Mushrooms consumption is increasing thanks to the presence in their composition of numerous bioactive compounds. As functional foods, mushrooms, represent a valid alternative to other foodstuff, for a balanced healthy nutrition for both humans and animals [1]. Medicinal mushrooms, represent a rich source of antioxidant compounds such as phenolic acids, flavonoids, carotenoids, and polysaccharides. In this survey, four species of medicinal mushrooms, Pisolithus tinctorius, Pleurotus eryngii, Leccinum scabrum, and L. versipelle were compared for their antioxidant activity and for the content of total phenolic compounds and flavonoids. Three different extracts were prepared for each mushroom using hot water (HW), ethanol (EtOH), and ethyl acetate (EA) as solvents for extraction. Each extract was tested for free radical scavenging activity, with different concentrations (from 20 mg/mL to 0.1 mg/mL), using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The radical scavenging activity was calculated as percentage of inhibition (%) measuring the absorbance of the blank at 517 nm and the absorbance of the extract sample. Butylated hydroxyanisole (BHA) was used as a positive control. All mushrooms extracts exhibited antioxidant activity, but P. tinctorius showed the highest DPPH radical scavenging activity for all the tested extracts and at all the concentration, with values ranging from 89.6±1.5 to 55.6±0.7 %, from 91.4±1.1 to 61.4±1.2 % and from 90.9±1.5 to 10.9±1.0% for HW, EtOH and EA, respectively. Total phenols of extracts were determined according to the Folin-ciocalteu’s assay [2]. The absorbance was measured spectrophotometrically at 760 nm. The content of total phenols was calculated based on the calibration curve of Gallic acid and results were expressed as milligrams of gallic acid equivalents (GAE) per gram of mushroom extract. P. tinctorius exhibited the highest values of total phenolic content for HW and EtOH extract with value of 63.9±0.9, 71.6±0.4 GAE/g, respectively, while L. scabrum and L. versipelle showed the highest values for AC extract (20.7±0.620.6±0.3 GAE/g, respectively). The quantification of total flavonoid content was conducted following the methodology of Kaewnarin et al., 2008, partially modified [3]. Absorbance was measured at 415 nm and the total flavonoid contents were calculated using a calibration curve of quercetin (QE) equivalents. Results were expressed as mg QE equivalents per gram of mushroom extract. P. eryngii EA extract showed the highest content of flavonoids (65.80±0.85 QE/g), while L. scabrum exhibited the highest values both for HW (17.70±1.13 QE/g) and EtOH (39.85±1.34 QE/g) extracts. Considering the high value of total phenolic compounds, but not of flavonoids, these results suggest that the highest antioxidant activity of P. tinctorius is probably due to other molecules which were not taken into consideration in this investigation, but which need further study in the future. In general, all four tested species exhibited good radical scavenging activity and therefore the possibility of being used as a functional food with high antioxidant properties.
Antioxidant properties, total phenolic and flavonoid content of different extracts of the medicinal mushrooms Pleurotus eryngii, Leccinum scabrum, Leccinum versipelle and Pisolithus tinctorius
Gargano, MLMembro del Collaboration Group
;
2024-01-01
Abstract
Mushrooms consumption is increasing thanks to the presence in their composition of numerous bioactive compounds. As functional foods, mushrooms, represent a valid alternative to other foodstuff, for a balanced healthy nutrition for both humans and animals [1]. Medicinal mushrooms, represent a rich source of antioxidant compounds such as phenolic acids, flavonoids, carotenoids, and polysaccharides. In this survey, four species of medicinal mushrooms, Pisolithus tinctorius, Pleurotus eryngii, Leccinum scabrum, and L. versipelle were compared for their antioxidant activity and for the content of total phenolic compounds and flavonoids. Three different extracts were prepared for each mushroom using hot water (HW), ethanol (EtOH), and ethyl acetate (EA) as solvents for extraction. Each extract was tested for free radical scavenging activity, with different concentrations (from 20 mg/mL to 0.1 mg/mL), using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The radical scavenging activity was calculated as percentage of inhibition (%) measuring the absorbance of the blank at 517 nm and the absorbance of the extract sample. Butylated hydroxyanisole (BHA) was used as a positive control. All mushrooms extracts exhibited antioxidant activity, but P. tinctorius showed the highest DPPH radical scavenging activity for all the tested extracts and at all the concentration, with values ranging from 89.6±1.5 to 55.6±0.7 %, from 91.4±1.1 to 61.4±1.2 % and from 90.9±1.5 to 10.9±1.0% for HW, EtOH and EA, respectively. Total phenols of extracts were determined according to the Folin-ciocalteu’s assay [2]. The absorbance was measured spectrophotometrically at 760 nm. The content of total phenols was calculated based on the calibration curve of Gallic acid and results were expressed as milligrams of gallic acid equivalents (GAE) per gram of mushroom extract. P. tinctorius exhibited the highest values of total phenolic content for HW and EtOH extract with value of 63.9±0.9, 71.6±0.4 GAE/g, respectively, while L. scabrum and L. versipelle showed the highest values for AC extract (20.7±0.620.6±0.3 GAE/g, respectively). The quantification of total flavonoid content was conducted following the methodology of Kaewnarin et al., 2008, partially modified [3]. Absorbance was measured at 415 nm and the total flavonoid contents were calculated using a calibration curve of quercetin (QE) equivalents. Results were expressed as mg QE equivalents per gram of mushroom extract. P. eryngii EA extract showed the highest content of flavonoids (65.80±0.85 QE/g), while L. scabrum exhibited the highest values both for HW (17.70±1.13 QE/g) and EtOH (39.85±1.34 QE/g) extracts. Considering the high value of total phenolic compounds, but not of flavonoids, these results suggest that the highest antioxidant activity of P. tinctorius is probably due to other molecules which were not taken into consideration in this investigation, but which need further study in the future. In general, all four tested species exhibited good radical scavenging activity and therefore the possibility of being used as a functional food with high antioxidant properties.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
