New triterpene oligoglycosides from the Caribbean sponge Erylus formosus

Seven new triterpene glycosides, erylosides R-1 (1). T-1 (3), T-2 (4), T-3 (5), T-4 (6), T-5 (7), and T-6 (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-3 beta-ol. (C) 2011 Elsevier Ltd. All rights reserved.