title: Targeting the intersubunit cavity of Plasmodium falciparum glutathione reductase by a novel natural inhibitor: computational and experimental evidence.
abstract: Glutathione reductase (GR), a homodimeric FAD-dependent disulfide reductase, is essential for redox homeostasis of the malaria parasite Plasmodium falciparum and has been proposed as an antimalarial drug target. In this study we performed a virtual screening against PfGR, using the structures of about 170,000 natural compounds. Analysis of the two top-scoring molecules, TTB and EPB, indicated that these ligands are likely to interact with the homodimer intersubunit cavity of PfGR with high binding energy scores of -9.67 and -9.60kcal/mol, respectively. Both compounds had a lower affinity for human GR due to differences in structure and electrostatic properties. In order to assess the putative interactions in motion, molecular dynamics simulations were carried out for 30ns, resulting in TTB being more dynamically and structurally favored than EPB. A closely related compound MDPI 21618 was tested on recombinant PfGR and hGR, resulting in IC50 values of 11.3±2.5μM and 10.2±1.7μM, respectively. Kinetic characterization of MDPI 21618 on PfGR revealed a mixed-type inhibition with respect to glutathione disulfide (Ki=9.7±2.3μM) and an uncompetitive inhibition with respect to NADPH. Furthermore, MDPI 21618 was found to inhibit the growth of the chloroquine-sensitive P. falciparum strain 3D7 with an IC50 of 3.2±1.9μM and the chloroquine-resistant Dd2 strain with an IC50 of 3.2+1.6μM. In drug combination assays with chloroquine, artemisinin, or mefloquine MDPI 21618 showed an antagonistic action, which might suggest partially overlapping routes of action. This study further substantiates research on PfGR as a potential antimalarial drug target.
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Chetna
authors: C
authors: Tyagi
authors: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen 35392, Germany.
authors: Jochen
authors: J
authors: Bathke
authors: Apaji Institute of Mathematics & Applied Computer Technology, Banasthali University, Tonk, Rajasthan 304022, India.
authors: Sukriti
authors: S
authors: Goyal
authors: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen 35392, Germany.
authors: Marina
authors: M
authors: Fischer
authors: Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena 07745, Germany.
authors: Hans-Martin
authors: HM
authors: Dahse
authors: Thematic Unit of Excellence on Computational Materials Science, S. N. Bose National Centre for Basic Sciences, Sector-III, Block - JD, Salt Lake, Kolkata 700098, India.
authors: Sajeev
authors: S
authors: Chacko
authors: Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University, Giessen 35392, Germany.
authors: Katja
authors: K
authors: Becker
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: abhinavgr@gmail.com.
authors: Abhinav
authors: A
authors: Grover
mesh_terms: D000962:Antimalarials / Q000009:adverse effects / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004791:Enzyme Inhibitors / Q000009:adverse effects / Q000737:chemistry* / Q000494:pharmacology*; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D057166:High-Throughput Screening Assays / Q000379:methods; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects; D006801:Humans; D020014:K562 Cells; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology*; D021122:Protein Subunits
chemical_list: D000962:Antimalarials; D004791:Enzyme Inhibitors; D021122:Protein Subunits; D005980:Glutathione Reductase
keywords: Glutathione reductase; Inhibitor; Malaria; Plasmodium falciparum; Screening