40 represents an interesting target for developing novel antidiabetic drug. In the current study, searching of potential natural hit candidate as agonist by using structure based computational approach.

Methods:

The GPR40 agonistic activity of natural compounds was searched by using Maestro through docking and Molecular Dynamics (MD) simulation application. Virtual screening by using IBScreen library of natural compounds was done and the binding modes of newer natural entity(s) were investigated. Further, MD studies of the GPR40 complex with the most promising hit found in this study justified the stability of these complexes.

Results:

The silicone chip-based approach recognized the most capable six hits and the ADME prediction aided the exploration of their pharmacokinetic potential. In this study, the obtained hit (ZINC70692253) after the use of exhaustive screening having binding energy -107.501 kcal/mol and root mean square deviation of hGPR40-ZINC70692253 is around 3.5 Å in 20 ns of simulation.

Conclusion:

Successful application of structure-based computational screening gave a novel candidate from Natural Product library for diabetes treatment. So, Natural compounds may tend to cure diabetes with lesser extent of undesirable effects in comparison to synthetic compounds and these novel screened compounds may show a plausible biological response in the hit to lead finding of drug development process. To the best of our knowledge, this is the first example of the successful application of SBVS to discover novel natural hit compounds using hGPR40.

The Race to Bash NASH: Emerging Targets and Drug Development in a Complex Liver Disease

Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease (NAFLD) characterized by liver steatosis, inflammation, and hepatocellular damage. NASH is a serious condition that can progress to cirrhosis, liver failure, and hepatocellular carcinoma. The association of NASH with obesity, type 2 diabetes mellitus, and dyslipidemia has led to an emerging picture of NASH as the liver manifestation of metabolic syndrome. Although diet and exercise can dramatically improve NASH outcomes, significant lifestyle changes can be challenging to sustain. Pharmaceutical therapies could be an important addition to care, but currently none are approved for NASH. Here, we review the most promising targets for NASH treatment, along with the most advanced therapeutics in development. These include targets involved in metabolism (e.g., sugar, lipid, and cholesterol metabolism), inflammation, and fibrosis. Ultimately, combination therapies addressing multiple aspects of NASH pathogenesis are expected to provide benefit for patients.

Panaxadiol saponins treatment caused the subtle variations in the global transcriptional state of Asiatic corn borer, Ostrinia furnacalis

Background

Methods

Results

Conclusion

Combining In Vitro Data and Physiologically Based Kinetic Modeling Facilitates Reverse Dosimetry to Define In Vivo Dose-Response Curves for Bixin- and Crocetin-Induced Activation of PPARγ in Humans

SCOPE

It is investigated whether at realistic dietary intake bixin and crocetin could induce peroxisome proliferator-activated receptor γ (PPARγ)-mediated gene expression in humans using a combined in vitro-in silico approach.

METHODS AND RESULTS

Concentration-response curves obtained from in vitro PPARγ-reporter gene assays are converted to in vivo dose-response curves using physiologically based kinetic modeling-facilitated reverse dosimetry, from which the benchmark dose levels resulting in a 50% effect above background level (BMD50 ) are predicted and subsequently compared to dietary exposure levels. Bixin and crocetin activated PPARγ-mediated gene transcription in a concentration-dependent manner with similar potencies. Due to differences in kinetics, the predicted BMD50 values for in vivo PPARγ activation are about 30-fold different, amounting to 115 and 3505 mg kg bw-1 for crocetin and bixin, respectively. Human dietary and/or supplemental estimated daily intakes may reach these BMD50 values for crocetin but not for bixin, pointing at better possibilities for in vivo PPARγ activation by crocetin.

CONCLUSION

Based on a combined in vitro-in silico approach, it is estimated whether at realistic dietary intakes plasma concentrations of bixin and crocetin are likely to reach concentrations that activate PPARγ-mediated gene expression, without the need for a human intervention study.

Thiazolidinediones: the Forgotten Diabetes Medications

PURPOSE OF REVIEW

Thiazolidinediones (TZDs) are the only pharmacologic agents that specifically treat insulin resistance. The beneficial effects of TZDs on the cardiovascular risk factors associated with insulin resistance have been well documented. TZD use has been limited because of concern about safety issues and side effects.

RECENT FINDINGS

Recent studies indicate that cardiovascular toxicity with rosiglitazone and increase in bladder cancer with pioglitazone are no longer significant issues. There are new data which show that pioglitazone treatment reduces myocardial infarctions and ischemic strokes. New data concerning TZD-mediated edema, congestive heart failure, and bone fractures improves the clinician's ability to select patients that will have minimal significant side effects. Thiazolidinediones are now generic and less costly than pharmaceutical company-promoted therapies. Better understanding of the side effects coupled with clear benefits on the components of the insulin resistance syndrome should promote TZD use in treating patients with type 2 diabetes.

Quantitative structural assessment of graded receptor agonism

Ligand-receptor interactions, which are ubiquitous in physiology, are described by theoretical models of receptor pharmacology. Structural evidence for graded efficacy receptor conformations predicted by receptor theory has been limited but is critical to fully validate theoretical models. We applied quantitative structure-function approaches to characterize the effects of structurally similar and structurally diverse agonists on the conformational ensemble of nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ). For all ligands, agonist functional efficacy is correlated to a shift in the conformational ensemble equilibrium from a ground state toward an active state, which is detected by NMR spectroscopy but not observed in crystal structures. For the structurally similar ligands, ligand potency and affinity are also correlated to efficacy and conformation, indicating ligand residence times among related analogs may influence receptor conformation and function. Our results derived from quantitative graded activity-conformation correlations provide experimental evidence and a platform with which to extend and test theoretical models of receptor pharmacology to more accurately describe and predict ligand-dependent receptor activity.

Dual peroxisome-proliferator-activated-receptor-α/γ activation inhibits SIRT1-PGC1α axis and causes cardiac dysfunction

Dual peroxisome proliferator-activated receptor (PPAR)α/γ agonists that were developed to target hyperlipidemia and hyperglycemia in type 2 diabetes patients, caused cardiac dysfunction or other adverse effects. We studied the mechanisms that underlie the cardiotoxic effects of a dual PPARα/γ agonist, tesaglitazar, in wild type and diabetic (leptin receptor deficient - db/db) mice. Mice treated with tesaglitazar-containing chow or high fat diet developed cardiac dysfunction despite lower plasma triglycerides and glucose levels. Expression of cardiac peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which promotes mitochondrial biogenesis, had the most profound reduction among various fatty acid metabolism genes. Furthermore, we observed increased acetylation of PGC1α, which suggests PGC1α inhibition and lowered sirtuin 1 (SIRT1) expression. This change was associated with lower mitochondrial abundance. Combined pharmacological activation of PPARα and PPARγ in C57BL/6 mice reproduced the reduction of PGC1α expression and mitochondrial abundance. Resveratrol-mediated SIRT1 activation attenuated tesaglitazar-induced cardiac dysfunction and corrected myocardial mitochondrial respiration in C57BL/6 and diabetic mice but not in cardiomyocyte-specific Sirt1-/- mice. Our data shows that drugs, which activate both PPARα and PPARγ lead to cardiac dysfunction associated with PGC1α suppression and lower mitochondrial abundance likely due to competition between these two transcription factors.

Flow cytometry-based FRET identifies binding intensities in PPARγ1 protein-protein interactions in living cells

PPARγ is a pharmacological target in inflammatory and metabolic diseases. Upon agonistic treatment or following antagonism, binding of co-factors is altered, which consequently affects PPARγ-dependent transactivation as well as its DNA-independent properties. Therefore, establishing techniques to characterize these interactions is an important issue in living cells. Methods: Using the FRET pair Clover/mRuby2, we set up a flow cytometry-based FRET assay by analyzing PPARγ1 binding to its heterodimerization partner RXRα. Analyses of PPARγ-reporter and co-localization studies by laser-scanning microscopy validated this system. Refining the system, we created a new readout to distinguish strong from weak interactions, focusing on PPARγ-binding to the co-repressor N-CoR2. Results: We observed high FRET in cells expressing Clover-PPARγ1 and mRuby2-RXRα, but no FRET when cells express a mRuby2-RXRα deletion mutant, lacking the PPARγ interaction domain. Focusing on the co-repressor N-CoR2, we identified in HEK293T cells the new splice variant N-CoR2-ΔID1-exon. Overexpressing this isoform tagged with mRuby2, revealed no binding to Clover-PPARγ1, nor in murine J774A.1 macrophages. In HEK293T cells, binding was even lower in comparison to N-CoR2 constructs in which domains established to mediate interaction with PPARγ binding are deleted. These data suggest a possible role of N-CoR2-ΔID1-exon as a dominant negative variant. Because binding to N-CoR2-mRuby2 was not altered following activation or antagonism of Clover-PPARγ1, we determined the effect of pharmacological treatment on FRET intensity. Therefore, we calculated flow cytometry-based FRET efficiencies based on our flow cytometry data. As with PPARγ antagonism, PPARγ agonist treatment did not prevent binding of N-CoR2. Conclusion: Our system allows the close determination of protein-protein interactions with a special focus on binding intensity, allowing this system to characterize the role of protein domains as well as the effect of pharmacological agents on protein-protein interactions.

Antiretroviral drug-induced endothelial dysfunction is improved by dual PPARα/γ stimulation in obesity

Obesity rates are rising in HIV-infected populations; however, the putative role of highly active antiretroviral therapy (HAART) in the development of endothelial and cardiovascular derangements in the presence of pre-existing overweight/obesity is unclear. Although dual peroxisome proliferator-activated receptors-alpha/gamma (PPARα/γ) stimulation mitigates HAART-induced metabolic dysfunction, vascular effects are unresolved. To investigate whether HAART induces vascular dysfunction in obesity and to explore the underlying mechanisms of PPARα/γ stimulation, male Wistar rats were placed on a high-calorie diet for 16 weeks. After 10 weeks, HAART (lopinavir/ritonavir, azidothymidine/lamivudine) with/without PPARα/γ agonist, Saroglitazar, was administered daily for six weeks. Excised thoracic aorta rings were subjected to isometric tension studies and Western blot measurements. HAART+Saroglitazar-treated obese animals recorded lower adiposity indices (4.3 ± 0.5%) vs. HAART only-treated obese rats (5.6 ± 0.3%; p < .01). Maximum acetylcholine-induced vasorelaxation (R_max), was lower in obese+HAART group (76.10 ± 3.58%) vs. obese control (101.40 ± 4.75%; p < .01). However, R_max was improved in obese+ HAART+Saroglitazar (101.00 ± 3.12%) vs. obese+HAART rats (p < .001). The mean LogEC₅₀ was improved in obese+HAART+Saroglitazar vs. obese+HAART group; p = .003. Improved endothelial function in obese+ HAART+Saroglitazar group was associated with upregulation of eNOS, PKB/Akt and downregulated p22-phox expression vs. obese+HAART group. Therefore, PPARα/γ stimulation attenuated HAART-induced endothelial dysfunction by upregulating vasoprotective eNOS, PKB/Akt signaling and downregulating pro-oxidative p22-phox expression.

Bone Marrow Adipocytes: The Enigmatic Components of the Hematopoietic Stem Cell Niche

Bone marrow adipocytes (BMA) exert pleiotropic roles beyond mere lipid storage and filling of bone marrow (BM) empty spaces, and we are only now beginning to understand their regulatory traits and versatility. BMA arise from the differentiation of BM mesenchymal stromal cells, but they seem to be a heterogeneous population with distinct metabolisms, lipid compositions, secretory properties and functional responses, depending on their location in the BM. BMA also show remarkable differences among species and between genders, they progressively replace the hematopoietic BM throughout aging, and play roles in a range of pathological conditions such as obesity, diabetes and anorexia. They are a crucial component of the BM microenvironment that regulates hematopoiesis, through mechanisms largely unknown. Previously considered as negative regulators of hematopoietic stem cell function, recent data demonstrate their positive support for hematopoietic stem cells depending on the experimental approach. Here, we further discuss current knowledge on the role of BMA in hematological malignancies. Early hints suggest that BMA may provide a suitable metabolic niche for the malignant growth of leukemic stem cells, and protect them from chemotherapy. Future in vivo functional work and improved isolation methods will enable determining the true essence of this elusive BM hematopoietic stem cell niche component, and confirm their roles in a range of diseases. This promising field may open new pathways for efficient therapeutic strategies to restore hematopoiesis, targeting BMA.

Binding of thiazolidinediones to the endoplasmic reticulum protein nutrient-deprivation autophagy factor-1

Nutrient-deprivation autophagy factor-1 (NAF-1, miner1; gene cisd2) is part of the [2Fe-2S]-containing protein family which includes mitoNEET (gene cisd1) and MiNT (miner2; gene cisd3). These proteins are redox active and are thought to play an important role in cellular energy homeostasis with NAF-1 playing a critical role in calcium regulation and aging. To date, no studies have investigated potential ligand interaction with NAF-1. Here we show that the thiazolidinediones pioglitazone and rosiglitazone along with the mitoNEET ligand, NL-1, bind to NAF-1 with low micromolar affinities. Further, we show that overexpression of NAF-1 in hepatocellular carcinoma (HepG2) cells reduces inhibition of mitochondrial respiration by pioglitazone. Our findings support the need for further efforts of the rational design of selective NAF-1 ligands.

Impact of a Single Hydrogen Substitution by Fluorine on the Molecular Interaction and Miscibility between Sorafenib and Polymers

We aim to understand the potential impact of a modest chemical modification of a drug molecule on the downstream design of its amorphous solid dispersion (ASD) formulation. To this end, we used sorafenib (SOR) and its fluorinated form, regorafenib (REG), as model drugs, to assess the impact of a single hydrogen substitution by fluorine on the molecular interaction and miscibility between drug and PVP or PVP-VA, two commonly used polymers for ASDs. In this study, we observed that the T_g values of PVP or PVP-VA based ASDs of SOR deviated positively from the Gordon-Taylor prediction, which assumes ideal mixing, yet the T_g of REG ASDs deviated negatively from or matched well with the ideal mixing model, suggesting much stronger drug-polymer interactions in SOR ASDs compared with the REG ASDs. Using solution NMR and computational methods, we proved that a six-member-ring formed between the carbonyl groups on the polymers and the uramido hydrogen of SOR or REG, through intermolecular hydrogen bonding. However, steric hindrance resulting from fluorination in REG caused weaker interaction between REG-polymer than SOR-polymer. To further confirm this mechanism, we investigated the molecular interactions of other two uramido-containing model compounds, triclocarban (TCC) and gliclazide (GCZ), with PVP. We found that TCC but not GCZ formed a hexatomic ring with PVP. We concluded that PVP based polymers can easily interact with N, N'-disubstituted urea compounds with a trans-trans structure in the form of hexatomic rings, and the interaction strength of the hexatomic ring largely depended on the chemistry of drug molecules. This study illustrated that even a slight chemical modification on drug molecules could result in substantial difference in drug-polymer interactions, thus significantly impacting polymer selection and pharmaceutical performance of their ASD formulations.

LATS1 and LATS2 suppress breast cancer progression by maintaining cell identity and metabolic state

In luminal B tumors LATS2 depletion results in metabolic rewiring whereas LATS1 depletion promotes the expression of basal-like features.

Deregulated activity of LArge Tumor Suppressor (LATS) tumor suppressors has broad implications on cellular and tissue homeostasis. We examined the consequences of down-regulation of either LATS1 or LATS2 in breast cancer. Consistent with their proposed tumor suppressive roles, expression of both paralogs was significantly down-regulated in human breast cancer, and loss of either paralog accelerated mammary tumorigenesis in mice. However, each paralog had a distinct impact on breast cancer. Thus, LATS2 depletion in luminal B tumors resulted in metabolic rewiring, with increased glycolysis and reduced peroxisome proliferator-activated receptor γ (PPARγ) signaling. Furthermore, pharmacological activation of PPARγ elicited LATS2-dependent death in luminal B-derived cells. In contrast, LATS1 depletion augmented cancer cell plasticity, skewing luminal B tumors towards increased expression of basal-like features, in association with increased resistance to hormone therapy. Hence, these two closely related paralogs play distinct roles in protection against breast cancer; tumors with reduced expression of either LATS1 or LATS2 may rewire signaling networks differently and thus respond differently to anticancer treatments.

Antidiabetic and Neuroprotective Effect of the N-Butanol Extract of Fragaria nilgerrensis Schlecht. in STZ-Induced Diabetic Mice

Diabetes has been associated with neurodegenerative disorders that are accompanied by memory loss and cognitive impairments, but there is no effective treatment for it at present. Fragaria nilgerrensis Schlecht. (FNS), a well-known Chinese materia medica, has been traditionally used for the folkloric treatment of diabetes and other diseases. However, its effects are poorly documented. Here, we investigated the antidiabetic and neuroprotective effect of FNS in diabetic mice. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) evaluations of N-butanol extract of Fragaria nilgerrensis Schlecht. (N-FNS) showed the presence of flavonoid and its structure is similar to scutellarin. For the first time, we show the potential neuroprotective and antidiabetic effects of FNS. After 4 weeks of FNS intervention, a significant decrease in blood glucose, increase in body weight, and amelioration in glucose tolerance were observed in FNS treated diabetic mice. In the acute study, FNS enhanced motor activity in the open field task and significantly prevented spatial-learning deficits in Morris water maze tests. Besides, synapse ultrastructure of the hippocampus showed that the mitochondrial morphology was basically restored and all the synaptic structural parameters were gradually normalized after treatment with FNS. Importantly, we found that the activities of SOD and CAT in liver and hippocampus of diabetic mice significantly increased after FNS administration. In vitro, FNS and scutellarin showed high DPPH radical scavenging activity. The study suggests that FNS exerted significant antidiabetic and neuroprotective effects which may be attributed to its antioxidant property.

Effects of pioglitazone on ventricular myocyte shortening and Ca(2+) transport in the Goto-Kakizaki type 2 diabetic rat

Pioglitazone (PIO) is a thiazolidindione antidiabetic agent which improves insulin sensitivity and reduces blood glucose in experimental animals and treated patients. At the cellular level the actions of PIO in diabetic heart are poorly understood. A previous study has demonstrated shortened action potential duration and inhibition of a variety of transmembrane currents including L-type Ca(2+) current in normal canine ventricular myocytes. The effects of PIO on shortening and calcium transport in ventricular myocytes from the Goto-Kakizaki (GK) type 2 diabetic rat have been investigated. 10 min exposure to PIO (0.1-10 microM) reduced the amplitude of shortening to similar extents in ventricular myocytes from GK and control rats. 1 microM PIO reduced the amplitude of the Ca(2+) transients to similar extents in ventricular myocytes from GK and control rats. Caffeine-induced Ca(2+) release from the sarcoplasmic reticulum and recovery of Ca(2+) transients following application of caffeine and myofilament sensitivity to Ca(2+) were not significantly altered in ventricular myocytes from GK and control rats. Amplitude of L-type Ca(2+) current was not significantly decreased in myocytes from GK compared to control rats and by PIO treatment. The negative inotropic effects of PIO may be attributed to a reduction in the amplitude of the Ca(2+) transient however, the mechanisms remain to be resolved.

Molecular Modeling Study for the Design of Novel Peroxisome Proliferator-Activated Receptor Gamma Agonists using 3D-QSAR and Molecular Docking

Type 2 diabetes is becoming a global pandemic disease. As an important target for the generation and development of diabetes mellitus, peroxisome proliferator-activated receptor γ (PPARγ) has been widely studied. PPARγ agonists have been designed as potential anti-diabetic agents. The advanced development of PPARγ agonists represents a valuable research tool for diabetes therapy. To explore the structural requirements of PPARγ agonists, three-dimensional quantitative structure–activity relationship (3D-QSAR) and molecular docking studies were performed on a series of N-benzylbenzamide derivatives employing comparative molecular field analysis (CoMFA), comparative molecular similarity indices analysis (CoMSIA), and surflex-dock techniques. The generated models of CoMFA and CoMSIA exhibited a high cross-validation coefficient (q²) of 0.75 and 0.551, and a non-cross-validation coefficient (r²) of 0.958 and 0.912, respectively. The predictive ability of the models was validated using external validation with predictive factor (r²_pred) of 0.722 and 0.682, respectively. These results indicate that the model has high statistical reliability and good predictive power. The probable binding modes of the best active compounds with PPARγ active site were analyzed, and the residues His323, Tyr473, Ser289 and Ser342 were found to have hydrogen bond interactions. Based on the analysis of molecular docking results, and the 3D contour maps generated from CoMFA and CoMSIA models, the key structural features of PPARγ agonists responsible for biological activity could be determined, and several new molecules, with potentially higher predicted activity, were designed thereafter. This work may provide valuable information in further optimization of N-benzylbenzamide derivatives as PPARγ agonists.

N-Arylation of ferrocenyl 2,4-thiazolidinedione conjugatesviaa copper-catalysed Chan–Lam cross coupling reaction with aryl boronic acids and their optoelectronic properties

Copper catalysed Chan–LamN-arylation of ferrocenyl 2,4-thiazolidinedione conjugates is described.

Rational screening of peroxisome proliferator-activated receptor-γ agonists from natural products: potential therapeutics for heart failure

CONTEXT

Peroxisome proliferator-activated receptor-γ (PPARγ) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. Activation of PPARγ pathway has been shown to enhance fatty acid oxidation, improve endothelial cell function, and decrease myocardial fibrosis in heart failure. Thus, the protein has been raised as an attractive target for heart failure therapy.

OBJECTIVE

This work attempted to discover new and potent PPARγ agonists from natural products using a synthetic strategy of computer virtual screening and transactivation reporter assay.

MATERIALS AND METHODS

A large library of structurally diverse, drug-like natural products was compiled, from which those with unsatisfactory pharmacokinetic profile and/or structurally redundant compounds were excluded. The binding mode of remaining candidates to PPARγ ligand-binding domain (LBD) was computationally modelled using molecular docking and their relative binding potency was ranked by an empirical scoring scheme. Consequently, eight commercially available hits with top scores were selected and their biological activity was determined using a cell-based reporter-gene assay.

RESULTS

Four natural product compounds, namely ZINC13408172, ZINC4292805, ZINC44179 and ZINC901461, were identified to have high or moderate agonistic potency against human PPARγ with EC₅₀ values of 0.084, 2.1, 0.35 and 5.6 μM, respectively, which are comparable to or even better than that of the approved PPARγ full agonists pioglitazone (EC₅₀=0.16 μM) and rosiglitazone (EC₅₀=0.034 μM). Hydrophobic interactions and van der Waals contacts are the primary chemical forces to stabilize the complex architecture of PPARγ LBD domain with these agonist ligands, while few hydrogen bonds, salt bridges and/or π-π stacking at the complex interfaces confer selectivity and specificity for the domain-agonist recognition.

DISCUSSION AND CONCLUSION

The integrated in vitro-in silico screening strategy can be successfully applied to rational discovery of biologically active compounds. The newly identified natural products with PPARγ agonistic potency are considered as promising lead scaffolds to develop novel chemical therapeutics for heart failure.

5-Ene-4-thiazolidinones - An efficient tool in medicinal chemistry

The presented review is an attempt to summarize a huge volume of data on 5-ene-4-thiazolidinones being a widely studied class of small molecules used in modern organic and medicinal chemistry. The manuscript covers approaches to the synthesis of 5-ene-4-thiazolidinone derivatives: modification of the C5 position of the basic core; synthesis of the target compounds in the one-pot or multistage reactions or transformation of other related heterocycles. The most prominent pharmacological profiles of 5-ene derivatives of different 4-thiazolidinone subtypes belonging to hit-, lead-compounds, drug-candidates and drugs as well as the most studied targets have been discussed. Currently target compounds (especially 5-en-rhodanines) are assigned as frequent hitters or pan-assay interference compounds (PAINS) within high-throughput screening campaigns. Nevertheless, the crucial impact of the presence/nature of C5 substituent (namely 5-ene) on the pharmacological effects of 5-ene-4-thiazolidinones was confirmed by the numerous listed findings from the original articles. The main directions for active 5-ene-4-thiazolidinones optimization have been shown: i) complication of the fragment in the C5 position; ii) introduction of the substituents in the N3 position (especially fragments with carboxylic group or its derivatives); iii) annealing in complex heterocyclic systems; iv) combination with other pharmacologically attractive fragments within hybrid pharmacophore approach. Moreover, the utilization of 5-ene-4-thiazolidinones in the synthesis of complex compounds with potent pharmacological application is described. The chemical transformations cover mainly the reactions which involve the exocyclic double bond in C5 position of the main core and correspond to the abovementioned direction of the 5-ene-4-thiazolidinone modification.

Insulin Sensitizing Pharmacology of Thiazolidinediones Correlates with Mitochondrial Gene Expression rather than Activation of PPARγ

Insulin sensitizing thiazolidinediones (TZDs) are generally considered to work as agonists for the nuclear receptor peroxisome proliferative activated receptor-gamma (PPARγ). However, TZDs also have acute, non-genomic metabolic effects and it is unclear which actions are responsible for the beneficial pharmacology of these compounds. We have taken advantage of an analog, based on the metabolism of pioglitazone, which has much reduced ability to activate PPARγ. This analog (PNU-91325) was compared to rosiglitazone, the most potent PPARγ activator approved for human use, in a variety of studies both in vitro and in vivo. The data demonstrate that PNU-91325 is indeed much less effective than rosiglitazone at activating PPARγ both in vitro and in vivo. In contrast, both compounds bound similarly to a mitochondrial binding site and acutely activated PI-3 kinase-directed phosphorylation of AKT, an action that was not affected by elimination of PPARγ activation. The two compounds were then compared in vivo in both normal C57 mice and diabetic KKAy mice to determine whether their pharmacology correlated with biomarkers of PPARγ activation or with the expression of other gene transcripts. As expected from previous studies, both compounds improved insulin sensitivity in the diabetic mice, and this occurred in spite of the fact that there was little increase in expression of the classic PPARγ target biomarker adipocyte binding protein-2 (aP2) with PNU-91325 under these conditions. An examination of transcriptional profiling of key target tissues from mice treated for one week with both compounds demonstrated that the relative pharmacology of the two thiazolidinediones correlated best with an increased expression of an array of mitochondrial proteins and with expression of PPARγ coactivator 1-alpha (PGC1α), the master regulator of mitochondrial biogenesis. Thus, important pharmacology of the insulin sensitizing TZDs may involve acute actions, perhaps on the mitochondria, that are independent of direct activation of the nuclear receptor PPARγ. These findings suggest a potential alternative route to the discovery of novel insulin sensitizing drugs.

Study of the interactions between Edaglitazone and Ciglitazone with PPARγ and their antiplatelet profile

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor with an important role in lipid metabolism, inflammation and cardiovascular diseases. PPARγ ligands have inhibitory effects on platelet aggregation via the cAMP pathway, which may confer them a protective cardioprotective role. Edaglitazone and Ciglitazone are two chemically-similar thiazolidinedione (TZD) drugs that have been described as potent PPARγ agonists; however, Edaglitazone is over 100 times more potent than Ciglitazone. Here, we report a computational study to describe the ligand binding and the experimental antiplatelet profiles of Edaglitazone and Ciglitazone. Both ligands presented similar orientations within the PPARγ binding site. Their polar heads exhibit complex hydrogen bond networks with the residues at arm I pocket, while their hydrophobic tails are oriented inside arm II or the entrance pocket. The bulkier and longer tail of Edaglitazone exhibited additional hydrophobic interactions, explaining its stronger binding to PPARγ supported by binding affinity calculations. On the other hand, both Edaglitazone and Ciglitazone displayed an antiplatelet activity, but only Edaglitazone retained such effect at low concentrations. Furthermore, we evidenced that Edaglitazone increases intraplatelet cAMP levels and prevents PPARγ secretion, explaining its greater antiplatelet activity. Altogether, the more potent PPARγ agonist Edaglitazone seems to be a potent antiplatelet agent.

Betulinic acid is a PPARγ antagonist that improves glucose uptake, promotes osteogenesis and inhibits adipogenesis

PPAR antagonists are ligands that bind their receptor with high affinity without transactivation activity. Recently, they have been demonstrated to maintain insulin-sensitizing and antidiabetic properties, and they serve as an alternative treatment for metabolic diseases. In this work, an affinity-based bioassay was found to be effective for selecting PPAR ligands from the dried extract of an African plant (Diospyros bipindensis). Among the ligands, we identified betulinic acid (BA), a compound already known for its anti-inflammatory, anti-tumour and antidiabetic properties, as a PPARγ and PPARα antagonist. Cell differentiation assays showed that BA inhibits adipogenesis and promotes osteogenesis; either down-regulates or does not affect the expression of a series of adipogenic markers; and up-regulates the expression of osteogenic markers. Moreover, BA increases basal glucose uptake in 3T3-L1 adipocytes. The crystal structure of the complex of BA with PPARγ sheds light, at the molecular level, on the mechanism by which BA antagonizes PPARγ, and indicates a unique binding mode of this antagonist type. The results of this study show that the natural compound BA could be an interesting and safe candidate for the treatment of type 2 diabetes and bone diseases.

Modification of the Orthosteric PPARγ Covalent Antagonist Scaffold Yields an Improved Dual-Site Allosteric Inhibitor

GW9662 and T0070907 are widely used commercially available irreversible antagonists of peroxisome proliferator-activated receptor gamma (PPARγ). These antagonists covalently modify Cys285 located in an orthosteric ligand-binding pocket embedded in the PPARγ ligand-binding domain and are used to block binding of other ligands. However, we recently identified an alternate/allosteric ligand-binding site in the PPARγ LBD to which ligand binding is not inhibited by these orthosteric covalent antagonists. Here, we developed a series of analogs based on the orthosteric covalent antagonist scaffold with the goal of inhibiting both orthosteric and allosteric cellular activation of PPARγ by MRL20, an orthosteric agonist that also binds to an allosteric site. Our efforts resulted in the identification of SR16832 (compound 22), which functions as a dual-site covalent inhibitor of PPARγ transcription by PPARγ-binding ligands. Molecular modeling, protein NMR spectroscopy structural analysis, and biochemical assays indicate the inhibition of allosteric activation occurs in part through expansion of the 2-chloro-5-nitrobenzamidyl orthosteric covalent antagonist toward the allosteric site, weakening of allosteric ligand binding affinity, and inducing conformational changes not competent for cellular PPARγ activation. Furthermore, SR16832 better inhibits binding of rosiglitazone, a thiazolidinedione (TZD) that weakly activates PPARγ when cotreated with orthosteric covalent antagonists, and may better inhibit binding of endogenous PPARγ ligands such as docosahexaenoic acid (DHA) compared to orthosteric covalent antagonists. Compounds such as SR16832 may be useful chemical tools to use as a dual-site bitopic orthosteric and allosteric covalent inhibitor of ligand binding to PPARγ.

Design, synthesis, molecular modeling and anti-hyperglycemic evaluation of novel quinoxaline derivatives as potential PPARγ and SUR agonists

In our effort to develop potent anti-hyperglycemic agents with potential agonistic activities toward PPARγ and SUR, three novel series of quinoxaline derivatives bearing sulfonylurea or sulfonylthiourea moieties with different linkers were designed and synthesized. Some of the newly synthesized compounds were evaluated in vivo for their anti-hyperglycemic activities in STZ-induced hyperglycemic rats. Compounds 15_a, 15_e, 19_b and 24_a exhibited the highest anti-hyperglycemic activities with % reduction in blood glucose level of (50.58, 43.84, 45.10 and 49.62, respectively). Additionally, eight compounds revealed potent anti-hyperglycemic activities were further evaluated in vitro for their PPARγ binding affinity and insulin-secreting ability as potential mechanisms for anti-hyperglycemic activity. Four compounds (15_a, 15_b, 15_d and 15_e) significantly bound to PPARγ with IC₅₀ values of 0.482, 0.491, 0.350 and 0.369μM, respectively. Moreover, Compounds 15_a and 15_b have demonstrated induction of insulin-secretion with EC₅₀ values of 0.92 and 0.98μM, respectively. Furthermore, molecular docking and pharmacophore generation techniques were carried out to investigate binding patterns and fit values of the designed compounds with PPARγ and SUR, respectively.

Protective Effect of PPARγ Agonists on Cerebellar Tissues Oxidative Damage in Hypothyroid Rats

The aim of the current study was to investigate the effects of peroxisome proliferator-activated receptor gamma (PPARγ) agonists on cerebellar tissues oxidative damage in hypothyroid rats. The animals included seven groups: group I (control), the animals received drinking water; group II, the animals received 0.05% propylthiouracil (PTU) in drinking water; besides PTU, the animals in groups III, IV, V, VI, and VII, were injected with 20 mg/kg vitamin E (Vit E), 10 or 20 mg/kg pioglitazone, and 2 or 4 mg/kg rosiglitazone, respectively. The animals were deeply anesthetized and the cerebellar tissues were removed for biochemical measurements. PTU administration reduced thiol content, superoxide dismutase (SOD), and catalase (CAT) activities in the cerebellar tissues while increasing malondialdehyde (MDA) and nitric oxide (NO) metabolites. Vit E, pioglitazone, and rosiglitazone increased thiol, SOD, and CAT in the cerebellar tissues while reducing MDA and NO metabolites. The results of present study showed that, similar to Vit E, both rosiglitazone and pioglitazone as PPARγ agonists exerted protective effects against cerebellar tissues oxidative damage in hypothyroid rats.

Thiazolidinediones and PPAR orchestra as antidiabetic agents: From past to present

Thiazolidinediones a class of drug, that provided a major breakthrough in the management of type 2 diabetes since 1990. Following the discovery of PPARs, TZDs were the first class to be reported as PPARγ modulators. This review is an attempt to summarize the chemical modifications around TZDs in past two decades to obtain a potent antidiabetic molecule. TZDs literature were initially dominated by their hypoglycemic & hypolipidemic activities, later PPARγ activity was also been incorporated. Moreover, in some cases, both benzyl and benzylidene derivatives were reported in the same manuscript for the sake of comparison. We thought of presenting the review on the basis of the variation in the linker region. Optimal linker at the time of discovery of the Ciglitazone was oxymethyl and it went on to evolve as oxyethyl (Pioglitazone) and oxyethylamino (Rosiglitazone). Few attempts were made to restrict the flexibility of the linker by introducing the cyclic structures and were summarized immediately after the respective linker class.

The Role of PPARγ in Cardiovascular Diseases

The peroxisome proliferator-activated receptors (PPAR) belong to the nuclear superfamily of ligand-activated transcription factors. PPARγ acts as a nutrient sensor that regulates several homeostatic functions. Its disruption can lead to vascular pathologies, disorders of fatty acid/lipid metabolism and insulin resistance. PPARγ can modulate several signaling pathways connected with blood pressure regulation. Firstly, it affects the insulin signaling pathway and endothelial dysfunction by modulation of expression and/or phosphorylation of signaling molecules through the PI3K/Akt/eNOS or MAPK/ET-1 pathways. Secondly, it can modulate gene expression of the renin- angiotensin system – cascade proteins, which potentially slow down the progression of atherosclerosis and hypertension. Thirdly, it can modulate oxidative stress response either directly through PPAR or indirectly through Nrf2 activation. In this context, activation and functioning of PPARγ is very important in the regulation of several disorders such as diabetes mellitus, hypertension and/or metabolic syndrome.

Development of Therapeutics That Induce Mitochondrial Biogenesis for the Treatment of Acute and Chronic Degenerative Diseases

Mitochondria have various roles in cellular metabolism and homeostasis. Because mitochondrial dysfunction is associated with many acute and chronic degenerative diseases, mitochondrial biogenesis (MB) is a therapeutic target for treating such diseases. Here, we review the role of mitochondrial dysfunction in acute and chronic degenerative diseases and the cellular signaling pathways by which MB is induced. We then review existing work describing the development and application of drugs that induce MB in vitro and in vivo. In particular, we discuss natural products and modulators of transcription factors, kinases, cyclic nucleotides, and G protein-coupled receptors.