Determination of reducing power by reducing ferricyanide complex
The reducing power assay of macrofungi was carried out by using the method described by Oyaizu (1986) with several modifications. Different concentrations of the extract (2 to 10 mg/ml) in 1.0 ml of distilled water was mixed with phosphate buffer (2.5 ml, 0.2 M, pH 6.6) and 1% potassium ferricyanide (2.5 ml). The mixture was incubated at 50°C for 20 minutes. Aliquots of trichloroacetic acid (2.5 ml, 10%) was added to the mixture a nd then centrifuged at 1036 ×g for 10 minutes. The upper layer of the solution (2.5 ml) was mixed with distilled water (2.5 ml) and FeCl3solution (0.3 ml, 0.1%). The absorbance was measured at 700 nm (SpectraMax Plus384, United States). The increasing absorbance of the reaction mixture was taken to mean an increase of reducing power. The standard (BHA) and quercetin were measured by using same procedures