Novel Derivatives of Eugenol as a New Class of PPARγ Agonists in Treating Inflammation: Design, Synthesis, SAR Analysis and In Vitro Anti-Inflammatory Activity.

The main objective of this research was to develop novel compounds from readily accessed natural products especially eugenol with potential biological activity. Eugenol, the principal chemical constituent of clove (Eugenia caryophyllata) from the family Myrtaceae is renowned for its pharmacological properties, which include analgesic, antidiabetic, antioxidant, anticancer, and anti-inflammatory effects. According to reports, PPARγ regulates inflammatory reactions. The synthesized compounds were structurally analyzed using FT-IR, 1HNMR, 13CNMR, and mass spectroscopy techniques. Molecular docking was performed to analyze binding free energy and important amino acids involved in the interaction between synthesized derivatives and the target protein. The development of the structure-activity relationship is based on computational studies. Additionally, the stability of the best-docked protein-ligand complexes was assessed using molecular dynamic modeling. The in-vitro PPARγ competitive binding Lanthascreen TR-FRET assay was used to confirm the affinity of compounds to the target protein. All the synthesized derivatives were evaluated for an in vitro anti-inflammatory activity using an albumin denaturation assay and HRBC membrane stabilization at varying concentrations from 6.25 to 400 µM. In this background, with the aid of computational research, we were able to design six novel derivatives of eugenol synthesized, analyzed, and utilized TR-FRET competitive binding assay to screen them for their ability to bind PPARγ. Anti-inflammatory activity evaluation through in vitro albumin denaturation and HRBC method revealed that 1f exhibits maximum inhibition of heat-induced albumin denaturation at 50% and 85% protection against HRBC lysis at 200 and 400 µM, respectively. Overall, we found novel derivatives of eugenol that could potentially reduce inflammation by PPARγ agonism.

Biphenyl-based small molecule inhibitors: Novel cancer immunotherapeutic agents targeting PD-1/PD-L1 interaction.

The immune checkpoint proteins are those key to the body's immunity which can either boost the immune system to protect the body from pathogens; or suppress the body's immunity system for the goal of self-tolerance. Cancer cells have evolved some mechanisms to boost the immuno-inhibitory checkpoints to bypass the immune system of the body. The binding of Programmed Cell Death-1 (PD-1) protein with its ligand Programmed Cell Death Ligand-1 (PD-L1) promotes this kind of immune-inhibitory signal. The discovery of immune checkpoint inhibitors was started in the early 21st century; with some success through monoclonal antibodies, peptides, and small molecules. Being the most reliable and safest way to target immune checkpoints, the scientific community is exploring possibilities to develop small molecule inhibitors. Among the different scaffolds of the small molecule, the most exposed and researched core molecule is Biphenyl-based scaffolds. We have described all of the possible biphenyl-based small molecules in this article, as well as their interactions with various amino acids in the binding cavity. The link between the in silico, in vitro, and in vivo activities of the PD-1/PD-L1 inhibitors are well connected. The Tyr56, Met115, Ala121, and Asp122 were detected as the crucial amino acids of the PD-1/PD-L1 inhibition. Additionally, a detailed binding pocket analysis of the PD-L1 receptor was carried out, where it was observed and confirmed that the binding pocket is tunnel-shaped and hydrophobic in nature. Finally, the structure-activity relationship of the biphenyl-based small molecule inhibitors was developed based on their activity and the binding interactions.

Design, parallel synthesis of Biginelli 1,4-dihydropyrimidines using PTSA as a catalyst, evaluation of anticancer activity and structure activity relationships via 3D QSAR studies.

Biginelli 1,4-dihydropyrimidines are extensively screened for their potential anticancer activity in the last decade. In this context, a series of Biginelli 1,4-dihydropyrimidines were designed and synthesised using PTSA as an efficient catalyst. The synthesised 1,4-dihydropyrimidines were screened for their anticancer activity against MCF-7 breast cancer cells by measuring cytotoxicity. The compounds exhibited activity ranging from weak to significant in terms of percentage cytotoxicity which is proportional to the anticancer activity. Amongst the screened compounds, compounds 4, 6 and 8 exhibited potential anticancer activity. Furthermore, CoMSIA studies were performed to derive the structure activity relationships in a 3D grid space by plotting experimental vs predicted cytotoxic activities. We have an opinion that, this developed model helps us in future to develop more potential 1,4-dihydropyrimidines for their cytotoxicity or anticancer activity.

Structure-based design and synthesis of new 4-methylcoumarin-based lignans as pro-inflammatory cytokines (TNF-α, IL-6 and IL-1ß) inhibitors.

Suppression of pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) along with nitric oxide reduction in RAW 264.7 cells by 7,8-dihydroxy-4-methylcoumarin, ethyl p-coumarate, ethyl caffeate and ethyl ferulate drove us to search structural-analogues of the aforementioned compounds through structure-based drug design. Docking studies revealed that substituted cinnamic acids and their ethyl esters (2-7c) showed higher GoldScore-fitness (GSF) and non-bonding interactions with target proteins than 7,8-dihydroxy-4-methylcoumarin (1a) and 7,8-dihydroxy-5-methylcoumarin (1b). With this background, the methylcoumarins (1a and 1b) and the cinnamic acid derivatives (2-7c) were fused in different permutations and combinations to generate sixty novel fused-cyclic coumarinolignans (FCLs) (8-13k). Docking studies on 8-13k indicated that several FCLs possess higher GSF, interesting active site interactions and distinctive π-π interactions compared to the standards (cleomiscosin A, diclofenac Na and prednisolone). Based on these findings, four novel FCLs (9d, 10d, 11d and 11e) were synthesized and tested for inhibition effect on TNF-α, IL-1ß and IL-6 expressions in LPS and oxalate crystal-induced in-vitro models. Compound 10d exhibited significant effect (P < 0.0001 at 100 µM) with an IC50 value of 8.5 µM against TNF-α. Compound 11e possessed IC50 values of 13.29 µM and 17.94 µM against IL-6 and IL-1ß, respectively. Study on SAR corroborated the requirement of C-4-methyl substituent in the coumarin moiety, dihydroxyl groups in the phenyl ring, and esterification of lignans for potent activity. Additionally, the reported excellent anti-inflammatory activity of cleomiscosin-A-glucoside was corroborated by from the higher GSF and better hydrophobic interactions than cleomsicosin A in the docking study. As an outcome, some novel and potentially active FCLs acting through NFκB and caspase 1 signaling pathways have been discovered as multiple cytokine inhibitors.

Thiazolidinediones as antidiabetic agents: A critical review.

Thiazolidinediones (TZDs) or Glitazones are an important class of insulin sensitizers used in the treatment of Type 2 diabetes mellitus (T2DM). TZDs were reported for their antidiabetic effect through antihyperglycemic, hypoglycemic and hypolipidemic agents. In time, these drugs were known to act by increasing the transactivation activity of Peroxisome Proliferators Activated Receptors (PPARs). The clinically used TZDs that suffered from several serious side effects and hence withdrawn/updated later, were full agonists of PPAR-γ and potent insulin sensitizers. These drugs were developed at a time when limited data were available on the structure and mechanism of PPARs. In recent years, however, PPAR-α/γ, PPAR-α/δ and PPAR-δ/γ dual agonists, PPAR pan agonists, selective PPAR-γ modulators and partial agonists have been investigated. In addition to these, several non PPAR protein alternatives of TZDs such as FFAR1 agonism, GPR40 agonism and ALR2, PTP1B and α-glucosidase inhibition have been investigated to address the problems associated with the TZDs. Using these rationalized approaches, several investigations have been carried out in recent years to develop newer TZDs devoid of side effects. This report critically reviews TZDs, their history, chemistry, mechanism mediated through PPAR, recent advances and future prospects.

Design, synthesis and glucose uptake activity of some novel glitazones.

Herein, we report a library consisting of some novel glitazones containing thiazolidinedione and its bioisosteres, rhodanine and oxadiazolidine ring structures as their basic scaffold for their antidiabetic activity. Twelve novel glitazones with diverse chemical structures were designed and synthesized by adopting appropriate synthetic schemes and analyzed. Later, subjected to in vitro glucose uptake assay in the absence and presence of insulin to confirm their antidiabetic activity using rat hemi-diaphragm. The titled compounds exhibited glucose uptake activity ranging weak to significant activity. Compounds 4, 5, 9, 11, 15, 16, 19 and 20 showed considerable glucose uptake activity apart from rosiglitazone, a standard drug. Compound 16 happens to be the candidate compound from this study to investigate further. The illustration about their design, synthesis, analysis and glucose uptake activity is reported here along with the in vitro and in silico study based structure-activity relationships.

Discovery of novel glitazones incorporated with phenylalanine and tyrosine: synthesis, antidiabetic activity and structure-activity relationships.

We report a series of new glitazones incorporated with phenylalanine and tyrosine. All the compounds were tested for their in vitro glucose uptake activity using rat-hemidiaphragm, both in presence and absence of insulin. Six of the most active compounds from the in vitro screening were taken forward for their in vivo triglyceride and glucose lowering activity against dexamethazone induced hyperlipidemia and insulin resistance in Wistar rats. The liver samples of rats that received the most active compounds, 23 and 24, in the in vivo studies, were subjected to histopathological examination to assess their short term hepatotoxicity. The investigations on the in vitro glucose uptake, in vivo triglyceride and glucose lowering activity are described here along with the quantitative structure-activity relationships.

Novel dual PPARα/γ agonists protect against liver steatosis and improve insulin sensitivity while avoiding side effects.

Insulin resistance is a feature of type 2 diabetes mellitus (T2D), and is strongly interconnected with non-alcoholic fatty liver disease (NAFLD). Peroxisome-proliferator activated receptor gamma (PPARγ) and peroxisome-proliferator activated receptor alpha (PPARα) are master regulators of insulin sensitivity and lipid metabolism, respectively. Thiazolidinediones (TZDs) such as pioglitazone, which target PPARα/γ, are highly effective at treating insulin resistance and NAFLD, but their clinical utility has been restricted by side effects such as weight gain, adipocyte hypertrophy and fluid retention. Therefore, there is urgent need for new safer and effective drugs. Thus, we aimed to develop novel dual PPARα/γ agonists to avoid their known side effects while preserving their overall therapeutic effects. Here, we show that our novel agonists G4 and G5 strongly stimulate glucose transporter 4 (GLUT4) translocation to the cell membrane in skeletal muscle cells, and manifest weaker lipogenic effect in adipocytes. Moreover, G4 and G5 improve systemic glucose metabolism, hyperinsulinemia, hyperlipidemia, and markers of liver injury in high fructose diet-induced insulin resistant rats. Mechanistic studies revealed that G4 and G5 enhance GLUT4, and AMPK in skeletal muscle and protect against liver steatosis by upregulating PPARα and improve whole-body insulin sensitivity by increasing PPARγ. Despite this increase in PPARγ activity, G4 and G5 inhibit the unwanted side effects such as weight gain due to adiposity, hypertrophy of adipocytes, and fluid retention unlike TZDs. These findings identify G4 and G5 as promising dual PPARα/γ agonists for the treatment of NAFLD and insulin resistance with improved safety.

Novel derivatives of eugenol as potent anti-inflammatory agents via PPARγ agonism: rational design, synthesis, analysis, PPARγ protein binding assay and computational studies.

Eugenol is a natural product abundantly found in clove buds known for its pharmacological activities such as anti-inflammatory, antidiabetic, antioxidant, and anticancer activities. It is well known from the literature that peroxisome proliferator-activated receptors (PPARγ) have been reported to regulate inflammatory responses. In this backdrop, we rationally designed semi-synthetic derivatives of eugenol with the aid of computational studies, and synthesized, purified, and analyzed four eugenol derivatives as PPARγ agonists. Compounds were screened for PPARγ protein binding by time-resolved fluorescence (TR-FRET) assay. The biochemical assay results were favorable for 1C which exhibited significant binding affinity with an IC50 value of 10.65 µM as compared to the standard pioglitazone with an IC50 value of 1.052 µM. In addition to the protein binding studies, as a functional assay, the synthesized eugenol derivatives were screened for in vitro anti-inflammatory activity at concentrations ranging from 6.25 µM to 400 µM. Among the four compounds tested 1C shows reasonably good anti-inflammatory activity with an IC50 value of 133.8 µM compared to a standard diclofenac sodium IC50 value of 54.32 µM. Structure-activity relationships are derived based on computational studies. Additionally, molecular dynamics simulations were performed to examine the stability of the protein-ligand complex, the dynamic behavior, and the binding affinity of newly synthesized molecules. Altogether, we identified novel eugenol derivatives as potential anti-inflammatory agents via PPARγ agonism.

A promising in silico protocol to develop novel PPARγ antagonists as potential anticancer agents: Design, synthesis and experimental validation via PPARγ protein activity and competitive binding assay.

Peroxisome proliferator-activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily is an excellent example of targets that orchestrates cancer, inflammation, lipid and glucose metabolism. We report a protocol for the development of novel PPARγ antagonists by employing 3D QSAR based virtual screening for the identification of ligands with anticancer properties. The models are generated based on a large and diverse set of PPARγ antagonist ligands by the HYPOGEN algorithm using Discovery Studio 2019 drug design software. Among the 10 hypotheses generated, Hypotheses 2 showed the highest correlation coefficient values of 0.95 with less RMS deviation of 1.193. Validation of the developed pharmacophore model was performed by Fischer's randomization and screening against test and decoy set. The GH score or goodness score was found to be 0.81 indicating moderate to a good model. The selected pharmacophore model Hypo 2 was used as a query model for further screening of 11,145 compounds from the PubChem, sc-PDB structure database, and designed novel ligands. Based on fit values and ADMET filter, the final 10 compounds with the predicated activity of ≤ 3 nM were subjected for docking analysis. Docking analysis revealed the unique binding mode with hydrophobic amino acid that can cause destabilization of the H12 which is an important molecular mechanism to prove its antagonist action. Based on high CDocker scores, Cpd31 was synthesized, purified, analyzed and screened for PPARγ competitive binding by TR-FRET assay. The biochemical protein binding results matched the predicted results. Further, Cpd31 was screened against cancer cells and validated the results.

Minutes of PPAR-γ agonism and neuroprotection.

Peroxisome proliferator-activated receptor gamma (PPAR-γ) is one of the ligand-activated transcription factors which regulates a number of central events and considered as a promising target for various neurodegenerative disease conditions. Numerous reports implicate that PPAR-γ agonists have shown neuroprotective effects by regulating genes transcription associated with the pathogenesis of neurodegeneration. In regards, this review critically appraises the recent knowledge of PPAR-γ receptors in neuroprotection in order to hypothesize potential neuroprotective mechanism of PPAR-γ agonism in chronic neurological conditions. Of note, the PPAR-γ's interaction dynamics with PPAR-γ coactivator-1α (PGC-1α) has gained significant attention for neuroprotection. Likewise, a plethora of studies suggest that the PPAR-γ pathway can be actuated by the endogenous ligands present in the CNS and thus identification and development of novel agonist for the PPAR-γ receptor holds a vow to prevent neurodegeneration. Together, the critical insights of this review enlighten the translational possibilities of developing novel neuroprotective therapeutics targeting PPAR-γ for various neurodegenerative disease conditions.

Two Rationally Identified Novel Glitazones Reversed the Behavioral Dysfunctions and Exhibited Neuroprotection Through Ameliorating Brain Cytokines and Oxy-Radicals in ICV-LPS Neuroinflammatory Rat Model.

The present study has planned to evaluate the neuroprotective activity of two novel glitazones in a neuroinflammatory rat model. Two novel glitazones were selected from an in-house virtual library of glitazones based on their docking scores against peroxisome proliferator-activated receptor-gamma (PPAR-γ) protein and other parameters studied in in silico computational studies. Initially, an acute oral toxicity study was carried out for glitazones in rats to assess the toxicity profile and to determine the therapeutic range for neuroprotective evaluation. Prior to induction of neuroinflammation, the treatments with glitazones (G1 and G2) and standard pioglitazone were made for four consecutive days to respective groups. On the fifth day, the neuroinflammation was induced by intracerebroventricular (ICV) administration of lipopolysaccharides (LPS) (2 µg/µl) using stereotaxic apparatus. After 7 days, the rats were subjected to behavioral assessment followed by neurobiochemical evaluation and histopathological studies. The pre-treatment with glitazones at two dose levels (15 and 30 mg/kg) has significantly reversed behavioral dysfunctions. Glitazones have shown significant reduction in the levels of LPO, NO, TNF-α, and IL-1ß and also increased the levels of antioxidant enzymes such as SOD, CAT, and GSH in the brain of LPS-administered rats. The neuroprotection exhibited by two novel glitazones is comparable with standard pioglitazone. The PPAR-γ-dependent amelioration of cytokines and oxy-radicals released by novel glitazones during neuroinflammatory conditions may be attributed to the reversal of behavioral dysfunctions through preventing the degeneration of neurons in major regions of the brain.

Rational Design, Synthesis, and In Vitro Neuroprotective Evaluation of Novel Glitazones for PGC-1α Activation via PPAR-γ: a New Therapeutic Strategy for Neurodegenerative Disorders.

In the present study, two structurally diverse novel glitazones were designed and synthesized for activation of central PGC-1α signaling through stimulation of PPAR-γ receptor. The functional interaction between PGC-1α and PPAR-γ is a key interaction in the normal physiology of neuroprotective mechanism. Therefore, activation of PPAR-γ-dependent PGC-1α co-activator signaling could be an effective strategy to exhibit neuroprotection in several neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, and cerebral ischemia. As part of rational design, analogs were designed manually based on principles of bioisosterism, followed by virtually screened using docking to predict the mode of interaction of compound towards the binding site and molecular dynamic simulation to observe the structural changes that occur during compound interaction with active site. The designed two glitazones (G1, G2) were synthesized and structurally analyzed. As part of evaluation, synthesized glitazones were subjected for preliminary neuroprotective evaluation in Lipopolysaccharide (LPS) intoxicated SH-SY5Y neuroblastoma cells. The results indicate that pre-treatment with synthesized glitazones have increased the percentage cell viability, protected the cell morphology, and decreased the release of pro-inflammatory cytokines (IL-1ß, TNF-α), lipid peroxide (LPO), and nitric oxide (NO) level in LPS intoxicated SH-SY5Y cells. Interestingly, among the two glitazones, G2 has shown significant neuroprotection in comparison to G1 and neuroprotective effect exerted by G2 was similar and comparable with the standard pioglitazone. Altogether, neuroprotection exhibited by this non-thiazolidione-based glitazones during neuroinflammatory conditions may be attributed to the activation of central PGC-1α signaling via PPAR-γ receptor.

Predicting anti-HIV activity of 1,3,4-thiazolidinone derivatives: 3D-QSAR approach.

HIV-1 (human immunodeficiency virus type-1) is the pathogenic retrovirus and causative agent of AIDS. HIV-1 RT is one of the key enzymes in the duplication of HIV-1. Inhibitors of HIV-1 RT are classified as NNRTIs and NRTIs. NNRTIs bind to a region that is not associated with the active site of the enzyme. Within the NNRTIs category, there is a set of inhibitors commonly referred to as thiazolidinone derivatives. The present 3D-QSAR study attempts to explore the structural requirements of thiazolidinone derivatives for anti-HIV activity. Based on the structures and biodata of previous thiazolidinone analogs, 3D-QSAR studies have been performed with a training set consisting of 96 molecules, which resulted in two reliable computational models, CoMFA and CoMSIA with r(2) values of 0.931 and 0.972, standard error of estimation (SEE) of 0.173 and 0.089, and q(2) values of 0.663 and 0.784, respectively, with the number of partial least-squares (PLS) components being six. It is shown that the steric and electrostatic properties predicted by CoMFA contours and the hydrogen bond acceptor, hydrogen bond donor, and hydrophobic properties predicted by CoMSIA contours are related to anti-HIV activity. The predictive ability of the resultant model was evaluated using a test set comprising of 17 molecules and the predicted r(2) values of CoMFA and CoMSIA models were 0.861 and 0.958, respectively. These models are more significant guide to trace the features that really matter especially with respect to the design of novel compounds.

Novel Biginelli dihydropyrimidines with potential anticancer activity: a parallel synthesis and CoMSIA study.

Novel Biginelli dihydropyrimidines of biological interest were prepared using p-toluene sulphonic acid as an efficient catalyst. All the thirty-two synthesised dihydropyrimidines were evaluated for their in vitro antioxidant activity using DPPH method. Only, compounds 28 and 29 exhibited reasonably good antioxidant activity. Furthermore, the synthesised Biginelli compounds were subjected for their in vitro anticancer activity against MCF-7 human breast cancer cells. The title compounds were tested at the concentration of 10 microg. Compounds exhibited activity ranging from weak to moderate and, from moderate to high in terms of percentage cytotoxicity. Among them, compounds 10 and 11 exhibited significant anticancer activity. In order to elucidate the three-dimensional structure-activity relationships (3D QSAR) towards their anticancer activity, we subjected them for comparative molecular similarity indices analysis (CoMSIA). Illustration regarding their synthesis, analysis, antioxidant activity, anticancer activity and 3D QSAR study is described.

QSAR Study on Thiazolidine-2,4-dione Derivatives for Antihyperglycemic Activity.

A set of seventy four molecules belonging to the class of thioglitazones were subjected to the QSAR analysis for their antihyperglycemic activity. All the molecules were subjected to energy minimization to get 3D structures, followed by conformational analysis to get the conformation of the molecule associated with the least energy and highest stability. Various physico-chemical parameters were then calculated using ALCHEMY 2000 software, namely, thermodynamic parameters, structure-dependant parameters, topological parameters and charge-dependant parameters. Multiple linear regression analysis was carried out on all the molecules. The final equation was developed by choosing optimal combination of descriptors after removing the outliers. Cross validation was performed by leave one out method to arrive at the final QSAR model for the chosen set of molecules to exhibit antihyperglycemic activity.