2.9. Determination of DPPH radical scavenging activity
This assay was based on the method of Brand-Williams, Cuvelier,
and Berset (1995) as modified by Li, Pickard, and Beta (2007). Briefly,
200 lL of crude extract (or fraction) was added to 3.8 mL of 60 lM
DPPH radical solution, which was freshly made. After 60 min of
incubation at room temperature, the absorbance at 515 nm was
measured. DPPH free radical scavenging activities of crude extracts
were expressed as lM of trolox equivalents (TE) per gram of rice
(dry weight basis) using a standard curve of trolox.