No abstract

Sixteen Schiff bases of quinazolin‐4‐one‐linked 1,3,4‐oxadiazoles were synthesized by reaction with different aromatic aldehydes. Purity of newly synthesized derivatives was confirmed through thin‐layer chromatography, combustion analysis, and melting point. The structure of the derivatives was confirmed by determining infrared spectroscopy, nuclear magnetic resonance, and mass spectroscopy. All the synthesized derivatives were evaluated for their analgesic and anti‐inflammatory activities in mice and rats, respectively. In animal studies, the derivative (E)‐3‐(5‐(4‐(4‐methoxybenzylideneamino)phenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2‐phenylquinazolin‐4(3H)‐one showed more potent analgesic activity and the derivative (Z)‐3‐(5‐(2‐(2‐hydroxybenzylideneamino)phenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2‐phenylquinazolin‐4(3H)‐one showed more potent anti‐inflammatory activity as compared with other derivatives. The results of the present study indicate that reactions of 3‐(5‐(4‐aminophenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2‐phenylquinazolin‐4(3H)‐one and 3‐(5‐(2‐aminophenyl)‐1,3,4‐oxadiazol‐2‐yl)‐2‐phenylquinazolin‐4(3H)‐one with different aromatic aldehydes produce Schiff bases of quinazolin‐4‐one‐linked 1,3,4‐oxadiazoles with potent analgesic and anti‐inflammatory activities.

A plethora of non‐steroidal anti‐inflammatory drugs are available in the market with adverse side effects like gastrointestinal irritation, bleeding, and ulceration. Currently, the focus of researcher on the development of better, synergistic molecules by the hybridization of two or more active biomolecule or ligands to develop newer derivative possessing good anti‐inflammatory activity with minimum side effects. In line with this, the present study was designed to synthesize a series of merged pharmacophore contaning1,2,4‐triazoles and substituted benzyl groups via thio linkage. Purity of the derivatives was confirmed by thin‐layer chromatography, combustion analysis, and melting point. Structure of these derivatives was set up by determining infrared spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectroscopy. All the synthesized derivatives were evaluated for their analgesic and anti‐inflammatory activities in mice and rats, respectively. In animal studies, the derivative 3‐(5‐(4‐nitrobenzylthio)‐4H‐1,2,4‐triazol‐3‐yl) pyridine showed more potent analgesic activity, and the derivative 3‐(5‐(2,4‐dimethylbenzylthio)‐4H‐1,2,4‐triazol‐3‐yl) pyridine showed more potent anti‐inflammatory activity as compared with other derivatives. The results of the present study indicate that reaction of pyridine linked 1,2,4‐triazole‐3‐thiol with different substituted benzyl halides to produce merged pharmacophore contaning1,2,4‐triazoles and substituted benzyl groups with potent analgesic and anti‐inflammatory activities. Docking studies were performed by using Argus lab, and all the derivatives exhibited good docking scores between −10 and −12 kcal/mol and were better as compared with standard drugs aspirin and indomethacin against cyclooxygenase‐2. Among all compounds, 3j has shown the maximum docking score and found in agreement to in pharmacological activities.

in Wiley Online Library (wileyonlinelibrary.com).Novel hybrid molecules were synthesized through the amalgamation of quinoxaline residue with 1,3,4oxadiazole molecule. The purity of obtained 1,3,4-oxadiazoles derivatives containing quinoxaline residue (total 11) was confirmed through thin-layer chromatography, combustion analysis, and melting point, whereas their structures were confirmed by infrared spectroscopy, nuclear magnetic resonance, and mass spectroscopy. In animal studies, the derivatives 4-(5-(4-(3-methylquinoxalin-2-yl)phenyl)-1,3,4-oxadiazol-2-yl)benzenamine and 2-(5-(4-(3-methylquinoxalin-2-yl)phenyl)-1,3,4-oxadiazol-2-yl)benzenamine showed excellent analgesic and anti-inflammatory activities, respectively, as compared with other derivatives. In order to rationalize the biological results of the derivatives, molecular docking studies were performed using Argus lab. The compounds exhibited good docking scores between À12.987 and À9.92 kcal/mol against cyclooxygenase-II (5IKQ) protein fragment.

The aim of the present investigation was to synthesize, characterize and evaluate analgesic and anti- inflammatory activities of 2, 5-disubstituted 1, 3, 4-oxadiazole derivatives. The reaction of starting material 4-chloro-m-cresol with ethyl chloroacetate in dry acetone affords ethyl (4-chloro-3-methylphenoxy) acetate, which after reacting with the hydrazine hydrate in ethanol yields 2(4-chloro-3-methylphenoxy) acetohydrazide. When 2(4-chloro-3-methylphenoxy) acetohydrazide was treated with different aromatic aldehydes, aromatic acids and carbon disulfide in alcoholic solution, different 3-acetyl-5-[(4-chloro-3-methylphenoxy) methyl]-2-aryl-2, 3-dihydro-1, 3, 4-oxadiazole and 2-[(4-chloro-3-methylphenoxy) methyl]-5-aryl-1, 3, 4-oxadiazole derivatives were obtained. Purity of the derivatives was confirmed by thin layer chromatography and melting point. Structure of these derivatives was set up by determining infrared spectroscopy, nuclear magnetic resonance spectroscopy and mass spectroscopy. Further, the synthesized derivatives were evaluated for their analgesic and anti-inflammatory activities in rodents. In animal studies, the derivatives 3-acetyl-5-[(4-chloro-3- methylphenoxy)methyl]-2-(4-methoxyphenyl)-2,3-dihydro-1, 3, 4-oxadiazole and 4-{5-[(4-chloro-3- methylphenoxy)methyl]-1, 3, 4-oxadiazol-2-yl}pyridine show more potent analgesic activity and the derivatives 2-{3-acetyl-5-[(4-chloro-3-methylphenoxy)methyl]-2,3-dihydro-1, 3, 4-oxadiazol-2-yl}phenol and 3-acetyl-5- [(4-chloro-3-methylphenoxy)methyl]-2-(4-methoxyphenyl)-2,3-dihydro-1, 3, 4-oxadiazole exhibit more potent anti-inflammatory effect as compared to other derivatives. The results of the current study indicate that cyclization of acetohydrazide produces novel oxadiazole derivatives with potent analgesic and anti-inflammatory activities.