Abstract: Response surface methodology was applied to optimize polysaccharide extraction from Paecilomyces hepiali Chen & Dai. The extracted polysaccharide was structurally elucidated. The optimal extraction conditions were found to be 4.5 h extraction with hot water at 98.0 ℃ at water/material ratio of 25:1 (mL/g). Under these conditions, the maximum polysaccharide yield of 9.69% was obtained and the polysaccharide mainly composed of neutral polysaccharide (84.7%) and uronic acid (9.5%). High performance size exclusion chromatography (HPESC), high performance anion exchange chromatography and FT-IR spectroscopy were used to analyze the structural characteristics of the polysaccharide. Results showed that the molecular weight of the polysaccharide was 61.6 kD, displaying a single chromatographic peak, and its structure contained a pyran ring. In addition, the polysaccharide was composed of arabinose, galactose, glucose, xylose, mannose and galacturonic acid, with a molar ratio of 2.5:31:36:1:15:4. The findings may be useful for future studies on the structure-activity relationship of polysaccharides from Paecilomyces hepiali Chen & Dai and for the development of new polysaccharide-based products.

Key words: polysaccharide from Paecilomyces hepiali Chen &, Dai, extraction optimization, response surface methodology, structural analysis