Triplicate aliquots of each sample (15 g) were extracted with
40 ml of a methanol:water (1:1) solution and centrifuged at
10 000g for 10 min at 4 C. The extraction was repeated twice.
Supernatants were combined to yield an aqueous fraction. The free
radical scavenging capacity was evaluated with the DPPH stable
radical. 0.1 ml of the diluted methanolic extract of sample was
added to 3.9 ml of DPPH (0.030 g l1
) in methanol. The method is
described extensively elsewhere (Sánchez-Moreno et al., 2003b).
The parameters EC50, which reflect 50% depletion of the initial
DPPH radical, and the time needed to reach the steady state at
EC50 concentration (tEC50) were calculated. The antiradical effi-
ciency (AE = 1/[EC50 tEC50]), a parameter that combines both factors,
was also calculated.
2.8.