Total Superoxide Dismutase (SOD) Activity Colorimetric Assay Kit (Xanthine Oxidase-NBT Method) 

Superoxide dismutase (Superoxide Dismutase, SOD; EC 1.15.1.1) is a class of essential antioxidant metalloenzymes that specifically catalyze the dismutation of superoxide anion radicals (O₂•^-) into hydrogen peroxide (H₂O₂) and molecular oxygen (O₂). SOD plays a critical role in the elimination of reactive oxygen species (ROS) and in maintaining cellular redox homeostasis. Owing to the extreme instability and very short half-life of superoxide radicals, their levels cannot be measured directly. Therefore, SOD activity is commonly determined by indirect methods based on the inhibition of superoxide-mediated chromogenic reactions. Currently, widely used chromogenic systems include nitroblue tetrazolium (NBT) and water-soluble tetrazolium salts such as WST-1 and WST-8, which enable accurate and quantitative assessment and comparative analysis of SOD activity.

MCE Total Superoxide Dismutase (SOD) Activity Colorimetric Assay Kit (Xanthine Oxidase-NBT Method) is based on the classical NBT colorimetric reaction (principle illustrated below). In this system, superoxide anions (O₂•^-) are generated by the coupled reaction of xanthine and xanthine oxidase (XO). The produced superoxide radicals reduce NBT to blue formazan, which exhibits a strong characteristic absorbance at 560 nm. SOD present in the sample scavenges superoxide anions, thereby inhibiting the reduction of NBT to formazan and resulting in decreased color development. The intensity of the blue color is inversely proportional to SOD activity: deeper color indicates lower SOD activity, whereas weaker color indicates higher SOD activity. Total SOD activity in samples can be quantitatively determined by measuring the absorbance at 560 nm using a visible spectrophotometer. This kit is suitable for the determination of SOD activity in various biological samples, including cell or tissue homogenate supernatants, whole blood, erythrocyte extracts, and serum.

This kit is designed to eliminate interference from hydrogen peroxide and effectively minimizes the impact of endogenous H₂O₂ present in biological samples on SOD activity measurements. For example, the addition of up to 0.1 mM hydrogen peroxide to SOD standards does not significantly affect the assay results. The 100 T format is sufficient for 100 tests.

4°C, 6 months.

Keep away from light.

1. Test samples may be stored at -70°C for up to 1 month. Repeated freeze/thaw cycles should be strictly avoided, as they may cause partial inactivation of SOD activity and compromise the accuracy of the assay results.

2. During the preparation of cell or tissue samples, lysis buffers or extraction solutions containing detergents such as Triton X-100 should be avoided, as they may interfere with the reaction system of this kit and affect the reliability of the assay results.

3. Antioxidants may interfere with this assay. For example, 0.1 mM ascorbic acid or 5 mM reduced glutathione (GSH) can significantly increase the measured absorbance. In such cases, even if the samples themselves are colorless, setting up Blank Control 3 as described in the protocol can effectively eliminate the interference caused by antioxidants in the samples.

4. This product is for R&D use only, not for drug, household, or other uses.

5. For your safety and health, please wear a lab coat and disposable gloves to operate.