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

Abstract

The antitumor antibiotic 'rubiflavin' was investigated. It was shown to be a mixture of several compounds, nine of which -after isolation by HPLC -could be identified by 'H-NMR spectroscopy. The rubiflavins A (4), B (S), C-l(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.

First enantiospecific Baker–Venkataraman-rearrangements aiming at the total synthesis of chiral anthrapyran antibiotics

“…[18][19][20][21] In addition, some representatives show interesting biological properties such as the new antitherpeutic agent, AH-1763 IIa, produced by the Streptomyces cyaneus strain 22 and recently prepared by synthesis, 23 or the novel neuronal cell protecting espicufolin 1, produced by a Streptomyces sp. 24 Another large group are rubiflavinones 2 [25][26][27] with an hexadiene side chain on C-2 or c-indomycinone 3 with a butanol side chain at C-2, 28 with a tertiary hydroxy group in the C-4 side chain. Herein we report for the first time on BakerVenkataraman reactions which occurred with virtually no racemization during base-catalyzed acyl transfer, extending the scope of the reaction considerably, for instance, for the synthesis of chiral or complex anthrapyran antibiotics as shown in Figure 1.…”

Naturally Occurring Chromone Glycosides: Sources, Bioactivities, and Spectroscopic Features

“…Compounds 168-192 are shown in Figures 22 and 23. The sources and the reported biological activities (if any) are summarized in Antibiotic with MIC (minimum inhibitory concentration) ranges from 0.19-1.56 µg/mL and potent antitumor activity [138] 169 Neopluramycin Streptomyces pluricolorescens [139,140] Antibiotics and potent antitumor activity [140] 170 14, 16-Epoxykidamycin Streptomyces pluricolorescens [141] Antibiotic against Gram-positive bacteria with MIC ranges from 0.5 to 10 µg/mL and antitumor activity [141] 171 Pluramycin A Streptomyces pluricolorescens [139,140] Antibiotic and antitumor activity [140] 172 Rubiflavin A Streptomyces species [142] Antibiotic and antitumor activity [142] 173…”

Bioactive C-Glycosides from Bacterial Secondary Metabolism

“…Other important "classical" pluramycins include the rubiflavins (e.g. 129), seven of which are C-glycosides [211], and epoxykidamycin 126, the most potent antibiotic of the mixture of pluramycins forming the non-covalently bound chromophore of the antitumour chromoprotein Largomycin FII [212,213].…”