New triterpene oligoglycosides from the Caribbean sponge Erylus formosus

Seven new triterpene glycosides, erylosides R1 (1), T1 (3), T2 (4), T3 (5), T4 (6), T5 (7), and T6 (8) along with the known formoside (2) were isolated from the sponge Erylus formosus collected along the Caribbean coast of Mexico. Glycoside 1 was determined as a trisaccharide, glycoside 2 as a tetrasaccharide while glycosides 3–8 were hexasaccharide. Their carbohydrate chains were unprecedented and have never been found in oligosaccharides from other biological sources, except Erylus spp. Three carbohydrate chains in the glycosides 3 and 6, 4 and 7, 5 and 8 correspondingly are new. The glycosides 1–5 have penasterol as aglycone while glycosides 6–8 proved to be glycoconjugates of 24-methylene-14-carboxy-lanost-8(9)-en-3β-ol.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Seven new triterpene glycosides were isolated from the sponge Erylus formosus. ► Three carbohydrate chains for three pairs of hexasaccharide glycosides are new. ► Carbohydrate chains architecture represents chemotaxonomic character for the genus.