Starfish saponins. Part 14. Structures of the steroidal glycoside sulphates from the starfish Marthasterias glacialis

Abstract

The major sulphated asterosaponins, marthasterosides A1, A2, B, and C, isolated from the starfish Marthasterias glacialis, have been completely characterized. Marthasterosides A1 and A2 are hexaglycosides and contain the same aglycone, thornasterol A. They have been established as 6α-O-{β-D-fucopyranosyl-(1→3)-β-D-fucopyranosyl-(1→2)-β-D-galactopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-β-D-quinovopyranosyl}-20-hydroxy-23-oxo-5α-cholest-9(11)-en-3β-yl sodium sulphate (6) and 6α-O-{β-D-fucopyranosyl-(1→3)-β-D-fucopyranosyl-(1→2)-β-D-quinovopyranpsyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-xylopyranosyl-(1→3)-β-D-quinovopyranosyl}-20-hydroxy-23-oxo-5α-cholest-9(11 )-en-3β-yl sodium sulphate (7) respectively. Marthasterosides B and C are the pentaglycosides (8) and (9); they contain the same oligosaccharide moiety, i.e. β-D-fucopyranosyl-(1→2)-β-D-fucopyranosyl-(1→4)-[β-D-quinovopyranosyl-(1→2)]-β-D-quinovo-pyranosyl-(1→3)-β-D-glucopyranosyl, which is attached to C-6 of 3β-sulphomarthasterone, i.e. 3β,6α-dihydroxy-5α-cholesta-9(11)24-dien-23-one, and of 3β-sulpho-24,25-dihydromarthasterone, respectively.