Perfil antioxidante de ácidos fenólicos naturais com potencial aplicação em emulsões cosméticas

Abstract

The lipid oxidation is a critical factor in the quality of water-in-oil cosmetic emulsions (A / O), due to the low oxidative stability of the vegetable oils used, especially in the presence of water, in which hydrolysis is possible. The cosmetic industry strategy has been the use of antioxidant additives, substances that have delayed effect on lipid oxidation when used in small quantities. The synthetic antioxidant Butyl Hydroxytoluene (BHT) is one of the most used, although there are serious reports regarding the harmful effects that it can cause in the human body, during regular exposure, which has motivated the search for antioxidants from natural sources. Synthetic antioxidants, such as BHT, shows phenolic hydroxylates which act as radical hydrogen donors that regenerate fatty acid molecules and disrupt the oxidative process. A viable alternative to replacing these are the natural phenolic acids normally found in edible vegetables with antioxidant activity as or more potent than synthetic antioxidants. With the aim of evaluating the antioxidant activity of 8 natural phenolic acids such as: caffeic acid (CAFA), ellagic acid (EA), ferulic acid (FA), gallic acid (GA), 4-hydroxybenzoic acid (HA), p-coumaric acid (PCA), trans-cinnamic acid (TCA) and vanillic acid (VA), added to sunflower oil (SFO) at concentrations of 0.03, 0.06 and 0.1%, the Rancimat test was applied. For comparative purposes, the synthetic antioxidant BHT was applied as a control. The results were expressed in period of oxidative induction (IP) in hours (h) and in protection factor (PF) expressed in %. According to the results, the antioxidant BHT showed no protective effect on OG at any of the concentrations evaluated, exhibiting IP values ranging from 5.3 ± 0.01 to 6.1 ± 0.09 h against IP value of 7.06 h of SFO, representing a pro-oxidant activity, which contributes to accelerate the process of oxidative degradation in the oil. In regard to the IP values obtained for phenolic acids, the best results were obtained for the GA (28.2 ± 0.11 h) in the concentration of 0.03% with PF 300%, CAFA in the concentration of 0.1 % (15.4 ± 0.17 h) with PF 15.4%, HA in the concentration of 0.1% (11.7 ± 0.19 h) with PF 66%, and EA at the concentration of 0.1% (10.5 ± 0.12 h) with PF 10.5%. The phenolic acids showed different behavior in relation to the increase in concentration. While in GA there was a decrease in PF; in CA, HA and EA there was an increase in PF. PCA was only effective at the concentration of 0.1% (8.0 ± 0.33) and PF 13%. The other phenolic acids were not effective in any of the concentrations evaluated by the Rancimat method.