Polar metabolites from the Antarctic starfish Labidiaster annulatus

Purification of the ethanolic extract of the Antarctic starfish L. annulatu s has led to the isolation of two sulfated pentaglycosides (1, 2) and to th e polyhydroxylated steroid (255)-5 alpha-cholestane-3 beta,6 beta, 15 alpha , 16 beta, 26-pentaol (3). Saponin 1 contains a novel pentasaccharide chain attached to C-6 of the steroidal aglycone. Identification of the compounds relied on interpretation of spectral data (H-1-NMR, (1')3C-NMR, FABMS) and on acid and enzymatic hydrolysis.