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R. H. THOMSON
and recently found in ergot (Chviceps pur pur ea, a pyrenomycete)
(128). The complex mixture of metabolites produced by the latter includes two anthraquinones, clavoxanthin (= endocrocin) and clavorubin,
which is not yet identified.
In structure, the fungal anthraquinones form a very compact group.
Nearly all are of the emodin type, the differences being mainly in the
pattern of hydroxylation: relative to emodin, hydroxyl groups may be
absent, as in chrysophanol (XXVI) and the hydroxy-methylanthraquinone (CX) [both of which are formed by Pachybasium candidum
(Sacc.) Peyronel (129)] or, additional hydroxyl groups may be introduced ortho or para to an existing one, as in catenarin (CVIII), or, as
in islandicin (XCVIII), both variations may be effected. Versicolorin
(CV) does not fit into this pattern, but the structure of this quinone
requires confirmation (130). Boletol is most unusual in having a 1,2,4
arrangement of hydroxyl groups like that found in the rubiaceous
quinones, and a carboxyl group in an alpha position. When the flesh of
some Boletus spp. is cut and exposed to air, it turns blue owing to the
formation of the diquinone (CXIII) by enzymatic oxidation. B. subtomentosus Linn, and B. chrysenteron Bull, both contain boletol but do
not turn blue when broken, which Bertrand (131) ascribed to the absence of laccase. The azaanthraquinone phomazarin (CXI) is a metabolic product of Phoma terrestris Hansen and is unique in structure. As
already noted, the formation of several related pigments by a single
fungus is quite common, and the amount is sometimes substantial. In
this respect the most remarkable organism is Penicillium islandicum,
from which the following pigments, amounting to approximately 20% of
the dry weight of the mycelium, have been obtained: islandicin,
chrysophanol, emodin, endocrocin, and catenarin, besides several dianthraquinones. No anthraquinols have been found in fungi, which is
hardly surprising, but anthrones have been isolated. Several members
of the Aspergillus glaucus series produce physcion (CII) and erythroglaucin (CIII) (in addition to auroglaucin and flavoglaucin), and five
species yielded, in addition, the two anthrones of physcion, which have
also been found in higher plants (132).
The dianthraquinones, first discovered in Raistrick's laboratory and
extensively studied in recent years by Shibata, are closely related to
the foregoing simpler compounds. Thus skyrin (CXIV) is diemodin,
and iridoskyrin (CXV) is diislandicin, and all four pigments are produced by P. islandicum together with the diquinones hydroxyskyrin
and pigment C (CXIV), the closely related yellow pigments rubroskyrin (CXVI) and luteoskyrin (CXVIII), and the other simple qui-
R. H. THOMSON
and recently found in ergot (Chviceps pur pur ea, a pyrenomycete)
(128). The complex mixture of metabolites produced by the latter includes two anthraquinones, clavoxanthin (= endocrocin) and clavorubin,
which is not yet identified.
In structure, the fungal anthraquinones form a very compact group.
Nearly all are of the emodin type, the differences being mainly in the
pattern of hydroxylation: relative to emodin, hydroxyl groups may be
absent, as in chrysophanol (XXVI) and the hydroxy-methylanthraquinone (CX) [both of which are formed by Pachybasium candidum
(Sacc.) Peyronel (129)] or, additional hydroxyl groups may be introduced ortho or para to an existing one, as in catenarin (CVIII), or, as
in islandicin (XCVIII), both variations may be effected. Versicolorin
(CV) does not fit into this pattern, but the structure of this quinone
requires confirmation (130). Boletol is most unusual in having a 1,2,4
arrangement of hydroxyl groups like that found in the rubiaceous
quinones, and a carboxyl group in an alpha position. When the flesh of
some Boletus spp. is cut and exposed to air, it turns blue owing to the
formation of the diquinone (CXIII) by enzymatic oxidation. B. subtomentosus Linn, and B. chrysenteron Bull, both contain boletol but do
not turn blue when broken, which Bertrand (131) ascribed to the absence of laccase. The azaanthraquinone phomazarin (CXI) is a metabolic product of Phoma terrestris Hansen and is unique in structure. As
already noted, the formation of several related pigments by a single
fungus is quite common, and the amount is sometimes substantial. In
this respect the most remarkable organism is Penicillium islandicum,
from which the following pigments, amounting to approximately 20% of
the dry weight of the mycelium, have been obtained: islandicin,
chrysophanol, emodin, endocrocin, and catenarin, besides several dianthraquinones. No anthraquinols have been found in fungi, which is
hardly surprising, but anthrones have been isolated. Several members
of the Aspergillus glaucus series produce physcion (CII) and erythroglaucin (CIII) (in addition to auroglaucin and flavoglaucin), and five
species yielded, in addition, the two anthrones of physcion, which have
also been found in higher plants (132).
The dianthraquinones, first discovered in Raistrick's laboratory and
extensively studied in recent years by Shibata, are closely related to
the foregoing simpler compounds. Thus skyrin (CXIV) is diemodin,
and iridoskyrin (CXV) is diislandicin, and all four pigments are produced by P. islandicum together with the diquinones hydroxyskyrin
and pigment C (CXIV), the closely related yellow pigments rubroskyrin (CXVI) and luteoskyrin (CXVIII), and the other simple qui-