A007 2 1

(1) Commercial kits A042-1 from Nanjing Jiancheng Bioengineering Institute (Nanjing, China) were used to measure serum non-esterified fatty acids (NEFA). (2) Commercial kits A111-2-1, A110-1-1, A001-3, A003-1, and A007-2-1 from Nanjing Jiancheng Bioengineering Institute (Nanjing, China) were used to detect total cholesterol (TCH) in the kidney tissue, triglyceride (TG), superoxide dismutase (SOD), malondialdehyde (MDA), and catalase (CAT) activities, respectively.

The antioxidant activity of DMG was estimated using the DPPH free radical scavenging method (Nanjing Jiancheng, A153-1-1, Nanjing, China). Briefly, 400 µL sample extract, or standard, and 600 µL of DPPH reagent were added and mixed vigorously. The reaction mixture was kept at room temperature for 30 min in the dark, and the discoloration of DPPH was obtained against a blank at 517 nm using the UV–Vis spectrophotometer (UV-2600, Shimadzu Europe).
Total SOD was tested by the xanthine oxidase method; the SOD activity was determined using assay kits (Nanjing Jiancheng, A001-1-1, China).
CAT activity was assessed using a commercial kit (Nanjing Jiancheng, A007-2-1, China) and quantified by analyzing the absorbance change rate of hydrogen peroxide at 240 nm [49 (link)].
The level of lipid peroxidation was quantified using 50 μL thawed RBCs lysates by the formation of the amount of malondialdehyde-thiobarbituric acid adduct in an acidic condition at 95 °C for 40 min. The absorbance of the samples was measured at 532 nm using the UV–Vis spectrophotometer (Nanjing Jiancheng, A003-1-1, China).
All the measurement methods are provided in the manufacturers’ instructions in detail.

The enzymatic activities assays were performed with fresh RBCs and washed RBCs after cryopreservation. The ATPases and catalase activities were measured using the inorganic phosphorus method (Nanjing Jiancheng, A070-5-4, China) and the ultraviolet method (Nanjing Jiancheng, A007-2-1, China), respectively. The operation was carried out following the kit instructions.

The levels of serum creatinine (Scr) and blood urea nitrogen (BUN) were measured with assay kits (Jiancheng bioengineering institute, Nanjing, China). The assay for malondialdehyde (MDA) content was performed according to the protocols of the MDA kit (A003-1-2, Jiancheng bioengineering institute, Nanjing, China). And the enzyme activity of superoxidase dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were examined by the test kits (A001-3-2, A007-2-1, A005-1-2, Jiancheng bioengineering institute, Nanjing, China). The detailed experimental protocols were provided in supplementary materials.