Chemical characterization and antioxidant activity of three mushroom species from Poland

Mushrooms contain a huge diversity of biomolecules with nutritional [1] and/or bioactive properties [2]. Phenolic compounds, ascorbic acid and tocopherols are considered to be the most responsible for their antioxidant activity [3]. In the present work, Boletus edulis, Lentinus edodes and Xerocomus badius, three mushroom species originated from Poland were analyzed for their chemical composition (nutritional value, primary and secondary metabolites) and antioxidant activity. The identified chemical compounds were correlated with the antioxidant properties, evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay (RSA), reducing power (RP), β-carotene bleaching inhibition (CBI) and lipid peroxidation inhibition by TBARS (thiobarbituric acid reactive substances) assay (LPI). Carbohydrates were the most abundant macronutrients, followed by proteins and ash. Fructose, mannitol and threalose were the predominant sugars, but glucose was only found in B. edulis. Polyunsaturated fatty acids predominated over monounsaturated and saturated fatty acids. Palmitic, oleic and linoleic acids were abundant in the three samples, but X. badius presented considerable amounts of linoleic acid and less amounts of oleic acid. α- and β- tocopherols were quantified in all the samples, but γ-tocopherol was only present in X. badius. The organic acids, oxalic and fumaric, were quantified in the three samples; quinic acid was only present in L. edodes, and malic and citric acids were only found in X. badius. p-Hydroxybenzoic, protocatechuic and cinnamic acids were quantified in all the species, while p-coumaric acid was only found in B. edulis. This species and X. badius revealed the highest antioxidant properties, lowest EC50 values, which were related with the higher amounts in phenolic compounds. B. edulis showed the highest RSA and RP (1.80 ± 0.01, 0.63 ± 0.02 mg/mL, respectively), while X. badius presented the highest CBI and LPI (1.10 ± 0.05, 0.37 ± 0.02 mg/mL, respectively).

Acknowledgements: FCT (Portugal) for financial support, strategic projects (PEst-C/QUI/UI0686/2011 and PEst-OE/AGR/UI0690/2011) and S.A. Heleno grant (BD/70304/2010).

Keywords: Mushrooms, nutritional value, antioxidant compounds, antioxidant activity

References:

[1] Kalac, P. (2009) Food Chem 113: 9 – 16.

[2] Lindequist, U, Niedermeyer, THJ et al. (2005) eCAM 2: 285 – 299.

[3] Ferreira, ICFR, Barros, L, et al. (2009) Curr Med Chem 16: 1543 – 1560.