Design, synthesis and biological evaluation of N-pyridinyl ureidobenzenesulfonates and their hydrochloride salts as novel water-soluble dihydroorotate dehydrogenase inhibitors inducing differentiation of acute myeloid leukemia cells

Abstract

A series of novel dihydroorotate dehydrogenase (DHODH) inhibitors designated as N-pyridinyl ureidobenzenesulfonates (PYRUB-SOs) and their hydrochloride salts were designed, synthesized, and evaluated for their biological activity. PYRUB-SOs exhibit antiproliferative activity at submicromolar to low micromolar concentrations on various cancer cell lines including, notably acute myeloid leukemia (AML) MOLM-13, THP-1 and HL-60 cells. Moreover, PYRUB-SO salts display higher aqueous solubility (up to 10 times) compared to their neutral counterparts. Additionally, the most potent PYRUB-SOs and their salts effectively arrest the progression of the cell cycle in the S-phase and induce the phosphorylation of histone H2AX, an indicator of replicative stress. They also inhibit DHDOH activity (IC₅₀ = 12-31 nM). In addition, molecular docking studies show their stable binding modes in the brequinar-binding site of DHODH. Furthermore, PYRUB-SOs trigger the differentiation of a significant portion of the population of both MOLM-13 and THP-1 cells as evidenced by increased CD11b single expression and increased CD11b and CD14 dual expression, respectively. Finally, they exhibit metabolic stability with half-lives varying from 57 to 216 min in rodent and human liver microsomes. Our study highlights that the new PYRUB-SO salts improve the water solubility of this new family of DHODH inhibitors while maintaining their biological activity.