NOVEL SULFATED OLIGOSACCHARIDES FROM THE SEA-CUCUMBER CUCUMARIA-FRONDOSA

The structures of a novel sulfated saponin, frondoside B (C59H92O31S2M2) [5], and frondecaside (C58H92O63S6M6) [6], a unique hexasulfated decasaccharide, have been deduced by nmr (500 MHz) methods. Based on H-1 COSY, relay COSY, NOESY, and C-13-nmr data, frondoside B was shown to have the structure 3-beta-O-{3-O-methyl-beta-D-glucopyranosyl-(1 BAR-arrow-pointing-right 3)-O-beta-D-6-sulfonatoglucopyranosyl-(1 BAR-arrow-pointing-right 4)-O-[beta-D-xylopyranosyl-(1 BAR-arrow-pointing-right 2)]-O-beta-D-quinovopyranosyl-(1 BAR-arrow-pointing-right 2)-O-beta-D-4-sulfonatoxylopyranosyl}-holost-7-ene sodium (or potassium) salt. From H-1-COSY, relay COSY, C-13-nmr data, T1 measurements, and comparison with nmr spectra of frondoside B, the structure of frondecaside was established as 3-O-methyl-6-sulfonato-beta-D-glucopyranosyl-(1 BAR-arrow-pointing-right 3)-O-beta-D-6-sulfonatoglucopyranosyl-(1 BAR-arrow-pointing-right 4)-O-[beta-D-xylopyranosyl-(1 BAR-arrow-pointing-right 2)]-O-beta-D-quinovopyranosyl-(1 BAR-arrow-pointing-right 2)-O-beta-D-4-sulfonatoxylopyranosyl-(1 BAR-arrow-pointing-right 1)-3-O-methyl-6-sulfonato-beta-D-glucopyranosyl-(1 BAR-arrow-pointing-right 3)-O-beta-D-6-sulfonatoglucopyranosyl-(1 BAR-arrow-pointing-right 4)-O-[beta-D-xylopyranosyl-(1 BAR-arrow-pointing-right 2)]-O-beta-D-quinovopyranosyl-(1 BAR-arrow-pointing-right 2)-O-beta-D-4-sulfonatoxylopyranoside sodium (or potassium) salt.