124
WERNER BERGMANN
cholesterol and spongosterol. When twenty-five years later the writer
began his studies on invertebrate sterols, the first sponge under investigation, the common red New England sponge, Microciona prolifera,
afforded yet another sterol, microcionasterol (82). A fourth sponge
yielded a fourth new sterol, chalinasterol (83). The extraordinary fact
that four different sponges had given four different sterols pointed to
an almost unbelievable diversity of sterols among sponges. Indeed it
seemed at this stage of the investigations that each family if not genus
of sponges might produce its own characteristic sterol.
These astonishing results of such preliminary studies, fortuitous as
they later proved to be, encouraged a comprehensive survey of sponge
sterols. It was anticipated that such a survey would lead to a better
understanding of the natural variations of the sterol molecule. It was
hoped that in addition it might provide data which could be incorporated into the taxonomy of sponges, which is so bewildering to the uninitiated and understood by so few. An introduction of chemical criteria
into the taxonomy of sponges would be traditional rather than novel.
Even the earliest division of the Porifera into Keratosa, Calcarea, and
Silicea was based on the chemical nature of their building material.
At present the sterol mixtures of more than fifty species of sponges
have been isolated by the writer and his associates (8) (see Table III).
Individual, identifiable sterols have been obtained from about one-half
of them. Sufficient data are known about the remainder to assign their
principal sterols to one or another of the classes previously discussed.
With the beginning of a more systematic study of sponge sterols it soon
became apparent that their diversity was not as spectacular as first indicated. Reinvestigation of the earlier sponge sterols proved them to be
mixtures. Doree's clionasterol was found to be composed of a monounsaturated sterol (II, R = L) for which the original name was retained,
and a di-unsaturated compound, poriferasterol (II, R = M) (84). These
two sterols were subsequently found to be the most common of the
sponge sterols (8). The spongosterol of Henze was separated into
cholestanol (IV, R = A) and the unique neospongosterol (IV, R = H)
(50). Microcionasterol proved to be a rather complex mixture in which
cholesterol (II, R== A) and cholestanol (IV, R = A) are the principal
components (85). These observations were then of particular interest
because they showed for the first time the presence of cholesterol in
the primitive phylum of sponges and also the natural occurrence of
cholestanol as a major rather than a minor sterol. The structure of
chalinasterol, at first misunderstood, has since been shown to be that of
24-methylenecholesterol (II, R = D) (38).
Several other, new sterols have been obtained from sponges. Among
WERNER BERGMANN
cholesterol and spongosterol. When twenty-five years later the writer
began his studies on invertebrate sterols, the first sponge under investigation, the common red New England sponge, Microciona prolifera,
afforded yet another sterol, microcionasterol (82). A fourth sponge
yielded a fourth new sterol, chalinasterol (83). The extraordinary fact
that four different sponges had given four different sterols pointed to
an almost unbelievable diversity of sterols among sponges. Indeed it
seemed at this stage of the investigations that each family if not genus
of sponges might produce its own characteristic sterol.
These astonishing results of such preliminary studies, fortuitous as
they later proved to be, encouraged a comprehensive survey of sponge
sterols. It was anticipated that such a survey would lead to a better
understanding of the natural variations of the sterol molecule. It was
hoped that in addition it might provide data which could be incorporated into the taxonomy of sponges, which is so bewildering to the uninitiated and understood by so few. An introduction of chemical criteria
into the taxonomy of sponges would be traditional rather than novel.
Even the earliest division of the Porifera into Keratosa, Calcarea, and
Silicea was based on the chemical nature of their building material.
At present the sterol mixtures of more than fifty species of sponges
have been isolated by the writer and his associates (8) (see Table III).
Individual, identifiable sterols have been obtained from about one-half
of them. Sufficient data are known about the remainder to assign their
principal sterols to one or another of the classes previously discussed.
With the beginning of a more systematic study of sponge sterols it soon
became apparent that their diversity was not as spectacular as first indicated. Reinvestigation of the earlier sponge sterols proved them to be
mixtures. Doree's clionasterol was found to be composed of a monounsaturated sterol (II, R = L) for which the original name was retained,
and a di-unsaturated compound, poriferasterol (II, R = M) (84). These
two sterols were subsequently found to be the most common of the
sponge sterols (8). The spongosterol of Henze was separated into
cholestanol (IV, R = A) and the unique neospongosterol (IV, R = H)
(50). Microcionasterol proved to be a rather complex mixture in which
cholesterol (II, R== A) and cholestanol (IV, R = A) are the principal
components (85). These observations were then of particular interest
because they showed for the first time the presence of cholesterol in
the primitive phylum of sponges and also the natural occurrence of
cholestanol as a major rather than a minor sterol. The structure of
chalinasterol, at first misunderstood, has since been shown to be that of
24-methylenecholesterol (II, R = D) (38).
Several other, new sterols have been obtained from sponges. Among