Design, robust synthesis, and anti-liver cancer activity of 2-hydrazono-5-acetyl-[1,3,4]thiadiazole and N'-ethylideneethanethiohydrazide derivatives: In vitro, gene expression, DNA damage, and DNA fragmentation.
A novel series of 2-hydrazono-5-acetyl-[1,3,4]thiadiazole (10-15) and N'-ethylideneethanethiohydrazide (17-21) derivatives were designed and synthesized using robust methodology and tested as anticancer agents against a panel of cancer cell lines, including PC3 (prostate cell line), A549 (lung carcinoma), HepG2 (hepatocellular carcinoma cell line), HCT116 (human colon cancer cell line), and the normal human fibroblast cell line (BJ1). The findings identified compounds coded 10 and 11 as the most promising candidates, with IC₅₀ values of 47 ± 0.24 μM and 50.8 ± 0.41 μM, respectively. Compound 10 exhibited selective cytotoxicity toward HepG2 cells with a selectivity index of 3.19. In contrast, the selectivity index for compound 11 could not be determined because it produced a negative effect on the BJ1 cells at the highest tested concentration. Furthermore, the mechanism of action of the most active compounds against liver cancer was explored through gene expression, DNA damage, and DNA fragmentation. Expression levels of the anti-apoptotic gene BCL-2 increased significantly (1 ± 0.046) in negative samples of liver cancer cell lines relative to the treated cell lines (10: 0.62 ± 0.033, and 11: 0.68 ± 0.038). BCL-2 expression decreased significantly in HepG2 + 10 (62% of control), followed by HepG2 + 11 (68% of control), and reached the lowest levels in HepG2 + Doxo (42% of control). In contrast, DNA damage values increased significantly in treated liver cancer cell line samples exposed to 10 (27.80 ± 1.36) and 11 (25.60 ± 1.29), as well as to the Doxo drug (33.20 ± 1.43). DNA fragmentation rates also increased significantly in treated liver cancer cells treated with 10 (24.48 ± 1.02), 11 (23.08 ± 0.94), and Doxo (29.54 ± 1.25) compared with the negative control.