Polysaccharide of caper (Capparis spinosa L.) Leaf: Extraction optimization, antioxidant potential and antimicrobial activity.

Three-variable-three-level Box-Behnken design-response surface methodology (BBD-RSM) based on the single-factor experiments was used to optimize the extracting parameters of crude polysaccharides (CPSs) from the Capparis spinosa leaves (CSL) including extraction time (ETi, 60-120min), extraction temperature (ETe, 60-80°C), and the water/solid ratio (W/S, 6-16). The optimal process conditions in order to the highest yield (6.73%) of CSL-CPSs were 119.8min ETi, 72.84°C ETe, and 15.97:1W/S.Structure of polysaccharide extracted at the optimal operating point were identified by Fourier transform-infrared spectroscopy (FT-IR). CSL-CPSs (50-300μg/L) revealed significantly scavenging activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH)and OH free-radicals in vitro. A much more antimicrobial activity using this polysaccharide against Gram-negative bacteria (Escherichia coli, Shigella dysenteriaeandSalmonella typhi) was found than Gram-positive bacteria (Bacillus panis and Staphylococcus aureus). CSL-CPSs can thus be used as anexcellent antioxidant and antimicrobial ingredient in food and medicinal preparations.