Antioxidant Capacity and Protein contents of Five Marine Microalgae

Antioxidant capacity, chlorophyll, marker pigment, and protein contents of four diatoms (Helicotheca tamesis, Haslea silbo, Nitzschia navis-varingica, and Asterionellopsis glacialis) and one cyanobacterium (Spirulina subsalsa) have been investigated. N. navis-varingica exhibited the highest chlorophyll a, fucoxanthin, ascorbic acid, and total antioxidant capacity (TAC) among the five species studied. Cupric-reducing antioxidant capacities of N. navis-varingica and H. silbo were higher than other species studied. A. glacialis exhibited the highest total superoxide dismutase (SOD) activity, H. silbo displayed the highest ascorbate peroxidase (APX) activity, and Spirulina subsalsa had the maximum phenolic and protein contents. Overall, compared to other studies in the literature, the contents of phenolics were at a moderate level, and ascorbic acid content, APX activity, and TAC were remarkably high. These findings emphasize the potential for novel applications of the microalgal species used in this study in biotechnology including pharmaceutical, cosmeceutical, food, and feed industries.