The Chinese name of MADB is N, N-bis (4-sulfobutyl) -3,5-dimethylaniline sodium salt, with a CAS of 209518-16-1. It is a highly water-soluble and sensitive peroxidase chromogenic substrate commonly used in laboratories. It can react with peroxidase to form a complex, and this complex can achieve the purpose of detecting peroxidase activity through color reaction, thereby evaluating the immune function of cells, the proliferation ability of tumor cells, and the toxicity of environmental pollutants to organisms. The main function of MADB as a chromogenic substrate is to provide a reactive chemical structure to convert reactive oxygen species generated by peroxidase enzymes into visible products. Because in this process, the structure of MADB has specific binding sites with the reaction products catalyzed by peroxides, making the binding between substrate and enzyme more tight and stable. When MADB reacts with peroxidase, the substrate is oxidized into an unstable intermediate, which is then converted into a stable product through the reduction of MADB. During this process, the color of the substrate will change, which can be used to evaluate the activity and stability of peroxidase, as the more active the enzyme, the more intermediates and products it produces, resulting in a more significant change in substrate color.