Jasmina Cilerdzic

Antioxidant and Antifungal Potential of Pleurotus ostreatus and Agrocybe cylindracea Basidiocarps and Mycelia

Basidiocarps of Pleurotus ostreatus and Agrocybe cylindracea are characterized by high nutritional value and numerous medicinal activities, though bioactivities of their mycelia have not been sufficiently studied. The aim of the study was to evaluate antioxidant and antifungal potentials of P. ostreatus and A. cylindracea basidiocarp extracts, as well as those obtained from mycelia cultivated in common synthetic medium and media enriched with various agro-industrial residues. The free radical scavenging activity of the extracts was determined spectrophotometrically, based on DPPH• reduction while antifungal potential was studied by a microdilution method. The highest level of DPPH• scavenging ability was obtained by an extract of P. ostreatus mycelium cultivated in wheat bran-enriched medium, while control medium favoured the antioxidant potential of A. cylindracea mycelium. Phenol compounds were the main carriers of antioxidant activity that was demonstrated by high coefficients for correlations between total phenol contents in extracts and level of DPPH• scavenging (0.94 for P. ostreatus extracts and 0.91 for A. cylindracea extracts). Only the extracts of A. cylindracea basidiocarp and control mycelium, at a concentration of 1.33 mg/mL, inhibited the growth of Microsporum gypseum and Aspergillus flavus, while basidiocarp extract at 1.67 mg/mL also had fungicidal effect against M. gypseum. These results revealed a considerable antioxidant potential of submergedly-cultivated mycelium which showed higher antioxidant activity than basidiocarp extracts. This is very important because significant amounts of mycelium biomass could be obtained more easily, cheaper and in a more controllable way than basidiocarps cultivation.

Potential of Submergedly Cultivated Mycelia of Ganoderma spp. as Antioxidant and Antimicrobial Agents.

The study aimed to evaluate the antiradical and antimicrobial (antibacterial and antifungal) potentials of ethanol mycelial extracts of selected Ganoderma species and strains and to define interand intraspecies diversity among Ganoderma species and strains. Ganoderma lucidum strains were good DPPH• scavengers (neutralizing up to 57.12% radicals), contrary to G. applanatum (20.35%) and G. carnosum (17.04%). High correlations between the activities and contents of total phenols in the extracts showed that these compounds were carriers of the activity. Results obtained by both discdiffusion and microdilution methods indicated that the extract of G. lucidum BEOFB 433 was the most potent antibacterial agent that inhibited growth of almost all bacterial species at a concentration of 1.0 mg/mL. Salmonella typhimurium was the most sensitive species to the mycelium extracts. Extracts of G. lucidum BEOFB 431 and BEOFB 434 showed the best antifungal activity since in concentration of 0.5 mg/mL inhibited the growth of Aspergillus glaucus (BEOFB 431) and the growth of A. glaucus and Trichoderma viride (BEOFB 434). Extracts of G. applanatum and G. lucidum BEOFB 431 had the strongest fungicidal effects, with lethal outcomes for A. glaucus and T. viride, respectively, being noted at a concentration of 1.17 mg/mL. Aspergillus niger was proved as the most resistant species.

Genoprotective Capacity of Alternatively Cultivated Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes), Basidiocarps.

Ganoderma lucidum is traditionally used in Eastern medicine to preserve vitality, promote longevity, and treat disease. It possesses immunomodulatory, antitumor, antimicrobial, and antiaging activities, among others, but one of the most important is its antioxidant property, which is the basis for other effects, because free radicals trigger many diseases. The substrate commonly used for commercial cultivation of G. lucidum is not environmentally friendly nor economically justified, so there is a need to find new alternative substrates. The aim of this study was to analyze the effect of substrate composition on the bioactivity of G. lucidum basidiocarps. G. lucidum was cultivated on 2 different substrates: (1) a mixture of wheat straw, grapevine branches, and wheat bran, and (2) wheat straw. Commercial fruiting bodies, cultivated on oak sawdust, were used as the control. 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, total phenols, and flavonoid content were determined spectrophotometrically to define the antioxidative potential of basidiocarp extracts. The comet test was performed to detect the degree of DNA damage in the cells that were exposed to G. lucidum extracts before and after the effect of oxidants. Higher antioxidative potential was observed for the extract of G. lucidum basidiocarps cultivated on wheat straw compared with that from the mixed substrate and especially with commercial ones. The alternatively cultivated basidiocarps also showed stronger antigenotoxic potential compared with commercial ones. The study showed that fruiting bodies produced on wheat straw, one of the most accessible and cheapest crop residues, are more potent antioxidant and antigenotoxic agents than commercially cultivated ones.