Synthesis, In Vitro Cytotoxicity and Bleomycin‐Dependent DNA Damage Evaluation of Some Heterocyclic‐Fused Pyrimidinone Derivatives

In this work, enaminones 1 a,b were used as precursors for the synthesis of novel fused heterocyclic ring systems (e. g. pyrazolo[3,4‐ d ]pyrimidinones, isoxazolo[5,4‐ d ]pyrimidinones, pyrimido[4,5‐ d ]pyrimidinones and related compounds) via their reactions with some N ‐nucleophiles. The cytotoxic activity of the designed products was assessed via the MTT colorimetric assay against human liver hepatocellular carcinoma (HepG2) and normal lung fibroblasts (WI‐38) cell lines using doxorubicin as a reference standard. Among the screened compounds, pyrazolo[3,4‐ d ]pyrimidinone 3 d and pyrimido[4,5‐ d ]pyrimidinones 6 a,b , 7 b and 8 a,b were selected as lead molecules because they showed significant activity against HepG2 cells and a weak cytotoxic effect against WI‐38 cells. In further, all of the compounds were subjected to the bleomycin‐dependent DNA damage studies. The results indicated that most of them have a remarkable ability to protect DNA compared to ascorbic acid as a standard compound.