Pharmaspec uv 1650 pc

The ferric-reducing effect of A. viridis extracts was determined according to the method suggested by Yen and Chen [17 (link)]. A. viridis extracts (1 mL) at various concentrations (50, 100, 150, 200, 250, and 300 μg/mL) were mixed with potassium phosphate buffer (0.2 M, pH 6.6, 2.5 mL) and potassium ferricyanide (1 g/100 mL, 2.5 mL). The mixtures were then incubated at 50°C for 20 min. After incubation, trichloroacetic acid (10%) was added to stop the reaction. An equal volume of distilled water was added to the mixtures followed by the addition of ferum chlorate (0.1 g/100 mL, 500 μL). The mixtures were then allowed to stand at room temperature for 30 min. A₇₀₀ was determined with a UV-visible spectrophotometer (Pharmaspec UV-1650PC, Shimadzu, Japan). The procedures were performed in triplicate and repeated with the standard antioxidants (ascorbic acid and α-tocopherol). The antioxidant activity (%) of the samples in FRAP assay was expressed as reducing power (%) according to the following formula: $\begin{array}{c}\text{Reducing\hspace{0.17em}\hspace{0.17em}power\hspace{0.17em}\hspace{0.17em}}\left(\%\right)=\frac{\left(\mathrm{A}{\mathrm{b}}_s\times \mathrm{A}{\mathrm{b}}_c\right)}{\mathrm{A}{\mathrm{b}}_s}\times \mathrm{100}\%,\end{array}$ where Ab_c is the absorbance of control and Ab_s is the absorbance of sample.

FTC assay was performed according to the method described by Ismail et al. [14 (link)]. A. viridis extracts (4 mg) were dissolved in methanol (4 mL) and mixed with linoleic acid (2.5%, 4.1 mL), phosphate buffer (50 mM, pH 7, 8 mL), and distilled water (3.9 mL). The mixtures were kept in screw-cap vials which were placed in an oven maintained at 40°C in the dark. The mixtures (100 μL) were added to ethanol (75%, 9.7 mL) and ammonium thiocyanate (30%, 100 μL). Three minutes after the addition of ferrous chloride solution (2 × 10² M in 3.5% hydrochloric acid, 100 μL) to the reaction mixtures, the absorbance was measured at 500 nm using a UV-visible spectrophotometer (Pharmaspec UV-1650 PC, Shimadzu, Japan). The procedure was repeated (at 24 h interval) until the absorbance of the control sample reached its maximum value. Ascorbic acid and α-tocopherol were used as the standard antioxidants.

The TPC of A. viridis extracts was determined according to Meda et al. [13 (link)] using Folin-Ciocalteu assay. Briefly, A. viridis extracts (100 mg) were dissolved in methanol (10 mL). The extracts (100 μL), sodium carbonate (7.5% (w/v), 2 mL), and Folin-Ciocalteu reagent (tenfold dilution, 2.5 mL) were mixed, vortexed, and incubated at 40°C for 30 min. The absorbance was measured at 760 nm using a UV-visible spectrophotometer (Pharmaspec UV-1650 PC, Shimadzu, Japan). TPC of A. viridis extracts were expressed as mg gallic acid equivalents/g dry weight.