Simple and rapid catalytic spectrophotometric determination of superoxide anion radical and superoxide dismutase activity in natural medical vegetables using phenol as the substrate for horseradish peroxidase

The coupling reaction of 4-aminoantipyrine (4-AAP) with phenol using the superoxide anion radical () as oxidizing agent under the catalysis of horseradish peroxidase (HRP) was studied. Based on the reaction, produced by irradiating vitamin B₂ (V_B2) was spectrophotometrically determined at 510 nm. Under the optimum experimental conditions, the relationship between A ₅₁₀ and concentration was linear in the range 9.14×10^–6–1.2×10^–4 mol L^–1. The detection limit was determined to be 1.37×10^–6 mol L^–1. A possible reaction mechanism was discussed. The effect of interferences and surfactants on the determination of was also investigated. The proposed method was applied to determine superoxide dismutase activity in garlic, scallion, and onion with satisfactory results.