Cupric Reducinging Activity From G. Procumbens Lab Report

extract (p < 0.05). These findings suggest that SF3 consisted of various individual compounds that have potential reducing power. As far as we know, this is the first report regarding cupric reducing activity in derived fractions from G. procumbens leaves. The antioxidant activity of plant materials or extracts is known to be associated with polyphenols and their chemical structures that contain hydroxyl groups acting as the primary antioxidant (Jun et al., 2014).

2.5.2. DPPH• scavenging activity assay
DPPH• scavenging activity was measured according to a previously published method (Brand-Williams, Cuvelier, & Berset, 1995) with some modifications. One half milliliter of each extract solution was added to 1 ml of a freshly prepared 0.1 mM
ABTS•+ were produced by the oxidation of a 7 mM ABTS solution with 2.45 mM potassium persulphate, and the mixture was allowed to stand in the dark at room temperature for 12–16 h before use. The resulting blue–green colored ABTS•+ solution was adjusted to an absorbance of 0.70 ± 0.02 at 734 nm. Briefly, 0.5 ml of the extract was added to 1 ml of the ABTS•+ solution and thoroughly mixed. After 6 min, the absorbance was measured at 734 nm against a control. The values were expressed as an IC50 value, which is the concentration of the extract that scavenges 50% of the ABTS•+. The ABTS•+ scavenging abilities of the crude extract as well as the ethyl acetate fraction and its sub-fractions are presented in Table 2. For the solvent partitioned fraction, a similar trend to the DPPH• scavenging results was observed in the ABTS•+ scavenging activity, with the highest activity being found in the ethyl acetate fraction (IC50 = 61.0 _g/ml), which was 3.7 times lower than those of the crude ethanolic extract (IC50 = 223.2 _g/ml). The SF3 showed the highest ABTS•+ scavenging activity (IC50 = 12 _g/ml) among all sub-fractions tested, followed by SF4, SF5, SF1 and SF2 (Niwat Kaewseejan a, 2015). The comparisons of the different sub-fractions showed that SF3 was 3.3-, 4.6-, 2.0- and 2.6-fold more active than SF1, SF2, SF4 and SF5, respectively. The observed differential scavenging
In brief, 60 _l of the extract, 180 _l of distilled water and 1.8 ml of FRAP reagent were added to the same test tube and thoroughly mixed. After incubation at 37 °C for 4 min, the absorbance was measured at 593 nm against a control. Data were calculated according to the following equation that was obtained with FeSO4 from a calibration curve and then expressed as mmol Fe(II) per g dry weight (mmol Fe(II)/g DW). The FRAP assay is a simple, rapid and inexpensive method of measuring the reductive ability of an antioxidant, and it is evaluated by the reduction of Fe(III) to Fe(II), as a measure of reducing antioxidant power (Benzie & Strain, 1996). The FRAP values of the crude extract as well as ethyl acetate and its five subfractions were expressed as mmol Fe(II) per g dry extract, and the results are shown in Table 2. Among the crude extract and solvent partitioned fractions, the highest amount of reducing power was observed in the ethyl acetate fraction with a FRAP value of 3.4 mmol Fe(II)/g DW. Of the ethyl acetate subfractions, the FRAP values of the five sub-fractions (SF1–SF5) ranged from 2.6 to 10.2 mmol Fe(II)/g DW, with a descending order of SF3 > SF4 > SF5 > SF1 > SF2 (p < 0.05), which