Avaliação da ação antioxidante de extratos hidrossolúveis das glebas imatura e madura do cogumelo Calvatia bicolor

Abstract

Fungi that have a fruiting body are called macrofungi and are popularly known as mushrooms. Several bioactive mushroom compounds have already been described with pharmacological activities, including carbohydrates. Antioxidants are molecules that are directly involved in combating oxidative stress, which is responsible for the emergence and worsening of various pathologies. In this work, the antioxidant activity of water-soluble extracts rich in carbohydrates from immature and mature glebes of the mushroom Calvatia bicolor were evaluated. The immature and mature glebes, delipidated with ethanol, were submitted to proteolytic extraction with different volumes (1v, 3v and 5v) of solvent (NaCl 0.25 M). Crude extracts of immature gleba (EB-GI1v, EB-GI3v and EB-GI5v) and mature gleba (EB-GM1v, EB-GM3v and EB-GM 5v) were solubilized in distilled water at 10 mg/mL for separation of water-soluble extracts by centrifugation. Soluble extracts (ES-GI1v, ES-GI3v and ES-GI5v) and (ES-GM1v, ES-GM3v and ES-GM5v) were analyzed for their chemical compositions, by electrophoresis and FTIR, and evaluated for total antioxidant capacity (CAT) and chelation of copper and iron. The average yield of dry mass of crude extracts from immature gleba ranged from 258 to 431 mg, and of the mature gleba from 69 to 81.5 mg. The yield of ES-GI was from 191 to 355 mg (79%) in relation to EB, and of mature gleba from 29.1 to 40.5 mg (47.7%) in relation to EB. The sugars, proteins, phenolic compounds and sulfate content of the ES-GI ranged from 43 to 51%, from 8.4 to 10.8%, from 0.4 to 0.5% and 0%, respectively. Among the ES-GM, the sugars, proteins, phenolic compounds and sulfate content ranged from 14.7 to 15.2%, from 20.3 to 26.1%, from 0.7 to 0.8% and from 1 to 1.4%, respectively. ES-GM1v, ES-GM3v and ES-GM5v showed metachromasia and a polydisperse profile indicating the presence of negatively charged polysaccharide groups (sulfated and carboxylated). ES-GI1v, ES-GI3v and ES-GI5v did not show metachromasia. FTIR analysis indicates that the extracts are composed of β-glucan polysaccharides and by sulfate esters. Among the ES-GI, CAT from 18.19 to 45.43 mg of ascorbic acid/g of sample, copper chelation from 27.7 to 51.8% and iron chelation from 3.1 to 88.8% were observed. ES-GM showed CAT from 12.99 to 22.19 mg of ascorbic acid/g of sample, copper chelation from 17.5 to 59.5% and iron chelation from 6.5 to 80.8%. ES-GM1v was the extract with the highest iron and copper chelating activity. And, In general, the best extraction condition to obtain extracts rich in polysaccharides and with antioxidant activities is using 1 volume of 0.25M NaCl. Since in addition to the yield characteristics and antioxidant activities, there is a reduction in cost and production time.