Euro Fed Lipid congress edition:9 location:Rotterdam, The Netherlands date:18-21 September 2011
In the past few years, there has been a search for herbal formulations to replace synthetic antioxidants traditionally used in nutrition. It is believed that microalgae might be a good natural source of antioxidants instead of higher plants, due to the high areal biomass yields and relatively high antioxidant power. Due to their phototrophic nature, unicellular microalgae are subject to reactive oxygen species (ROS), generated during photosynthesis. To counteract the detrimental effects of ROS on cell constituents, microalgae need a defense mechanism expressed by the presence of antioxidants. In higher plants, phenolics are an important class of secondary metabolites that provide protection against oxidative stress. However, little is known about their importance in microalgal cells, since antioxidant activity of microalgae is mainly ascribed to carotenoids.
The current knowledge, from both literature data and own results, on the impact of both carotenoids and phenolics on the antioxidant power of microalgae is discussed. New data on varying types of extract from commercially available biomass samples of diverse algal species are presented. Our own results from the antioxidant measurements on these extracts indicate that antioxidant activity strongly depends on the assay used, varies amongst algal species and that both carotenoid and phenolic components are important contributors to the reducing power of microalgae. Furthermore, the role of endogenous antioxidants on the prevention of (auto-)oxidation of microalgal oil, which is rich in polyunsaturated fatty acids, is discussed. Finally, new results on the effects of nutrient composition (N and P limitation) and UV-stress on the formation of antioxidant components in continuous culture are discussed.