Total antioxidant capacity (TAC) assay

TAC assay is one of the analyses usually performed to assess the antioxidant status in human blood samples related to various diseases. Evaluation of TAC characterizes the general ability of the body to fight oxidative stress by making antioxidant compounds. TAC can be easily assessed in human plasma using a spectrophotometric method (24,28). Plasma samples diluted at 1:25 in phosphate-buffered saline (PBS, pH=7.4) were mixed with 0.1 mM 2,2 diphenyl-1-picrylhydrazyl radical reagent (DPPH, v/v) and incubated in a dark room for 30 min. After incubation, the samples were separated by centrifugation for 3 min at 20,000 x g and OD was read at 520 nm using a UV-VIS spectrophotometer. TAC was expressed as mmol DPPH/l. All reagents used were provided by Sigma-Aldrich; Merck KGaA.