Structure-guided development of purine amide, hydroxamate, and amidoxime for the inhibition of non-small cell lung cancer.

An 8-oxopurine-6-carboxamide compound (1a) was previously identified as an inhibitor of non-small cell lung cancer (NSCLC). In this study, more than 30 purine-6-carboxamide derivatives with variations at the C2, N7, C8, and N9 positions were synthesized to investigate the structure-activity relationship as a basis for the construction of an advanced pharmacophore model. This model suggests that purine-6-hydroxamate and purine-6-amidoxime analogs could form more hydrogen bonds with a target protein to enhance the inhibitory activities against H1975 cells. Among the series of analogs, hydroxamate 17 and amidoxime 19a exhibited excellent potency against H1975 cells (IC < 1.5 μM) and other lung cancer cells with either wild-type or mutated epidermal growth factor receptor (EGFR). Mouse experiments indicated that compounds 17 and 19a were efficient anticancer agents with no appreciable toxicity. The mechanisms of action for the induction of cell apoptosis were determined to involve microtubule fragmentation and p53-mediated signaling pathways.