Extraction optimisation and lipid-lowering activity of Auricularia heimuer polysaccharides

Abstract

Assessments of molecular weight distribution and activity/efficacy of Auricularia heimuer polysaccharides (AAP) are of substantial significance for its extraction process optimisation. In the present study, single-factor orthogonal test and response surface methodology were employed to optimise extraction conditions of AAP. Furthermore, a rat hyperlipidaemia model was established to compare the lipid-lowering activity of polysaccharides obtained by three extraction methods. Conditions for enzymatic hydrolysis were optimised as pH 5.0, 1% cellulase, 2.5% substrate concentration and enzymolysis time of 1.5 h, leading to an up to 31.8% polysaccharide yield and 89.13% of polysaccharides within the molecular weight range of 5 000 Da to 10 000 Da. The results of animal experiments showed that the lipid-lowering activity of enzymolysis-extracted polysaccharides was significantly higher than that of water- and ultrasonic-extracted ones (P < 0.01). So the present study revealed that enzymatic hydrolysis-extracted polysaccharides showed the strongest hypolipidaemia activity, providing a basis for the development of A. heimuer-based functional foods and drugs.