The influence of selected potential oncostatics of plant origin on the protein biosynthesis in vitro.

Five potential oncostatics of plant origin (reserpine, amphotericin B, rutoside, digoxin, dry aloe extract), and cyclic AMP were investigated for their effect on protein synthesis. The solutions of digoxin and dry aloe extract inhibited protein biosynthesis in vitro. The direct inhibiting effect of digoxin on the ribosomes suggests that this drug forms an inactive complex with this organelle. Therefore it can be concluded that ribosome is the target site of digoxin action. Aloin and aloeemodin are responsible for the inhibitory effect of the solution of dry aloe extract. They inhibit markedly [14C]-leucine incorporation into proteins. Aloin and aloeemodin do not influence directly the ribosomes, but they inhibit elongation factors and peptidyltransferase activities in the complete elongation system. Some preliminary experiments have shown that direct interaction between these substances and elongation factor EF-2 should be taken in account. This observation is the subject of further experiments, in which the characteristics of the inhibitory effect of the components isolated from dry aloe extract will be performed.