The freeze-dried find more extract was dissolved in distilled water. Identification of the peaks of the investigated compounds was carried out by comparison of their retention times with those obtained by injecting standards in the same conditions, as well as by spiking the samples with stock standard solutions. The concentrations of the identified compounds in the extract samples were calculated by means of the regression parameters obtained from calibration curves. All standard calibration curves showed high degrees of linearity (r2 > 0.99). The following standards of flavonoids, phenolic acids and aromatic compounds were used as standards: gallic acid,
protocatechuic acid, syringic acid, caffeic acid, cinnamic acid, p-coumaric acid, benzoic acid, pyrogallol, catechin, myricetin and quercetin. Water was treated in a Milli-Q water purification system (TGI Pure Water Systems, USA). A HPLC system (Shimadzu, Tokyo) with a LC-20AT Shimadzu system controller, Shimadzu SPD-20 A UV–Vis detector, equipped with a reversed-phase Shimpak C18 column (4.6 × 250 mm), maintained CYC202 supplier at 30 °C, was used for analysis of organic acids. All samples in duplicate were filtered through a 0.22 μm filter unit (Millex® – GV, Molsheim, France) before injection and the solvents were filtered through a 0.45 μm
filter (Whatman, Maidstone, England). A solvent system consisting of Milli-Q water:phosphoric acid (99.9:0.1) was used as mobile phase at a flow rate of 1 mL/min and the injection PAK6 volume was 20 μL. Run time was 10 min and detection of organic acids was carried out at 230 nm. Identification of the peaks of the investigated compounds was carried out by comparison of their retention times with those obtained by injecting standards
in the same conditions, as well as by spiking the samples with stock standard solutions. The concentrations of the identified compounds in the extract samples were calculated by means of the regression parameters obtained from calibration curves. All standard calibration curves showed high degrees of linearity (r2 > 0.99) (data not shown). The following standards of organic acids were used: citric, ascorbic, oxalic, succinic, tartaric, malic, malonic, lactic, fumaric, trans-aconitic, oxaloacetic, acetic, propionic, butyric and α-ketoglutaric acids. Water was treated in a purification system (TGI Pure Water Systems, USA). The 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay was done as described previously (Soares et al., 2009). Briefly, the stock solution was prepared by dissolving 24 mg DPPH in 100 mL methanol and then stored at −20 °C until needed. The working solution was obtained by mixing 10 mL stock solution with 45 mL methanol to obtain an absorbance of 1.1 ± 0.02 units at 515 nm. A volume of 150 μL of each extract (final concentrations ranging from 50 to 800 μg/mL) was allowed to react with 2850 μL of the DPPH solution (final concentration of 0.1 mmol/L), vigorously shaken and maintained for 1 h at room temperature in the dark.
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