Novel sulfated oligosaccharides from the sea cucumber Cucumaria frondosa

Abstract

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 1H COSY, relay COSY, NOESY, and 13C-nmr data, frondoside B was shown to have the structure 3 beta-O-(3-O-methyl-beta-D-glucopyranosyl-(1----3)-O-beta-D-6- sulfonatoglucopyranosyl-(1----4)-O-[beta-D-xylopyranosyl-(1----2)] -O-beta- D-quinovopyranosyl-(1----2)-O-beta-D-4-sulfonatoxylopyranosyl++ +)-holost-7-ene sodium (or potassium) salt. From 1H-COSY, relay COSY, 13C-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----3)-O-beta-D-6- sulfonatoglucopyranosyl-(1----4)-O-[beta-D-xylopyranosyl-(1----2)] -O-beta- D-quinovopyranosyl-(1----2)-O-beta-D-4-sulfonatoxylopyranosyl++ +-(1----1)-3-O- methyl-6-sulfonato-beta-D-glucopyranosyl-(1----3)-O-beta-D-6- sulfonatoglucopyranosyl-(1----4)-O-[beta-D-xylopyranosyl-(1----2)] -O-beta- D-quinovopyranosyl-(1----2)-O-beta-D-4-sulfonatoxylopyranoside+ ++ sodium (or potassium) salt.