The ABTS solution was freshly prepared for each assay. Cornextracts (150 HL each) were allowed to react with 3 mLof ABTS solution for 2 h in the dark. The absorbance was obtained at 734 nm using a spectrophotometer. The standard curve was linear between 50 and 500 HM of Trolox solution. Results are expressed in wmolTrolox equivalents (TE)lg fresh weight.
2.9.2. DPPH radical-scavenging activity
The DPPH antioxidant-activity assay was performed as per Brand-Williams et al. (1995) with modifications. The stock solution was prepared by dissolving 24 mg DPPH with 100 mL methanol. Corn extracts (77 HL) were added to react with 3 mL of the DPPH solution for 15 min in the dark. The absorbance was taken at 515 nm. The standard curve was linear between 50 and 500 HM of Trolox solution. Results are expressed in HmolTroloxlg fresh weight.
2.9.3. FRAP assay
The FRAP (ferric reducing antioxidant power) assay was done as per Benzie and Strain (1999) with slight modifications. The stock solutions included 300 mM acetate buffer (pH 3.6); 10 mM TPTZ solution in 40 mM HCl; and 20 mM FeCl3.6H20 solution. Fresh working solution was prepared by mixing 25 mL of acetate buffer 2.5 mL of TPTZ solution; and 2.5 mL of FeCl3.6H20 solution. Corn extract (200 HL) was allowed to react with 3.8 mL of the FRAP solution for 30 min in the dark. The colored products were taken at 593 nm. The standard curve was linear between 50 and 400 HM of Trolox solution. Results are expressed in umorTroloxlg fresh weight