Synthesis and biological evaluation of phosphoinositide 3-kinase (PI3K) inhibitors based on a quinoxaline scaffold

Based on the structure of inhibitors XL765 and WR23, the quinoxaline scaffold was selected as an attractive structure for drug design. In this protocol, the 2-position of quinoxaline was modified with a substituted phenoxy fragment. Meanwhile, the linking chain at the 3-position was changed to a sulfonyl hydrazine or was removed. A series of substituent groups were added at the 6-position of the quinoxaline scaffold. Twenty-two quinoline derivatives were designed and synthesized, and their structures were confirmed by ¹H NMR, ¹³C NMR, and ESI-MS. All compounds were screened for anti-tumor activity in vitro in A549, MCF-7, HCT-116 and HepG2 cancer cells. The results showed that P6b was effective, P6e and P6f had better activity against HCT116 (IC₅₀=3.24, 4.78 and 4.50 μmol·L^-1), and P6d had strong inhibitory effect on MCF-7 (IC₅₀=0.228 7 μmol·L^-1).