3.2.1. Reducing power
In general, an increased absorbance of the reaction mixture indicates increased reducing power (Manmohan, Arindam, Hemendra, Sushil, & Kalpesh, 2011). The antioxidant activi- ties of natural compounds are likely to exhibit mutual correlations with their reducing powers, potentially due to their hydrogen-donating ability (Xiang & Ning, 2008). The presence of reducers converts the Fe3+/ferricyanide complex to the ferrous form. Fe3+ reduction is often used as an indicator of electron- donating activity, which is a vital antioxidant mechanism of action of phenolic compounds. The presence of antioxidants in the sample would reduce the conversion of Fe3+ to Fe2+ by donating an electron, and Fe2+ complex formation can be moni- tored by measuring the formation of Perl’s Prussian blue (Fe4[Fe(CN)6]3) at 700 nm.