Measurement and Clinical Significance of Biomarkers of Oxidative Stress in Humans

Table 4

Common used methods for NEAC measurements.

Method	Reaction and quantification	Limitations and confoundings
HAT; ORAC	AAPH—induced: R-phycoerytherin (red) or fluorescein (green) fluorescence decay; Competitive reaction kinetic, AUC	Lipophilic antioxidants not included; Proteins
HAT; TRAP	AAPH—induced: R-phycoerytherin fluorescence decay (red); DCFH ➔ DCF fluorescence increase (green); Competitive reaction kinetic, lag phase	Lipophilic antioxidants not included; Not all the antioxidants give a lag phase; Self-propagation of DCF radicals
HAT; Crocin bleaching	AAPH- or AMVN-induced absorbance decay (450 nm); Competitive reaction kinetic, Stern-Volmer-like relation	Bilirubin and carotenoids that absorb at the wavelength of determination
HAT; TAP	MeO-AMVN induced; C11-BODIPY fluorescence increase (green); Competitive reaction kinetic, AUC
TAS	Fenton reaction-induced dianisidyl radical absorbance increase (444 nm); Competitive, endpoint, TEAC
SET (Randox)	Fenton reaction-induced ABTS radical formation (734 nm); Competitive reaction, endpoint, TEAC
SET; ABTS^•+	Absorbance decay (734 nm); Noncompetitive, endpoint, TEAC
SET; DPPH^•	Absorbance decay (515 nm); Noncompetitive, endpoint, EC50	Carotenoids that absorb at the wavelength of determination
SET; FRAP	Absorbance increase (593 nm); Noncompetitive, endpoint	SH not included; Biliverdin absorb at the wavelength of determination
SET; CUPRAC	Neocuproine absorbance increase (450 nm).; Noncompetitive, endpoint	Bilirubin and carotenoids that absorb at the wavelength of determination

AAPH: 2,2′-azobis(2-methylpropionamidine) dihydrochloride; ABTS: 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid); AMVN: 2,2′-azobis 2,4-dimethylnaleronitrile; AUC: area under the curve; CUPRAC: copper-reducing assay; DCFH: 2′,7′-dichlorodihydrofluorescein; DPPH: 2,2-diphenyl-1-picrylhydrazyl; EC50: efficient concentration (EC), the amount of antioxidant necessary to decrease by 50%; FRAP: ferric reducing antioxidant power; HA: T hydrogen atom transfer; MeO-AMVN: 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile); NEAC: nonenzymatic antioxidant capacity; ORAC: oxygen radical antioxidant capacity; SET: single electron transfer; SH: thiols; TAC: total antioxidant capacity; TAP: total antioxidant performance; TAS: total antioxidant status; TEAC: Trolox equivalent antioxidant capacity; TRAP: total radical-trapping antioxidant parameter.