Studies in the Biochemistry of Micro-organisms. Part VII.—Kojic Acid (5-Hydroxy-2-Hydroxymethyl-γ-Pyrone)

In 1907 Saito isolated from the finely powdered mycelium of Aspergillus oryzœ , grown on steamed rice, an organic acid which he was unable to identify, but which, from a general consideration of its chemical properties, he supposed to be β-resorcyl carbonic acid. Yabuta (1912), from the results of analysis, ascribed to the acid the empirical formula C 12 H 14 O 8, and gave to it the name “ kojic acid.” He described its preparation from the mycelium of Aspergillus oryzœ , grown on rice, and also from “ Koji,” and pointed out that it gives an intense wine red colour with ferric chloride solution, which may be recognized even at a dilution of 1 : 200,000. Of interest from a mycological point of view is Yabuta’s observation that kojic acid is produced by a few other species of Aspergillus , but not by the majority, nor by species of Penicillium or Mucor .