Use of the Chlorpromazine Radical Cation for the Antioxidant Activity Estimation

In this paper it is studied the ways by which the radical cation chromophore of chlorpromazine, produced through a reaction between chlorpromazine maleate and potassium persulfate in hydrochloric acid medium, can be applied in realization an evaluation method of the antioxidant activity. The chlorpromazine radical cation is a radical with biological relevance, being involved in oxidative processes of human body. It presents the maximum absorption in the visible field of spectrum (λ= 525 nm) and its interaction with antioxidant substances determine a linear inhibition of color proportionally with the antioxidant concentration. It is followed the optimization of the parameters in the generation reaction of the cation radicals of chlorpromazine in vitro (wavelength, pH, molar ratio chlorpromazine – persulfate). It has been studied the interaction between chlorpromazine cation radicals and gallic acid (as standard antioxidant) and a new spectrophotometric method in VIS for the estimation total antioxidant activity, expressed as gallic acid molar equivalents (GAE), has been realised. The method was validated by statistical techniques, the main parameters being established: analytical range (10-50 and 50-100 μM /L gallic acid), the linearity of response function (r2 having values 0.9975 and respectively 0.9964), the linearity of results, the limit of detection (LOD) and limit of quantification (LOQ), the system precision, the method precision (RSD = 4.18%, respectively 4.06%), the intermediate precision, the accuracy (percent recovery – 98.1%, respectively 99.6%). For the application of method to the evaluation of antioxidant activity from different mediums there were established two standard diagrams, by plotting the relative absorbance or the percent inhibition as a function of the standard antioxidant concentration. The method is rapid, less expensive, sensitive and accurate; it may be applied to the antioxidant activity evaluation, at low pH, from the plant extracts.