It is well-known that the hepatotoxicity of THA and its derivatives is a critical issue that needs to be addressed in the early stage of drug discovery. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide) colorimetric assay performed on human hepatocellular carcinoma (HepG2) cell line was applied to investigate the preliminary hepatotoxicity profile of all the developed derivatives . The results are summarized in Table . The IC₅₀ values of the synthesized compounds ranged from 2.71 to 120.3 µM. Among the compounds, the deuterated analogue of THA (7) exhibited the lowest cytotoxicity, followed by derivatives substituted with pyridine and pyrimidine of the THA scaffold, specifically 5a and 5e. However, all synthesized compounds demonstrated higher cytotoxicity than the reference compound THA.