Malondialdehyde (MDA) and Superoxide Dismutase (SOD) Assays

Assays of the malondialdehyde (MDA) content and superoxide dismutase (SOD) activity involved commercially available kits (Jiancheng Bioengineering, Nanjing, China). Plasma was diluted with saline to an appropriate concentration to estimate the MDA content and SOD activity. All procedures were performed under the guidance of the manufacturer’s instructions. MDA levels were measured using a 2-thiobarbital acid method. Optical density was measured at 532 nm. The results were expressed as nmol/mg protein. SOD activity was determined based on its ability to inhibit the oxidation of superoxide anions produced by a xanthine-xanthine oxidase system. One unit of SOD activity was defined as a 50% reduction of optical density at 450 nm absorbance. The results were expressed as U/ml. Colorimetry was used for determination, and the absorbance values and standard equation were used for the assay.