Novel nonsteroidal steroid sulfatase inhibitors containing glutamic acid unit

In the present work, we designed and successfully synthesized novel steroid sulfatase (STS) inhibitors based on coumarin, tyramine, triazole, and flavone cores with an additional glutamic acid residue in the structure. The molecular modeling studies revealed that designed derivatives have potential to bind to the molecular target active site, at least theoretically. The biological activity of synthesized compounds was evaluated under a two-step procedure including enzymatic assay and cellular studies using human choriocarcinoma JEG-3 cells. Among the synthesized compounds, the derivative 54E was the most active in both enzymatic and cellular experiments. This result agreed with the molecular modeling data, which indicated that derivative 54E demonstrates the highest affinity to the STS active site. In the enzymatic assay, the remaining STS activity values of 12.97, 17.58, and 20.52 % were observed at 10, 1, and 0.1 μM concentrations of compound 54E, respectively. The IC₅₀ value of 22 nM determined in an experiment with JEG-3 cells for compound 54E was close to the IC₅₀ value determined for the reference STS inhibitor Irosustat (2.7 nM). During the evaluation of the uptake mechanism of the compound 54E, we found that organic anion transporting polypeptides (OATPs) may be responsible for its internalization into the cells. Furthermore, the incubation of zebrafish larvae with the compound 54E revealed no detectable toxic effects in vivo indicating that the compound 54E is a very promising candidate for further preclinical investigations.