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4-isothiocyanate-2,2,6,6-tetramethyl-piperidine-l-oxyl has the strongest effects on the DNA synthesis and viability of isolated leukemia 7712 cells. This compound is a very potent inhibitor of DNA synthesis with 50% inhibition of cell DNA synthesis occurring at 2.2 μg/ml, while the LD50 for white mice is 277 mg/kg. During the concentration of 50 μg/ml, the inhibition of DNA synthesis is 99.7%, which is unable to damage the DNA replicate templet. The inhibition of this compound, a combination of nitroxide and isothiocyanate, appears to be stronger than that of the sum of the two separate actions. Much more moderate effects are seen for all the other nitroxide radicals. After reducing nitroxide to hydroxyla-mine, there is no inhibition for DNA synthesis. The free radical mechanism of carcinogene-sis and antitumor action has been discussed.
This is a very potent inhibitor of DNA synthesis with 50% inhibition of While the LD50 for white mice was 277 mg / kg, the inhibition of DNA synthesis was 99.7%, which is unable to damage the DNA replicate templet. The inhibition of this compound, a combination of nitroxide and isothiocyanate, appears to be stronger than that of the sum of the two separate actions. Much more moderate effects are seen for all the other nitroxide radicals. is no inhibition for DNA synthesis. The free radical mechanism of carcinogene-sis and antitumor action has been discussed.