The ABTS assay initially reported by Re et al. (1999) was used
with some modifications. Briefly, the ABTS•+ radical was prepared
by mixing 50mL of ABTS•+ solution (2mM) with 200L of K2S2O8
solution (70 mM). This mixture was stored in the dark for 16 h, at
room temperature. On a daily basis the ABTS•+ solution was diluted
with pH 7.4 phosphate buffered saline (PBS) solution to an initial
absorbance of 0.700±0.019 at 734 nm. For the assessment of the
radical scavenging activity, an aliquot of 100L methanolic solution
with a concentration (w/v) of 10mg/mL was added to 1.8mL
of ABTS•+ solution and the absorbance decrease ( = 734 nm) was
recorded during 6min. Results were expressed in terms of mol
Trolox eq per 100 g of dried plant antioxidant capacity (mol eq
Trolox/100 g Trolox/100 g dried plant).