Sulfated Steroidal Glycosides, Regulusosides S1 and S2, from the Tropical Starfish Pentaceraster regulus

Two new sulfated steroidal glycosides were isolated from the EtOH extract of the tropical starfish Pentaceraster regulus. Regulusoside S1 was proposed to be the sodium salt of (24R)-3-O-(2-O-methyl-β-D-xylopyranosyl)-24-ethyl-5α-cholestane-3β,6α,8,15α,16β,29-hexaol 16-O-sulfate. Regulusoside S2 was its analog and contained an additional β-D-xylopyranose residue in a side chain on aglycon C-29. The structures of the isolated compounds were established by 2D NMR spectroscopy and tandem mass spectrometry with electrospray ionization (ESI).