A mild and efficient extraction method for polysaccharides from Sinonovacula constricta and study of their structural characteristic and antioxidant activities.

The aim of this paper is to develop a mild and efficient extraction method for polysaccharides from Sinonovacula constricta (SCP) using enzyme extraction, and analyze the structural characteristics and antioxidant activities of the two purified polysaccharide fractions (SCP-1 and SCP-2). Firstly, enzyme extraction conditions were optimized, and the conditions were found to be, as follows: enzymolysis time 173.0 min, pH 8.2, enzymolysis temperature 50.0 ℃ and enzyme content 4.0%. Comparison between enzymatic extraction and water extraction was obtained from visual, UV-visible and IR spectrum images. The results clearly indicate that there is no significant difference between them with regard to the composition of the SCP fraction, but the polysaccharide content produced by enzymatic extraction is higher. Then, the physicochemical properties and structural characteristics of SCP-1 and SCP-2 were investigated using FT-TR, UV, GC and HPGPC. The carbohydrate content, sulfuric radicals and uronic acids of the two fractions were detected. Both SCP-1 and SCP-2 were mainly consisted of glucose, but their molecular weights were different. In addition, compared the Fe2+ chelating activity, ABTS+ radical and superoxide radical scavenging activity, and lipid peroxidation inhibition activity of SCP-1 and SCP-2, it turned out that SCP-2 had stronger antioxidant activity than SCP-1.