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.

Abstract

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) isoal-loxazine, respectively.