Extraction optimization, preliminary characterization and immunological activity of polysaccharides from figs

Complex enzyme extraction (CEE), purification, characterization of fig polysaccharides (FPs) from dried figs were investigated. Orthogonal experiment was used to optimize the concentration of cellulose, pectinase and papain. Response surface methodology (RSM) was employed to optimize extraction conditions. The optimum extraction conditions were: enzyme concentration of 1.5%, 1.5%, 0.5% (wt%) of pectinase, papain, cellulose, ratio of water to raw material 40.3 mL/g, extraction time 54.1 min, temperature 34.15 °C and pH 3.8. Under these conditions, the experimental yield was 7.98 ± 0.17%. Two homogeneous heteropolysaccharides (FPs-1-1, FPs-2-1) were purified by DEAE-Sepharose and Sephadex G-200 chromatography, which were composed of rhamnose, arabinose, xylose, mannose, glucose and galactose with molecular weight of 1.52 × 106 and 4.75 × 105 Da, respectively. The bioactivity assay showed that FPs-1-1 and FPs-2-1 could more significantly enhance splenic lymphocyte proliferation, phagocytosis and NO production of macrophages, could be explored as potential immunopotentiating agent for use in functional food or medicine.