Phoma Wasabiae was inoculated on the culuture solution of potato which contained
20% of glucose, and incubated in static state at 25℃.
The process of colour change of the culture medium was studied with regard to the
change of composition of medium and separation of polyphenol from the coloured
culture medium.
1) The colour of the culture medium changes gradually to a reddish orange colour from the surface of medium with the growth of Phoma Wasabiae. The colour changes blackish during 3 or 4 weeks. And then, the absorbance of a visible light at 412 or 413 mμ increases gradually.
2) Under an ultraviolet ray of the wavelength 365 mμ the culture medium has a bluewhite fluorescence, and it changes to a deep green colour with colouring of the medium.
3) Polyphenols were extracted with ethyl acetate from the precipitate which separated from the coloured culture medium with lead acetate solution. The result of study by the use of paper chromatography on the extract, the existence of an yellowish orange coloured substrate was proved. Moreover, it was recognized that when excess petroleum ether was added to the concentrated ethyl acetate extract, an orange-yellow substrate was deposited. Upon recrystallization from aqueous methanol it gave red needles. It was found that the crystal had a trihydroxy-1, 4-naphthoquinone structure, therefore the author proposes the name, "wasabiquinone", for the pigment because of a metabolic product of Phoma Wasabiae. The structure of wasabiquinone will be described in forthcoming reports.