Starfish saponins. Part 34. Novel steroidal glycoside sulphates from the starfish Asterias amurensis
A reinvestigation of the extracts from the starfish Asterias amurensis has led to the isolation of eight novel steroidal glycosides along with major amounts of the already reported glycoside B2(1), ovarian asterosaponin-1 (3), and ovarian asterosaponin-4 (4). Four novel compounds are ‘asterosaponins’ assigned as the asteroside A (8), B (9), C (10), and D (11), consisting of a Δ9(11)-3β,6α-dihydroxysteroidal moiety, a pentasaccharide portion attached at C-6, and a sulphate group at C-3. Asterosides A–C possess the same saccharide portion, β-D-quinovopyranosyl-(1 → 2)-β-D-galactopyranosyl-(1 → 4)-[β-D-quinovopyranosyl-(1 → 2)]-β-D-xylopyranosyl-(1 → 3)-β-D-quinovopyranosyl, already encountered in glycoside B-2, while the saccharide chain of asteroside D is identical with that of ovarian asterosaponin-4 (4) and differs from the previous one by the replacement of the galactose by glucose. Main differences among the novel ‘asterosaponins’ reside in the steroid side chains.
The second group of saponins consists of four new polyhydroxysteroidal xylopyranosides, designated amurensosides A–D (12)–(15). Three of them, A–C, are sulphated compounds.