new antibiotics, method for preparation thereof and preparations containing these substances for the treatment of leukemia.

摘要

Neothramycin A and neothramycin B are obtained by culturing a neothramycin-producing strain of the genus Streptomyces under aerobic conditions in a medium containing assimilable carbon and sources of nitrogen. The resulting mixture can be fractionated. Treatment of each of the two neothramycins with methanol yields a mixture of methylneothramycin A and methylneothramycin B, which can again be fractionated. All the four compounds are valuable pharmaceuticals for use against leukaemia.