Novel pyrazolo[3,4-d]pyrimidine–hydantoin hybrids as selective anticancer agents: Synthesis, cytotoxicity, structural activity relationship (SAR), and molecular docking studies

Cancer remains one of the most serious global health challenges, and the limited selectivity and high toxicity of many current chemotherapeutic agents highlight the urgent need for new, more effective anticancer drugs. In this study, a novel series of pyrazolo[3,4-d]pyrimidine derivatives incorporating hydantoin, thioacrylonitrile, and thiophene moieties was designed and synthesized as potential selective anticancer agents. The synthesized compounds were evaluated for their cytotoxic activity using the MTT assay against human liver carcinoma (HePG-2) and breast adenocarcinoma (MCF-7) cell lines, in addition to normal VERO and WI-38 cells. Structure–activity relationship (SAR) analysis was performed to identify key structural features responsible for biological activity. Furthermore, molecular docking studies were conducted against human DNA topoisomerase (PDB: 1T8I) to investigate the possible binding modes and molecular interactions of the most active compounds. The novelty of this work lies in the rational hybridization of the pyrazolo[3,4-d]pyrimidine scaffold with hydantoin and thioacrylonitrile functionalities to enhance anticancer potency and selectivity. The results revealed that compounds 6, 8 , and 10 exhibited strong cytotoxic activity comparable to 5-fluorouracil, while showing lower toxicity toward normal cells. SAR studies demonstrated that the presence of open-chain thioacrylonitrile or thio-carbonyl groups is crucial for activity, whereas cyclization into thiophene or incorporation of an azo–hydantoin moiety leads to reduced potency. Molecular docking analysis of the compounds with potent anticancer activities 6 , 8 , 10, and 5-fluorouracil (reference) against PDB: 1T8I protein revealed distinct binding profiles. Compound 8 established superior binding affinity (S = -6.8623 kcal/mol). While compound 10 exhibited a good binding score (S = -6.8419 kcal/mol), proposing improved as a potential anticancer agent.