Abstract:The total amino acid compositions and amino acid scores, phenol extracts and their antioxidant activities, and polysaccharides and their antioxidant activities of six wild edible Boletus mushrooms from the Yunnan province were analyzed to study their nutritive and antioxidative characteristics. The results showed that 17 amino acids were present in almost all of the six species. The total amino acid (TAA) contents ranged from 23.13% DW (B. bicolor) to 30.69% DW (B. speciosus), with significant differences in TAA contents among the different species (p<0.05). The proportion of hydrophobic amino acids was relatively high. Aspartic acid, glutamic acid, glycine, alanine, and cysteine were among the most abundant amino acids present in the six species. Amino acid scores ranged from 0.59 (B. speciosus) to 0.94 (B. bicolor). All six species were rich in polyphenol, with polyphenol contents ranging from 1.20 mg GAE/g DW (B. Sinicus) to 10.32 mg GAE/g DW (B. speciosus). The polyphenol extracts exhibited significant antioxidative effects on OH, DPPH free radicals, and lipid peroxidation. Notably, the inhibition of lipid peroxidation by the phenol extracts of B. bicolor and B. craspedius were significantly higher than that by butylated hydroxytoluene (p<0.05). The water-soluble crude polysaccharides of the six species ranged from 11.67% DW (B. craspedius) to 20.00% DW (B. speciosus). Two polysaccharide fractions soluble in 60% and 40% ethanol from the crude polysaccharides showed appreciable antioxidative activities in four evaluation systems. In summary, the six wild edible Boletus mushrooms showed high nutritive value, strong antioxidative activity, and rich composition of polyphenols and polysaccharides; they are thus potential resources for antioxidants.
