The extracts were obtained according to the method described
by Larrauri, Ruperez, and Saura-Calixto (1997). Briefly, samples
were weighed (in grams) in centrifuge tubes and extracted sequentially
with 40 mL of methanol/water (50:50, v/v) at room temperature
for 1 h. The tubes were centrifuged at 25,400g for 15 min, and
the supernatant was recovered. Then, 40 mL of acetone/water
(70:30, v/v) was added to the residue at room temperature. The
samples were extracted for 60 min and centrifuged. To determine
the antioxidant activity as well as total flavonoid, total monomeric
anthocyanin and phenolic contents, the methanol and acetone extracts
were combined and brought to a final volume of 100 mL
with distilled water.