Optimization of the antioxidant capacity of a mixture of carotenoids and α-tocopherol in the development of a nutritional supplement

The objective of the present study was to determine the interaction between alpha-tocopherol, beta-carotene and lycopene in the formulation of a nutritional supplement using a "simplex-centroid" design and response surface methodology (RSM). Mixtures containing different proportions of each compound had their antioxidant activity (AOA) evaluated by the percent inhibition of spontaneous autoxidation. The regression model fitted to the experimental data demonstrated that the linear terms and only the quadratic terms containing the lycopene variable had a significant impact on the AOA response. A validation assay for the model was performed. The observed value obtained experimentally for AOA did not differ significantly from the value estimated by the adjusted model. The results showed that no synergism occurred between the three compounds when rat brain homogenate was used as the oxidable substrate, and also suggested that RSM can be applied to estimate the behavior of mixed ingredients in nutritional supplements. (c) 2005 Elsevier Ltd. All rights reserved.