New steroidal oligoglycosides mycalosides B-I (2-9) have been isolated from the polar extract of the Caribbean sponge Mycale laxissima, and their structures have been elucidated by 1D and 2D NMR ((1)H, (13)C, DEPT, COSY-45, COSY-RCT, HSQC, HMBC, and NOESY spectra) and MALDI-TOF mass spectrometry. Mycalosides B (2) and C (3) were shown to be 27- and 28-nor derivatives of the previously known tetraoside mycaloside A (1). Mycaloside D (4) differs from 1 only in the presence of an additional acetyl group in the carbohydrate moiety. Mycaloside E (5) was structurally identified as a 28-nor-4-dehydroxy derivative of 1. Mycalosides F-H (6-8), differing from each other by the structures of their side chains and nonacetylated (7, 8) or acetylated (6) tetrasaccharide carbohydrate moieties, have new 5(6)-unsaturated 3 beta,4 beta,21-trihydroxy-15-keto-steroidal aglycons. Mycaloside I (9) is a tetraoside of a new 7,24(28)-diunsaturated 3beta,15 beta,29-trihydroxystigmastane aglycon. It was established that the total fraction of the mycalosides as well as mycalosides A (1) and G (7) inhibit the fertilization of eggs by sperm of the sea urchin Strongylocentrotus nudus preincubated with these compounds.

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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.

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