Inhibitory effects of pentamidine analogues on protein biosynthesis in vitro.

Pentamidine despite its rather high toxicity, is currently in clinical use. For development of new drugs of this type it is important to know the mechanism of their action. Two new amidines (I and II) and 4',6-diamidino-2-phenylindole (DAPI) were found in preliminary experiments to inhibit protein synthesis in vitro in the cell-free rat liver system. The three compounds differed in the precise mode of action. The inhibitory effect of I on the activity of the eukaryotic elongation factor eEF-2 and ribosomes seems to suggest that the binding site of eEF-2 on the ribosome was blocked by this compound. eEF-2 has been identified as the primary target of II and eEF-1 as the primary target of DAPI in the system studied.