Design and Synthesis of Novel Hydrazone-Linked 1,2,3-Triazole-Pyrazole Derivatives: In vitro Cytotoxicity, Antimicrobial and Molecular Docking Studies

A series of novel hydrazone-linked 1,2,3-triazole-pyrazole derivatives (7a-l) were rationally designed and synthesised through an efficient multistep synthetic strategy. The key intermediates were constructed via diazotisation–azidation followed by cycloaddition to generate the 1,2,3-triazole core, which was further functionalised to afford the target hydrazone derivatives. Final compounds were evaluated for their in vitro anticancer and antimicrobial activities. Antiproliferative screening against selected human cancer cell lines revealed that compounds bearing electron-withdrawing substituents exhibited superior cytotoxicity compared to electron-donating analogues. Among the synthesised derivatives, 7d (p-Cl) and 7c (p-NO2) exhibited the lowest IC50 values against the MCF-7 cell line (0.10 and 0.55 µM, respectively), comparable to doxorubicin (0.92 µM) under the same conditions. In antibacterial assays, halogen and fluoro-substituted derivatives demonstrated comparatively improved activity, with compounds 7b, 7d, 7i and 7k showing notable potency. Antifungal evaluation revealed that nitro-, fluoro- and methoxy-substituted analogues, particularly 7c, 7e and 7f, displayed enhanced activity against the tested strains. Molecular docking studies suggested favourable binding interactions with selected biological targets. Based on the obtained results, it is concluded that hydrazone-linked 1,2,3-triazole-pyrazole hybrids act as promising scaffolds for further optimisation toward anticancer and antimicrobial applications.