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.
Erel
Ozcan
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Clinical Biochemistry Department, Medical Faculty, Research Hospital, Harran University, Sanliurfa TR63200, Turkey. erelozcan@hotmail.com
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