Camptothecin (CPT) belongs to the alkaloid group of natural products and is a specific DNA topoisomerase I (Topo I) inhibitor (IC50=679 nM) with specificity. Camptothecin has antitumor activity and induces apoptosis.

Topotecan (NSC-609669) is a Topoisomerase I inhibitor,and is an antineoplastic agent used to treat ovarian cancer that works by inhibiting DNA topoisomerases.

SN-38 (NK012) is the active metabolite of Irinotecan, a DNA topoisomerase I (Topo I) inhibitor, which inhibits DNA and RNA synthesis (IC50=0.077/1.3 μM). SN-38 has antitumor activity and induces autophagy.

Irinotecan (CPT-11), a derivative of camptothecin, is an inhibitor of DNA topoisomerase I (Topo I). Irinotecan has antitumor activity by preventing DNA strand reattachment through binding to the Topo I complex, resulting in double-stranded DNA breaks and cell death.

Vincosamide is an alkaloid from Psychotria leiocarpa extract, inhibits the acetylcholinesterase (AChE) activity with anti-inflammatory activity. Vincosamide can effect relaxation of the supercoiled pBR322 plasmid DNA in the presence of Cu2+.

2β,3β,23α-Trihydroxy-12-oleanen-28-oic acid shows cytotoxic activities to human lung adenocarcinoma(A-549)cell lines. 2α,3β,23-Trihydroxyolean-12-en-28-oic acid and 2α,3β,23-trihydroxyurs-12-en-28-oic acid exhibit cytotoxicity in vitro against the growth of human cancer cells lines HepG-2,with IC50 values of 16.13 ± 3.83, 15.97 ± 2.47 uM, respectively.

10-Methoxycamptothecin possesses high anti-cancer activity.

(±)-10-Hydroxycamptothecin (Hydroxy Camptothecine) is an alkaloid isolated from the stem wood of the Chinese tree, Camptotheca acuminata. This compound selectively inhibits the nuclear enzyme DNA topoisomerase, type I. Several semisynthetic analogs of camptothecin have demonstrated antitumor activity.

1. 7-Ethylcamptothecin has the superior antitumor activity than CPT. (a). 7-Ethylcamptothecin has a stronger growth-inhibiting activity against tumor cells. (b). 7-Ethylcamptothecin remains in the intestinal tract for a longer time and in higher amounts when administered in vivo.

Topotecan hydrochloride (NSC609699) is an antineoplastic agent used to treat ovarian cancer.

10-Nitro-camptothecin is a natural product

Irinotecan hydrochloride trihydrate (CPT-11 HCl Trihydrate) keeps DNA from unwinding by inhibiting topoisomerase 1.

9-Methoxycamptothecin (MCPT) has antitumour activities through topoisomerase inhibition.

9-Hydroxycampothecin is a camptothecin derivative with anticancer activity.

(S)-10-Hydroxycamptothecin (10-HCPT) is a DNA topoisomerase I inhibitor, utilized as a clinical therapy agent against hepatoma.

12-Ethyl-9-hydroxycamptothecin is a natural product isolated from Camptotheca acuminata Decne

Irinotecan Hydrochloride (CPT-11 hydrochloride) is the hydrochloride salt of a semisynthetic derivative of camptothecin. Irinotecan, a prodrug, is converted to a biologically active metabolite 7-ethyl-10-hydroxy-camptothecin (SN-38) by a carboxylesterase-converting enzyme. One thousand-fold more potent than its parent compound irinotecan, SN-38 inhibits topoisomerase I activity by stabilizing the cleavable complex between topoisomerase I and DNA, resulting in DNA breaks that inhibit DNA replication and trigger apoptotic cell death. Because ongoing DNA synthesis is necessary for irinotecan to exert its cytotoxic effects, it is classified as an S-phase-specific agent.