The evidence of free radicals in tumor tissue and the possibility of their experimental influencing by means of antioxidants justifies the search for new pharmacological groups of tumor inhibiting agents. The authors synthesized a sterically inhibited, heterocyclic, bifunctional, non-toxic radical binding antioxidant of secondary amine type. The structural change is interpreted with the possibility of recombination characteristic for secondary amine groups and the double chain closing effect. The conjugation effect secures mobility of the hydrogen atom. The compound contains 10 to 12 per cent dimer-trimer of higher biological activity than monomers, due to higher molecular weight. An additional pharmacodynamic advantage compared to hitherto known antioxidants consists in its lower vapour volutility and the biradicality.