Effect of processing on the content and biological activity of polysaccharides from Pleurotus ostreatus mushroom

•The amount of crude polysaccharides was quantified in fresh and processed mushrooms.•The isolated polysaccharides differed in their chemical composition.•The polysaccharides exerted antioxidant and antiproliferative activity.•The content and the activity of polysaccharides was decreased due to the processing.

Water soluble polysaccharides (WSP) were isolated from processed and non-processed fruiting bodies of oyster mushroom (Pleurotus ostreatus). The processing methods involved: blanching, boiling and blanching followed by fermenting with a strain of lactic acid bacteria (Lactobacillus plantarum). The yields of WSP ranged from 78.7 ± 1.5 mg/g to 120.1 ± 4.9 mg/g dry weight of sample. Blanching did not affect the content of WSP. Boiling for 15 min, led to the substantial decrease in the amount of WSP (34.7% decline). The isolated samples differed in carbohydrate, protein and phenolics content. FTIR spectroscopy of the WSP samples confirmed the presence of both α- and β-glycosidic linkages. Gel permeation chromatography showed the presence of compounds having the molecular weight of 198.3, 11.9, 3.1 kDa. The samples possessed antioxidant capacity measured by ABTS method (14.14 ± 0.63 to 29.48 ± 1.12 μmoles of Trolox per 1 g dw) and FRAP assay (2.49 ± 0.54 to 16.52 ± 0.55 μmoles of Trolox equivalents per 1 g dw). The antioxidant potential was decreased by the processing. Similarly, antiproliferative activity of WSP towards human breast cell lines (MCF-7 and T-47D) was lower due to the processing.