Ac-Exatecan is acetylated Exatecan . Exatecan (DX-8951) is a common toxin component in ADC preparation (ADC Cytotoxin) and an inhibitor of DNA topoisomerase I (IC50=2.2 μM).
References:
[1]. Mitsui I, et al. A new water-soluble camptothecin derivative, DX-8951f, exhibits potent antitumor activity against human tumors in vitro and in vivo. Jpn J Cancer Res. 1995 Aug;86(8):776-82.