Identification of the chemical structures of schizoflavins as 7,8-dimethyl-10-(2,3,4-trihydroxy-4-formylbutyl)isoalloxazine and 7,8-dimethyl-10-(2,3,4-trihydroxy-4-carboxybutyl)isoalloxazine.

Studies to elucidate the chemical structures of new flavins formed by Schizophyllum commune, namely schizoflavin (SF), were carried out. It was found by an enzymatic study that riboflavin (FR) was apparently converted via SF2 to SF1, and that SF2 was a direct precursor of SF1. SF1 was crystallized from water and repeated recrystallization produced yellow needles. The carboxylic group in SF1 and the aldehyde group in SF2 were detected by spot tests. Elemental analyses and the spectroscopic analyses of the crystalline SF1 supported the existence of carboxylic group in the terminal of its ribityl moiety. From these experimental results, schizoflavins were revealed to be oxidation products of FR that C-5' site of its ribityl moiety is oxidized. Consequently, SF1 and SF2 were identified as 7,8-dimethyl-10-(2,3,4-trihydroxy-4-carboxybutyl) isoalloxazine and 7,8-dimethyl-10-(2,3, 4-trihydroxy-4-formylbutyl) isoalloxazine, respectively.