4.5.2. Glutathione Peroxidase Activity

GPx activity was detected in the plasma of peripheral blood. Twenty-five μL samples were centrifuged at 1000× *g* for 10 min at 4 ◦C. The plasma was collected and diluted with the GPx sample buffer (1:2) included in the kit. GPx activity was determined according to the instructions for the Cayman Chemicals Glutathione Peroxidase Assay Kit (No. 703102; Ann Arbor, MI, USA). One unit of GPx was defined as the amount of enzyme that oxidized 1 nmol of NADPH/min. The absorbance was read at 340 nm in a Multiskan™ FC microplate reader (Thermo Scientific™, Vantaa, Finland). GPx activity was determined in duplicate (per sample) and according to the GPx standard curve.
