The model of scavenging DPPH radical is a widely used method
to evaluate the free radical scavenging activities of antioxidants. In
the DPPH assay, the antioxidants are able to reduce the stable
DPPH radical (purple) to the non-radical form DPPH-H (yellow).
The DPPH scavenging activities of antioxidants are attributed to
their hydrogen donating abilities.