Oxoisoaporphine as Potent Telomerase Inhibitor

Two compounds previously isolated from traditional Chinese medicine, Menispermum dauricum (DC), 6-hydroxyl-oxoisoaporphine (H-La), and 4,6-di(2-pyridinyl) benzo[h] isoindolo[4,5,6-de] quinolin-8(5H)-one (H-L-b), were known to have in vitro antitumor activity and to selectively bind human telomeric, c-myc, and bcl-2 G-quadruplexes (G4s). In this study, the binding properties of these two compounds to telomerase were investigated through molecular docking and telomeric repeat amplication protocol and silver staining assay (TRAP-silver staining assay). The binding energies bound to human telomerase RNA were calculated by molecular docking to be 6.43 and 9.76 kcal/mol for H-L-a and H-L-b, respectively. Compared with H-L-a, the ligand H-L-b more strongly inhibited telomerase activity in the SK-OV-3 cells model.