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Behandlung der Daunorubicin‐ Verbindung (I) (= ldarubicin) mit dem aufgeführten Streptomyces‐Stamm ergibt das Dihydroderivat (II) (== Idarubicinol).

A mutant strain of Streptomyces peucetius produced an anthracycline antibiotic whose structure has been established to be 4-O-demethyl-l3-dihydrodaunorubicin (4), by application of spectroscopic methods and chemical degradation.A new synthesis of 4-O-demethyldaunorubicin (carminomycin 1, 2) starting from daunomycinone, together with the comparison of the antitumor activity of the anthracycline glycosides 2 and 4 are also reported.During the course of our screening for new anthracycline antibiotics, 4-O-demetlyl-13-dihydrodaunorubicin (13-dihydrocarminomycin, 4) was found to be produced by a mutant strain of Streptomyces peucetius, the daunorubicin-producing microorganism. The structure of the glycoside was determined by spectroscopic method and chemical degradation including direct comparison of its aglycone with a sample of 13-dihydrocarminomycinone obtained by sodium borohydricle reduction of semi-synthetic carminomycinone.The present paper describes also the synthesis of 4-O-demethyldaunomycinone (carminomycinone, 6) and of 4-0-demethyldaunorubicin (carminomycin I, 2) starting from daunomycinone (5) together with the comparison of the antitumor activity of the glycosides 2 and 4 with those of daunorubicin (1) and of 13-dihydrodaunorubicin (3).