Ultrasonic-assisted Extraction, Purification, Antioxidant and Antibacterial Activity of Polysaccharide from Cornus Officinalis Leaves

The ultrasonic-assisted extraction process of polysaccharide from Cornus officinalis leaves (COLP) was optimized. After isolation and purification, the antioxidant and antibacterial activities of polysaccharide were studied in vitro. The extraction rate was highest under conditions of ultrasonic power 340 W, solvent to solid ratio 26:1(v/w), extraction temperature 71 °C and extraction time 2.3 h, reaching 7.04%, which was consistent with the model predicted value. The crude polysaccharide was isolated and purified by DEAE-52 cellulose chromatography column, and four components COLP-1, COLP-2, COLP-3 and COLP-4 were obtained. Then, Sephadex G-100 chromatography column was used to purify COLP-1 and COLP-3, and two components COLP-1-1 and COLP-3-2 were obtained. COLP-1-1 had strong scavenging ability against DPPH free radicals, against hydroxyl radical, and superoxide anion radical, with the highest clearance rate reaching 81.48%, 79.48% and 72.87% respectively. COLP-3-2 also had strong scavenging ability against DPPH free radicals, against hydroxyl radical, and superoxide anion radical, with the highest clearance rate reaching 88.57%, 76.64% and 86.08% respectively. The results indicated that COLP-1-1 and COLP-3-2 had higher antioxidant activity, and the antioxidant activity of COLP-3-2 was stronger than COLP-1-1. The†results of antibacterial activity showed†that COLP-1-1 had the highest antibacterial activity on Bacillus subtilis and weaker antibacterial activity on Escherichia coli, Salmonella typhimurium and Staphylococcus aureus; COLP-3-2 had a certain antibacterial activity on Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium and Bacillus subtilis.