The use of Pleurotus ostreatus by-products for the preparation of a gel-like polysaccharide with bioactive properties

Abstract

The mushroom Pleurotus ostreatus is widely produced in Brazil and its stipes are discarded before commercialization. In the present study, this agricultural fungal waste (mushroom stipes), was analyzed by preparing an aqueous extract and obtaining the polysaccharides by ethanol precipitation (POS-extract). The fraction presented 37 % of carbohydrates and small amounts of proteins and phenolic compounds. Rheological analyses showed a high viscosity and a gel-like behavior depending on temperature and concentration. The main polysaccharides present were β-glucans and mannogalactans, which were confirmed by the enzymatic method, monosaccharide composition, and NMR. Methylation analyses showed a high content of 1,6-linkages for both polysaccharides. The POS-extract was tested on Caco-2 cells to observe cytotoxicity and cell migration ability. Incubation with different concentrations of POS-extract showed no significant cytotoxic effects (p ≥ 0.05) and promoted wound closure of the injured monolayer by 95 % after 72 h (at 300 μg/mL). The preliminary results indicate a promising application of mushroom by-products, containing easily extractable bioactive compounds.