Cortinarius atrovirens

In recent years atrochrysone (4) and several other pre-anthraquinones have been isolated from fungi and higher plants (Scheme 2). The parent compound 4 occurs in the toadstools Cortinarius atrovirens and . odoratus (ref. 3). The monomethyl ethers torosachrysone (7) (ref. 4) and asperflavin (8) (ref. 5) are produced by Cassia torosa and Aspergillus flavus, respectively. Torosa-chrysone-8-O-methyl ether (9) has been found in fruitbodies of several toadstools along with its trans-4-hydroxy derivative 10 (ref. 3). Further compounds of this type, e.g. vismione A (11) and B (12), have been isolated from Vismia species (ref. 6). With the only exception of 7, the absolute configuration of these pre-anthraquinones remains unknown. 

Among toadstools belonging to Cortinarius subgenus Phlegmacium the principal pigments are derivatives of 3,4-dihydroanthracen-l (2//)-one and, in contrast to the situation in Dermocybe, anthraquinones themselves play only a subordinate role (617). The pivotal biosynthetic intermediate atrochrysone (321) is present in Cortinarius atrovirens and C. odoratus (Table 28) where it is accompanied by the 4-hydroxy derivatives (322) and (323) of varying stereochemistry. The dimethyl ether... 

In addition to atrochrysone (321) Cortinarius atrovirens contains the 5,5 -linked dimer atrovirin-B (336), and pigments derived therefrom (Table 31). The structure of atrovirin-B was deduced from the n.m.r. spectrum (Table 32) and the mass spectrum in which only a weak dibenzofuran ion is observed (see below) 384, 515). 

However, only very few toadstools produce pigments such as (343) in which both the 6- and 6 -hydroxy groups remain free. Notable among these is Cortinarius atrovirens which owes much of its dark green colour to the presence of 4,4 -dioxoflavomannin-A (346). 

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