680
R. H. THOMSON
adult, and there is a progressive increase with age of the quantity of
yellow fluid in the gland sacs.
The biogenesis of these quinones is obscure. Brunet and Kent (209,
210) have shown that an o-quinone produced by the colleterial glands
of the cockroach Periplaneta americana is formed from the ß-glucoside
of a phenolic precursor, protocatechuic acid. Homogentisic acid, which
could be derived from tyrosine, is a possible phenolic precursor, and so
of course is quinol, which, according to Dennell (193), is formed in the
larval cuticle of Calliphora vomitoria from phenylalanine and tyrosine
and is utilized there for quinone tanning. The hydroxylating system
which gives rise to quinol is nonenzymatic and nonspecific, and is
possibly not confined to the cuticle. However, although Roth and
Stay (196) found both a ß-glucosidase and a polyphenoloxidase in
the tracheal glands of D. punctata, no ß-glucoside or other phenolic
precursor could be detected. Rao and Seshadri (202) have drawn
attention to an interesting relationship between these quinones and
the tocopherols. The latter can be synthesized in vitro by condensing
quinols with phytol, and the in vivo synthesis may be essentially
similar. It is not known if this occurs in animals, but it is noteworthy
that the quinols corresponding to the alkylated quinones in Table V
could, if condensed with phytol, provide all the known tocopherols.
Ubiquinones also appear in insects. Crane and Lester (83) identified
coenzyme Q 9 in the housefly (Musca domestica) and the cabbage butterfly (Pieris rapae) by extraction of the whole organism, and Morton
(216) has found both Q 9 and Q 10 in the larvae of the blowfly. Heller
and Szarkowska (217) have demonstrated the presence of quinone reductase in the bodies of the pupa and imago of the hawk moth Celerio
euphorbias Linn, and concluded that a quinone was involved in the
respiratory system of these animals. No quinone was identified, but it
seems likely that ubiquinones play an integral part in insect respiration.
b. Anthraquinones. Three of the most important natural dyestuffs
are closely related anthraquinones produced by Coccidae. These are the
following: (a) Carminic acid (CXXXVI) (218), the coloring principle
of cochineal, which consists of the dried bodies of the Mexican species
Dactylopius coccus Costa, found on various Cactaceae. The same, or a
closely related pigment, is produced by the South American species D.
confusus Cockerell, D. tomentosus Lamarck, and D. indicus Green, and
probably also by species of the European genus Porphyrophora, e.g., P.
polonicus Linn. Cochineal still enjoys a limited use, mainly in the coloring of food. (b) Kermesic acid (CXXXVII) is the principal pigment of
kermes (219), probably the most ancient dyestuff on record. This was
formerly obtained from Kermococcus ilicis Linn., which infests the
kermes oak (Quercus coccifera Linn.) (c) Laccaic acid (220) is the
R. H. THOMSON
adult, and there is a progressive increase with age of the quantity of
yellow fluid in the gland sacs.
The biogenesis of these quinones is obscure. Brunet and Kent (209,
210) have shown that an o-quinone produced by the colleterial glands
of the cockroach Periplaneta americana is formed from the ß-glucoside
of a phenolic precursor, protocatechuic acid. Homogentisic acid, which
could be derived from tyrosine, is a possible phenolic precursor, and so
of course is quinol, which, according to Dennell (193), is formed in the
larval cuticle of Calliphora vomitoria from phenylalanine and tyrosine
and is utilized there for quinone tanning. The hydroxylating system
which gives rise to quinol is nonenzymatic and nonspecific, and is
possibly not confined to the cuticle. However, although Roth and
Stay (196) found both a ß-glucosidase and a polyphenoloxidase in
the tracheal glands of D. punctata, no ß-glucoside or other phenolic
precursor could be detected. Rao and Seshadri (202) have drawn
attention to an interesting relationship between these quinones and
the tocopherols. The latter can be synthesized in vitro by condensing
quinols with phytol, and the in vivo synthesis may be essentially
similar. It is not known if this occurs in animals, but it is noteworthy
that the quinols corresponding to the alkylated quinones in Table V
could, if condensed with phytol, provide all the known tocopherols.
Ubiquinones also appear in insects. Crane and Lester (83) identified
coenzyme Q 9 in the housefly (Musca domestica) and the cabbage butterfly (Pieris rapae) by extraction of the whole organism, and Morton
(216) has found both Q 9 and Q 10 in the larvae of the blowfly. Heller
and Szarkowska (217) have demonstrated the presence of quinone reductase in the bodies of the pupa and imago of the hawk moth Celerio
euphorbias Linn, and concluded that a quinone was involved in the
respiratory system of these animals. No quinone was identified, but it
seems likely that ubiquinones play an integral part in insect respiration.
b. Anthraquinones. Three of the most important natural dyestuffs
are closely related anthraquinones produced by Coccidae. These are the
following: (a) Carminic acid (CXXXVI) (218), the coloring principle
of cochineal, which consists of the dried bodies of the Mexican species
Dactylopius coccus Costa, found on various Cactaceae. The same, or a
closely related pigment, is produced by the South American species D.
confusus Cockerell, D. tomentosus Lamarck, and D. indicus Green, and
probably also by species of the European genus Porphyrophora, e.g., P.
polonicus Linn. Cochineal still enjoys a limited use, mainly in the coloring of food. (b) Kermesic acid (CXXXVII) is the principal pigment of
kermes (219), probably the most ancient dyestuff on record. This was
formerly obtained from Kermococcus ilicis Linn., which infests the
kermes oak (Quercus coccifera Linn.) (c) Laccaic acid (220) is the