Synthesis and Characterization of Some New Oxadiazole Derivatives as Antiinflammatory Agents

Oxadiazoles have impacted numerous areas of drug discovery like muscarinic antagonists, benzodiazepines receptor partial agonists, dopamine transporters, antirhinovirals, growth hormone secretagogues, 5-HT antagonists, antispasmodics, nematocidals, fungicidal and microbicides, analgesics, anti-inflammatory, anticonvulsant, antibacterial, immunosuppressants, antiplatelet and antithrombics. Oxadiazoles are known to be bio-isosters for amide and esters. Due to a good metabolic stability oxadiazole ring exhibits an improved pharmacokinetic and in-vivo performance. Owing to this property this heterocyclic ring is considered as an important structural motif for the pharmaceutical Industry. In the present work, an attempt was made to synthesize some novel oxadiazole derivatives by converting the Aromatic carboxylic acids into acid esters by conventional esterification. The esters obtained were treated with hydrazine hydrate to give aromatic hydrazides. Those hydrazides on refluxing with carbon di sulfide in presence of potassium hydroxide yielded different oxadiazole derivatives. Then those oxadiazole derivatives were subjected to acetylation and aromatic group attachment. The synthesized compounds were characterized and confirmed by IR and ¹HNMR spectroscopy and then screened for antiinflammatory activity. The anti-inflammatory activity of newly synthesized oxadiazole derivatives were carried out by the carrageenan induced rat hind paw edema method using Diclofenac sodium as standard. Among the twelve newly synthesized oxadiazole derivatives ten compounds showed considerable activity comparable with standard.