Identification of novel piperazinylquinoxaline derivatives as potent phosphoinositide 3-kinase (PI3K) inhibitors

Background: Development of small-molecule inhibitors targeting phosphoinositide 3-kinase (PI3K) has been an appealing strategy for the treatment of various types of cancers. Methodology/Principal Finding: Our approach was to perform structural modification and optimization based on previously identified morpholinoquinoxaline derivative WR1 and piperidinylquinoxaline derivative WR23 with a total of forty-five novel piperazinylquinoxaline derivatives synthesized. Most target compounds showed low micromolar to nanomolar antiproliferative potency against five human cancer cell lines using MTT method. Selected compounds showed potent PI3Kα inhibitory activity in a competitive fluorescent polarization assay, such as compound 22 (IC₅₀ 40 nM) and 41 (IC₅₀: 24 nM), which induced apoptosis in PC3 cells. Molecular docking analysis was performed to explore possible binding modes between target compounds and PI3K. Conclusions/Significance: The identified novel piperazinylquinoxaline derivatives that showed potent PI3Kα inhibitory activity and cellular antiproliferative potency may be promising agents for potential applications in cancer treatment.