Isolation and structures of erylosides from the carribean sponge Erylus goffrilleri

Eight new triterpene glycosides, erylosides R (1), S (2), T (3), U (4), F-5-F-7 (5-7), and V (8), were isolated from the sponge Erylus goffrilleri collected near Arresife-Seko Reef (Cuba). Structures of 1 and 2 were determined as the corresponding monosides having aglycons related to penasterol with additional oxidation and methylation patterns in their side chains. Eryloside T (3) was structurally identified as the Delta(7)-isomer of 1, containing an unusual (14 -> 9)-lactone ring in the tetracyclic aglycon moiety, and eryloside U (4) was shown to be the 7,8-epoxide of 3. Erylosides F-5-F-7 (5-7) and V (8) contain new variants of carbohydrate chains with two (5-7) and three (8) sugar units, respectively.