Studies in the biochemistry of micro-organisms. 91. The colouring matters of Penicillium islandicum Sopp. Part 3. Skyrin and flavoskyrin

Abstract

Two hitherto undescr. coloring matters, skyrin and flavoskyrin, were isolated from the mycelium of laboratory cultures of a morphologically typical but biochemically atypical strain of P. islandicum. Skyrin, C30H18O10, crystallizes as clusters of orange-red rods or as yellow, hexagonal plates and does not melt below 380[degree]. Several of its derivatives are described. When an alkaline solution of skyrin is treated with sodium dithionite, Na2S2O4, it undergoes reductive cleavage into two molecules of emodin, C15H12O5, 4:5:7-trihydroxy-2-methylanthraquinone. Flavoskyrin, C15H12O5, crystallizes as yellow needles, m.p. 215[degree] (decomp.) Flavoskyrin loses a molecule of water to yield chrysolphanol, C15H12O5, 4:5-dihydroxy-2-methyl-anthraquinone, either by heating at its melting point or by the action of cold concentrated sulphuric acid. The chrysophanol already reported as a metabolic product of this strain of P. islandicum was shown not to be an artifact produced, during its isolation, by decomposition of flavoskyrin. Possible structures for skyrin are discussed.