Characterization of Hypericum perforatum polysaccharides with antioxidant and antimicrobial activities: Optimization based statistical modeling.

In this study, the extracting parameters of crude polysaccharides (CPSs) from the Hypericum perforatum (HP) including extraction time (ETi, 60-180min), extraction temperature (ETe, 60-90°C), and the water/solid ratio (W/S, 10-30 was optimized by using three-variable-three-level Box-Behnken design-response surface methodology (BBD-RSM) based on the single-factor experiments. The optimal extraction conditions were as follow: ETi 117.5min, ETe 74.28°C, and W/S 20.3:1. Under these conditions, the experimental yield was 6.69%. Fourier transform-infrared spectroscopy (FT-IR) was used to identify structure of polysaccharide extracted at the optimal operating point. HP-CPSs was proved to possess antioxidant activities including 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and OH free-radicals scavenging activates in vitro. The antibacterial activities of HP-CPSs against Escherichia coli, Shigella dysenteriae and Salmonella typhi, Bacillus cereus and Staphylococcus aureus were evaluated by determining clear growth inhibition zone diameters and by essays in liquid media. Overall, the results indicated that those polysaccharides could offer promising sources of polysaccharides for future application as antioxidant ingredients in the food industry.