Pharmacophore-based screening for identification of Human Acyl-CoA cholesterol acyltransferase inhibitors: An in-silico study

Abstract:: Human Acyl-CoA cholesterol acyltransferase (ACAT) plays an important role in catalysis of reaction which converts cholesterol into cholesteryl esters and long-chain fatty acyl coenzyme A. The inhibition of ACAT has therapeutically potential roles in hypercholestrolemia, atherosclerosis and coronary heart disease. For better understanding of essential chemical features for ACAT inhibition and identifying novel inhibitors, a three-dimensional (3D) chemical-feature-based quantitative QSAR pharmacophore model for available ACAT inhibitors have been developed for first time using Discovery Studio 2.5. The best model (Hypo1) having lowest total cost (84.14), highest cost difference (69.67), highest correlation coefficient (0.94), and lowest RMS (1.15Å), constitutes of one hydrogen bond acceptor, one hydrogen bond donor, two hydrophobic aromatic and one hydrophobic aliphatic feature. Validation of Hypo1 was further done using test set activity prediction, Fischer’s randomization method and decoy data set to check the reliability of the model. The validated Hypo1 was then used as a 3D search query for virtual screening to retrieve potential inhibitors from National cancer institute (NCI), ChemDiv and Specs databases. Finally, ADMET properties of selected compounds were calculated. The result shows the good potential of the newly found ACAT inhibitors. Finally, the two compounds have been obtained as novel hits to design the Novel ACAT inhibitors.

Novel LC/MS/MS and High-Throughput Mass Spectrometric Assays for Monoacylglycerol Acyltransferase Inhibitors

Monoacylglycerol acyltransferase enzymes (MGAT1, MGAT2, and MGAT3) convert monoacylglycerol to diacylglycerol (DAG). MGAT1 and MGAT2 are both implicated in obesity-related metabolic diseases. Conventional MGAT enzyme assays use radioactive substrates, wherein the product of the MGAT-catalyzed reaction is usually resolved by time-consuming thin layer chromatography (TLC) analysis. Furthermore, microsomal membrane preparations typically contain endogenous diacylglycerol acyltransferase (DGAT) from the host cells, and these DGAT activities can further acylate DAG to form triglyceride (TG). Our mass spectrometry (liquid chromatography–tandem mass spectrometry, or LC/MS/MS) MGAT2 assay measures human recombinant MGAT2-catalyzed formation of didecanoyl-glycerol from 1-decanoyl-rac-glycerol and decanoyl-CoA, to produce predominantly 1,3-didecanoyl-glycerol. Unlike 1,2-DAG, 1,3-didecanoyl-glycerol is proved to be not susceptible to further acylation to TG. 1,3-Didecanoyl-glycerol product can be readily solubilized and directly subjected to high-throughput mass spectrometry (HTMS) without further extraction in a 384-well format. We also have established the LC/MS/MS MGAT activity assay in the intestinal microsomes from various species. Our assay is proved to be highly sensitive, and thus it allows measurement of endogenous MGAT activity in cell lysates and tissue preparations. The implementation of the HTMS MGAT activity assay has facilitated the robust screening and evaluation of MGAT inhibitors for the treatment of metabolic diseases.