page_title: Camptothecin
section_title: Structures
hierarchical_section_title: Camptothecin / Structures
context_page_description: Camptothecin is a topoisomerase poison. It was discovered in 1966 by M. E. Wall and M. C. Wani in systematic screening of natural products for anticancer drugs. It was isolated from the bark and stem of Camptotheca acuminata, a tree native to China used as a cancer treatment in Traditional Chinese Medicine. CPT showed remarkable anticancer activity in preliminary clinical trials. However, it has low solubility, so synthetic and medicinal chemists have developed numerous syntheses of camptothecin and various derivatives to increase the benefits of the chemical, with good results. Four CPT analogues have been approved and are used in cancer chemotherapy today, topotecan, irinotecan, belotecan, and trastuzumab deruxtecan. Camptothecin has also been found in other plants including Chonemorpha fragrans.
context_section_description: CPT has a planar pentacyclic ring structure, that includes a pyrrolo[3,4-β]-quinoline moiety (rings A, B and C), conjugated pyridone moiety (ring D) and one chiral center at position 20 within the alpha-hydroxy lactone ring with (S) configuration (the E-ring). Its planar structure is thought to be one of the most important factors in topoisomerase inhibition.
caption: Binding of CPT to topoisomerase I and DNA