Optimization of ultrasonic extraction process of polysaccharides from Ornithogalum Caudatum Ait and evaluation of its biological activities.

Ultrasonic extraction technique (UET) was used to extract crude polysaccharides (OCAP) from Ornithogalum Caudatum Ait (OCA), an orthogonal experiment (L(9) (3)(4)) was applied to optimize extraction conditions. Membrane separation technology and gel filtration chromatography were used to fractionate OCAP, the antioxidant and immunomodulatory activities were evaluated by radical scavenging and spleen lymphocyte proliferation assay. The optimal conditions were determined: extraction time 60min, ultrasound power 500W, ratio of water to raw material 30ml/g and extraction number 3. Under these conditions, the yield of OCAP was 36.77±1.76%. OCAP was fractionated into three major fractions (OCAP-I, OCAP-II and OCAP-II), that all fractions possessed considerable antioxidant activity. OCAP-II and OCAP-III exhibited good immunomodulatory activities. The results indicated that UET is a very useful method for extraction bioactive polysaccharides from plant materials. OCAP could be explored as a potential antioxidant and immunostimulating agent for use in medicine or functional foods.