DPPH scavenging assay was carried out according to the previously
published method (Pownall, Udenigwe, & Aluko, 2010).
Briefly, 500 lL of 100 lM DPPH solution in methanol was mixed
with 100 lL of sample dilutions and 400 lL of 50 mM phosphate
buffer, pH 7.0. Blank consisted of 400 lL buffer, 100 lL of sample
dilutions and 500 lL of methanol. Control was prepared by mixing
500 lL of phosphate buffer and 500 lL of DPPH solution. Mixture
was incubated at room temperature in darkness for 30 min, and
absorbance was measured at 517 nm. DPPH radical scavenging
activity (%) was calculated as {(A517c _ A517s)/A517c} _ 100, where
c and s represent control DPPH and sample, respectively. Results
were expressed as IC50 values, which represent concentration