Extraction of polysaccharide by ethanol/ammonium sulphate aqueous two-phase system from the Argentina anserina and its antibacterial and antioxidant activity

An extraction procedure and method of Argentina anserina polysaccharides(AAP)and its antibacterial and antioxidant activity evaluation were established. The response surface methodology(RSM)and BBD central composite design coupling aqueous two phase system was used to optimize the optimal extraction model parameter between extraction factors and yields of AAP polysaccharide. The inhibition zone which was used to estimate the antibacterial activities were determined by filter paper diffusion method. The scavenging effect to the hydroxyl radical and superoxide radical were detected with the oxidation of ferrous sulfate-salicylic acid-hydrogen peroxide and self-oxidation of pyrogallic acid system. The optimum extraction conditions were found to be extraction temperature of 55 ℃,extraction time of 60 min and ration of liquid to materials of 1∶35 g/mL. Under these conditions,the extraction efficiency of AAP polysaccharides achieved(14.46%±0.12%). The result of antibacterial activity indicate that RP polysaccharides present high sensitive to Staphylococcus aureus and Escherichia coli antioxidant and antimicrobial,while present moderately sensitive to Bacillus subtilis. The result showed that AAP polysaccharides had selective antimicrobial activity in vitro. The evaluation of antioxidant activity suggested that the AAP polysaccharides exhibited significant antioxidant activity and obtained maximum scavenging activity of(76.38%±0.21%)(3.6 mg/mL)and(25.01%±0.14%)(3.0 mg/mL)respectively. The quadratic multinomial regression mode between extraction factors and yield was established,while the extraction method of qualitative and quantitative by response surface methodology coupling BBD design was achieved. The antioxidant and antimicrobial result showed that AAP possess antioxidant and antimicrobial activity in vitro.