Synthesis of N-arylidene-2-(2-Phenoxyphenyl) Acetohydrazides as Anti-Inflammatory Agents

Diclofenac sodium has been used for its anti-inflammatory actions for about 28 years, but since all the non-steroidal anti-inflammatory drugs (NSAIDs) suffer from the lethal gastro intestinal (GI) toxicities, diclofenac sodium is not an exception. The free –COOH group is thought to be responsible for the GI toxicity associated with all traditional NSAIDs. In the present research, the main motto was to develop new chemical entities as potential anti-inflammatory agents with no GI toxicities. A new type of 2-(2-phenoxyphenyl) acetohydrazide possessing N-arylidene substituents, was synthesized for evaluation as anti-inflammatory agents. The starting material 2-(2-Phenoxyphenyl) acetohydrazide was synthesized from 2-phenoxybenzoic acid in several steps according to the previous published method. Various substituted arylidene-2-phenoxynicotinic acid hydrazide derivatives were synthesized by the reaction of hydrazide 17 with selected aldehydes and screened for their potential anti-inflammatory activity. The structure of synthesized compounds was confirmed by different nuclear magnetic resonance technique, Fourier transform infrared spectroscopy (FTIR) and Mass-spectrometry data format. Qualitative structure-activity relationship data, acquired using the carrageenan-induced rat paw edema assay, showed that this group of arylidene-2-phenoxybenzoic acid hydrazides exhibit anti-inflammatory activity with significant reduction of rat paw edema (17-58% reduction in inflammation at different time intervals) in comparison with control group and a moderate to good activity range in comparison with diclofenac as the reference drug. Compounds 9a, 9d and 9e exhibited the most prominent and consistent anti-inflammatory activity. The compound, N-(4-Chlorobenzylidene)-2-(2-phenoxyphenyl) acetohydrazide (9d), exhibited the most in-vivo activity (32-58% reduction in inflammation) compared to the reference drug diclofenac (35-74% reduction in inflammation) in a carrageenan induced rat paw-edema assay.