Anti-acute myeloid leukemia activity of 2-chloro-3-alkyl-1,4-naphthoquinone derivatives through inducing mtDNA damage and GSH depletion.

2-Chloro-3-alkyl-1,4-naphthoquinone derivatives were synthesized and tested as the anti-acute myeloid leukaemia agents. The compound 9b (2-chloro-3-ethyl-5,6,7-trimethoxy-1,4-naphthoquinone) was the most potent toward HL-60 leukaemia cells. In mechanistic study for 9b, the protein levels of mtDNA-specific DNA polymerase γ (poly-γ) and mtDNA transcription factor A (mt-TFA) were decreased after the 24 h treatment, showing the occurrence of mtDNA damage. And 9b triggered cell cycle arrest at S phase accompanied by a secondary block in G2/M phase which had a direct link to the process of mtDNA damage. The dissipations of mitochondrial membrane potential and ATP also proceeded. On the other hand, 9b promoted the generation of ROS and resulted in the oxidation of intracellular GSH to GSSG. This process was coupled to the formation of adduct between 9b and GSH, detected by the UV-Vis spectrum and HRMS analysis. Depletion of GSH by buthionine sulfoximine enhanced ROS level and produced higher cytotoxicity, suggesting GSH was involved in the anti-leukemic mechanism of 9b. Together, our results provide new insights on the molecular mechanism of the derivatives of 2-chloro-1,4-naphthoquinone and 9b might be useful for the further development into an anti-leukemia agent.