SPIN-LABELED ANTITUMOR DERIVATIVES OF PODOPHYLLOTOXIN

Three spin-labeled antitumor derivatives of podophyllotoxin, containing an iminoxyl radical,have been synthesized.Preliminary pharmacological tests showed that these derivatives have significant antitumor activity in several experimental tumor systems with a marked decrease in toxicity compared with the parent compound.The relative intensities of ESR signals of these spin-labeled compounds were linearly proportional to their concentrations, the levels of the agent in blood and organs of mice or rabbits can be measured via ESR spectrometry.