6-Substituted 1,4-Naphthoquinone Oxime Derivatives (III): Synthesis and Cytotoxic Evaluation

As a continuous study, a set of 23 new 6-substituted 1,4-naphthoquinone oxime derivatives are synthesized and screened for their in vitro cytotoxic activity. Four of those oxime derivatives demonstrate more potent cytotoxic activity towards K562, HCT-15, and HCT-116 cell lines than a reference drug 5-Fu. In particular, compound 21g exhibits the strongest inhibitory activity against K562 cell lines with IC50 values of 1.25 μM. According to flow cytometry data, compound 21g can arrest cell cycle at S phase and induce a strong apoptotic response in K562 cells. The preliminary structure-activity relationship study shows that the nature of substituents in positions 6 and 1' of 1,4-naphthoquinone derivatives significantly affect their cytotoxic activity.