Marine lipids
Introduction
Sponges, which occupy a low position on the evolutionary scale, are wellknown for their exceptional biochemical diversity. Among their various
metabolites, sterols have been well-documented since the pioneer studies
(Bergmann & Feeney, 1949; Bergmann et al., 1950). Moreover, these primitive multicellular animals are difficult to classify due to their lack
of organization and to the few available useful morphological characteristics (Bergquist, 1978). Thus, sponges often pose a difficult identification task for systematists. Nevertheless, taxonomy is essential to
the development of marine natural products. The use of taxonomic
knowledge makes it possible to focus investigation on sponge genera
which offer the greatest potential, especially for biologically active
compounds. There is a need for common chemicals relative to a particular taxon that are easy to obtain and identify.
Sterols were the first group of sponge metabolites to be used in biochemical taxonomic studies. The increased resolving power of analytical methods has allowed the identification of new sterols, even when
present in trace amounts, as illustrated by Djerassi and coworkers
through the discovery of many new bioalkylation features (Popov et
al., 1976; Cho & Djerassi, 1987; Doss & Djerassi, 1988). More than
100 unprecedented sterols have been found in marine sponges. Various
sponges from different sites and orders have been investigated to date.
Sterols in cell membranes are present in almost all species and show
great variation in quantity and composition. Certain sponges possess
very low sterol content or may be devoid of sterols. Several extensive
studies have been achieved (Bergquist et al., 1980, 1986, 1991), and
helpful data have been obtained by comparing the complete sterol composition of different sponge species. It was demonstrated in a number of
previous studies, and verified in the case ol the sponges investigated
by us, that sterol composition is usually qualitatively stable, irrespective of the season and collection site. Furthermore, marine sponge
sterols are known to occur predominantly in free form.
As part of our investigations on Senegalese sponges, we conducted a
systematic comparative chemical study of sterols (Sjostrand et al., 1981;
Barnathan et al., 1992). A sufficient number of different sponge specimens was needed to allow group characteristics of families to be
appraised. This work is divided into two parts, each devoted to a particular sponge family. The first deals with sterols from Suberitidae
sponges, and the second with sterols from a very distant sponge family,
namely Halichondriidae.
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Introduction
Sponges, which occupy a low position on the evolutionary scale, are wellknown for their exceptional biochemical diversity. Among their various
metabolites, sterols have been well-documented since the pioneer studies
(Bergmann & Feeney, 1949; Bergmann et al., 1950). Moreover, these primitive multicellular animals are difficult to classify due to their lack
of organization and to the few available useful morphological characteristics (Bergquist, 1978). Thus, sponges often pose a difficult identification task for systematists. Nevertheless, taxonomy is essential to
the development of marine natural products. The use of taxonomic
knowledge makes it possible to focus investigation on sponge genera
which offer the greatest potential, especially for biologically active
compounds. There is a need for common chemicals relative to a particular taxon that are easy to obtain and identify.
Sterols were the first group of sponge metabolites to be used in biochemical taxonomic studies. The increased resolving power of analytical methods has allowed the identification of new sterols, even when
present in trace amounts, as illustrated by Djerassi and coworkers
through the discovery of many new bioalkylation features (Popov et
al., 1976; Cho & Djerassi, 1987; Doss & Djerassi, 1988). More than
100 unprecedented sterols have been found in marine sponges. Various
sponges from different sites and orders have been investigated to date.
Sterols in cell membranes are present in almost all species and show
great variation in quantity and composition. Certain sponges possess
very low sterol content or may be devoid of sterols. Several extensive
studies have been achieved (Bergquist et al., 1980, 1986, 1991), and
helpful data have been obtained by comparing the complete sterol composition of different sponge species. It was demonstrated in a number of
previous studies, and verified in the case ol the sponges investigated
by us, that sterol composition is usually qualitatively stable, irrespective of the season and collection site. Furthermore, marine sponge
sterols are known to occur predominantly in free form.
As part of our investigations on Senegalese sponges, we conducted a
systematic comparative chemical study of sterols (Sjostrand et al., 1981;
Barnathan et al., 1992). A sufficient number of different sponge specimens was needed to allow group characteristics of families to be
appraised. This work is divided into two parts, each devoted to a particular sponge family. The first deals with sterols from Suberitidae
sponges, and the second with sterols from a very distant sponge family,
namely Halichondriidae.
88