Design, synthesis, and hypoxia-inducible factor-1α inhibitory activity evaluation of panaxadiol derivatives containing a thiazole moiety

The hypoxia-inducible factor-1α (HIF-1α) pathway has been implicated in tumor angiogenesis, growth, and metastasis. Therefore, the inhibition of this pathway is an important therapeutic target for cancer. Here, three series of panaxadiol derivatives containing a thiazole moiety (5a-l, 7a-i, and 9a-i) were synthesized and evaluated for HIF-1α inhibitory activity using a Hep3B cell-based luciferase reporter assay. Compounds 5d and 7b showed the strongest inhibitory activity with IC50 values of 17.37 and 6.42 μM, respectively, and did not show any significant cytotoxicity. Western blot assay results indicated that these two compounds exhibited more potent inhibition, compared with panaxadiol, of the expression of HIF-1α protein in Hep3B cells at a concentration of 50 µM. Molecular docking experiments were also performed to investigate the structure–activity relationship.