A new tumor-inhibitory antibiotic, 6-diazo-5-oxo-L-norleucine, has been isolated in crystalline form from culture broths of an unidentified Streptomyces. Characteristic physical properties of the compound have been determined. The structure of the antibiotic was proven by periodic acid oxidation to L-glutamic acid and Wolff rearrangement to -aminoadipic acid.

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Butirosin, a new water-soluble aminoglycosidic antibiotic complex, active against gram-positive and gram-negative bacteria, has been isolated from fermentation filtrates of Bacillus circulans by ion exchange. The complex has been resolved into isomeric A and B components, C21H41N5012, by means of Dowex 1 X 1 or Dowex 1 X 2 chromatography. Properties ofthe free bases and the N, N', N", N"'-tetraacetyl derivatives of butirosin A and B are given.

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Isolation of Three Crystalline Antibiotics from Streptomyces plicatus 743 Action of Sodium Metaperiodate.-A solution (1 ml.) of the compound (0.732 mg.) in water was oxidized in the usual way with sodium metaperiodate (0.02 M) and after 30 min.(when the reaction was found to be complete), 'excess oxidant was estimated volumetrically with sodium thiosulfate. Using a value of 340 for the molecular weight, the uptake of periodate was calculated as 2 moles/mole. A check on this figure was obtained by following the oxidation spectrophotometrically,16 when the same value was obtained, and the reaction was shown to be virtually complete after 20 min.A qualitative test for formaldehyde using chromotropic acid on the periodate oxidized material was strongly positive. The compound (2 mg.) was oxidized with sodium metaperio- (10)