Kinetics of the reaction between Moringa oleifera leaf extracts and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical

In this study, an antioxidant-rich extract was obtained by leaching Moringa oleifera leaves. The activity of the extract against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical was measured by determining a second-order rate constant (k2). The reaction between the mixture of antioxidants in the extract and the DPPH was monitored by measuring the absorbance at 517 nm in 30-second intervals for a period of 600 s. The absorbance exhibited a rapid decay within the first 100 s, followed by a slower decay. The absorbance data were fitted to a bi-exponential model. The curve fitting showed a linear relationship between the initial concentration of antioxidants and the reaction rate with the coefficient of determination values greater than 0.9979. The k2 value was 0.0870 ± 0.0007 mg/mL.