Ring fusion strategy for synthesis and lead optimization of sulfur-substituted anthra[1,2-c][1,2,5]thiadiazole-6,11-dione derivatives as promising scaffold of antitumor agents.

A series of sulfur-substituted anthra[1,2-c][1,2,5]thiadiazole-6,11-diones were synthesized and evaluated using the cell proliferations, apoptosis and NCI-60 cell panel assays. Also, the signaling pathways that account for their activities were investigated. Compounds 2, 3, 4a, 4d, 4f, 4i, 4k, 5b, 5c, 5d, 5f, 5g, 6b, 6c, 6d, 6e, 6g, 7a and 7g were selected by NCI. Among the tested compounds, 6g appeared to be the most active compound of this series that not only induced apoptosis in DU-145 cancer cells but also attenuated the ERK1/2 and p38 signaling pathways. All test compounds exhibited diverse cytostatic and cytotoxic activities that warrant further development as potential anticancer agents.