The ferric
reducing
activity
of a single compound in solution, a
food extract or biological fluid can be measured by the FRAP (Ferric
Reducing Antioxidant Power) assay. Antioxidant properties have
been determined in both aqueous-organic extracts and their residues
by the FRAP assay. The method followed Benzie and Strain
(1996) and Pulido, Bravo, and Saura-Calixto (2000) through the
use of a Tecan Sunrise plate reader spectrophotometer. The method
is based on the reduction of Fe3+ TPTZ (2,4,6-tripyridyl-striazine)
complex to ferrous at low pH. Briefly, 160 ll of working
reagent prepared daily was mixed well with 10 ll of diluted
sample and the absorbance was recorded at 595 nm after 30 min
incubation at 37 C. Methanolic solutions of known Trolox concentrations
were used for calibration