A series of novel indolylquinones have been synthesized by treating halogeno-quinone with
2-substituated indole derivatives in the presence of kalium carbonate and TEBA in acetonitrile at room
temperature. These compounds were evaluated for their antiproliferative activity against human
MDA-MB-231 and MCF-7 breast cancer cell lines. All the tested compounds showed potent mircomolar
cytotoxicity activity in both breast cancer cell lines. 3d (IC50 value ¼ 2.29 mg/mL for MCF-7 cells) and 3g
(IC50 value ¼ 3.99 mg/mL for MDA-MB-231 cells) displayed the most potent antiproliferative activity of
the series. Also, in vitro anticancer activity of the compounds further showed that bis-indolylquinones
were more active than mono-indolylquinones. Fluorescence microscopy analysis indicated that
compound 3d and 3g inhibited breast cancer cells proliferation by triggering apoptotic cell death.