Isolation and Structure Elucidation of Some Components of the Antitumor Antibiotic Mixture ‘Rubiflavin’

The antitumor antibiotic ‘rubiflavin’ was investivated. It was shown to be a mixture of several compounds, nine of which ‐ after isolation by HPLC ‐ could be identified by 1H‐NMR spectroscopy. The rubiflavins A (4), B (5), C‐1(6), C‐2(7), D(8), and E(9) are pluramycin antibiotics differing only in their side chains at C(2). Rubiflavin B(5) was found to be identical with kidamycin, rubiflavin F(10) with isokidamycin. Two unpolar compounds isolated which lack the two sugar rings typical for pluramycin antibiotics were called rubiflavinone C‐1 (2) and C‐2 (3); they are the ‘aglycones’ of the corresponding rubiflavins.