On mixing DPPH solution with a substance that can donate a hydrogen atom, it gives rise to the reduced form with the loss of violet colour. The delocalisation also gives rise to the deep violet colour, with an absorption in ethanol solution at around 520 nm. 1), so that the molecules do not dimerise, like most other free radicals. The odd electron of nitrogen atom in DPPH is reduced by receiving a hydrogen atom from antioxidants to the corresponding hydrazine (Contreras-Guzman and Srong 1982).ĭPPH is characterized as a stable free radical by virtue of the delocalisation of the spare electron over the molecule as a whole (Fig. The assay is based on the measurement of the scavenging capacity of antioxidants towards it. This method was developed by Blois ( 1958) with the viewpoint to determine the antioxidant activity in a like manner by using a stable free radical α, α-diphenyl-β-picrylhydrazyl (DPPH C 18H 12N 5O 6, M = 394.33).
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