Determinação da atividade antioxidante e compostos fenólicos totais em óleos essenciais

Abstract

Antioxidants are compounds that have the function of slowing down or even prevent the oxidation of lipids or other molecules and, thus, antioxidants prevent the initiation or propagation of oxidation chains. Synthetic antioxidants cause serious problems to the health of their consumers. To avoid problems caused by the synthetic antioxidants, researchers are trying to find natural products that have antioxidant activity and thus replace the synthetic antioxidants. Research indicates that increases the number of consumers and the scientific community interested in consuming natural antioxidants, especially those found in fruits and vegetables. Among the natural antioxidants, the most used are phenolic compounds because of their redox properties and chemical structures. This research has proposes to quantify the total phenolic and also, study the activity of essential oil sin relation to its antioxidant effect. Compounds present in the oils (ginger, rosemary, cloves, sweet orange, mint and star anise). the quantification of the total phenolic compounds carried out using the Folin - Ciocalteu reagent. The results obtained by the survey, has expressed in equivalent of gallic acid. The antioxidant activity was determined by DPPH method and expressed in relation to the concentration required to inhibit 50% of DPPH also was used AAI (Antioxidant Activity Index). The studies reveals the essential oil that has a higher concentration of phenolic compounds was that extracted using clove (0.9690 µg EAG µg-1), followed by the orange oil (0.0990 µg EAG µg-1), ginger (0.0599 µg EAG µg -1 ), star anise (0,0528 µg EAG µg-1), rosemary (0.0184 µg EAG µg-1) and mint (0,0156 µg EAG µg -1). The best results of IC50 was present in the essential oil from cloves (3.15 µg mL-1) followed by rosemary (8805 µg) and ginger (25020 µg) and the result for AAI was found in the oil of cloves, 10.73. It verified the existence of antioxidant activity by the TEAC (Trolox Equivalent Antioxidant Capacity) Trolox, a synthetic antioxidant, used also to determine as the antioxidant activity caused by TEAC (Trolox). It was an equivalent reference for both of methods and for the DPPH and too ABTS. The oils showed better performance in TEAC in ABTS e DPPH respectively were clove oil (15.84 µM Trolox µg-1, 2.13 µM Trolox µg-1), followed by rosemary oil (2.8 x 10-4 µM Trolox µg-1; 9.65 x 10-4 µM Trolox µg-1) and ginger (5.31 x 10-4 µM Trolox µg-1, 3.26 x 10-5 µM Trolox µg-1). It was possible to verify, in some cases, no correlation between antioxidant capacity and content of phenolic compounds.