Synthesis, Anti-Inflammatory Activity and Molecular Docking Studies of 1,4,5,6-Tetrahydropyrimidine-2-Carboxamides

Pharmaceutical Sciences, 2021, 27(3), 353-365 doi:10.34172/PS.2020.100 https://ps.tbzmed.ac.ir/ Research Article Synthesis, Anti-Inflammatory Activity and Molecular Docking Studies of 1,4,5,6-Tetrahydropyrimidine-2-Carboxamides Volodymyr Ya. Horishny1, Pavlo V. Zadorozhnii2* , Ivanna V. Horishnia1, Vasyl S. Matiychuk3 Department of Pharmaceutical, Organic and Bioorganic Chemistry, Danylo Halytsky Lviv National Medical University, Pekarska 69, Lviv, 79010, Ukraine. Department of Pharmacy and Technology of Organic Substances, Ukrainian State University of Chemical Technology, Gagarin Ave., 8, Dnipro 49005, Ukraine. 3 Department of Organic Chemistry, Ivan Franko National University of Lviv, 6 Kyryla і Mefodia, Lviv, 79005, Ukraine. 1 2 Article Info Article History: Received: 26 September 2020 Accepted: 18 December 2020 ePublished: 18 December 2020 Keywords: -Antiinflammatory activity -COX-1 -COX-2 -Molecular docking -SAR analysis -Tetrahydropyrimidine Abstract Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world. The widespread use of NSAIDs is associated with a number of serious side effects and complications observed for both selective and non-selective COX inhibitors. Therefore, the search for new COX inhibitors, which along with their effectiveness will have minimal side effects, is a very important and urgent task. Methods: This work studied the synthesis of new 1,4,5,6-tetrahydropyrimidine-2carboxamides based on the reaction of 2-morpholin-4-yl-N-(het)aryl-2-thioxoacetamides with 1,3-diaminopropane. All obtained compounds were tested for anti-inflammatory activity in vivo and in silico conditions. All synthesized 1,4,5,6-tetrahydropyrimidine-2-carboxamides were tested for influence on the course of the exudative phase of the inflammatory process based on the carrageenan model of paw edema of laboratory nonlinear heterosexual white rats weighing 220-250 g, using Diclofenac as a reference. Optimization of the geometry of the studied structures and molecular docking was carried out using the ArgusLab 4.0.1 software package. Results: The target products were obtained with yields of 71-98% and easily isolated from the reaction mixture. The best anti-inflammatory activity was found in N-(4-chlorophenyl)-1,4,5,6tetrahydropyrimidine-2-carboxamide and in N-[4-chloro-3-(trifluoromethyl)phenyl]-1,4,5,6tetrahydropyrimidine-2-carboxamide, suppression of the inflammatory response was 46.7% and 46.4%, respectively. The results of molecular docking with COX-1 and COX-2 enzymes were in good agreement with the experimental data, R2 > 0.92 and R2 > 0.83, respectively. Conclusion: The compounds under study were shown to be promising as potential antiinflammatory agents. Introduction Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used drugs in the world.1 Their anti-ability to alleviate the symptoms of inflammation and pain is usually due to the inhibition of cyclooxygenases (COX) - enzymes involved in the synthesis of prostanoids.2,3 COX-14,5 and COX-26 isoforms of the enzyme form the greatest interest as biological targets for NSAIDs. COX-1 is a constitutive enzyme, that is, it works almost constantly and performs physiologically important functions,7 while COX-2 is an inducible enzyme, that is, it begins to function in certain situations.7The widespread use of NSAIDs is associated with a number of serious side effects and complications observed for both selective and non-selective COX inhibitors.8 Therefore, the search for new COX inhibitors, which along with their effectiveness will have minimal side effects, is a very important and urgent task. Work is underway to find potential NSAIDs among substances of natural origin,9 as well as synthetic derivatives of azepine,10 benzimidazole,11,12 triazole,13-15 1,3,4-oxadiazole,16-20 xanthone,21 coumarin,22-24 quinazoline,25,26 pyrrolidinone,27,28 pyrrolisine,29 30-32 33 34 pyrazole, 1,3-thiazole, pyridazine, and other cyclic and acyclic systems.35 Recently, pyrimidine derivatives have been of increasing interest as potential COX inhibitors.36 Usually, they exhibit anti-inflammatory and analgesic activity in vivo,37-46 and also give good results in in silico studies.47,48 This work is devoted to the synthesis and study of the anti-inflammatory properties of 1,4,5,6-tetrahydropyrimidine-2-carboxamides. It should be noted that this class of amides is practically unexplored, methods for their preparation have not been developed and nothing is known about their biological *Corresponding Author: Pavlo V. Zadorozhnii, E-mail: ©2021 The Author(s). This is an open access article and applies the Creative Commons Attribution License (http://creativecommons.org/licenses/bync/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. Horishny et al. activity either. At the same time, derivatives of 6-oxo1,4,5,6-tetrahydropyrimidine-2-carboxylic acid and compounds obtained by transformation of the 6-oxo group in their structure as well as condensed analogues based on them are well studied. In particular, they are inhibitors of various enzymes,49,50 exhibit antimicrobial51,52 and anti-inflammatory properties.53 These facts indicate a high pharmacological potential of the compounds of 1,4,5,6-tetrahydropyrimidine series, and therefore, further research in this direction is an urgent and promising task. Materials and Methods Materials All starting materials were purchased from Merck and used without purification. NMR spectra were determined with «Varian Mercury VX-400 », (400 MHz and 100 MHz) spectrometer, in DMSO-d6. Melting points were determinated in open capillary tubes and are uncorrected. MS (ESI) spectra were recorded on an LC-MS system HPLC Agilent 1100 (Agilent Technologies Inc., Santa, Clara, CA USA) equipped with a diode array detector Agilent LC\MSD SL. Parameters of analysis: Zorbax SB C18 column (1.8 μm, 4.6-15 mm, PN 821975-932), solvent water – acetonitrile mixture (95:5), 0.1% of aqueous trifluoroacetic acid; eluent flow 3 mL/min; injection volume 1 μL. IR spectra were recorded on a Vertex 70 Bruker” (Bruker, Karlsruhe.,Germany) spectrometer in KBr pellets. Methods The general procedure for the preperation of 2-morpholin4-yl-N-(het)aryl-2-thioxoacetamides 2a-k, 6a,b A suspension of 0.009 mol of crushed sulfur in 9 mL of morpholine was stirred for 5 minutes. A solution of 0.003 mol of the corresponding chloroacetamide 1a-k or 5a, b in 3 mL of DMF was added in portions to the formed cherrybrown solution. The reaction mixture was continued to stir for 60 minutes, and then it was poured into 100 mL of water and left for 1 day. The precipitate formed was filtered off, washed with water, dried and recrystallized from alcohol. 2-Morpholin-4-yl-N-phenyl-2-thioxoacetamide (2a). White crystals; yield 0.41g (55%); mp 168-170°C; IR (cm1 ): 3313.55 (NH), 1655.81 (C=O), 1599.88 (C (...truncated)