Phenolic compounds and antioxidant activity of two regions Portugal propolis

The aim of the present work was to evaluate the total phenolic compounds, quantified and identified the phenolic and flavonoid compounds and also the antiodoxidant activity of the propolis, collected from two regions of Portugal (Trás-os-Montes and Beira-Baixa). The total phenolic content was determined by Folin-Ciocalteu method and identified by Thin Layer Chromatography (TLC) bi-dimensional. The antioxidant activity was evaluated by 1.1-diphenyl-2-picrylhydrazyl scavenging (DPPH) and reducing power assays. The results showed that Tras-os-Montes propolis (329mg/g eq. gallic acid) had a higher content in phenolic compounds of the methanolic extracts than Beira-Baixa propolis (151mg/g eq. gallic acid). The value of the antioxidant activity determined by the DPPH assay was EC50 = 6.22µg/mL and EC50 = 52.00 µg/mL for Trás-os-Montes and Beira-Baixa propolis, respectively. Similar trend was obtained by the reducing power assays (EC50 = 4µg/mL and EC50 = 39µg/mL for the same samples, respectively). Through analysis of the results we can see that the propolis sample of Trás-os-Montes was a highest antioxidant activity, probably due to the amount of total phenolic compounds. Our results suggest that the concentration of propolis of Tras-os-Montes necessary to obtain an antioxidant activity is very low, making possible the use of this propolis as a natural antioxidant.

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