Table 1.

Commonly used methods for measurement in vitro of antioxidant activity

Bioassay	Reagents Involved in the Reaction	Detection	Method
DPPH (Diphenyl-1-picrylhydrazyl) assay	Free radical (DPPH•+)	Decrease of Abs. at 515 nm	Spectrophotometric or colorimetric
ORAC Assay (Oxygen Radical Absorbance Capacity)	2,2′-azobis(2-amidino-propane) dihydrochloride (AAPH) to produce free radical β-phycoerythrin or Fluorescein or Pyrogallol red	Decrease of fluorescence	Fluorescence spectroscopy
TRAP assay (total peroxyl radical trapping antioxidant parameter)	2,2′-azobis(2-amidopropane) hydrochloride (ABAP) to produce free radical Luminol	Decrease of luminescence	Chemiluminescence
FCT (ferric thiocyanate) assay	Ferrous chloride, formation of red ferric thiocyanate	Increase of Abs. at 500 nm	Spectrophotometric
FRAP (Ferric Reducing Antioxidant Power) assay	FeCl3·6H2O, formation of blue ferrous complexes	Increase of Abs. at 593 nm	Colorimetric
CUPRAC, Cupric Ion Reducing Antioxidant Capacity	Cupric neocuproine, formation of Cu(I)-neocuproine	Increase of Abs. at 550 nm	Spectrophotometric
ABTS [2,2′-azino-bis (3-ehtylbenzothiazoline-6-sulfonic acid) diamonium salt] assay	Free radical (ABTS•+)	Decrease of Abs. at 415 nm	Colorimetric
Methods of inhibited autoxidation	Lipid molecules, azoinitiator	O2 consumption/hydroperoxide formation	Oxygen electrode, pressure gauge, detection of conjugated dienes

Note: Abs, absorbance.