Searching for new proteins of fungal origin with potential medical application

MARÍA EUGENIA DÍAZ; SEBASTIÁN KRAVETZ; FEDERICO G. BAUDOU; LORENA GONZÁLEZ; MAURICIO DE MARZI

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica; 2019

Currently, interest in obtaining fungal bioactive compounds with medical applications has been renewed due to their great diversity and unique bioactivity compared to other natural sources. Bioactive proteins constitute an important part of the functional components in fungi, as they can have antioxidant, antitumor and immunomodulatory activity. In particular, the antioxidant activity is of great interest since the uncontrolled production of free radicals has been related to several diseases, including different types of cancer. The aim of this work was to obtain extracellular proteins and enriched protein extracts from Pleurotus ostreatus fruiting bodies and mycelium in order to evaluate their antioxidant potential. In order to achieve this goal, P. ostreatus mycelium was grown on potato dextrose agar for 7 days and a plug of culture was inoculated on potato dextrose broth. After 10 days, mycelium was harvested and liquid media was collected. Mycelium and fruiting bodies obtained from the local market were lyophilized and homogenized with Tris-Glycine buffer pH 8.4. The homogenates were centrifuged and the supernatants and collected liquid media were treated with ice cold ethanol to precipitate soluble proteins. The precipitates were resuspended in buffer. Protein concentration was measured by Bradford method and a SDS-PAGE was performed. Antioxidant activity of homogenates and extracts was evaluated using 2,2-azino-bis-3- ethylbenzothiazoline-6-sulfonic acid (ABTS). ABTS radicals were generated by the reaction of ABTS 7 mM and potassium persulfate 2.45 mM overnight at room temperature in the dark. For the assay, homogenates and extracts were incubated with the radical ABTS for 30 min in the dark and the absorbance was measured at 734 nm. The results showed that the homogenates have a great antioxidant capacity, being higher in that obtained from fruiting bodies. As for protein-enriched extracts, although the antioxidant activity of those corresponding to extracellular proteins and mycelium was lower, the one obtained from fruiting bodies showed similar values to mycelium homogenate. Therefore, these results are promising to continue the search for new proteins with application in medicine.