Nobiloside, a new neuraminidase inhibitory triterpenoidal saponin from the marine sponge Erylus nobilis

A neuraminidase inhibitor, nobiloside (1), was isolated from the marine sponge Erylus nobilis Thiele, 1903. Its structure was determined as a penasterol trisaccharide. The absolute configurations were determined by NMR and chiral GC analysis. It inhibited neuraminidase from the bacterium Clostridium perfringens with an IC50 value of 0.46 mug/mL.