Synthesis and Cytotoxicity of Some Thieno[2,3‐d]pyrimidine Derivatives

A series of compounds 5‐amino‐2‐ethylmercapto‐4‐phenyl‐6‐subistitutedthieno[2,3‐d]pyrimidines ( 8a–d ), 4‐chloro‐7‐ethylmercapto‐9‐phenylpyrimido[5′,4′:4,5]thieno[3,2‐d]triazine ( 9 ), and 2‐ethylmercapto‐8‐oxo‐4‐phenyl‐7‐(4‐chlorophenyl)pyrimido [4′,5′:4,5]thieno[2,3‐d]pyrimidine ( 10 ) were synthesized and their structures were confirmed by 1 H NMR , 13 C NMR, and MS . All compounds were evaluated for their IC 50 values against three cancer cell lines ( MCF ‐7, HUH ‐7 and BHK ) and WISH cells. The IC 50 of compound ( 8d ) was calculated for each cell line. Interestingly, the IC 50 for the normal human amnion WISH cell line was much higher (723 µg/mL) than those found for the tumor cell lines BHK (17 µg/mL), HUH ‐7 (5.8 µg/mL), and MCF ‐7 (8.3 µg/mL). The proliferation inhibition of normal ( WISH ) and tumor ( BHK , HUH ‐7, and MCF ‐7) cells by compound ( 8d ) was investigated using MTT assay, and the IC 50 was calculated after 48 h of treatment for each cell line.