34] Isolation, chemical synthesis, and properties of roseoflavin

Abstract

This chapter discusses the isolation, synthesis, and properties of roseoflavin. Roseoflavin is a red pigment found in the culture filtrate of Streptomyces davawensis (strain No. 768) that was isolated from a soil in the Philippines. It is identified as 8-dimethylamino-8-demethyl- D -riboflavin, and has a weak antibacterial and antiriboflavin activity. The rose red color of roseoflavin is characteristic, and it is easily detected on thin-layer chromatograms. Roseoflavin is reducible, with Na 2 S 2 O4, and the reduced form (yellow) is autoxidizable. It is photosensitive, especially in organic solvent, and degraded to 8-methylamino-8-demethyl-D-riboflavin in the alkaline solution and to 8-dimethylamino-8-demethyllumichrome in acidic solution. Therefore, it interferes with the assay of riboflavin by the lumiflavin fluorescence method. By hot alkali treatment, it is hydrolyzed to urea and 1,2-dihydro-6-methyl-7-dimethylamino-2-keto-1-D-ribityl-3- quinoxalinecarboxylic acid. Roseoflavin has weak antibacterial activity against some gram-positive bacteria, especially Staphylococcus aureus , Sarcina lutea , Bacillus cereus , and Bacillus subtilis . Roseoflavin binds with egg white apoprotein with a lower affinity than riboflavin. It is phosphorylated by flavokinase. Though it binds with apoenzymes, it is inactive as coenzyme with lactate oxygenase from Myobacteriurn phlei , old yellow enzyme (FMN form), and bacterial luciferase.