Skip to main content
. Author manuscript; available in PMC: 2020 Jun 25.
Published in final edited form as: Chem Biol. 2010 May 28;17(5):421–433. doi: 10.1016/j.chembiol.2010.04.012

Figure 3. Top1 Inhibitors.

Figure 3.

(A) Camptothecin and its clinical derivatives. The facile and reversible opening of the α-hydroxylactone E ring of camptothecin is shown at the top. Topotecan and irinotecan are the two FDA-approved camptothecins. Irinotecan is a prodrug; its active metabolite is SN-38. Belotecan is approved in South Korea.

(B) Synthetic E-ring-modified camptothecin derivatives. Whereas diflomotecan (a homocamptothecin) can still be converted irreversibly to a carboxylate, the α-keto derivative S39625 is chemically stable while still being a potent Top1 inhibitor.

(C) Noncamptothecins. The indenoisoquinolines and one dibenzonaphthyridinone are beginning clinical trials.