Camptothecin (CAS: 7689-03-4) is a pentacyclic indole alkaloid isolated from Camptotheca acuminata (Nyssaceae family). As a specific inhibitor of topoisomerase I (Topo I), its unique antitumor mechanism has pioneered new directions in cancer drug development. Derivatives such as irinotecan and topotecan have become first-line clinical chemotherapeutic agents. In 2020, WHO listed it as an "Essential Medicine" and a representative anticancer natural product.

Product Name: Camptothecin

IUPAC Name: (S)-4-Ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14(4H,12H)-dione

CAS No.​: 7689-03-4

Molecular Formula: C₂₀H₁₆N₂O₄