DPPH, Free Radical is a cell-permeable, stable free radical that acts as a hydrogen radical scavenger. Originally developed to detect melanin metabolites in the urine of subjects with malignant melanoma, it has found numerous applications as a general antioxidant detector. Useful in inducing free-radical injury to tissues and as a screening tool for detecting free radical scavenging activity of antioxidants. The ability of a compound to decolorize DPPH free radical signifies the reactivity of the tested compound. Used in the quantitative determination of aliphatic and aromatic thiols by indirect spectroscopy and for photometric determination of tocopherol.A sensitive colormetric free radical scavenger.