Antitumor anthracycline antibiotics. Structure-activity and structure-cardiotoxicity relationships of rubidazone...

A series of rubidazone analogues (4-14) with varying phenyl group substituents was prepared. The effect of these compounds on inhibition of nucleic acid synthesis in cultured cells, on in vivo antitumor properties, and on cardiotoxicity was examined. Substituent effects on drug-DNA binding as indicated by DNA melting temperature measurements were also investigated. Substituent effects were essentially absent among the rubidazone analogues in in vivo and in vitro test systems which measure cytotoxic characteristics; however, the rubidazone analogues varied substantially in their cardiotoxic effects and this variation was closely correlated with the electronic character of the phenyl substituent.