Synthesis and evaluation of cytotoxic activities of artemisinin derivatives.

Artemisinin is a naturally occurring antimalarial agent which has shown potent anticancer activity. In this work, new artemisinin derivatives with the piperazine group were synthesized. The cytotoxic activities of derivatives 5a-5d were evaluated by MTT assay against ten cell lines. The results showed that 5a-5d were more effective in inhibiting cancer cell growth than artemisinin. 5d was the most active against HepG2 and PLC-PRF-5 cells and presented no cytotoxicity on L-02 cells. Hoechst 33342 staining and flow cytometry experiment revealed that 5d could induce HepG2 and PLC-PRF-5 cell apoptosis. Flow cytometry analysis showed that 5d induced the loss of mitochondrial membrane potential (MMP) and increased the levels of intracellular free calcium and reactive oxygen species. 5d also induced cell cycle arrest in G2/M phase in HepG2 cells. According to the results of Western blotting and caspase-3 kit, 5d could significantly increase the content of p53, bax, Apaf-1, and caspase-3 and decrease the protein level of bcl-2, pro-caspase-9, and pro-caspase-3 in HepG2 cells. These findings indicate that 5d activates the mitochondria-mediated apoptotic pathway in HepG2 cells and may merit further investigation as a potential therapeutic agent for hepatocellular carcinoma.