Some recent studies on the metabolites of fungi and lichens

Abstract

Various anthraquinonoid colouring matters grouped into (a) monomeric anthraquinones, (b) bianthraquinones and (c) modified bianthraquinones were isolated from Penicillium islandicum, P. rugulosum, and other fungi. The unusual cagelike structures of hepatotoxic luteoskyrin, (—)rubroskyrin, (+)rugulosin and their analogues are elucidated. The absolute stereochemical structures of these fungal colouring matters have been established on the basis of the x-ray crystallographical analysis of a bromination product of (+)tetrahydrorugulosin. The photoreaction of (—)luteoskyrin is discussed in elucidating the structure of the product, lumiluteoskyrin. In addition, (—)flavoskyrin, isolated from a strain of Penicillium islandicum, has now been proved to be a modified bianthraquinone. An unusual dimerization reaction of the dihydroanthraquinones which were synthesized as model compounds for flavoskyrin is also discussed. (+)Rugulosin, skyrin, some fungal modified bixanthones and their related compounds have recently been found in certain lichens. The biogenetical correlation between the metabolites of fungi and lichens is discussed in the light of studies on the secondary metabolism of lichen mycobionts. © 1973, Walter de Gruyter. All rights reserved.