Antioxidant potential of NATIVE Extracts
Ferric Reducing Antioxidant Power assay measures the test samples antioxidant capacity to reduce ferric iron (Fe3+) to ferrous iron (Fe2+). This reaction develops a blue colour that increases with Fe2+ production. The assay is therefore spectrophotometric and the colour change is measured at 594nm. Quantitative results are determined against a ferrous iron standard curve and results are expressed as Fe2+ equivalents (μM).
DPPH or 2,2-diphenyl-1-picrylhydrazyl is a radical cation used in the assay to measure a test sample's radical scavenging ability. During an incubation period, antioxidants in the test sample transfer hydrogen ions to reduce DPPH to DPPH-H. A colour change results from the reaction and the solution develops from purple to yellow. Quantitative results are determined against a standard curve of Trolox (Vitamin E analogue), and results are expressed as Trolox equivalents and inhibition ratios. The assay is limited to antioxidant compounds that are soluble in 50% ethanol solutions. Despite this consideration DPPH assays are quick, efficient and able to show antioxidant potential in complex biological mixtures such as plant extracts.