Synthesis, characterization and studies on the antitumor activity of novel dibenzoxanthene derivatives

Three new dibenzoxanthenes were synthesized and their antitumor activity were investigated. Compounds 3a-3c showed significant cytotoxicity to HeLa cells. The 1,3-diphenylisobenzofuran (DBPF) assay demonstrated that compounds could produce singlet oxygen. Cell cloning and wound healing assays demonstrated that compounds 3a-3c effectively inhibited HeLa cell cloning and migration. After entering the mitochondria, the compounds caused a decrease in mitochondrial membrane potential, an increase in intracellular ROS and Ca2+levels, and blocked the cell cycle in the G2/M phase. Through protein immunoblotting, the apoptotic mechanism was studied, the results show that 3a-3c regulated Bcl-2 family protein, caused abnormal mitochondrial function, which led to mitochondrial apoptotic pathway. ROS, GPX4, GSH and MDA assay indicated that compounds 3a-3c caused intracellular lipid peroxidation in HeLa cells leading to ferroptosis. GSDME cleavage and elevation of LDH release induced the occurrence of pyroptosis. Therefore, we conclude that the compounds cause cell death through three pathways: apoptosis, ferroptosis and pyroptosis.