The Anti-Breast Cancer Activity of Dihydroartemisinin-5-methylisatin Hybrids Tethered via Different Carbon Spacers

Sixteen dihydroartemisinin-5-methylisatin hybrids 6a–c and 7a–m tethered via different carbon spacers were assessed for their antiproliferative activity against MCF-7, MDA-MB-231, MCF-7/ADR and MDA-MB-231/ADR breast cancer cell lines as well as cytotoxicity towards MCF-10A cells to investigate the influence of the length of carbon spacers on the activity. The preliminary results illustrated that the length of the carbon spacer was the main parameter which affected the activity, and hybrids tethered via the two-carbon linker showed the highest activity. Amongst the synthesized hybrids, the representative hybrid 7a (IC(50): 15.3–20.1 µM) not only demonstrated profound activity against both drug-sensitive and drug-resistant breast cancer cell lines, but also possessed excellent safety and selectivity profile. Collectivity, hybrid 7a was a promising candidate for the treatment of both drug-sensitive and drug-resistant breast cancers and worthy of further preclinical evaluations.