Microalgae and Cyanobacteria Antioxidant Capacity under Stress Conditions

Microalgae and cyanobacteria are photosynthetic organisms that produce a wide range of bioactive compounds that act as antioxidants such as carotenoids, chlorophylls, enzymes, fatty acids, and phycobiliproteins. This indicates that they have efficient protection mechanisms. Therefore, its use in human health and nutrition is of great interest. Different stress conditions modify cell metabolism either by increasing or modulating the activities of antioxidant enzymes of superoxide dismutase, catalase, peroxidase, as well as nonenzymatic compounds such as vitamin E and C, carotenoids, flavonoids, phycobiliproteins, among others. In this chapter, culture strategies are presented for cyanobacteria and microalgae for the evaluation of their antioxidant capacity. In Arthrospira maxima and Phormidium persicinum, the effect of nitrogen starvation and UV radiation was analyzed. In Ettlia oleoabundans, two independent experiments were carried out, nutrient limitation and the effect of marine culture media. In Dunaliella salina, the effect of total nitrogen deficiency, high salinity, light intensity, and temperature was evaluated. Nitrogen starvation or UV in A. maxima and P. persicinum showed an improvement in enzymatic antioxidant activity. The limitation of nutrients in E. oleoabundans increased the antioxidants and other bioactive compounds; in the marine culture media, an accumulation of up to 56% of lipid was obtained and gain of monounsaturated and polyunsaturated fatty acids was observed. Finally, D. salina increases the concentration of β-carotene, lycopene, and lutein. Accordingly, these results suggest that the culture stress conditions can be stimulated for the commercial production of antioxidants in the cyanobacteria and microalgae species.