An evaluation of the suitability of the onion test for studying the biological activity of potential antitumor drugs on the example of ledakrin

The onion test was employed in this study. The effect of ledakrin on the synthesis of DNA and protein in meristematic cells of onion adventitious roots was examined. Comparison of the results revealed their similarity to data on animals and bacteria. It was found that inhibition of DNA synthesis is high and seems to precede the inhibition of protein synthesis (which is very low). Also, the difference between the lowest active concentration and lethal dose is, similarly as in mammals, slight (low therapeutic index). It was found that ledakrin is quickly taken up from the incubation medium by the roots; during the first six hours of incubation, a major part of the supplied compound enters into them. During postincubation, the compound is excreted into the medium by the roots; during the first day of postincubation, 10%, during the following days, 0.2-2.0% of the amount taken up by the roots is excreted. During the first hour of incubation, the drug enters all of the root meristematic - tissues, while after 7 days of postincubation, this compound, or its metabolites, is still present in small amounts in the meristem