Novel Canthin-6-one Derivatives: Design, Synthesis, and Their Antiproliferative Activities via Inducing Apoptosis, Deoxyribonucleic Acid Damage, and Ferroptosis

[Image: see text] A series of novel canthin-6-one (CO) derivatives (8a–l) were designed and synthesized by introducing different amide side chains at the C-2 position, and their water solubility, antiproliferative activity, and preliminary mechanism were investigated. Most compounds displayed high cytotoxicity exhibiting low-micromolar IC(50) values against four human cancer cell lines, especially HT29 cells. Meanwhile, the water solubility of active CO derivatives was significantly improved. Among these compounds, compound 8h with the N-methyl piperazine group exhibiting the highest antiproliferative capability with an IC(50) value of 1.0 μM against HT29 cells, which was 8.6-fold lower than that of CO. Furthermore, 8h could upregulate the levels of reactive oxygen species, leading to mitochondrial damage. In addition, 8h could promote cell apoptosis and DNA damage by regulating the expression of apoptosis-associated proteins (Bcl-2 and cleaved-caspase 3) and the DNA damage-associated protein (H2AX). Most importantly, 8h also exerted ferroptosis by reducing the GSH level and GPX4 expression as well as increasing the lipid peroxidation level. Thus, the novel CO derivative 8h with N-methylpiperazine represents a promising anticancer candidate and warrants a more intensive study.