Optimization of production and antioxidant activity of fucoxanthin from marine haptophyte algae, Isochrysis galbana

This study compared the biomass production, fucoxanthin production and antioxidant capacity of the fucoxanthin from the marine haptophyte algae, Isochrysis galbana under different nitrogen concentrations. At first step in the salinity test, I. galbana could grow in 20‰ and 35‰ but the 35‰ salinity was optimal. At second step, five different nitrogen concentrations (N-NO3) of 2, 4, 8, 12 12 mM, at the salinity of 35‰, were investigated. Algal cell density increased as nitrogen concentrations increased, but a low growth rate occurred in the culture with the highest nitrogen concentration (12 mM). The maximum cell density of 72× and the maximum amount of fucoxanthin (18.1 mg g-1) was obtained in I. galbana cultured in media containing four mM nitrogen (N-NO3). The purified fucoxanthin exhibited strong antioxidant properties, with the effective concentration for 50% scavenging (EC50) of 1, 1-dihpenyl-2- picrylhydrazyl (DPPH) radical, being 0.2 mg/ml. This study suggests that the production and fucoxanthin concentration of I. galbana can be improved using nitrogen-replete culture in 35‰ salinity. Also under this condition this microalgaecan be a commercial source of fucoxanthin for human health and nutrition.