St. George's mushroom, Calocybe gambosa (Fr.) Donk: A promising source of nutrients and biologically active compounds

The composition of biologically active compounds of Calocybe gambosa (Lyophyllaceae) was analysed, and the antioxidant and cytotoxic activities were tested in vitro. C. gambosa was low in energy, fat, and carbohydrates, but rich in proteins and fibres. The total polyphenol content in the extracts was low (23.08 ± 0.67 in aqueous and 24.99 ± 4.25 μg GA mg⁻¹ of extract in methanolic extract). The methanolic extract showed anti-DPPH radical activity with an IC₅₀ of 626.10 ± 25.20 μg mL⁻¹. The sample of C. gambosa is rich in nucleotides and amino acids responsible for its pleasant taste. The nucleoside and 5′-monophosphates contents were 0.97 mg g⁻¹ and 2.32 mg g⁻¹ of dry mushroom, respectively. The contents of essential and non-essential amino acids were 18.41 ± 0.06 and 41.75 ± 0.30 mg g⁻¹ d.w., respectively. The percentages of saturated and unsaturated fatty acids were 42.6% and 57.4%, respectively. The most abundant water-soluble and fat-soluble vitamins were B1 and E, respectively. Cytotoxic effect of the extracts was examined against different cancer cell lines, and the best cytotoxicity was showed by the peptide extract against colon cancer cell line LS174.