Ulososide B, a new unusual norlanostane-triterpene glycoside and its genuine aglycone from the Madagascar sponge Ulosa sp.
A new triterpene glycoside ulososide B (1) was isolated from the sponge Ulosa sp and its structure was elucidated on the basis of spectroscopic data and chemical transformations, including isolation of genuine aglycone (2) in result of acid hydrolysis with TFA.
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New triterpene oligoglycosides from the Caribbean sponge Erylus formosus
2011, Carbohydrate ResearchCitation Excerpt :Taking into consideration that l-arabinose, d-glucose, and d-galactose were identified in the hydrolysate of glycosidic fraction the structure of eryloside T6 (8) was established as 3β-O-{[β-d-glucopyranosyl-(1→2)-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl-(1→3)-α-l-arabinopyranosyl-(1→3)]-[β-d-galactopyranosyl-(1→2)]-α-l-arabinopyranosyl}-24-methylene-14-carboxy-lanosta-8(9)-en. Several genera of sponges, for example, Asteropus,17,18 Ulosa,19,20 Mycale21,22 contain oligoglycosides differing from related compounds isolated from other sponge genera not only in aglycones, but also in carbohydrate moieties. Every structural group of sponge glycosides (sarasinosides, ulososides, mycalosides) can be considered as a genus-specific chemotaxonomic marker.
Synthesis of two trisaccharides related to the triterpenoid saponin eryloside isolated from the sponge Erylus nobilis
2011, Tetrahedron AsymmetryCitation Excerpt :The hydrazine mediated cleavage of the N-phthalimido group followed by acetylation and global de-O-acylation will provide the target trisaccharides (Scheme 1). At first, the 6-O-position of the known p-methoxyphenyl 3,4-isopropylidene-β-d-galactopyranoside 34 was benzoylated by using a molar equivalent of benzoyl cyanide (BzCN)5 in the presence of catalytic Et3N to afford the acceptor, p-methoxyphenyl 6-O-benzoyl-3,4-isopropylidene-β-d-galactopyranoside 4 in 87% yield. Acceptor 4 was glycosylated with the known p-tolyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-1-thio-β-d-glucopyranoside 56 using N-iodosuccinimide (NIS) in the presence of La(OTf)37 to afford the disaccharide, p-methoxyphenyl 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl-(1→2)-6-O-benzoyl-3,4-O-isopropylidene-β-d-galactopyranoside 6 in 82% yield.
Steroid glycosides from marine organisms
2011, SteroidsCitation Excerpt :A part of sponge oligoglycosides fall rather into the category of nor-triterpene than steroid derivatives. There are several well-known structural groups, including sarasinosides [17–20], ulososides [21,22] and some of erylosides [23], which have di- or monomethylsterol derivatives as aglycons. For the past nine years, new representatives of these groups were described.
Chapter 8. The widespread distribution of natural products
2002, Tetrahedron Organic Chemistry Series