The relationship between chemical structure, micronucleus-inducing and antitumor activities was studied in four newly synthesized pyrazolo pyrymidine compounds (DGB-216, DGB-227, DGB-228 and DGB-331). In bone marrow erythrocytes of mice no one of compounds was active. Only DGB-216 has slight antitumor activity and increases the mean life span of mice with Ehrlich ascite carcinoma by 11 %, while others were practically non-active. Changes in the chemical structures of the compounds lead to substantial changes in the acute toxicity only. The search of antitumor compounds among the derivatives of -6-etoxycarbonyl-pyrazolo[1,5a]-pyrymidine and -2-methyl-pyrazolo[1,5a]-pyrymidine is useless, as it has been shown in the present investigation. But the search of compounds with antitumor properties among derivatives of pyrazolo pyrymidines is a perspective idea because recently some very active antitumor compounds based on mentioned strusture were synthesized in Italy and the USA.
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