Design and synthesis of 2-phenylnaphthalenoids and 2-phenylbenzofuranoids as DNA topoisomerase inhibitors and antitumor agents

•Eight 2-phenylnaphthalenoids and twenty four 2-phenylbenzofuranoids were synthesized.•2-Phenylnaphthalenoids were TopoIIα poisons.•2-Phenylbenzofuranoids were TopoIIα catalytic inhibitors rather than poisons.•Scaffold hopping is useful to medicinal chemistry evolution of TopoIIα inhibitors.

Eight 2-phenylnaphthalenoids (2PNs) (3a–h) and twenty four 2-phenylbenzofuranoids (2PBFs) (4a-–4j, 5a–5j, 6a, 6f–6h) were successfully designed, synthesized and their antiproliferative and in vitro DNA topoisomerase inhibitory activities were evaluated. Nine compounds (four 2PNs and five 2PBFs) showed either TopoI or TopoIIα inhibitory activities. Six compounds (four 2PNs and two 2PBFs) exhibited potent cytotoxicity with IC50 values for 72 h exposure ranging from 0.3 to above 20 μM against MDA-MB-231, MDA-MB-435, HepG2 and PC3 cell lines. The two 2PBFs displayed comparable and even better antiproliferative as well as TopoIIα inhibitory activities than 2PNs. Interestingly, the active 2PBFs displayed different mechanisms of TopoIIα inhibition from that of 2PNs, suggesting that the chromophore scaffold replacement may result in a change of the binding site of inhibitors to TopoIIα. Furthermore, the mechanisms of antiproliferation on MDA-MB-231 cells indicate that compounds 5a and 5f are promising for further development of anticancer agents. The results of this study reveal that the evolutionary strategy of medicinal chemistry through scaffold hopping is a promising strategy for structure optimization of TopoIIα inhibitors.

Graphical abstractCompounds 5a and 5f selectively inhibit TopoIIα, induce DNA damage and apoptosis in MDA-MB-231 cells.Figure optionsDownload full-size imageDownload as PowerPoint slide