Lipid Peroxidation Inhibition Assay

Each extract was tested for its inhibition against lipid peroxidation by thiocyanate method with some modifications [26 (link)]. Briefly, solutions containing 50 µL of the sample solution in DMSO with the concentration of 1 mg/mL, 50 µL of 50% linoleic acid in DMSO, 50 µL of 10% aqueous solution of ammonium thiocyanate (NH₄SCN), and 50 µL of 2 mM ferrous chloride (FeCl₂) solution, were incubated at 37 °C for 1 h. The absorbance was measured at 500 nm by using a multimode detector (Beckman Coulter DTX880, Fullerton, CA, USA). The inhibitory activity was calculated using the following equation:
when a is an absorbance of linoleic acid, NH₄SCN, and FeCl₂ mixture, b is an absorbance of the solvents, c is an absorbance of sample solution, linoleic acid, NH₄SCN, and FeCl₂ mixture, and d is an absorbance of sample solution and the solvents. The entire experiment was done in triplicate.