Background: An electrochemical method based on cyclic voltametry techniques
was used to measure the antioxidant activity of two ferrocene-nucleobases.
Objective: The present study aims to measure the antioxidant activity of two ferrocene derivatives
bearing nucleobases; the technique is based on the reaction of the in-situ electrochemical
generated superoxide anion radical with ferrocene-nucleobases.
Method: The decrease in the anodic peak current density of the O2 / O2
.− redox couple following
the addition of ferrocene-nucleobases was used to measure the antioxidant activity
and binding parameters of 1-ferrocenylmethylthymine and 1-ferrocenylmethylcytosine
with superoxide anion radical.
Conclusion: Both 1-Ferrocenylmethylthymine and 1-Ferrocenylmethylcytosine showed
higher antioxidant activity (0.34 ± 0.03 and 0.045 ± 0.02 mg/mL respectively) than that of
standard antioxidant α-tocopherol (3.04 ± 0.03 mg/mL). The value of the binding free energy
ranging from -16.1 kJ.mol-1 for 1-ferrocenylmethylthymine to -21.8 kJ.mol-1 for 1-
ferrocenylmethylcytosine suggests an electrostatic interaction of superoxide anion radical
with both compounds which has been found to be the dominant interaction mode. The kinetics
of the interaction reaction of the compounds was quantified having second-order rate
constant values equal to 4.0 and 16.5 M-1 s-1 respectively.
Keywords: Antioxidant activity coefficient, binding free energy, cyclic voltammetry, ferrocene, homogeneous
rate constant, nucleobases, superoxide, anion radicals.
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