Pengfei Cheng

Trifluoromethyl-promoted homocamptothecins: Synthesis and biological activity

The homocamptothecin (hCPT) represents a new class of topoisomerase inhibitor which combines enhanced plasma stability and strong antitumor activity. Fluorine imparts desirable characteristics to drugs by modulating both the pharmacokinetics and pharmacodynamic properties of a drug. Therefore, in an attempt to improve the antitumor activity of homocamptothecins, seven new 7-trifluoromethylated homocamptothecin derivatives were prepared by proline-catalyzed Friedlander annulation. The antitumor activity in vitro and in vivo on cancer cell lines, and inhibitory properties of topoisomerase I-mediated DNA cleavage of compounds 6c and 8b were evaluated. Several of these trifluoromethylated hCPT derivatives (such as 6a, 6b and 6c) possessed higher in vitro antitumor activity than topotecan (TPT). Especially, the compound 6c showed effective in vivo antitumor activity comparable to that of TPT.

Phosphate ester derivatives of homocamptothecin: Synthesis, solution stabilities and antitumor activities

Homocamptothecins (hCPTs) represents a new promising class of topoisomerase I inhibitors with enhanced stability and superior antitumor activity. Some phosphodiesters and phosphotriesters homocamptothecin derivatives were designed and synthesized based on our previous synthetic route. The cytotoxicity in vitro on three cancer cell lines and antitumor activity in vivo, and inhibitory properties of topoisomerase I of these derivatives were evaluated. Among them compounds 24e and 24f exhibited higher cytotoxic activity than IRT and the former exhibited the best antitumor activity in vivo and solution stability both at pH 7.4 and pH 3.0.

Synthesis and biological evaluation of novel 7-acyl homocamptothecins as Topoisomerase I inhibitors

A series of novel 7-acyl derivatives of homocamptothecin (hCPT) were designed and synthesized with the purpose to improve antitumor activity of hCPT, via Minisci free-radical reaction from 10-methoxyhomocamptothecin. All the compounds were evaluated for in vitro cytotoxicity against three cancer cell lines (A549, MDA-MB-435 and HCT116). For MDA-MB-435 cell line, compounds, 6a, 6b, 6k and all of 7-alkylcabonyl homocamptothecin derivatives showed higher in vitro inhibitory activities than topotecan (TPT). Furthermore, compounds 6d, 6e, and 6k showed highly potent inhibitory activities with the IC50 values from less than 1 nM to 2.2 nM. In Topoisomerase I (Topo I)-induced DNA cleavage assay, compounds 6a, 6d, and 6k, as compared to CPT, revealed higher Topo I inhibitory activity.

Synthesis and Biological Evaluation of Novel Homocamptothecins Conjugating with Dihydropyrimidine Derivatives as Potent Topoisomerase I Inhibitors

Homocamptothecin (hCPT) is a camptothecin (CPT) homologue with the insertion of a methylene (CH2) spacer between the alcohol moiety and carbonyl group of the classical six‐membered α‐hydroxylactone ring. This modification provides higher lactone stability and did not impair its activity against topoisomerase I (Topo I), but rather appears to improve it compared to CPT. In an attempt to improve the antitumor activity of homocamptothecins, a series of novel hCPT derivatives conjugating with dihydropyrimidine (DHPM) derivatives was designed and synthesized based on a synthetic route which couples 7‐formylhomocamptothecin with different dihydropyrimidine derivates. Most of the synthesized compounds exhibited good antiproliferative activity on tumor cell lines A549, MDA‐MB‐435 and HCT116. Furthermore, this class of compounds showed superior Topo I inhibition activity comparable to or higher than CPT.

Synthesis and evaluation of 9-benzylideneamino derivatives of homocamptothecin as potent inhibitors of DNA topoisomerase I

A series of novel 9-benzylideneamino derivatives of homocamptothecin were synthesized via Friedlaender cyclization from our obtained intermediate 5. All the compounds were evaluated for in vitro cytotoxicity against three cancer cell lines (A549, LOVO and MDA-MB-435). Most of these derivatives possessed potent growth inhibitory effect on all the tested cell lines and four compounds (6d, 6f, 6i, 6k) showed higher inhibitory activities with the IC50 values of 2.3 nM-9.8 nM against breast cancer cell than topotecan. As compared to CPT, compound 6f revealed higher topoisomerase I inhibitory activity.

Synthesis and Biological Evaluation of 7-Alkenyl Homocamptothecins as Potent Topoisomerase I Inhibitors

Homocamptothecin (hCPT) is a camptothecin (CPT) derivative with a seven‐membered β‐hydroxylactone E ring, which shows higher lactone stability and improves topoisomerase I (Topo I) inhibition activity. In an attempt to improve the antitumor activity of homocamptothecins, a series of 7‐alkenyl‐homocamptothecin derivatives was designed and synthesized based on a semisynthetic route starting from CPT. Most of the synthesized compounds exhibit higher cytotoxic activities on the A‐549 tumor cell line than topotecan (TPT). Some compounds such as 2a and 2o show a broad in vitro antitumor spectrum and exhibit superior Topo I‐inhibition activity.

Synthesis of 9-(heteroarylmethylidene)amino derivatives of homocamptothecin with biological activities.

Six 9‐(heteroarylmethylidene)amino derivatives, 2a–2f, of homocamptothecin were synthesized for the first time by total synthesis in 22 steps and biologically evaluated as inhibitors of topoisomerase I. Moreover, the antitumor activities of 2a–2f against three human tumor cell lines, i.e., A‐549, MDA‐MB‐435, and HCT‐116, were determined and the results showed that compound 2c was the most active homocamptothecin derivative against the A‐549 (IC50=0.046 μM) and HTC‐116 tumor cells (IC50=3.67 μM), with a ca. 50 times higher activity than the reference drug topotecan (TPT) against the lung cancer cell line A‐549.

Synthesis of novel benzoxanthone analogues as non-Camptothecin topoisomerase I inhibitors

Structure modification of the side chain of the lead compound benzoxanthone provided a series of benzoxanthone analogues and 12 of them were first reported. The results showed that most of these compounds had moderate cytotoxicity against tumour cells with the 50% inhibition concentration in the micromolar range. Furthermore, benzoxanthone derivatives 5, 6c, 7a and 7e, showed potent topoisomerase I (Topo I) inhibitory effect and the results indicated that some compounds had potential for development as non-Camptothecin (CPT) topoisomerase I inhibitors.