engleski

The influence of extraction solvent on the antioxidant activity of wild and cultivated Croatian mushrooms

Due to their savory taste and valuable nutritional properties, mushrooms are common in numerous cuisines. They are especially appreciated in Asian countries where therapeutic and medicinal properties have been ascribed to certain species, and where mushrooms have a long history of use in traditional medicine. It has recently been established that the antioxidant activity of mushrooms is largely due to their content of phenolics. The antitumor, antiviral, anti-inflammatory and immunomodulating properties of different kinds of mushrooms have already been reported. The purpose of this study was to determine the antioxidant activity and total phenol (TP) content in three wild native Croatian species Auricularia auricula-judae (woody ear), Sarcoscypha austriaca (scarlet cup), and Strobilurus esculentus (sprucecone cap), as well as four different species of cultivated mushrooms Agaricus bisporus (common mushroom, brown and white variants), Pleurotus ostreatus (oyster mushroom) and Lentinula edodes (shiitake). The extracts were prepared in methanol and water by mixing (100 rpm) at room temperature for 24 hours. The TP content was determined spectrophotometrically using the Folin-Ciocalteu method, and the antioxidant activity was measured in a reaction with 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH assay) and ferric-tripyridyltriazine (Fe3+-TPTZ) complex (FRAP assay). In general, greater TP content was determined for water extracts of all analyzed mushrooms ; on the average, 5.8&#61620; greater in comparison to methanol extracts (Table 1). The greatest TP content was determined in the methanol (1.98 mg GAE/g) and water (9.03 mg GAE/g) extracts of the common mushroom, A. bisporus (white variant). Antioxidant activity was also higher for water extracts, which is evident from the obtained higher reducing power values for water extracts (FRAP method) and lower EC50 values (DPPH assay). Except in the case of P. ostreatus, where the methanol extract exhibited slightly better scavenging properties (data for methanol extracts not shown), in general, the scavenging activity of water extracts of all tested mushrooms was significantly (P < 0.05) higher than that of methanol extracts. The scavenging capacities of water extracts of A. auricula-judae, S. austriaca, P. ostreatus and S. esculentus, in a concentration range of 10-50 mg/mL are shown in Fig. 1a, while the scavenging capacities of A. bisporus (brown and white variant), and L. edodes water extracts, in a concentration range of 0-10 mg/ mL, are shown in Fig. 1b. The results are expressed as percentage inhibition, I, of the DPPH radical in the presence of different mushroom extract concentrations, c. It is evident that the studied mushroom extracts scavenge the stable DPPH radical to different extents over the tested concentration range ; with increasing extract concentration the scavenging effect was more pronounced. Among our three wild mushrooms, the water extract of S. esculentus exhibited the best DPPH scavenging activity (Fig. 1a), which is in accordance with its highest TP content among the wild mushrooms (Table 1).

antioxidant activity; mushrooms; solvent; Croatia; total phenols

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