Effect of molecular size on the activity of adriamycin analogues: a quantitative structure-activity relationship study.

The in vitro anti-tumor activity (inhibition of human lymphoblastic leukemia cells) of some adriamycin analogues is found to be significantly correlated with the van Waals volume (VW) of the substituents. Activity is also found to be well correlated with first-order valence molecular connectivity index (1 chi V) but no correlation is found to exist between it and the hydrophobic parameter, log P (P: octanol-water partition coefficient). On the basis of these findings, it is suggested that the activity would be affected by the steric influence and to some extent by the electronic character of the substituents. From the correlating equations, it is observed that the size of C-7 glycoside ring and that of NHR2 group at its third position would greatly affect the activity. The size of C-14-R1 however, is not found to have much effect on the activity.