(S)-(+)-Camptothecin

Potent anticancer compound. Cell permeable potent DNA topoisomerase I (Topo I) complex inhibitor. Potent apoptosis inducer. Binds reversibly to the DNA topoisomerase I complex, inhibiting the reassociation of DNA after cleavage by topoisomerase I and traps the enzyme in a covalent linkage with DNA. The enzyme complex is ubiquinated and destroyed by the 26S proteasome, consequently depleting cellular topoisomerase I. Prevents DNA re-ligation and therefore causes DNA damage which results in apoptosis. Inhibits mitochondrial topoisomerase I (mtTop1). Blocks the cell cycle at low dose and induces apoptosis in a large number of normal and tumor cell lines by cell cycle-dependent and cell cycle-independent processes. Antiprotozoal and antimalarial compound. Inhibitor of HIV replication and of other viruses. Suppresses nitric oxide (NO) biosynthesis. Shown to suppress TNF-alpha-induced expression of the inflammasome and cyclooxygenase 2 (COX-2).