[Cytostatic action of semisynthetic rubomycin derivatives].

The cytostatic effect of some semi-synthetic derivative of rubomycin, an antitumor antibiotic, was studied with two methods, i.e. the method of spectrophotometric determination of the increase of the total amount of nucleic acids and the radiometric method based on measuring the intensity of incorporation of labeled thymidine. The results obtained with the two methods were similar. 9 semi-synthetic derivatives of rubomycin were studied with respect to the tumor cells NK/Li. The cytostatic effect of 8 out of these derivatives was 2-170 times lowers than that of rubomycin. The cytostatic effect of N-ethylrubomycin was equal to that of the initial antibiotic.