Optimization and characterization of Mytilus coruscus polysaccharide and investigation on antitumor activity

Abstract

This study aimed to optimize the enzymatic extraction of polysaccharides from Mytilus coruscus using the response surface method, characterize its composition, and investigate its antitumor activity in vivo. Employing a three-level and four-variable Box–Behnken design and setting the Mytilus coruscus polysaccharides (MCP) extraction yield (%) as response value, the optimum enzymatic extraction conditions were as follows: extraction time was 173.34 min, extraction temperature was 56.82°C, extraction pH was 5.64, and the ratio of liquid to fresh flesh was 19.82. Under the optimized conditions, the predicted extraction yield indicated by the response surface methodology (RSM) model was 19.68%, which showed compliance to the experimental yield (19.53%). GC-MS was used to detect the monosaccharide composition and methylation analysis, it was showed that MCP was composed of Rhamnose, Arabia sugar, fructose, mannose, glucose, and galactose with a molar ratio of 1.92:1.29:8.18:27.90:27.63:29.50 and the main linkage type was 1→4 linked glucose, the molecular weight of the polysaccharide was about 57 kDa determined by high-performance gel permeation chromatography (HPGPC). The antitumor activity was investigated in mice. The tumor growth inhibitory rate, spleen index, and thymus index were calculated. The tumor inhibition rates of medium and high-dose MCP were 21.8% and 32.9%, respectively, which were significantly different with the model group. Spleen index and thymus index significantly increased in medium and high-dose MCP group. It was obvious that MCP could improve immunity and inhibit the growth of tumors.