2.4.2. DPPH radical-scavenging capacity
DPPH radical-scavenging capacity was determined as described
previously (Kuda & Yano, 2009) with slight modification. Briefly,
sample diluted solution (0.1 mL) and ethanol (0.1 mL) were put
into a 96-well microplate, and absorbance at 517 nm (Abs1) was
measured using the microplate-reader (SH-1000 Lab). Next,
1 mmol/l DPPH radical in was added and incubated at 37 C for
30 min and the absorbance (Abs2) was measured again. The
DPPH radical-scavenging capacity was calculated using the following
formula: