Production of Antioxidant by the Green Alga Dunaliella salina

The variation of the lipophilic (carotenoids and α-tocopherol) and hydrophilic (glutathione and ascorbic acid) antioxidant contents, and the activities of antioxidant enzyme such superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), as well as cellular malonaldehyde and stable radicals of D. salina in response to ultraviolet B (UV-B radiation 290-320 nm) and secondary carotenoid induction conditions (nitrogen starvation and high NaCl concentration) were examined. The results indicate that nitrogen deficiency combined with NaCl stress and UV-B irradiated is potential increase of both lipophilic and hydrophilic antioxidant contents. Also, HPLC analysis of carotenoids extracts showed that D. salina accumulated significant quantities of β–carotene and secondary carotenoids, mainly astaxanthin and zeaxanthin. Furthermore, the activity of antioxidant enzymes CAT, SOD and POD showed a positive significant correlation with the antioxidant content and with the exposured UV-B irradiance. Cellular malondialhyde content and quantities of alkyl radical-PER signal indicators of lipid peroxidation were much higher in irradiant cells compared to unirradiant cells. These result revealed that D. salina had high resistance to environmental conditions. These qualities therefore make D. salina good candidates for successful culture in open ponds to production of useful materials, such as β–carotene, astaxanthin, zeaxanthin, ascorbic acid and α-tocopherol. Also, it could be used to provide a rich source of such antioxidant for health foods.