Synthesis and antitumor activity of novel aroylthiourea derivatives of podophyllotoxin

A novel series of 4β-[(4-substituted) aroylthiourea] derivatives of podophyllotoxin were synthesized and their abilities to inhibit the growth of cancer cells were investigated by MTT assay. Compound 4a possessed the highest cytotoxicity on HepG2, A549 and HCT-116 cancer cell lines with the IC50 values of 0.1 μM. Apoptosis in HCT-116 cells induced by compound 4a was observed by Hoechst33342-Propidium iodide (PI) and acridine orange (AO)-ethidium bromide (EB) double staining assays. DNA flow cytometric analysis revealed that 4a induced cell cycle arrest at G2/M phase and kDNA decatenation assay indicated that 4a inhibited topoisomerase IIα-mediated kDNA decatenation. Our results indicated that compound 4a possessed promising antitumor activity, which need to be studied further.