Roseoflavin, a natural pigment originally isolated from Streptomyces davawensis, is an antimetabolite analog of Riboflavin and flavin mononucleotide that has antimicrobial properties.In Vitro: Roseoflavin, a chemical analog of flavin mononucleotide (FMN) and riboflavin that has antimicrobial activity, can directly bind to FMN riboswitch (Kd~100 nM) aptamers and downregulate the expression of an FMN riboswitch-lacZ reporter gene in B. subtilis.