The DPPH free
radical scavenging activities of various samples were
measured using method of Chu et al. (17) with some
modifications. DPPH solution (6.5×10−5 mol/L) was prepared
in methanol and was sonicated for 5 min to obtain the
stable free radical DPPH. Two mL fresh DPPH solution
was mixed with 50 μL of each of the various samples, in
a 1-cm path length microcuvette. The mixtures were stored
in the dark for 16 min. After the reaction the absorbency
was measured at 517 nm using a UV/Vis spectrophotometer.
A known antioxidant, ascorbic acid, was used to compare
the free radical scavenging activity of each concentrate.
phosphate buffered saline (PBS), DPPH solution, and
methanol were used as the standard, control, and blank,
respectively. All tests were performed in triplicate. The
percentage of free radical scavenging activity was
calculated according to the following formula: