[Cytostatic action of N-ethyl-13-dihydrorubomycin on the cells of various tumor strains].

The cytostatic effect of rubomycin and N-ethyl-13-dihydrorubomycin, its semisynthetic derivative, was studied with a radiometric method based on measuring the intensity of labeled thymidine incorporation into the tumor cells of NK/Ly, sarcoma 37 and leukemia P-388 and a method for total determination of nucleic acids in the cell hydrolysates of these tumor strains. Spectrophotometric determination of the total content of DNA and RNA in the tumor cells of NK/Ly showed that the inhibitory effect of the derivative was 6 times higher than that of rubomycin. Radiometric estimation of their cytostatic activity and the studies with the cells of ascitic sarcoma 37 and leukemia P-388 demonstrated that the inhibitory effect of N-ethyl-13-dihydrorubomycin was lower than that of rubomycin.