Glutathione is a tripeptide present in the body and is used as an enzyme substrate for glutathione peroxidase, glutathione S-transferase, thioltransferase, etc. It is involved in antioxidants that protect cells from damage by reactive oxygen species. and Glutathione normally exists in its reduced form (GSH) and is converted to its oxidized form (GSSG) by stimulation such as oxidative stress; thus, the ratio of GSH to GSSG is used as an indicator of oxidative stress. Eventually, the ratio of GSH to GSSG is used as an indicator of oxidative stress. OxiTec™ Glutathione(GSH/GSSG/Total) Assay Kit is a product for measuring the ratio of total GSH to GSSG,GSH present in a sample. Total GSH is measured at an absorbance of 412 nm as the oxidized GSSG is reduced to two GSHs by NADPH, Glutathione reductase, and the reduced GSH and GSH present in the existing sample react with DTNB to form yellow TNB. In addition, the amount of GSSG can be measured by first removing the reduced GSH with Masking Reagent (M2VP) and reducing only the oxidized GSSG to GSH, and the ratio of GSSG / GSSH can be measured.