Biological potential of polysaccharide extracts obtained from commercially grown oyster mushroom strain

Abstract

Fungal members of the class Basidiomycetes are recognized as potential sources of bioactive compounds, which can be used in a possible replacement of the synthetic antioxidants and antibiotics by the naturally originated ones. Genus Pleurotus includes over 50 species of edible and medicinal mushrooms with great economic importance. Their fruiting bodies are rich in carbohydrates (28 - 50%), edible fibers (3-50%), protein (10 - 30%), essential amino acids (25-35%), vitamins (C, A, B, D), minerals (K, P, Mg, Na, Fe, Zn) and lipids (3-5%).The aim of this research was to compare biological characteristic of different extracts obtained from Oyster mushroom fruiting body, as well as to identify the organic compounds responsible for detected activities and finally to summarize available data on the factors that could affect on their antioxidant and antimicrobial activity. Samples of two types of polysaccharide extracts, namely hot water (HW) and hot alkaline (HA) ones were prepared from fruiting bodies of the industrially grown oyster mushroom Pleurotus ostreatus P80. Extracts were examined for their antimicrobial and antioxidant biological activity. The antibacterial activity was the widest against the Gram-positive bacteria Staphylococcus aureus for both types of polysaccharide extracts. HA extract singled out as the most effective against Gram-negative bacteria Proteus hauseri with microbicidal concentration of 2.5 mg mL–1 . HW polysaccharide extract was better antioxidant which was shown through the lower EC50 values of DPPH scavenging ability and ferric-reducing antioxidant power. EC50 values of the DPPH scavenging activity of the polysaccharides from HW and HA extracts were found to be particularly low, 0.6 and 0.7 mg mL-1 , respectively. EC50 values of the ferric-reducing antioxidant power were 4.3 and 4.5 mg mL-1 for HW and HA samples. Using spectroscopic methods it was found that HW extracts contained more protein (399 mg g-1 ) and phenolic compounds (6.36 mg g-1 ) compared to HA sample (20 mg g-1 protein and 4.96 mg g-1 phenolic compounds). Structural FT-IR analysis also confirmed higher content of glucans in HW polysaccharides.