Comparative evaluation of free radical scavenging activity and total metabolite profiles among 30 macrofungi species.

Abstract

The high antioxidant content of mushrooms such as polyphenols, polysaccharides, carotenoids, ergothioneine, glutathione, vitamins, and other compounds, has sparked interest in their potential use in preventive and therapeutic medicine. Therefore, this study aimed to evaluate the antioxidant potential of various macrofungi by measuring 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity and quantifying two classes of compounds: phenolics (TPC) and polysaccharides, both endo- (IPS) and exopolysaccharides (EPS). Species-specific abilities to produce mycelium, polysaccharides, and polyphenols were observed under submerged cultivation without agitation over 14 days. Mycelium productivity (P_M) ranged significantly from 292 ± 11 to 1110 ± 37 mg·L⁻¹·day⁻¹, with the highest values observed in Ophiocordyceps sinensis (1110 ± 37 mg·L⁻¹ ·day⁻¹), Pleurotus djamor (1090 ± 14 mg·L⁻¹·day⁻¹), and Cordyceps militaris (1080 ± 90 mg· L⁻¹·day⁻¹). The DPPH inhibition values of the extracts varied from 4.30 ± 0.20 to 87.9 ± 0.80%, while TPC ranged from 0.35 ± 0.10 to 34.6 ± 0.80 mg GAE/g d.w. Lentinula edodes was the best source of produced IPS (10.3 ± 0.35 g·L^-1), while Hypsizygus marmoreus exhibited the highest EPS content (2.24 ± 0.30 g·L^-1). Overall, IPS levels across species were higher, ranging from 1.56 to 10.3 g·L^-1. In half of the fungal species, the mycelium exhibited superior antioxidant activity compared to culture broth. However, in the majority (66.7%), TPC was higher in the culture broth than in the fungal mycelium. Distinct scavenging abilities and metabolite profiles were observed among different isolates. Notably, the mycelium of Fomitopsis pinicola and L. edodes showed the highest DPPH inhibition and TPC. The antioxidant activity and TPC varied depending on the culture medium, and solvents used. The highest DPPH inhibition (90%) and TPC (38.5 ± 0.40 mg GAE/g d.w.) were observed in the methanol (MeOH) extract of F. pinicola mycelium grown in Sabouraud dextrose medium. Similarly, MeOH and ethyl acetate (EtOAc) extracts demonstrated strong DPPH inhibition (over 87%), while the maximum TPC (40.0 ± 0.60 mg GAE/g d.w.) was detected in the water (H₂O) extract of L. edodes mycelium cultivated in glucose-peptone-yeast medium. A positive correlation was found between TPC and antioxidant activity, with Pearson's coefficient of 0.6615 for fungal mycelium, 0.1192 for culture broth, and 0.8924 and 0.7143 for F. pinicola and L. edodes, respectively. Both fungal mycelium and culture broth exhibit significant potential as natural antioxidants. These can be applied in nutraceuticals, food products, and nutritional supplements, offering diverse health benefits. Additionally, this study is a pioneering exploration of Auriporia aurea, Hohenbuehelia myxotricha, Lepista luscina, Oxyporus obducens, and Pseudospongipellis litschaueri, highlighting their largely unexplored potential for antioxidant applications.