A novel automated direct measurement method for total antioxidant capacity using a new generation, more stable ABTS radical cation.
OBJECTIVE
To develop a novel colorimetric and automated direct measurement method for total antioxidant capacity (TAC).


METHODS
A new generation, more stable, colored 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS(*+)) was employed. The ABTS(*+) is decolorized by antioxidants according to their concentrations and antioxidant capacities. This change in color is measured as a change in absorbance at 660 nm. This process is applied to an automated analyzer and the assay is calibrated with Trolox.


RESULTS
The novel assay is linear up to 6 mmol Trolox equivalent/l, its precision values are lower than 3%, and there is no interference from hemoglobin, bilirubin, EDTA, or citrate. The method developed is significantly correlated with the Randox- total antioxidant status (TAS) assay (r = 0.897, P < 0.0001; n = 91) and with the ferric reducing ability of plasma (FRAP) assay (r = 0.863, P < 0.0001; n = 110). Serum TAC level was lower in patients with major depression (1.69 +/- 0.11 mmol Trolox equivalent/l) than in healthy subjects (1.75 +/- 0.08 mmol Trolox equivalent/l, P = 0.041).


CONCLUSIONS
This easy, stable, reliable, sensitive, inexpensive, and fully automated method described can be used to measure total antioxidant capacity.
Clinical Biochemistry Department, Medical Faculty, Research Hospital, Harran University, Sanliurfa TR63200, Turkey. erelozcan@hotmail.com
Ozcan
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Erel
D000975:Antioxidants / Q000032:analysis* / Q000378:metabolism; D001331:Automation / Q000379:methods; D052160:Benzothiazoles; D003863:Depression / Q000097:blood; D006801:Humans; D006861:Hydrogen Peroxide; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*; D013451:Sulfonic Acids / Q000378:metabolism*
D000975:Antioxidants; D052160:Benzothiazoles; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D006861:Hydrogen Peroxide; D007501:Iron