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

2,2-Diphenyl-1-picrylhydrazyl (DPPH) is a stable, synthetic free radical extensively used in pharmaceutical and nutritional research as a chemical probe to evaluate the antioxidant potential of various substances. Characterized by its deep violet color in organic solvents, DPPH possesses an unpaired electron delocalized over the entire molecule, which gives it a strong absorption band around 517 nm [1, 4]. When an antioxidant compound is introduced, it neutralizes the DPPH radical by donating a hydrogen atom or an electron, causing the solution to turn pale yellow or colorless [3, 6]. This transition allows for the quantitative determination of the radical-scavenging efficiency of natural extracts and synthetic drugs using a spectrophotometer [10]. Although DPPH is a standard tool for high-throughput screening of antioxidant activity in vitro, it is not a biological molecule and does not exist in the human body [9, 11]. Consequently, while it serves as a valuable indicator for preliminary drug discovery, it is not a therapeutic target for clinical treatment [10].

Other names

DPPH radical1,1-Diphenyl-2-picrylhydrazyl2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazylDiphenylpicrylhydrazyl

DPPH acts as a hydrogen atom or electron acceptor. When reacting with an antioxidant, the DPPH radical is reduced to 2,2-diphenyl-1-picrylhydrazine (DPPH-H), resulting in a colorimetric shift from deep violet to pale yellow, which is measured spectrophotometrically at approximately 517 nm [1, 3, 10].