Potent antitumor 9-anilinoacridines and acridines bearing an alkylating N-mustard residue on the acridine chromophore:: Synthesis and biological activity

A series of 9-anilinoacridine and acridine derivatives bearing an alkylating N-mustard residue at C4 of the acridine chromophore were synthesized. The N-mustard pharmacophore was linked to the C4 of the acridine ring with an O-ethyl ( O-C-2), O-propyl ( O-C-3), or O-butyl ( O-C-4) spacer. It revealed that all newly synthesized compounds were very potent cytotoxic agents against human leukemia and various solid tumors in vitro. These agents did not exhibit cross-resistance against vinblastine-resistant ( CCRF-CEM/VBL) or taxol-resistant ( CCRF-CEM/taxol) cells. It also showed that these agents were DNA cross-linking agents rather than topoisomerase II inhibitors. Of these agents, compounds 27a and 27c were shown to have potent antitumor activity in nude mice bearing the human breast carcinoma MX-1 xenograft. The therapeutic efficacies of these two agents are comparable to that of taxol.