Comparison of antitumor properties of nitracrine and amsacrine analogs

For seven new methoxy and/or nitro derivatives of acridine antitumor drugs, nitracrine and amsacrine, biological activity in a few in vitro tests, as well as activity against experimental murine tumors Sarcoma-180 and Leukemia L1210 were investigated. Acute toxicity on mice (LD50) was also determined. High activity in vitro and specific activity against Sa-180 were found to be characteristic features of nitracrine, whereas amsacrine was characterized by high antileukemic activity. Methoxylation of position 2 of the acridine ring in both drugs suppressed their characteristic activity. Besides, substitution of the aminoalkyl side chain in nitracrine by methanesulfon-m-anisidine group suppressed its high antitumor activity, and the presence of a nitro group in position 1 of amsacrine suppressed its antileukemic activity. Comparison of biological properties of nitracrine, amsacrine and their analogs indicated differences in some steps of their mode of action.