β -glucan and antioxidant activities of four edible mushroom extracts from Thailand

Abstract

The commercial mushroom extracts from Thailand, Lentinus squarrosulus, Pleurotus sajor-caju, Pleurotus ostreatus, and Volvariella volvacea, could be sources of β-glucan and antioxidant. The objective of this research was to evaluate the β-glucan content and antioxidant activities of the mushroom extracts prepared from different extraction conditions. Various solvents, including water, ethanol, acid, and alkali were used for the mushroom extraction. The mushroom extracts were evaluated for their β-glucan content, total phenolic compounds, and antioxidant properties. Among all extraction conditions, the alkaline extracted (BE) P. ostreatus and P. sajor-caju showed high level of β-glucan content with 25.82 ± 3.87% w/w and 23.08 ± 0.56% w/w, respectively. Large amounts of total phenolic compounds were obtained from V.  volvacea and L. squarrosulus extracted with water at 60^oC (W60) as 38.07 ± 2.53 and 34.78 ± 5.69 mg gallic acid equivalent/g extract, respectively.  Excellent scavenging of ABTS radicals and FRAP assay were also observed in W60 of V.  volvacea as 67.12 ± 4.41 and 36.46 ± 3.44 mg trolox equivalent/g extract, respectively. The metal chelating effect of P. ostreatus was the highest at 66.13 ± 1.63 mg EDTA equivalent/g extract but was not significantly different from V.  volvacea (63.76 ± 0.51 mg EDTA equivalent/g extract) (p > 0.05). In conclusion, alkaline extraction was the most suitable for β -glucan and metal chelating activity extracts whereas water extraction was suitable for antioxidant extracts. These simple extraction conditions could be applied in producing high bioactive compounds and antioxidant active ingredients from local mushrooms for further addition in food and health products.