Total Superoxide Dismutase (SOD) Activity Colorimetric Assay Kit (WST-8 Method) 

MCE Total Superoxide Dismutase (SOD) Activity Colorimetric Assay Kit (WST-8 Method) is based on a water-soluble tetrazolium salt (WST-8) chromogenic system (see schematic illustration of the assay principle). Superoxide anions (O₂•^-) generated by the xanthine–xanthine oxidase (XO) reaction system reduce WST-8 to a stable, water-soluble formazan product with a characteristic strong absorbance at 450 nm. SOD in the sample scavenges superoxide anions, thereby inhibiting the reduction of WST-8 to formazan and resulting in decreased color development. The color intensity is inversely correlated with SOD activity, i.e., higher absorbance indicates lower SOD activity and vice versa. Total SOD activity in samples can be quantitatively determined by measuring the absorbance at 450 nm using a visible spectrophotometer or microplate reader.

The reaction product of WST-8 is a stable, water-soluble formazan, allowing quantitative analysis based on a single time-point absorbance reading. This makes the assay well suited for high-throughput applications and drug screening. Compared with the conventional NBT method, the WST-8 method provides a broader inhibition response range for SOD activity, with a maximal inhibition rate approaching 100%, improved tolerance to common interfering substances, larger absorbance changes at equivalent SOD activities, a wider linear range, higher analytical sensitivity and can detect SOD as low as 0.5 U/mL.

This kit is suitable for the determination of SOD activity in a wide range of biological samples, including cell or tissue homogenate supernatants, whole blood, erythrocyte extracts, and serum. The provided SOD Sample Preparation Buffer enables direct lysis of cells without the need for additional homogenization steps, facilitating convenient and efficient sample preparation.

The 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.

Reaction Stock Solution (40×), Enzyme Solution, SOD Sample Preparation Buffer, SOD Assay Buffer: 4°C, 1 year. Keep away from light.

WST-8: -20°C, 1 year. 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.