2.2.4.2. DPPH radical-scavenging capacity assay. The DPPH
radical-scavenging activities of OLE, OFE, BPOL and BPOF were
determined according to a previously reported method
(Brand-Williams, Cuvelier, & Berset, 1995) with slight modifications.
A 0.5-mL aliquot of sample solution was mixed with
2.5 mL of a 0.5 mM methanolic solution of DPPH. The mixture
was shaken vigorously and incubated for 30 min in the dark
at room temperature.The absorbance was measured at 517 nm
against a blank, using a UV–vis spectrophotometer.The results
are expressed as the percent inhibition of the DPPH radical,
which was calculated using the equation [(A0 − A1)/A0] × 100,
where A0 is the absorbance of the DPPH solution without the
sample.Vc and BHT were used as positive controls in this assay.