Total Superoxide Dismutase Assay Kit (WST-8 Method)

Superoxide Dismutase (SOD) is a critical antioxidant defense enzyme that catalyzes the dismutation of the superoxide anion radical (O₂·⁻) into hydrogen peroxide (H₂O₂) and molecular oxygen (O₂). By scavenging excess superoxide radicals, SOD protects cells against oxidative damage. Aberrant SOD activity is closely associated with aging, inflammation, neurodegenerative diseases, and various chronic conditions. Thus, accurate measurement of SOD activity is essential for evaluating oxidative stress status, studying antioxidant mechanisms, and disease diagnosis.

This kit employs the WST-8 method, where xanthine oxidase (XO) generates superoxide anions to reduce WST-8 into a soluble formazan dye. SOD inhibits this reaction dose-dependently. Therefore, SOD activity is inversely proportional to formazan production. Compared to traditional NBT or Cytochrome C methods, this kit offers higher sensitivity, a broader linear range, superior formazan solubility, and excellent stability, making it ideal for high-throughput screening. Furthermore, the assay buffer is supplemented with catalase to eliminate interference from endogenous H₂O₂, ensuring reliable results.

Figure 1. Validation of SOD standard detection. (A)​ Nonlinear correlation between SOD activity and ΔA450 (A_blank1 – A_standard). (B)​ Nonlinear relationship between SOD activity and the inhibition rate. (C)​ Double-reciprocal plot showing satisfactory linear correlation between inhibition rate and SOD activity.