Antiplatelet properties of novel N-substituted-phenyl-1,2,3-triazole-4-acylhydrazone derivatives

This paper describes the design, synthesis and pharmacological evaluation of new N-acylhydrazone (NAH) compounds, belonging to the N-substituted-phenyl-1,2,3-triazole-4-acylhydrazone class ( 2a– p). Classical heteroaromatic ring bioisosterism strategies were applied to the previously reported N-phenylpyrazolyl-4-acylhydrazone derivative 1, elected as lead-compound due to its important anti-aggregating profile on arachidonic acid induced platelet aggregation (IC 50=24±0.5 μM), from which emerge this new series 2. These new compounds 2a– p were readily synthesized, characterized and tested on platelet aggregation assays induced by collagen (5 μg/mL), ADP (5 μM) and arachidonic acid (100 μM) in rabbit citrated platelet-rich plasma. Compounds 2b, 2d, and 2h were found to be the most potent, exhibiting a significant antiplatelet activity on arachidonic acid- and collagen-induced platelet aggregation. In addition, these new antiplatelet agents are free of gastric ulcerogenic effect and presented discrete anti-inflammatory and analgesic properties. The N- para-chlorophenyltriazolyl-4-acylhydrazone compound 2h produced the highest inhibitory effect on collagen (IC 50=21.6±0.4 μM) and arachidonic acid-induced platelet aggregation (IC 50=2.2±0.06 μM), suggesting that the nature of the substituent on the phenyl ring of the N-heteroaromatic system of NAH moiety may be an important structural requirement for the improvement of antiplatelet activity, in comparison with lead-series 1. The design, synthesis, and antiplatelet properties of new N-substituted-phenyl-1,2,3-triazole-4-acylhydrazone derivatives ( 2a– p) is reported.