Orthogonal test design for optimization of the extraction of polysaccharides from Phascolosoma esulenta and evaluation of its immunity activity.

Yield of polysaccharides from Phascolosoma esulenta obtained by phosphate buffer extraction through an orthogonal experiment (L9(3)(4)) were investigated to get the best extraction conditions. The results showed that extraction temperature, ratio of phosphate buffer to raw material, extraction time, and ratio of trypsinase to raw material were the main four variables that influenced the yields of extracts. The highest yield was obtained when extraction temperature, ratio of phosphate buffer to raw material, extraction time and ratio of trypsinase to raw material were 40°C, 2, 5.5h and 1.6, respectively. The immunity-stimulating method showed that polysaccharides from P. esulenta could significantly raise liver, spleen and thymus index of mice and enhance Con A-stimulated mouse spleen cells proliferation. These results indicate that polysaccharides from P. esulenta had significantly higher immunity-stimulating activities.