5.2. Mode of action
The main mode of action of camptothecin against cancer cells includes binding with topoisomerase I to form a cleavable complex in-between DNA strands. Topoisomerase I involve in the unwinding of DNA strands during replication and ligation of DNA after replication. CPT inhibits the re-ligation function of topoisomerase I by forming a stable complex with it (Liu et al., 2015a) (Fig. 11 ).