7-Ethylcamptothecin is derived from Camptothecin with anti-cancer activity against various murine tumors through inhibition of Topo I (topoisomerase).

Rubitecan is an oral topoisomerase inhibitor.

9-Aminocamptothecin, a natural product isolated and purified from the barks of Camptotheca acuminata Decne, is an active derivative of camptothecin, which belongs to the general group of chemotherapy drugs called topoisomerase inhibitors. 9-Aminocamptothecin is an inhibitor of Topo I.

Topotecan HCl is the first topoisomerase I-directed cytotoxic agent to enter clinical trials in the United States.

SN-38 is an active metabolite of CPT-11 that inhibits DNA topoisomerase I, DNA synthesis and causes frequent DNA single-strand breaks.

Irinotecan HCl inhibits topoisomerase 1 and prevent DNA from unwinding.

Sophoridine is naturally occuring alkaloid found in the plant Sophora flavescens, which could suppresses cell growth of human medulloblastoma through the inhibition of the FoxM1, NF‑κB and AP‑1 signaling pathway.

Camptothecin is a potent DNA enzyme topoisomerase I (topo I) inhibitor with an IC50 and IC70 of 50 nM and 0.225 μM for breast cancer cell line MDA-MB-231.