Optimization for the extraction of polysaccharides from Nostoc commune and its antioxidant and antibacterial activities

A Box-Behnken design was used to optimise the extraction conditions for polysaccharide from Nostoc commune. The optimum extraction conditions were as follows: number of extractions, 4; extraction temperature, 100 °C; water-to-raw material ratio, 1:79.9; and per extraction time, 3.5 h. The experimental polysaccharide yield under the optimum conditions was 25.7% ± 1.8%, which agreed with the predicted yield. The polysaccharide extracted from N. commune exerted a strong 1,1-diphenyl-2-picrylhydrazyl radical scavenging ability but weak superoxide radical and hydroxyl radical scavenging activities. The polysaccharide also demonstrated antibacterial activities against Staphylococcus aureus and Escherichia coli.