Design, synthesis, and biological evaluation of novel diclofenac analogs as promising anti-inflammatory agents

Abstract

INTRODUCTION: Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used as analgesics and antipyretics in the treatment of pain, fever, and rheumatoid arthritis. Major side effect with treatment of NSAIDs is gastric irritation. 1,3,4-thiadiazole is an imperative scaffold since several of these derivatives are known to be associated with multiple biological activities such as anti-inflammatory, antibacterial, anti-cancer, anti-tubercular, and immunosuppressive. Literature survey reveals that certain compounds bearing this nucleus possess significant anti-inflammatory activity with reduced ulcerogenic effect. MATERIALS AND METHODS: In the present research work, we have synthesized thirteen 2-(2-[2,6-dichlorophenylamino] phenyl) acetohydrazide derivatives (4a–4m) and four 2,6-dichloro-N-(2-[6-phenylimidazo[2,1-b][1,3,4]thiadiazol-yl] methyl] phenyl) benzenamine derivatives (6a–6d) derived from diclofenac. All these newly synthesized compounds were screened for in vivo acute anti-inflammatory activity by carrageenan-induced rat paw edema method at a dose of 10 mg/kg bw. RESULTS AND DISCUSSION: Structures of these novel compounds were characterized based on their physicochemical and spectral analysis. Perusal of the activity data strongly suggests that compound 4d was most promising with significant anti-inflammatory activity, while moderate to good activity was observed for compounds 4a, 4c, g, 4i, and 4l. Among the imidazo (2,1-b) 1,3,4-thiadiazole series (6a–6d), compound 6b exhibited excellent anti-inflammatory activity, while compounds 6a, 6c and 6d displayed reasonably to good anti-inflammatory activity as compared to standard drug diclofenac. CONCLUSION: Among the series of synthesized compounds, two derivatives (4d and 6b) have displayed the most encouraging results and could be further exploited for developing newer anti-inflammatory agents with better efficacy and safety, which necessitates further investigations.

Keywords

• 1
• 3
• 4-thiadiazole
• anti-inflammatory activity
• Diclofenac
• Schiff base