Antioxidant activity and cytotoxicity of exopolysaccharide from mushroom Hericium coralloides in submerged fermentation

Abstract

Mushrooms of the genus Hericium spp. represent a series of delicious edible mushrooms with medicinal value. Here, for the first time, the species native to Iran, the mushroom Hericium coralloides, was collected in Mazandaran province, identified, and registered with the NCBI under accession number MW136052. The production of exopolysaccharides (EPS) in submerged culture was optimized using the response surface method. Among the physicochemical and culture medium conditions tested, rotation speed and concentration of maltose and peptone of soybean significantly affected the production of EPS. The proposed model predicts maximum EPS production (0.13 g/L) at 50 g/L maltose, 3 g/L soy peptone, and 1 g/L yeast extract, pH = 6.5, 200 rpm, inoculum at 5% v/v, and 22 °C. The molecular weight of the EPS chains was 413 and 1578 Da. EPS has antioxidant action (EC50 = 6.59 mg/mL) and cytotoxic activity against cancer cells. The viability of AGS and MKN-45 cancer cell lines declined to 20 and 30% after 48 h of the EPS treatment. H. coralloides EPS could be considered a natural dietary anti-cancer supplement. Further studies are necessary to understand the mechanism of the H. coralloides EPS activity on the cell cycle of cancer cells and to prove its action in vivo.

Supplementary information: The online version contains supplementary material available at 10.1007/s13399-022-03386-0.

Keywords: Anticancer; Antioxidant; Exopolysaccharide; Hericium coralloides; MW136052; Optimization; Submerged culture.

Fig. 1

Characteristics of H. coralloides isolated from Mazandaran forests. Fruiting body of H. coralloides (a), optical microscope image of fungal hyphae with lactophenol cotton blue staining (b), and image of basidia and glostidia of this fungus (c). Phylogeny of H. coralloides, reconstructed from the ITS dataset (d)

Fig. 2

Three-dimensional diagram of effect of pH and temperature in different rotation speed and inoculum on the production of EPS using D-optimal surface response method (a–c). Three-dimensional diagram of effect of maltose and yeast extract in different soy peptone concentrations on the production of EPS using CCD (d, e)

Fig. 3

GPC analysis of H. coralloides EPS molecular weight (a). FTIR (b) and XRD (c) of H. coralloides EPS

Fig. 4

Antioxidant activity (DPPH assay) of different EPS concentrations. Error bars indicate mean ± standard deviation (a). Cell viability of AGS and MKN-45 cancer cell lines treated with EPS for 24 h (b) and 48 h (c) measured with MTT assay (*p < 0.05, **p < 0.01, ***p < 0.001)