Active metabolite of CPT-11 (Cat. No. 2688) that inhibits DNA topoisomerase I (IC50 values are 0.74 and 1.9 μM in P388 and Ehrlich cells respectively). Inhibits DNA and RNA synthesis (IC50 values are 0.077 and 1.3 μM respectively) but does not affect protein synthesis. Displays potent antitumor activity against a range of human tumor cell lines (IC50 values are 3.3, 13, 19 and 22 nM for HCT-116, BEL-7402, HL60 and HELA cells respectively). Purity 98%. MW (observed): 392.4