2,2-diphenyl-1-picrylhydrazyl (DPPH) (DPPH)

2,2-diphenyl-1-picrylhydrazyl (DPPH) is a stable organic free radical compound that serves as a standard reagent in chemical and biochemical assays to measure the antioxidant capacity of various substances (PubChem CID 2735032). It is characterized by a deep violet color in solution, which results from the delocalization of its unpaired electron across the molecular structure (Wikipedia). When DPPH encounters a molecule capable of donating a hydrogen atom or an electron, it is reduced to its non-radical form, 2,2-diphenyl-1-picrylhydrazine, causing the solution to turn pale yellow (Kedare & Singh, 2011). This colorimetric change is typically measured using spectrophotometry at a wavelength of approximately 517 nm to quantify the radical scavenging activity of antioxidants such as ascorbic acid or polyphenols. Because DPPH is a synthetic laboratory reagent and does not occur naturally in biological systems, it is not classified as a therapeutic target for drug intervention. Instead, it is an essential tool for the initial in vitro screening of potential therapeutic agents that aim to mitigate oxidative stress in various diseases.

Other names

1,1-diphenyl-2-picrylhydrazylDPPH radical2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazylDPPH•

DPPH acts as a stable free radical that undergoes reduction by accepting a hydrogen atom or an electron from an antioxidant molecule, leading to its decolorization (Kedare & Singh, 2011).