Breast cancer is the most common type of cancer in women. Although current treatments can increase patient survival, they are rarely curative when the disease is advanced (metastasis). Therefore, there is an urgent need to develop new cytotoxic drugs with a high selectivity toward cancer cells. Since repurposing approved drugs for cancer therapy has been a successful strategy in recent years, in this study, we screened a library of antiviral piperazine-derived compounds as anticancer agents. The compounds included a piperazine ring and aryl urea functions, which are privileged structures present in several anti-breast cancer drugs. The selective cytotoxic activity of a set of thirty-four 4-acyl-2-substituted piperazine urea derivatives against MCF7 breast cancer cells and MCF 10A normal breast cells was determined. Compounds 31, 32, 35, and 37 showed high selective anticancer activity against breast cancer cells and were also tested against another common type of cancer, non-small cell lung cancer (A549 lung cancer cells versus MRC-5 lung normal cells). Compounds 35 and 37 also showed selectivity against lung cancer cells. These results suggest that compounds 35 and 37 may be promising hit compounds for the development of new anticancer agents.

We recently screened a series of new aziridines β-D-galactopyranoside derivatives for selective anticancer activity and identified 2-methyl-2,3-[N-(4-methylbenzenesulfonyl)imino]propyl 2,3-di-O-benzyl-4,6-O-(S)-benzylidene-β-D-galactopyranoside (AzGalp) as the most promising compound. In this article, we explore the possible mechanisms involved in the cytotoxicity of this aziridine and evaluate its selective anticancer activity using cancer cells and normal cells from a variety of tissues. Our data show that AzGalp induces DNA damage (comet assay). Cells deficient in the nucleotide excision repair (NER) pathway were hypersensitive to the cytotoxicity of this compound. These results suggest that AzGalp induces bulky DNA adducts, and that cancer cells lacking a functional NER pathway may be particularly vulnerable to the anticancer effects of this aziridine. Several experiments revealed that neither the generation of oxidative stress nor the inhibition of glycolysis played a significant role in the cytotoxicity of AzGalp. Combinations of AzGalp with oxaliplatin or 5-fluorouracil slightly improved the ability of both anticancer drugs to selectively kill cancer cells. AzGalp also showed selective cytotoxicity against a panel of malignant cells versus normal cells; the highest selectivity was observed for two acute promyelocytic leukemia cell lines. Additional preclinical studies are necessary to evaluate the anticancer potential of AzGalp.