Novel β-carboline-based indole-4,7-quinone derivatives as NQO1 inhibitor with potent antitumor activities by inducing ROS, apoptosis, and DNA damage.

Eighteen new β-carboline-based indole-4,7-quinone derivatives (12a-i and 13a-i) were designed and synthesized, and their in vitro and in vivo antiproliferative activities were studied. Most of target compounds showed strong inhibition on three human tumor cells' proliferation. In particular, the most active compound 13g not only displayed more prominent antiproliferative activities than β-lapachone, a clinical antitumor candidate, but also exerted significant NAD(P)H: quinone-oxidoreductase-1 (NQO1) inhibitory activity and NQO1-dependent cytotoxicity in HT29 cells. Furthermore, 13g dose-dependently induced high ROS levels in HT29 cells, and selectively inhibited cancer cell but not non-tumor colon cell proliferation in vitro. Importantly, 13g promoted HT29 cell apoptosis and DNA damage by regulating relative apoptotic proteins and H2AX expression. Finally, 13g displayed significant growth inhibition of HT29 human colorectal adenocarcinoma xenograft in mice without overt toxicity.