Structure-Based Design and Synthesis of Regioisomeric Disubstituted Aminoanthraquinone Derivatives as Potential Anticancer Agents

Continuing our ongoing studies on cytotoxic substances, we report the synthesis and cytotoxic properties of a series of symmetric 1,5-diamino-9,10-anthraquinones with potentially bioreducible groups. Symmetric amination of 1,5-dichloro-9,10-anthraquinone with the appropriate primary amines in the presence of DMF furnished the structurally related aminoanthraquinone analogs 1-19. Their in vitro cytotoxic activity was evaluated using rat glioma C6 cells, human hepatoma G2 cells, and 2.2.15 cells. Several compounds exhibited very high antitumor activities in these assays. Compound 4 efficiently inhibited C6 cells, human hepatoma G2 cells, and 2.2.15 cells, as determined by means of the XTT colorimetric assay. The antiproliferative activity of 4 was markedly enhanced, reaching a potency comparable to those of the powerful anticancer agents mitoxantrone, adriamycin, and cisplatin. Biological evaluations and structure/activity relationships within this class of novel aminoanthraquinones are discussed.