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.