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.