An alkaloid isolated from the stem wood of the Chinese tree, Camptotheca acuminata. This compound selectively inhibits the nuclear enzyme DNA TOPOISOMERASES, TYPE I. Several semisynthetic analogs of camptothecin have demonstrated antitumor activity.
Camptothecin is a plant secondary metabolite used as an anti-cancer drug that damages DNA, leading to the destruction of the cell. Camptothecin affects the activity of the enzyme topoisomerase I, whose normal action is to cleave, unwind, and religate DNA. When camptothecin binds to topoisomerase I, it will be able to cleave but not to religate DNA.