LAUSR

Seven novel pyrazole derivatives (4a–g) and four novel starting compounds incorporating substituted pyridine moieties were synthesized successfully. Cell viability assay for the tested compounds was performed, and the inhibitory concentrationlogarithmic 50 (LogIC50) values of the compounds were calculated after a 24‐h treatment. Four of the examined compounds (3d, 3g, 4f, and 4g) showed comparable cytotoxic activity against CaCo‐2 compared to the standard drug docetaxel at 0.1 and 1 μM concentrations. Although the LogIC50 of docetaxel was −0.678 μM for CaCo‐2 cells at 24 h, the LogIC50 values of compounds were −0.794, −0.567, −0.657, and −0.498 μM, respectively. Five of the compounds (2d, 2g, 3d, 3g, and 4e) showed comparable cytotoxic activity against MCF‐7 at 0.1 μM concentration compared to docetaxel (p < 0.05). Docking studies revealed the compounds have a good affinity to the active site of the human topoisomerase II β enzyme. The antioxidant capacities of all compounds were determined using both 1,1‐diphenyl‐2‐picrylhydrazyl and metal chelation methods. Although the compounds did not show significant antioxidant activity, relatively effective are compounds 3c, 3d, and 3g, which are hydrazine derivatives with approximately 50% antioxidant activity of standard antioxidants at concentrations of 62.5 and 125 μg/ml.