Aspergillus versicolorの代謝生産物に関する研究

(第3報) Versicolorinの理化学的性質及び化学構造

抄録

Versicolorin was yellow orange color needle, m. p. 282°, soluble in acetone, ethyl acetate, alcohol, and ether, sparingly soluble in-benzene, but insoluble in petroleum ether, and water. It gave orange coloryvith FeCl₃.
It was dissolved into purple color in aqueous NaOH solution, and when heated with zinc dust, its color faded. When shaken in the air, it regained the original color.
The molecular formula C₁₅H₁₀O₆ was proposed from the results of elementary analysis and molecular weight determination. Considering the fact that ultraviolet absorption spectrum of versicolorin was similar to that of aloaemodin and flungulaemodin, it was supposed to be anthraquinone having similar structures to them.
Versicolorin gavea tetraacetyl derivative by acetylation, and a trimethyl derivative by methylation. Therfore, one of the four hyroxyl radicals was assumed to be a form of hyroxymethyl. And as its alcoholic solution gave orange color when it was added with magnesium acetate, it was observed to contain hyroxyl at m-position. Besides in anthraquinones found as metabolic products of fungi, and of settled structures, . two hydroxyl or methoxyl were all observed to be at 1 and 8 positions, and methyl, hydroxymethyl, and carboxyl were all at β-position. Therefore versicolorin was assumed to contain hydroxyls at 1, 3, and 8 positions, and hydroxy methyl at β-position.
Of anthraquinone containing hydroxyls at 1, 3, and 8 positions, and hydroxymethyl at 6 position, ω-hydroxyemodin and citreorosein have been known so far but in many respects versicolorin did not agree with them.
Summarizing the above mentioned results, therefore, the authors proposed the following structure.