The substances of plant origin that inhibit protein biosynthesis.

Some plants were used for a long time in folk medicine as sources of anti-tumour remedies. Their effects on protein biosynthesis in vitro have been examined and described. The separate features of the peptide elongation system, isolated from tumoural cells, have been demonstrated. Some elongation factors or ribosomes have been shown to be a target site for the inhibition of protein biosynthesis caused by the substances isolated from various sources. The glycoside and caffeic acid, isolated from Melissa officinalis leaves, inhibited protein biosynthesis by direct influence the elongation factor eEF-2. The activity of this factor was also inhibited by aloin and aloeemodin. Saponin glycoside and its aglycon, isolated from Verbascum thapsiforme flowers, as well as digoxin, emetine and cepheline directly inactivated ribosomes. "Chagi" fraction, isolated from Inonotus obliquus, is responsible for the inhibitory effect caused by the aqueous tannin--less extract from this fungus. The target site for quercetin has been found to be the subunit form EF-1 alpha. It may be supposed that, the plant inhibitors of protein biosynthesis could be utilized for searching specific antitumoural preparations.