Preparation, physicochemical and structural characterizations, and bioactivities of polysaccharides from Corbicula fluminea industrial distillate

Abstract

Corbicula fluminea distillate (CFD), as an industrial sub-product of the steaming process of C. fluminea, is rich in polysaccharides, proteins, and amino acids and has important developmental value. In this study, therefore, three water-soluble polysaccharides (CFDPs: CFDP-D, CFDP-U, and CFDP-T) were extracted and separated from CFD through direct ethanol precipitation, ultrasound-assisted extraction, and three-phase partitioning (TPP), respectively. Results demonstrated that the three extraction methods had important influences on extraction yields, chemical compositions, molecular weights, monosaccharide and amino acid constituents, structural characteristics, and microstructures as well as biological activities of CFDPs. Specifically, CFDP-T had higher yield (60.92% ± 3.58%), carbohydrate content (91.05% ± 1.22%), and uronic acid content (8.55% ± 0.18%) and lower protein content (7.15% ± 0.15%) than CFDP-D and CFDP-U. The three CFDPs were acidic proteoheteroglycans combined through O-glycosidic bonds and had high molecular weights of 1.93–2.41 × 107 Da and the same monosaccharide and amino acid compositions but different contents. Compared with CFDP-D and CFDP-U, CFDP-T exhibited more excellent free radical scavenging and stimulating (1.57 ± 0.03 μM, 500 μg/mL) activities on RAW264.7 macrophages in vitro. Therefore, our findings suggested that CFDP-T obtained from CFD by TPP had the potential to be a functional food ingredient in food industry.