Quantitative assessment of the antioxidant activity of red propolis EEP and its fractions were performed according to the methods described in the literature [33 (link), 34 (link)] with a few modifications. The solvent ethanol was used as blank. The inhibition of free radical DPPH by the samples was monitored by measuring the decrease in absorbance of solutions with different concentrations.
The EEP, hexane, chloroform and ethyl acetate fractions of EEP at an initial concentration of 1.0 mg•mL−1 were diluted with ethanol until achieving final concentrations of 25.0, 15.0, 10.0, 5.0 and 2.5 μg•mL−1. Then, 1.0 mL of 0.3 mM DPPH in ethanol was added to 2.5 mL of the EEP and it fractions, and the reaction was left to develop in dark at room temperature (26 °C) over 30 min. The absorbance readings were then performed with a spectrophotometer (Model UV-1700, Shimadzu, Kyoto, Japan) at 518 nm.
The EEP, hexane, chloroform and ethyl acetate fractions of EEP at an initial concentration of 1.0 mg•mL−1 were diluted with ethanol until achieving final concentrations of 25.0, 15.0, 10.0, 5.0 and 2.5 μg•mL−1. Then, 1.0 mL of 0.3 mM DPPH in ethanol was added to 2.5 mL of the EEP and it fractions, and the reaction was left to develop in dark at room temperature (26 °C) over 30 min. The absorbance readings were then performed with a spectrophotometer (Model UV-1700, Shimadzu, Kyoto, Japan) at 518 nm.
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