FORBESIDE D (C62H101O31SNA), A NEW SAPONIN FROM ASTERIAS-FORBESI - COMPLETE STRUCTURE BY NUCLEAR-MAGNETIC-RESONANCE (300 MHZ) METHODS

The structure of forbeside D (C62H101O31SNa), a saponin from the starfish Asterias forbesi, has been deduced entirely by nuclear magnetic resonance methods using a 300 MHz instrument. Based on 2D-COSY, HECTOR, single and multiple RCT, NOESY and HETCORSL experiments, the structure of forebeside D has been shown to be the monosodium salt of 6-alpha-O-{beta-D-galactopyranosyl-(1-->3)-beta-D-fucopyranosyl-(1-->2)-beta-D-fucopyranosyl-(1-->4)-[beta-D-quinovopyranosyl-(1-->2)]-alpha-L-arabinopyranosyl-(1-->3)-beta-D-quinovopyranosyl}20S-hydroxy-3-beta-sulfo-oxy-5-alpha-cholesta-9(11),24-diene. This is the first example of a starfish saponin featuring an arabinopyranosyl unit.