658
R. H. THOMSON
Coenzymes Q* occur in the fungi (83) as in other divisions of the
plant kingdom but are not ubiquitous. Three have been isolated from
Ascomycetes: Q 7 and Q 9 from Torula utilis (115, 116), Q 6 from Saccharomyces cerevisiae (117). The latter has also been identified in S.
cavalieri and S. fragilis, but it is not formed under anaerobic conditions,
which is consistent with its respiratory function. Coenzyme Q 1() , the
isoprenolog commonly found in higher animals and plants, is also present
in Neurospora crassa; in the phycomycete Mucor corymbifer it is replaced by Q 9 . This family of quinones appears to be absent from the
Basidiomycetes,f but in four species (Psalliota campestris, Coprinus
atramentarius, Ustilago zea, and a Polyporus sp.) examined by Lester
and Crane (83), a new lipid-soluble quinone was detected. This new
substance, basidioquinone, can be recognized spectroscopically by a
broad band at 255 m/x, which disappears on reduction with potassium
borohydride and is replaced by a peak at 295 ηΐμ. Nothing is known of
the structure of this quinone which occurs in highest concentration in
actively growing fungal tissue.
b. Naphthoquinones.
The few known fungal naphthoquinones,
(XCIII) to (XCVII), have all been obtained in laboratory culture on
synthetic media. They mostly show weak antibiotic properties, which
attracted attention and led to their chemical investigation. There is one
example (XCIII) in the Agaricaceae and another in Aspergillus, but
otherwise the naphthoquinones have little botanical connection with
the fungal benzoquinones. The two Fusarium quinones, (XCVI) and
(XCVII), are closely related, and indeed both have been isolated from
the same species. [The red pigment bostrycoidin, Οι 7 Ηιι0 6 ·ΟΟΗ 3 , a
metabolite of F. bostrycoides Wr. and Rkg. may belong to this group
(118).] The hemiacetal structure of fusarubin is rare in natural products (apart from the sugars), and this quinone is also unusual in that it
occurs in cultures of F. solani (Mart.) App. and Wr. partly in a watersoluble reduced state. The corresponding water-soluble pigment fusarubinogen, has been isolated, and was found to be a sulfuric ester of
fusarubin (119). The structure postulated for mollisin (XCV) is not
established on the present evidence (120), and further investigation
may show it to be more closely related to javanicin, but it is noteworthy
that this pigment was obtained from an inoperculate discomycete. The
orange pigment mycochrysone, C 2 oHi 2 0 7 , also produced by an inoperculate discomycete, is a more complicated molecule, which appears
to be, in part, a pen-hydroxy-/?-naphthoquinone (121). The pigments
of the Discomycetes have been somewhat neglected and may repay
further study.
* These quinones are discussed more fully on page 692.
f See however, reference 117a.
R. H. THOMSON
Coenzymes Q* occur in the fungi (83) as in other divisions of the
plant kingdom but are not ubiquitous. Three have been isolated from
Ascomycetes: Q 7 and Q 9 from Torula utilis (115, 116), Q 6 from Saccharomyces cerevisiae (117). The latter has also been identified in S.
cavalieri and S. fragilis, but it is not formed under anaerobic conditions,
which is consistent with its respiratory function. Coenzyme Q 1() , the
isoprenolog commonly found in higher animals and plants, is also present
in Neurospora crassa; in the phycomycete Mucor corymbifer it is replaced by Q 9 . This family of quinones appears to be absent from the
Basidiomycetes,f but in four species (Psalliota campestris, Coprinus
atramentarius, Ustilago zea, and a Polyporus sp.) examined by Lester
and Crane (83), a new lipid-soluble quinone was detected. This new
substance, basidioquinone, can be recognized spectroscopically by a
broad band at 255 m/x, which disappears on reduction with potassium
borohydride and is replaced by a peak at 295 ηΐμ. Nothing is known of
the structure of this quinone which occurs in highest concentration in
actively growing fungal tissue.
b. Naphthoquinones.
The few known fungal naphthoquinones,
(XCIII) to (XCVII), have all been obtained in laboratory culture on
synthetic media. They mostly show weak antibiotic properties, which
attracted attention and led to their chemical investigation. There is one
example (XCIII) in the Agaricaceae and another in Aspergillus, but
otherwise the naphthoquinones have little botanical connection with
the fungal benzoquinones. The two Fusarium quinones, (XCVI) and
(XCVII), are closely related, and indeed both have been isolated from
the same species. [The red pigment bostrycoidin, Οι 7 Ηιι0 6 ·ΟΟΗ 3 , a
metabolite of F. bostrycoides Wr. and Rkg. may belong to this group
(118).] The hemiacetal structure of fusarubin is rare in natural products (apart from the sugars), and this quinone is also unusual in that it
occurs in cultures of F. solani (Mart.) App. and Wr. partly in a watersoluble reduced state. The corresponding water-soluble pigment fusarubinogen, has been isolated, and was found to be a sulfuric ester of
fusarubin (119). The structure postulated for mollisin (XCV) is not
established on the present evidence (120), and further investigation
may show it to be more closely related to javanicin, but it is noteworthy
that this pigment was obtained from an inoperculate discomycete. The
orange pigment mycochrysone, C 2 oHi 2 0 7 , also produced by an inoperculate discomycete, is a more complicated molecule, which appears
to be, in part, a pen-hydroxy-/?-naphthoquinone (121). The pigments
of the Discomycetes have been somewhat neglected and may repay
further study.
* These quinones are discussed more fully on page 692.
f See however, reference 117a.