Design, synthesis, biological evaluation and molecular dynamic simulation study of 5-(phenoxymethyl)-1,2,4-oxadiazole derivatives as selective SphK1/2 inhibitors

• Design, synthesis and SAR analysis of novel SphK1/2 selective inhibitors. • Molecular docking and molecular dynamics simulations are investigated. • The SphK1 inhibitor 33b inhibited PASMCs proliferation and migration under hypoxia. • 33b is a substrate-competitive inhibitor, reducing S1P level in vitro and in vivo . • The SphK2 inhibitor 33i inhibited proliferation and migration of HepG-2. Sphingosine kinase (SphK1/2) is emerging as a promising target in the field of diseases associated with excessive cell proliferation through regulation of the dynamic balance between ceramide (Cer), sphingosine (Sph), and sphingosine-1-phosphate (S1P). In this work, we synthesized six series of SphK1/2 inhibitors. 33b demonstrated high selectivity and significant inhibition towards SphK1, and showed potential in the treatment of pulmonary arterial hypertension (PAH). Meanwhile, 33i exhibited high selectivity for SphK2, effectively inhibiting the proliferation and migration of cancer cells and causing a notable arrest in the G2 phase of the cell cycle. Molecular dynamic simulations investigated the interaction of 33b with Ser254, Asp421 in SphK1 and 33i with Asp586, Ser297 and Arg321 in SphK2 is essential for their binding. Subsequently, we confirmed that 33b is a substrate competitive inhibitor of SphK1, resulting in increased Sph levels and decreased S1P levels in vitro and in vivo . Finally, 33b and 33i showed half-lives of 9.01 h and 1.89 h in liver microsomes, respectively.