Structural investigation of a uronic acid-containing polysaccharide from abalone by graded acid hydrolysis followed by PMP-HPLC-MSn and NMR analysis

A new strategy was applied to elucidate the structure of a polysaccharide from abalone gonad (AGSP). It was hydrolyzed by 0.05 M, 0.2 M, 0.5 M, and 2.0 M TFA at 100 degrees C for 1 h, sequentially. Every hydrolysate was ultrafiltrated (3000 Da) to collect oligo- and monosaccharides, and the final retentate was further hydrolyzed with 2.0 M TFA at 110 degrees C and 121 degrees C for 2 h, respectively. 1-Phenyl-3-methyl-5-pyrazolone (PMP) derivatization followed by HPLC-MSn analysis was applied to detect the sugar residues in these hydrolysates, which allowed proposing their location in the polysaccharide structure. The retentate after 0.5 M TFA hydrolysis was confirmed as the polysaccharide backbone, and it was further analyzed by 1D and 2D NMR spectroscopy. Thus, the structural elucidation of AGSP was accomplished, and it has a backbone of -> 4)-beta-GlcA(1 -> 2)-alpha-Man(1 -> repeating unit with Fuc, Xyl and Gal in the branch. Theanalytical strategy demonstrated was useful to characterize the structure of polysaccharides. (C) 2014 Elsevier Ltd. All rights reserved.