喜树碱(Camptothecin，CPT)，是一种细胞毒性喹啉类生物碱，能抑制DNA拓扑异构酶(TOPO I)。

1966年由M.E. Wall和M.C. Wani 通过有系统的筛选天然物质，进而发现的抗癌药物。

喜树碱是从产于中国的喜树(喜树，幸福树)树皮和枝干分离出来，早期为传统中医疗法治疗癌症的方法。喜树碱在初步临床试验有显著的抗癌特性、溶解度低以及含有高度的药物不良反应特性。药用化学家进而利用这些特性开发出了多样的合成喜树碱和各种衍生品，以增加良好的效果。现今已有两个喜树碱的类似物批准，并为癌症进行化疗，如拓扑替康和伊立替康。

Camptothecin (CPT) is a cytotoxic quinoline alkaloid which inhibits the DNA enzyme topoisomerase I (topo I). 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 (Camptotheca, Happy tree), a tree native to China used as a cancer treatment in Traditional Chinese Medicine. CPT showed remarkable anticancer activity in preliminary clinical trials but also low solubility and (high) adverse drug reaction. Because of these disadvantages synthetic and medicinal chemists have developed numerous syntheses of Camptothecin and various derivatives to increase the benefits of the chemical, with good results. Two CPT analogues have been approved and are used in cancer chemotherapy today, topotecan and irinotecan.