Quantification of antioxidants by using chlorpromazine hydrochloride: application of the method to food and medicinal plant samples.

Chlorpromazine hydrochloride (CPH) (3-(2-chloro-phenothiazine-10-yl)-propyl] dimethylamine hydrochloride) has been the subject of a large number of studies employing a broad spectrum of oxidants, and chosen to examine the course of electron transfer reactions. We report on a method to determine the antioxidant activity of some food and medicinal plants using the oxidation of CPH by chromium(VI) to form a stable CPH radical in the 1:1 orthophosphoric acid-ethyl alcohol (OPA-EtOH) medium. The pink color of the control solution was measured at λ(max) of 530 nm. Nine standard antioxidants have been studied by this method, along with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The EC50, TEC50, antioxidant efficacy and the stoichiometric values for antioxidants have been evaluated. The radical scavenging activity expressed as EC50 ranged from 9.2 µg/mL in Camellia sinensis to 448.18 µg/mL in Cuminum cyminum. The application of a simple and versatile antioxidant capacity assay for dietary polyphenols and medicinal plant extracts, which are commonly used in Ayurveda opens its relevance in the field of antioxidant analysis.

Amaranth dye in the evaluation of bleaching of cerium (IV) by antioxidants: application in food and medicinal plants.

A simple, low-cost, sensitive, and diversely applicable spectrophotometric method for the determination of total antioxidant capacity of several medicinal plants and food has been developed. The method is based on the bleaching of cerium (IV) by antioxidants and dye in slightly acid medium at room temperature. The unbleached dye, imparting pink color to the solution, is measured at λ(max) 530 nm which is directly proportional to the antioxidant concentration. The method is reproducible, and the trolox equivalent antioxidant capacities (TEAC coefficients) of the tested antioxidant compounds were correlated with those found by reference method such as ABTS. The recommended method was applied for the determination of total antioxidant capacity of medicinal and food samples. The performance of the recommended method was evaluated in terms of Student's t-test and variance ratio F-test, which indicated the significance of proposed method over the reference method.