Phytochemical Profile and Antioxidant Activity of Some Widely Consumed Mushrooms ^†

For the last few decades, mushrooms have been used both as a food (due to their high nutritional value) and as a medicine [1]. Mushrooms contain a great variety of biological compounds (such as polysaccharides, minerals, phenolic compounds, and sterols) with a wide range of therapeutic effects (antioxidant, anticancer, immunomodulatory, hypoglycemic, etc.) [2]. The aim of our study was the phytochemical screening and the evaluation of the antioxidant capacity of some widely consumed edible mushrooms, such as Hypsizygus tessellates (Bull.) Singer (commonly known as shimeji or white beech mushroom), Tremella fuciformis Berk. (commonly known as silver ear fungus), and Auricularia polytricha Fr. (commonly known as ear fungus). The material consisted of fresh (white beech) and air-dried (silver ear and ear fungus) mushrooms, acquired from a local supermarket in Bucharest in 2019. The phytochemical screening was determined based on qualitative assays, i.e., specific chemical reactions (Carr Price reagent for carotenoids, sulphuric acid/acetic anhydride for free sterols, Folin–Ciocalteu Reagent for polyphenols, and precipitation in methanol for polysaccharide identification), thin layer chromatography (TLC) [3], and quantitative analysis through spectrophotometric determination of the total phenol contents (expressed as tannic acid equivalents), free sterols (expressed as ergosterol equivalents), as well as by the gravimetric evaluation of polysaccharide contents [4]. The antioxidant activity was determined based on the scavenger capacity toward 2,2-diphenyl-1-picryl hydrazyl (DPPH) free radical, and the ferric reducing power assays [4]. The antioxidant activity was expressed as EC50 (mg/mL). Analyzed mushrooms are an important source of lipophilic (carotenoids and sterols) and hydrophilic (polyphenols and polysaccharides) compounds. TLC analysis revealed the presence of ergosterol for all analyzed mushrooms. Regarding the quantitative assays, the highest content of the phenolic compounds was observed for white beech mushroom (0.65 g/100 g mushroom), followed by the silver ear fungus (0.07 g/100 g mushroom), and the ear fungus (0.05 g/100 g mushroom). Regarding the content of free sterols, the highest value was determined for Tremella fuciformis Berk. (0.27 g/100g mushroom), whilst Hypsizygus tessellates (Bull.) Singer contained the highest amount of polysaccharides (4.48 g/100 g mushroom). The best antioxidant activity (determined by both methods) was observed for the white beech mushroom, in correlation with the highest phenolic content. Analyzed mushrooms are an important source of bioactive compounds with antioxidant activity. Our preliminary results are valuable in order to obtain dry extracts that will be further analyzed for their antioxidant activity both in vitro (using different cell lines) and in vivo (preclinical studies) regarding their beneficial role in metabolic or cardiovascular disease treatment, for which oxidative stress is a key factor.