DPPH is a chromogen-radical-containing
compound that can directly react with antioxidants.
When the DPPH radical is scavenged by antioxidants
through the donation of hydrogen to form stable
DPPH-H molecule, the colour is changed from purple
to yellow. Stable radical DPPH has been widely
used for the determination of primary antioxidant,
that is, the free radical scavenging activities of pure
antioxidant compounds, plants, fruit extracts and
food materials (Shi et al., 2006).