Voltammetric behavior of sodium 7-methoxyl-4′-hydroxylisoflavone-3′-sulfonate and its application^†

Voltammetric behavior of sodium 7-methoxyl-4′-hydroxylisoflavone-3′-sulfonate (SMHS) in the aqueous solution from pH 1 to 5 was studied by linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. Experimental results showed that in 0.2 mol*L⁻¹ sodium citrate-hydrochloric acid buffer solution (pH=4.65), SMHS caused only one reduction wave at −1.34 V (vs. saturated calomel electrode, SCE), which was an h-reversible adsorptive wave of SMHS protonized involving one electron and one proton. The peak current of SMHS on linear sweep voltammogram was proportional to its concentration in the range of 8.0 × 10 −8.0·10 mol*L⁻¹ (r = 0.995). and the detection limit was 5.0·10⁻-⁶mol*L⁻¹. The method was applied to determination of SMHS, in synthetic samples. In addition, its scavenging effect on superoxide anion radical was studied by the auto-oxidation of pyrogallol in HCI-tris buffer solution (pH = 8.2) in order to explain its peculiar biological effects. The experimental results proved that SMHS has antioxidant quality, and it is an efficient free radical scavenger of superoxide anion radical.