Comparative Research of Antioxidant, Antimicrobial, Antiprotozoal and Cytotoxic Activities of Edible Suillus sp. Fruiting Body Extracts

The aim of this study was to evaluate bioactive properties of <i>Basidiomycota</i> fungi, mainly <i>Suillus</i> sp. Wide spectrum of activities were revealed for <i>S. variegatus</i>, <i>S. luteus</i>, <i>S. bovinus</i> and <i>S. granulatus;</i> and obtained results were compared with other common fungi. Total Phenolic Content (TPC) varied from 245.32 ± 5.45 to 580.77 ± 13.10 (mg (GAE) per 100 g of dry weight) in methanolic extracts of <i>S. bovinus</i> and <i>S. granulatus</i> fruiting bodies, respectively. In ethyl acetate extracts, the highest TPC were obtained for <i>S. variegatus</i> (310 ± 9.68, mg (GAE)/100 g, dry matter), and the lowest means for <i>S. luteus</i> (105 ± 3.55, mg (GAE)/100 g dry weight). The ethyl acetate extracts of the tested <i>Suillus</i> species exhibited a stronger antioxidant activity (AA) to scavenge DPPH^● and ABTS^•+ than the methanolic ones, and the highest effects were determined for <i>S. luteus</i> (EC₅₀, 0.15 ± 0.05 and 0.23 ± 0.05%, respectively). In the case of methanolic extracts, the highest AA were evaluated for <i>S. granulatus</i>. (EC₅₀ for DPPH^● and ABTS^•+, 0.81 ± 0.30 and 0.95 ± 0.22%, respectively). The ABTS^•+ scavenging potential varied from 0.25 ± 0.05 to 0.74 ± 0.10 (mmol/L, TROLOX equivalent, for <i>S. granulatus</i> and <i>S. variegatus</i> fruiting body extracts, respectively) in the ethyl acetate extracts. <i>S. granulatus</i> extracts demonstrated the widest range of antimicrobial effects against both gram-positive and gram-negative bacteria (from 11.7 ± 1.3 to 28.5 ± 3.3 mm against <i>Pseudomonas aeruginosa</i> and <i>Bacillus mycoides</i>, respectively); and against two fungal strains (up to 13.6 ± 0.4 mm on <i>Meyerozyma guilliermondii</i>) in agar disc diffusion tests. Our study revealed that methanolic extracts of the most tested <i>Suillus</i> sp. were not active enough against the tested parasites: <i>Trypanosoma cruzi</i>, <i>Trypanosoma brucei</i>, <i>Leishmania infantum</i> and <i>Plasmodium falciparum</i>. Only <i>S. variegatus</i> extracts showed good antiprotozoal effects against <i>P. falciparum</i> (12.70 µg/mL). Cytotoxic activity was observed on human diploid lung cells MRC-5 SV2 by <i>S. granulatus</i> extracts (64.45 µg/mL). For comparative purposes, extracts of other common Lithuanian fungi, such as <i>Xerocomus</i> sp. (<i>X. badius</i>, <i>X. chrysenteron</i> and X. <i>subtomentosus</i>), <i>Tylopilus felleus</i>, <i>Phallus impudicus</i> and <i>Pycnoporus cinnabarinus</i> were investigated for their activity. The <i>P. cinnabarinus</i> extracts demonstrated the highest and broadest overall effects: 1.32 µg/mL against <i>T. brucei</i>, 1.46 µg/mL against <i>P. falciparum</i>, 3.93 µg/mL against <i>T. cruzi</i> and 21.53 µg/mL against <i>L. infantum</i>. Additionally, this extract exhibited strong cytotoxicity on MRC-5 cells (13.05 µg/mL). The investigation of bioactive fungal metabolites is important for the development of a new generation of antioxidants, antimicrobials, antiparasitic and anticancer agents.