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 1 H‐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.