Chemical action of X-rays on nucleic acids and related substances in aqueous systems. 2. The mechanism of the action of X-rays on nucleic acids in aqueous systems

Two hitherto undescribed colouring matters, skyrin and flavoskyrin, have been isolated from the mycelium of laboratory cultures of a morpho- logically typical but biochemically atypical strain of PeniciUium iklandicum Sopp.2. Skyrin, C30H18010, crystallizes as clusters of orange-red rods or as yellow, hexagonal plates and does not melt below 3800.Several of its derivatives are described.3. When an alkaline solution of skyrin is treated with sodium dithionite, Na2S204, it undergoes reductive cleavage into two molecules of emodin, C15H1005, 4:5:7-trihydroxy-2-methylanthraquinone.4. Flavoskyrin, C15H12056, crystallizes as yellow needles, m.p. 2150 (decomp.).5. Flavoskyrin loses a molecule of water to yield chrysophanol, C15H1004, 4:5-dihydroxy-2-methyl- anthraquinone, either by heating at its melting point or by the action ofcold concentrated sulphuric acid.6.The chrysophanol already reported as a meta- bolic product ofthis strain ofP.iklandicum has been shown not to be an artifact produced, during its isolation, by decomposition of flavoskyrin.7. Possible structures for skyrin are discussed.