Potential modulating effect of the Ascaris suum nicotinic acetylcholine receptor (nAChR) by compounds GSK575594A, diazepam and flumazenil discovered by structure-based virtual screening approach
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Parasitic infections are a widespread health problem and research of novel anthelmintic compounds is of the utmost importance. In this study we performed a virtual screening campaign by coupling ligand-based pharmacophore, homology modeling and molecular docking. The virtual screening campaign was conducted using a joined pool of the Drugbank database and a library of purchasable compounds in order to identify drug like compounds with similar pharmacological activity. Our aim was to identify compounds with a potential antihelmintic modulatory effect on nicotinic acetylcholine receptors (nAChR). We derived a 3D pharmacophore model based on the chemical features of known Ascaris suum nAChR modulators. To evaluate the in silico predictions, we tested selected hit compounds in contraction assays using somatic muscle flaps of the Ascaris suum neuromuscular tissue. We tested the modulatory effects of GSK575594A, diazepam and flumazenil hit compounds on nematode contractions induced by acetyl... choline (ACh). The compound GSK575594A (3 μM) increased the Emax by 21 % with the EC50 dose ratio of 0.96. Diazepam (100 μM) decreased the Emax by 15 % (1.11 g to 0.95 g) with the EC50 ratio of 1.42 (shifted to the left from 11.25 to 7.93). Flumazenil decreased the EC50 value (from 11.22 μM to 4.88 μM) value showing dose ratio of 2.30, and increased the Emax by 4 % (from 1.54 g to 1.59 g). The observed biological activity was rationalized by molecular docking calculations. Docking scores were calculated against several binding sites within the Ascaris suum homology model. We constructed the homology model using the ACR-16 subunit sequence. The compound GSK575594A showed strong affinity for the intersubunit allosteric binding site within the nAChR transmembrane domain. The binding modes of diazepam and flumazenil suggest that these compounds have a comparable affinity for orthosteric and allosteric nAChR binding sites. The selected hit compounds displayed potential for further optimization as lead compounds. Therefore, such compounds may be useful in neutralizing the growing resistance of parasites to drugs, either alone or in combination with existing conventional anthelmintics.
Keywords:Antihelmintic compounds / Ascaris suum / Contraction assays / GSK575594A / Homology modelling / Ligand-based pharmacophore modelling / Molecular docking, virtual screening / Parasite nAChR
Source:Molecular and Biochemical Parasitology, 2021, 242
- Elsevier B.V.
- Ministry of Education, Science and Technological Development, Republic of Serbia, Grant no. 451-03-68/2020-14/200161 (University of Belgrade, Faculty of Pharmacy) (RS-200161)
- Development of herbal medicines and biocides on the basis of Carvacrol, Thymol and Cinnamaldehyde for use in veterinary medicine, animal husbandry and food production without harmful residues (RS-31087)
- Ministry of Education, Science and Technological Development, Republic of Serbia, Grant no. 451-03-68/2020-14/200143 (University of Belgrade, Faculty of Veterinary Medicine) (RS-200143)
- Ministry of Higher Education, Science and Technology of the Republic of Slovenia through Research Program Grant P1-0012