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Author: search.filters.author.Deepa, P.R.Subject: search.filters.subject.Molecular docking

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    In silico and in vitro analysis of PPAR – α / γ dual agonists: Comparative evaluation of potential phytochemicals with anti-obesity drug orlistat
    (Elsevier, 2022) Deepa, P.R.; Sharma, Pankaj Kumar; Murugesan, Sankaranarayanan
    Obesity is an abnormal fat accumulation disorder in the metabolic syndrome constellation, and a risk factor for diabetes, cardiovascular disorders, non-alcoholic fatty liver disease (NAFLD), and cancer. Nuclear receptors (Peroxisome proliferator-activated receptor, PPAR) are implicated in metabolic syndrome and NAFLD, and have potential for therapeutic targeting. Nuclear receptors are ligand-dependent transcription factors that have diverse roles in metabolism, including regulating genes involved in lipid and glucose metabolism, modulating inflammatory genes, and are crucial for maintaining metabolic flexibility. PPAR activates adipose triglyceride lipase, which then releases fatty acids as ligands for PPAR, indicating the interdependency of nuclear receptors and lipases. Here, molecular docking was performed with selected phytochemical ligands that can bind with PPAR-α/γ (PDB ID: 2ZNN and 2ATH, respectively) using Glide module of Schrodinger software followed by molecular dynamics simulation study using Desmond module, and ADMET analysis. Interestingly, orlistat which is a well-known lipase and fatty acid synthase inhibitor also demonstrated favorable binding affinity with both PPAR-α/γ (−10.96 kcal/mol against PPARα and −10.26 kcal/mol against PPARγ). The highest docking scores were however shown by the flavonoids - rutin (−14.88 kcal/mol against PPARα and −13.64 kcal/mol against PPARγ), and its aglycone, quercetin (−10.08 kcal/mol in PPARα and −9.89 kcal/mol in PPARγ). The other phytochemicals (genistein, esculin, daidzin, naringenin, daidzein, dihydroxy coumarin, hydroquinone) showed lower binding affinity as dual agonists. The anti-obesity effects were experimentally validated in cultured adipocytes, which revealed better lipid inhibition by rutin and quercetin than orlistat (quercetin > rutin > orlistat) pointing to their strong potential in anti-obesity treatment.
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    Comparative docking of dual conformations in human fatty acid synthase thioesterase domain reveals potential binding cavity for virtual screening of ligands
    (Taylor & Francis, 2017) Deepa, P.R.
    Human fatty acid synthase (hFASN), a homo dimeric lipogenic enzyme with seven catalytic domains, is an important clinical target in cancer, metabolic syndrome and infections. Here, molecular modelling and docking methods were implemented to examine the inter-molecular interactions of thioesterase (TE) domain in hFASN with its physiological substrate, and to identify potential chemical inhibitors. TE catalyses the hydrolysis of thioester bond between palmitate and the 4’ phosphopantetheine of acyl carrier protein, releasing 16-carbon palmitate. The crystal structure of hFASN TE in two inhibitory conformations (A and B) were geometry-optimized and used for molecular docking with palmitate, orlistat (a known FASN inhibitor) and virtual screening against compounds from National Cancer Institute (NCI) database. Relatively, low binding affinity was observed during the complex formation of palmitate with A (−.164 kcal/mol) and B (−.332 kcal/mol) forms of TE, when compared with orlistat-docked TE (A form: −5.872 kcal/mol and B form: −5.484 kcal/mol), clearly indicating that the native inhibited conformation (crystal structure) was unfavourable for substrate binding. We used these orlistat dual binding modes as positive controls for prioritizing the ligands during virtual screening. From 2, 31,617 molecules in the NCI database, 916 high-scoring compounds (hit ligands) were obtained for A-form and 4582 for B-form of the TE-domain, which were then ranked according to glide docking score, XP H bond score, absorption, distribution, metabolism and excretion and binding free energy (Prime/MM-GBSA). Consequently, two top scoring ligands (NSC: 319661 and NSC: 153166) emerged as promising drug candidates that may be tested in FASN-over-expressing diseases.