Acanthifoliosides, minor steroidal saponins from the Caribbean marine sponge Pandaros acanthifolium
Seven novel steroid glycosides, acanthifoliosides A-F (1-6) and the methyl ester of 6 (7), were isolated from the marine sponge Pandaros acanthifolium as minor components. Acanthifoliosides are characterized by a rare C-15 and C-16 oxidized D ring which was previously found in saponins produced by starfishes. Very uncommon is the presence of additional sugar residues at C-15 or C-16. Their structures were determined on the basis of extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. The absolute configurations of the aglycones were assigned by comparison between experimental and TDDFT calculated CD spectra of 1, whereas the absolute configurations of the monosaccharide units were determined by chiral GC analyses of the acid methanolysates. Some of the acanthifoliosides exhibit moderate antiprotozoal activity but to a lesser extent than the most potent pandarosides.
Main Authors: | , , , , , , |
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Format: | Journal Contribution biblioteca |
Language: | English |
Published: |
2011
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Subjects: | Sponges, |
Online Access: | http://hdl.handle.net/1834/3866 |
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Summary: | Seven novel steroid glycosides, acanthifoliosides A-F (1-6) and the methyl ester of 6 (7), were
isolated from the marine sponge Pandaros acanthifolium as minor components.
Acanthifoliosides are characterized by a rare C-15 and C-16 oxidized D ring which was
previously found in saponins produced by starfishes. Very uncommon is the presence of
additional sugar residues at C-15 or C-16. Their structures were determined on the basis of
extensive spectroscopic analyses, including two-dimensional NMR and HRESIMS data. The
absolute configurations of the aglycones were assigned by comparison between experimental
and TDDFT calculated CD spectra of 1, whereas the absolute configurations of the
monosaccharide units were determined by chiral GC analyses of the acid methanolysates. Some
of the acanthifoliosides exhibit moderate antiprotozoal activity but to a lesser extent than the
most potent pandarosides. |
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