Ethanolic extracts from three commercial edibe mushrooms: determination of ergosterol contente and evaluation of bioactives properties
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resumo
Mushrooms are rich in several bioactive metabolites among them are phenolic compounds, terpenoids,
polysaccharides, lectins, and steroids including mycosterols, namely ergosterol [1]. Ethanolic extracts
prepared by maceration of several mushroom species have been recently described as having antiinflammatory
properties [2]. In the present work, ethanolic extracts of Agaricus bisporus L., Lentinus
edodes (Berk.) Pegler and Pleurotus ostreatus (Jacq. ex Fr.) P.Kumm., purchased from a local
supermarket in the Northeast of Portugal, were obtained by Soxhlet and chemically characterized in terms
of ergosterol content by HPLC-UV. The antioxidant properties of these extracts were evaluated through
DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity (RSA), reducing power (RP), p.
carotene bleaching inhibition (CBI) and lipid peroxidation inhibition in TBARS (thiobarbituric acid
reactive substances) assay (LPI); the antioxidant activity of ergosterol was also evaluated by the DPPH
assay. The anti-inflammatory activity of the same extracts and ergosterol was evaluated in LPS
(lipopolysaccharide) stimulated RAW 264.7 macrophages, through the inhibition of NO production. A.
bisporus revealed the highest content in ergosterol (44.8 ± 0.4 mg/ g extract) followed by P. ostreatus (34
± 3 mg/ g extract) and finally L. edodes (8.9 ± 0.1 mg/ g extract). A. bisporus showed the highest RSA, RP
and CBI (EC50 values= 7.0 ± 0.8, 2.3 ± 0.1 and 1.4 ± 0.1 mg/mL, respectively), while L. edodes presented
the highest LPI (2.5 ± 0.1 mg/mL ); ergosterol revealed higher RSA (0.46±0. 0 I mg/mL) than the extracts.
Concerning the anti-inflammatory potential, the most efficient species was L. edodes (lC50 value = 164 ±
16 J.lg/mL), followed by A. bisporus (185 ± 16 J.lg/mL) and finally P. ostreatus (290 ± 10 J.lg/mL).
However, ergosterol presented lower activity (338 ± 23 J.lg/mL) due to its low solubility in the culture
medium. The higher antioxidant properties displayed by A. bisporus can be related with its higher
ergosterol content, while in the anti-inflammatory activity this relation cannot be established also due to
the low solubility of ergosterol in the cells culture medium, decreasing the ergosterol availability. More
studies are being conducted regarding the ergosterol solubility. Several compounds have been implicated
in the bioactivity of mushrooms and in this study we have found that ergosterol can give an important
contribution.
