Design, synthesis, molecular docking and anticancer activity of benzothiazolecarbohydrazide–sulfonate conjugates: insights into ROS-induced DNA damage and tubulin polymerization inhibition†

Abstract

A series of novel benzothiazolecarbohydrazide–sulfonate conjugates 6a–l were designed, synthesized, and then assessed as potential antiproliferative agents in three distinct human cancer cell lines: MCF-7 (breast cancer), HCT-116 (colon cancer), and PC3 (prostate cancer), along with a normal cell line (BJ-1). The reference standard used was 5-fluorouracil. The results obtained reveal that the newly synthesized analogs demonstrate varying degrees of cytotoxicity against the targeted cell lines; however, compounds 6i and 6e exhibited the highest efficacy against MCF-7, HCT-116, and PC3 cells with IC₅₀ values of 78.8 ± 2.6, 81.4 ± 1.9, and 90.6 ± 2.7 μM, respectively, compared to an IC₅₀ of 78.4 ± 4.2 μM for 5-FU in MCF-7 cells, 29.2 ± 1.7 μM in HCT-116 cells and >200 μM in PC3 cells. Moreover, the most potent compounds demonstrated acceptable safety profiles when evaluated aganist BJ-1 cells. Consequently, compound 6i, which possesses no cytotoxicity towards BJ-1 cells and displays promising anticancer activity, was further investigated for its impact on tubulin polymerization compared to control MCF-7 cells, 210.3 and 632.9 pg ml⁻¹, respectively. Compound 6i was found to significantly elevate the ROS levels in treated cancer cells, resulting in an 8.3-fold increase in DNA fragmentation compared to untreated cells. Additionally, it raised the percentage of accumulated cells in the G2 phase from 6.85% to 18.27% in MCF-7 cells. A molecular docking technique was conducted to elucidate the binding energy, binding pose, and binding interactions of compound 6i, revealing a strong fit within the active sites of the tubulin–colchicine binding site (CBS). This study provides valuable insights into the design and synthesis of novel anticancer agents targeting tubulin polymerization.