Chemistry
All laboratory grade reagents were obtained commercially from Aldrich or Merck Company. The reactions were monitored by thin layer chromatography (TLC) performed on commercially available Merck precoated plates (silica gel 60 F254, 0.25 mm). The structures of the synthesized compounds were confirmed by IR, LC/MS and 1HNMR. Perkin Elmer 843 IR and Agilent 6410 (QQQ) LC/MS were used to obtain IR and Mass spectra respectively.1HNMR spectra were recorded on a Bruker advance II (500 MHz) spectrophotometer using [D6] DMSO as a solvent. Water solubility was determined experimentally in 1.0 mL of sodium phosphate buffer (0.1 M, pH 7.4) at 25 ± 1 °C (
9,
15). The logP (octanol/water partition coefficient (P)) values were calculated by Crippen’s method using CS ChemBioDraw Ultra version 12.0 software and melting points were taken on a Electrothermal 9100 apparatus and are uncorrected. The designed compounds were synthesized as shown in
Figure 3.
Schematic representation of synthesis of the designed compounds. Reagents and conditions: (a) 4-aminobenzoic acid, anhydrous Na2CO3, THF, rt, 6-12 h, 60-85%; (b) H2SO4, EtOH, reflux, 24 h, 58-65%; (c) NH2NH2.H2O, EtOH, rt, 12 h, 70-80%; (d) phthalic anhydrides, toluene, rt, 24 h, 65-70%; (e) succinic anhydride, toluene, rt, 18 h, 72-80%.
General procedure for the preparation of 4-(4-substitutedbenzamido)benzoic acid (2a-2e)
A solution of 4-aminobenzoic acid (1.68 mmol) and para substituted benzoylchlorides (1.68 mmol) in dry THF, in presence of anhydrous Na2CO3 (1.68 mmol) was stirred at room temperature for 6-12 h. The solvent was evaporated and the precipitate was washed with water and recrystallized from ethanol 96% to give final products.
4-benzamidobenzoic acid (2a)
Yield: 85%; white crystalline powder; mp: 150-151 °C, IR (KBr): υ (cm-1) 2887-3045 (OH), 3340 (NH), 1675, 1650 (C=O); LC-MS (ESI) m/z = 242 (M+1, 25%), 264 (M+23, 100%).
4-(4-fluorobenzamido)benzoic acid (2b)
Yield: 80%; white crystalline powder; mp: 155-156 °C, IR (KBr): υ (cm-1) 2857-3125 (OH), 3379 (NH), 1696, 1685 (C=O); LC-MS (ESI) m/z = 260 (M+1, 30%), 282 (M+23, 100%).
4-(4-chlorobenzamido)benzoic acid (2c)
Yield: 75%; white crystalline powder; mp: 138-140 °C, IR (KBr): υ (cm-1) 2730-3045 (OH), 3320 (NH), 1695, 1670 (C=O); LC-MS (ESI) m/z = 276 (M+1, 60%), 298 (M+23, 100%).
4-(4-methylbenzamido)benzoic acid (2d)
Yield: 80%; white crystalline powder; mp: 145-147 °C, IR (KBr): υ (cm-1) 2630-3145 (OH), 3340 (NH), 1670, 1690 (C=O); LC-MS (ESI) m/z = 256 (M+1, 30%), 278 (M+23, 100%).
4-(4-methoxybenzamido)benzoic acid (2e)
Yield: 60%; cream crystalline powder; mp: 150-152 °C, IR (KBr): υ (cm-1) 2807-3015 (OH), 3320 (NH), 1695, 1660 (C=O); LC-MS (ESI) m/z = 272 (M+1, 40%), 294 (M+23, 100%).
General procedure for the preparation of Ethyl 4-(4-substitutedbenzamido)benzoate (3a-3e)
8.06 mmol of 2 was dissolved in ethanol (15 mL) and concentrated sulfuric acid (0.5 mL) was added. The solution was refluxed for 24 h. Then, ethanol was evaporated and the remnant was alkalized after being cooled in the ice bath with NaOH 20% and extracted with diethyl ether. The diethyl ether phase was washed first with aqueous NaOH 20% and water and dried with anhydrous sodium sulfate and evaporated.
Ethyl 4-benzamidobenzoate (3a)
Yield: 60%; white crystalline powder; mp: 95-97, IR (KBr): υ (cm-1) 3340 (NH), 1720, 1670 (C=O); LC-MS (ESI) m/z = 270 (M+1, 100%), 292 (M+23, 30%).
Ethyl 4-(4-fluorobenzamido)benzoate (3b)
Yield: 65%; white crystalline powder; mp: 90-92 °C, IR (KBr): υ (cm-1) 3330 (NH), 1715, 1670 (C=O); LC-MS (ESI) m/z = 288 (M+1, 100%), 310 (M+23, 55%).
Ethyl 4-(4-chlorobenzamido)benzoate (3c)
Yield: 63%; white crystalline powder; mp: 96-97 °C, IR (KBr): υ (cm-1) 3315 (NH), 1690, 1730 (C=O); LC-MS (ESI) m/z = 304 (M+1, 100%).
Ethyl 4-(4-methylbenzamido) benzoate (3d)
Yield: 65%; white crystalline powder; mp: 99-100 °C, IR (KBr): υ (cm-1) 3340 (NH), 1730, 1680 (C=O); LC-MS (ESI) m/z = 284 (M+1, 50%), 306 (M+23, 100%). Ethyl 4-(4-methoxybenzamido)benzoate (3e)
Yield: 58%; cream crystalline powder; mp: 105-106 °C, IR (KBr): υ (cm-1) 3330 (NH), 1715, 1690 (C=O); LC-MS (ESI) m/z = 300 (M+1, 100%).
General procedure for the preparation of 4-substituted-N-(4-hydrazinecarbonyl) phenyl)benzamide (4a-4e)
7.24 mmol of 3 and 10 mL hydrazine hydrate (200 mmol) were added to 10 mL ethanol. The mixture was stirred for 12 h at room temperature. Afterward, the solvent was evaporated and white precipitates washed with diethyl ether, and recrystallized from a mixture of ethanol and a few drops of water.
N-(4-(hydrazinecarbonyl)phenyl)benzamide (4a)
Yield: 80%; white crystalline powder; mp: 120-122 °C, IR (KBr): υ (cm-1) 3397, 3307 (NH), 1647 (C=O); LC-MS (ESI) m/z = 256 (M+1, 100%).
4-Fluoro-N-(4-hydrazinecarbonyl)phenyl)benzamide (4b)
Yield: 70%; white crystalline powder; mp: 125-126 °C, IR (KBr): υ (cm-1) 3336, 3317 (NH), 1659 (C=O); LC-MS (ESI) m/z = 274 (M+1, 100%).
4-Chloro-N-(4-hydrazinecarbonyl)phenyl)benzamide (4c)
Yield: 75%; white crystalline powder; mp: 127-129 °C, IR (KBr): υ (cm-1) 3340, 3327 (NH), 1670 (C=O); LC-MS (ESI) m/z = 290 (M+1, 100%).
4-Methyl-N-(4-hydrazinecarbonyl)phenyl) benzamide (4d)
Yield: 80%; white crystalline powder; mp: 120-121 °C, IR (KBr): υ (cm-1) 3336, 3307 (NH), 1659 (C=O); LC-MS (ESI) m/z = 270 (M+1, 100%).
4-Methoxy-N-(4-hydrazinecarbonyl) phenyl)benzamide (4e)
Yield: 70%; white crystalline powder; mp: 130-131 °C, IR (KBr): υ (cm-1) 3320, 3307 (NH), 1680 (C=O); LC-MS (ESI) m/z = 286 (M+1, 100%).
General procedure for the preparation of 2-(2-(4-(4-substitutedbenzamido)benzoyl)hydrazinyl)carbonylbenzoic acid (5a-5e )
A solution of 4 (1.68 mmol) and phtalic anhydrides (1.68 mmol) in dry toluene was stirred at room temperature for overnight. The solvent was evaporated and the precipitate was washed with water and recrystallized from ethanol 96%.
2-(2-(4-benzamido)benzoyl) hydrazinylcarbonylbenzoic acid (5a)
Yield: 70%; white crystalline powder; mp: 170 °C, IR (KBr): υ (cm-1) 2665-3315 (OH), 3268, 3231 (NH), 1694, 1666 (C=O); LC-MS (ESI) m/z = 404 (M+1, 100%); 1HNMR (DMSO/500 MHz): 7.57 (6H, m, H3, H4, H5-benzamido, H3, H4, H5-benzoicacid), 7.70 (1H, d, H6-benzoic acid, J = 8.0 Hz), 7.90 (2H, d, H3, H5-benzoyl, J = 8.0 Hz), 7.95 (2H, d, H2, H6-benzoyl, J = 8.0 Hz), 8.06 (2H, dd, H2, H6-benzamido, J = 8.0, 3.5 Hz), 10.35 (3H, s, NH), 12.00 (1H, br s, COOH).
2-(2-(4-(4-fluorobenzamido)benzoyl)hydrazinyl)carbonylbenzoic acid (5b)
Yield: 65%; white crystalline powder; mp: 172 °C, IR (KBr): υ (cm-1) 2657-3330 (OH), 3235, 3224 (NH), 1710, 1667 (C=O); LC-MS (ESI) m/z = 422 (M+1, 20%), 444 (M+23, 100%); 1HNMR (DMSO/500 MHz): 7.34 (2H, t, H3, H5-benzamido, J = 8.7 Hz), 7.58 (3H, m, H3, H4, H5-benzoicacid), 7.74 (1H, d, H6-benzoic acid, J = 8.5 Hz), 7.90 (2H, d, H3, H5-benzoyl, J = 8.5 Hz), 7.95 (2H, d, H2, H6-benzoyl, J = 8.5 Hz), 8.06 (2H, dd, H2, H6-benzamido, J = 8.7, 2.5 Hz), 10.35 (1H, s, NH), 10.45 (2H, br s, NH), 12.01 (1H, br s, COOH).
2-(2-(4-(4-chlorobenzamido)benzoyl)hydrazinyl)carbonylbenzoic acid (5c)
Yield: 70%; white crystalline powder; mp: 173 °C, IR (KBr): υ (cm-1) 2673-3270 (OH), 3250, 2865 (NH), 1677, 1657 (C=O); LC-MS (ESI) m/z = 438 (M+1, 100%); 1HNMR (DMSO/500 MHz): 7.14 (2H, d, H3, H5-benzamido, J = 8.7 Hz), 7.55 (3H, m, H3, H4, H5-benzoicacid), 7.74 (1H, d, H6-benzoic acid, J = 8.7 Hz), 7.80 (2H, d, H3, H5-benzoyl, J = 8.5 Hz), 7.90 (2H, d, H2, H6-benzoyl, J = 8.5 Hz), 8.00 (2H, d, H2, H6-benzamido, J = 8.7 Hz), 10.05 (1H, s, NH), 10.35 (2H, br s, NH), 12.20 (1H, br s, COOH).
2-(2-(4-(4-methylbenzamido)benzoyl)hydrazinyl)carbonylbenzoic acid (5d)
Yield: 65%; white crystalline powder; mp: 174 °C, IR (KBr): υ (cm-1) 2859-3400 (OH), 3308, 3227 (NH), 1700, 1680 (C=O); LC-MS (ESI) m/z = 418 (M+1, 100%), 440 (M+23, 60%); 1HNMR (DMSO/500 MHz): 2.39 (3H, s, CH3), 7.04 (2H, d, H3, H5-benzamido, J = 8.1 Hz), 7.25 (3H, m, H3, H4, H5-benzoicacid), 7.44 (1H, d, H6-benzoic acid, J = 8.7 Hz), 7.70 (2H, d, H3, H5-benzoyl, J = 8.0 Hz), 7.80 (2H, d, H2, H6-benzoyl, J = 8.0 Hz), 7.90 (2H, d, H2, H6-benzamido, J = 8.1 Hz), 10.25 (3H, s, NH), 12.20 (1H, br s, COOH).
2-(2-(4-(4-methoxybenzamido)benzoyl)hydrazinyl)carbonylbenzoic acid (5e)
Yield: 68%; white crystalline powder; mp: 170 °C, IR (KBr): υ (cm-1) 2940-3492 (OH), 3318, 3228 (NH), 1712, 1643 (C=O); LC-MS (ESI) m/z = 434 (M+1, 100%), 456 (M+23, 80%); 1HNMR (DMSO/500 MHz): 3.84 (3H, s, OCH3), 6.95 (2H, d, H3, H5-benzamido, J = Rezaee zavareh E et al. / IJPR (2014), 13 (supplement): 51-59 56
8.1 Hz), 7.05 (3H, m, H3, H4, H5-benzoicacid), 7.20 (1H, d, H6-benzoic acid, J = 8.7 Hz), 7.30 (2H, d, H3, H5-benzoyl, J = 8.5 Hz), 7.60 (2H, d, H2, H6-benzoyl, J = 8.5 Hz), 7.80 (2H, d, H2, H6-benzamido, J = 8.1 Hz), 10.00 (3H, s, NH), 12.00 (1H, br s, COOH).
General procedure for the preparation of 4-(2-(4-(4-substitutedbenzamido)benzoyl)hydrazinyl)-4-oxobutanoic acid (6a-6e)
A solution of 4 (1.68 mmol) and succinic anhydride (1.68 mmol) in dry toluene was stirred at room temperature for 18 h. The solvent was evaporated and the precipitate was washed with water and recrystallized from methanol.
4-(2-(4-benzamidobenzoyl) hydrazinyl)-4-oxobutanoic acid (6a)
Yield: 80%; white crystalline powder; mp: 172 °C, IR (KBr): υ (cm-1) 2890-3402 (OH), 3235, 3021 (NH), 1684, 1667 (C=O); LC-MS (ESI) m/z = 356 (M+1, 100%), 378 (M+23, 50%); 1HNMR (DMSO/500 MHz): 2.40 (4H, s, CH2CH2), 7.57 (3H, m, H3, H4, H5-benzamido), 7.95 (4H, m, H2, H3, H5, H6-benzoyl), 8.27 (2H, dd, H2, H6-benzamido, J = 8.7, 3.5 Hz), 10.18 (3H, s, NH), 12.10 (1H, br s, COOH).
4-(2-(4-(4-fluorobenzamido)benzoyl)hydrazinyl)-4-oxobutanoic acid (6b)
Yield: 72%; white crystalline powder; mp: 170 °C, IR (KBr): υ (cm-1) 2936-3373 (OH), 3306, 3262 (NH), 1685, 1649 (C=O); LC-MS (ESI) m/z = 374 (M+1, 100%), 396 (M+23, 90%); 1HNMR (DMSO/500 MHz): 2.48 (4H, s, CH2CH2), 7.37 (2H, t, H3, H5-benzamido, J = 8.7 Hz), 7.90 (4H, m, H2, H3, H5, H6-benzoyl), 8.07 (2H, dd, H2, H6-benzamido, J = 8.7, 2.5 Hz), 10.18 (1H, s, NH), 10.44 (1H, s, NH), 10.57 (1H, s, NH), 12.10 (1H, br s, COOH).
4-(2-(4-(4-chlorobenzamido)benzoyl)hydrazinyl)-4-oxobutanoic acid (6c)
Yield: 75%; white crystalline powder; mp: 168 °C, IR (KBr): υ (cm-1) 2965-3492 (OH), 3297, 3043 (NH), 1686, 1644 (C=O); LC-MS (ESI) m/z = 390 (M+1, 100%); 1HNMR (DMSO/500 MHz): 2.38 (4H, s, CH2CH2), 7.27 (2H, d, H3, H5-benzamido, J = 8.7 Hz), 7.80 (4H, m, H2, H3, H5, H6-benzoyl), 8.00 (2H, d, H2, H6-benzamido, J = 8.7 Hz), 10.28 (1H, s, NH), 10.40 (1H, s, NH), 10.57 (1H, s, NH), 12.10 (1H, br s, COOH).
4-(2-(4-(4-methylbenzamido)benzoyl)hydrazinyl)-4-oxobutanoic acid (6d)
Yield: 80%; white crystalline powder; mp: 160 °C, IR (KBr): υ (cm-1) 2942-3501 (OH), 3312, 3273 (NH), 1702, 1661 (C=O); LC-MS (ESI) m/z = 370 (M+1, 100%); 1HNMR (DMSO/500 MHz): 2.39 (3H, s, CH3), 2.48 (4H, s, CH2CH2), 7.07 (2H, d, H3, H5-benzamido, J = 8.7 Hz), 7.50 (4H, m, H2, H3, H5, H6-benzoyl), 7.95 (2H, d, H2, H6-benzamido, J = 8.7 Hz), 10.20 (3H, s, NH), 12.00 (1H, br s, COOH).
4-(2-(4-(4-methoxybenzamido)benzoyl)hydrazinyl)-4-oxobutanoic acid (6e)
Yield: 72%; white crystalline powder; mp: 165 °C, IR (KBr): υ (cm-1) 2981-3513 (OH), 3323, 3284 (NH), 1709, 1667 (C=O); LC-MS (ESI) m/z = 386 (M+1, 20%), 408 (M+23, 100%); 1HNMR (DMSO/500 MHz): 2.38 (4H, s, CH2CH2), 3.84 (3H, s, OCH3), 7.00 (2H, d, H3, H5-benzamido, J = 8.3 Hz), 7.30 (4H, m, H2, H3, H5, H6-benzoyl), 7.75 (2H, d, H2, H6-benzamido, J = 8.3 Hz), 10.70 (3H, s, NH), 12.00 (1H, br s, COOH).
Docking studies
The high resolution crystal structure of sEH (PDB code: 3ANS) complexed with 4-cyano-N-[(1S, 2R)-2-phenylcyclopropyl]benzamide was retrieved from RCSB Protein Data Bank. The structures of compounds were investigated using the Lamarckian genetic algorithm search method implemented in AutoDock 4.0 software. The receptors were kept rigid, and ligands were allowed to be flexible. Polar hydrogens and Kollman united atom partial charges were added to the individual protein atoms. Each structure was energy minimized under MM+ method in HyperChem8 software and converted to pdbqt format file using AutoDockTools 4.0 version1.5.4. A docking grid box was built with 40, 40 and 40 points in 25.8460, 24.0730 and 114.8150 directions in the catalytic site of protein and the number of generations and maximum number of energy evaluations was set to 100 and 2,700,000, respectively. Docking results were clustered with a root mean square deviation (RMSD) of 0.5 Å and evaluated by Pymol software.
In-vitro biological activity
Biological evaluation was performed by Cayman fluorescence-based human soluble epoxide hydrolase assay kit (item number 10011671). The enzyme and inhibitors were incubated for 15 min in 25 mM Bis-Tris/HCl buffer (200 μL; pH 7.0) at 30 °C. 3-phenyl-cyano (6-methoxy-2-naphthalenyl) methyl ester-2-oxiraneacetic acid (PHOME) was used as the substrate for assay. The reference inhibitor for assay is AUDA, one of the most effective inhibitors of sEH with 50% inhibitory activity in 1 nM concentration. Test samples were dissolved in DMSO and tested in 1 nM concentration in duplicate to the determination of the inhibitory activity.