Camptothecin binds to the topoisomerase I and DNA complex (the covalent complex) resulting in a ternary complex, and thereby stabilizing it. This prevents DNA relegation and therefore causes DNA damage which results in apoptosis.
Camptothecin demonstrated strong anticancer activity in preliminary clinical trials but also low solubility and adverse drug reaction. Camptothecin is believed to be a potent topoisomerase inhibitor that interferes with the essential function of topoisomerase in DNA replication.
Acute oral toxicity (LD50) in mouse: 50.1 mg/kg