Today's challenges and tomorrow's opportunities: ligands to peroxisome proliferator-activated receptors as therapies for type 2 diabetes and the metabolic syndrome

In silico screening of potential antidiabetic phytochemicals from Phyllanthus emblica against therapeutic targets of type 2 diabetes

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus emblica Linn. (Syn. Emblica officinalis Gaertn.), has been used to cure many ailments of human beings. Literature survey demonstrates that it has many pharmacological activities i.e. antidiabetic, antioxidant, anti-microbial, antifungal, antiallergic, antiviral, and anticancer properties.

AIM OF THE STUDY

The present study aimed to identify the novel plant-derived antidiabetic compounds from P. emblica to understand the molecular basis of antidiabetic activities.

MATERIAL AND METHODS

Text mining analysis of P. emblica and its disease association was carried out using server DLAD4U. Due to the highest score of P. emblica with diabetes, the virtual screening of a phytochemical library of P. emblica against three targets of diabetes was carried out. After that FAF-Drug4, admetSAR and DruLiTo servers were used for drug-likeness prediction. Additionally, pharmacophore modeling was also carried out to understand the antidiabetic activity of screened compounds.

RESULTS

The docking scores, drug-likeness and pharmacophore studies found that Ellagic acid, Estradiol, Sesamine, Kaempferol, Zeatin, Quercetin, and Leucodelphinidin are potential antidiabetic compounds.

CONCLUSIONS

Our study shows that phytochemicals of P. emblica are very potential antidiabetic candidates. Using the modern techniques these molecules could be used to develop an effective antidiabetic drugs from a natural resource.

In Silico Identification of Potent PPAR-γ Agonists from Traditional Chinese Medicine: A Bioactivity Prediction, Virtual Screening, and Molecular Dynamics Study

The peroxisome proliferator-activated receptors (PPARs) related to regulation of lipid metabolism, inflammation, cell proliferation, differentiation, and glucose homeostasis by controlling the related ligand-dependent transcription of networks of genes. They are used to be served as therapeutic targets against metabolic disorder, such as obesity, dyslipidemia, and diabetes; especially, PPAR-γ is the most extensively investigated isoform for the treatment of dyslipidemic type 2 diabetes. In this study, we filter compounds of traditional Chinese medicine (TCM) using bioactivities predicted by three distinct prediction models before the virtual screening. For the top candidates, the molecular dynamics (MD) simulations were also utilized to investigate the stability of interactions between ligand and PPAR-γ protein. The top two TCM candidates, 5-hydroxy-L-tryptophan and abrine, have an indole ring and carboxyl group to form the H-bonds with the key residues of PPAR-γ protein, such as residues Ser289 and Lys367. The secondary amine group of abrine also stabilized an H-bond with residue Ser289. From the figures of root mean square fluctuations (RMSFs), the key residues were stabilized in protein complexes with 5-Hydroxy-L-tryptophan and abrine as control. Hence, we propose 5-hydroxy-L-tryptophan and abrine as potential lead compounds for further study in drug development process with the PPAR-γ protein.

New 2-(aryloxy)-3-phenylpropanoic acids as peroxisome proliferator-activated receptor α/γ dual agonists able to upregulate mitochondrial carnitine shuttle system gene expression

The preparation of a series of 2-(aryloxy)-3-phenylpropanoic acids, resulting from the introduction of different substituents into the biphenyl system of the previously reported peroxisome proliferator-activated receptor α/γ (PPARα/γ) dual agonist 1, allowed the identification of new ligands with higher potency on PPARα and fine-tuned moderate PPARγ activity. For the most promising stereoisomer (S)-16, X-ray and calorimetric studies in PPARγ revealed, at high ligand concentration, the presence of two molecules simultaneously bound to the receptor. On the basis of these results and docking experiments in both receptor subtypes, a molecular explanation was provided for its different behavior as a full and partial agonist of PPARα and PPARγ, respectively. The effects of (S)-16 on mitochondrial acylcarnitine carrier and carnitine-palmitoyl-transferase 1 gene expression, two key components of the carnitine shuttle system, were also investigated, allowing the hypothesis of a more beneficial pharmacological profile of this compound compared to the less potent PPARα agonist fibrates currently used in therapy.

New 2-aryloxy-3-phenyl-propanoic acids as peroxisome proliferator-activated receptors alpha/gamma dual agonists with improved potency and reduced adverse effects on skeletal muscle function

The preparation of a new series of 2-aryloxy-3-phenyl-propanoic acids, resulting from the introduction of a linker into the diphenyl system of the previously reported PPARalpha/gamma dual agonist 1, allowed the identification of new ligands with improved potency on PPARalpha and unchanged activity on PPARgamma. For the most interesting stereoisomers S-2 and S-4, X-ray studies in PPARgamma and docking experiments in PPARalpha provided a molecular explanation for their different behavior as full and partial agonists of PPARalpha and PPARgamma, respectively. Due to the adverse effects provoked by hypolipidemic drugs on skeletal muscle function, we also investigated the blocking activity of S-2 and S-4 on skeletal muscle membrane chloride channel conductance and found that these ligands have a pharmacological profile more beneficial compared to fibrates currently used in therapy.

Tryptophan-containing dipeptide derivatives as potent PPARgamma antagonists: design, synthesis, biological evaluation, and molecular modeling

The discovery of peroxisome proliferator-activated receptor gamma (PPARgamma) antagonists (also termed "selective PPARgamma modulators, SPPARgammaM") is now of a great interest in the treatment of diabetes and obesity. The structure of compound 1a (G3335, Fig. 1), a novel class of PPARgamma antagonist, is entirely different from that of other reported PPARgamma antagonists. A series of 35 novel analogues (1b-l, 9a-d, 13a-t) were designed, synthesized and evaluated against the agonistic effects exerted by rosiglitazone. These results indicated that most functional groups of 1a were conserved, and six new compounds (1b, 1c, and 9a-d) exhibited strong PPARgamma antagonistic activities (IC(50) values of 5.2-25.8 microM) against 10 microM rosiglitazone in the promotion of the PPARgamma-LBD-CBP (ligand-binding domain and cAMP-response-element binding protein) interaction as investigated by yeast two-hybrid technology based assay. Molecular modeling studies for compounds 1a-d, 1h, 9c-d, and 13a were also presented.