Characterization of acidic polysaccharides from the mollusks through acid hydrolysis

•A method was demonstrated for uronic acid-containing polysaccharide (UACP) analysis.•UACPs were identified by analyzing disaccharides in their acid hydrolysates.•This method was applied to investigate the distribution of UACPs in 20 shellfishes.•The prevalence of chondroitin sulfate and heparin were observed in shellfishes.•Three non-glycosaminoglycan UACPs were found in 7 mollusks. Uronic acid-containing polysaccharides (UACPs) including glycosaminoglycans (GAGs) exist widely in nature. Herein we propose an elegant methodology to identify UACPs by analyzing their disaccharides produced from the acid hydrolysis using HPLC–MSn upon 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization. Based on the optimization of experimental conditions by the single factor experiment and orthogonal test design, the combination of 1.3M TFA at 105°C for 3h is found to be the optimum. Subsequently, these conditions were applied to investigate the distribution of UACPs in 20 selected species of edible Bivalvia and Gastropoda. PMP-disaccharides derived from UACPs in mollusks were identified by comparing the retention time and mass spectra with those of the reference PMP-disaccharides from hyaluronic acid (HA), chondroitin sulfate (CS), heparin (HP), and AGSP with →4)-GlcA(1→2)-Man(1→ repeating units. The analysis reveals the prevalence of CS in the shellfishes as well as the HP, and existence of three non-GAG UACPs in 7 mollusks.