Herbs as antioxidants in oxidation of marine lipids
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- Institutt for biologi 
Marine lipids have beneficial health effects due to the high content of long chain polyunsaturated omega-3-fatty acids (LC-PUFA), especially EPA (eicosapentanoic acid) and DHA (docosahexanoic acid) and they aretherefore of interest to use in products for human consumption.Marine phospholipids are very susceptible to lipid oxidation, due to the high amount of n-3 PUFAs, which cause loss of sensory and nutritional value in foods.In order to prevent the oxidation reactions, it is important to find out more on how different factors and compounds, such as pro- and antioxidants in the food, affect these reactions.The prooxidant activity of 𝐹𝑒3+, 𝐹𝑒2+ and Hemoglobin was tested and 𝐹𝑒3+ was selected as a prooxidant in the studied lipid system, which is the most abundant prooxidant in the emulsified system.The aim of this study was to evaluate the antioxidant activity in 12 selected herbs using three different antioxidant capacity assays: Folin-Ciocalteu (FC), 2,2-diphenyl-1-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). Based on the results of these assays, antioxidant capacity of the most prominent antioxidants from the assays was determined in a liposome model system with marine phospholipids, where the rate of oxygen uptake was used to measure rate of lipid oxidation. Propyl gallate, a representative of a synthetic food antioxidant, was used as a reference due to its known high antioxidant capacity. This study also showed inhibitory effects of propyl gallate on iron catalyzed oxidation of marine phospholipids in liposomes.Antioxidant activity of the 5 selected herbs was measured by means of inhibition percentage of oxygen uptake in the liposome (phospholipid dispersion in buffer). With respect to the obtained results, Sage, Rosemary and Dill exhibited antioxidative effects, while Lemon balm and basil were found to be prooxidants at the tested concentrations.The comparison of the results obtained by the assays and by the study of the antioxidant effects in the liposome model system with catalyzed oxidation indicates that the AOC of the compounds could be dependent on the oxidation system and the applied prooxidants.