2.3. Total phenolic content
Total phenolic content (TPC) in the each extract were determined
according to the method of Gutfinger (1981). Each extract
(1.0 mL) was mixed with 1.0 mL of Na2CO3 solution (2 g/100 mL
H2O), and then the mixture was allowed to stand at room temperature
for 3 min. After the addition of 0.2 mL Folin-Ciocalteu
reagent (2-fold diluted with H2O), the reaction was kept for
30 min in the dark room, followed by centrifugation at 13,400 g
for 5 min. The absorbance of supernatant was measured at 750 nm
by using a spectrophotometer (Shimadzu UV-1601, Tokyo, Japan),
and TPC were expressed as garlic acid equivalents.