2.7. Free radical scavenging capacity
The free radical scavenging activity of the extract in standard
batches was determined using 2,2-diphenyl-1-picrylhydrazyl
(DPPH) (Brand-Williams et al., 1995). The analysis was performed
in microplates by adding 15 mL of extract to 300 mL of a methanolic
DPPH solution (153 mM). Subsequently, the absorbance at
l ¼ 517 nm was read (Cary 50 MPR, Varian Italia, Cernusco sul
Naviglio, Milano, Italy). The absorbance of DPPH without antioxidant
(control)was used for baseline measurements. The scavenging
activity was expressed as the 50% inhibitive concentration (IC50),
which was defined as the sample concentration (mg dry weight of
the extracts necessary to inhibit the radical activity of 1mL of DPPH
by 50% during a 60-min incubation period. These experiments were
performed in triplicate and the results are expressed as mean
value ± standard deviation.