In a previous study, a significant correlation was demonstrated between the antioxidant activity and phenolic content of four macroalgae[37], although, there have been few other studies on the relationship between these two parameters for algae. Therefore, there is not yet any concrete scientific evidence for how much phenolic compounds contribute to the total antioxidant capacity in algae. Although phenolic compounds can be principal antioxidant compounds in many plant species like vegetables, fruits and medicinal plants[29,55,56], they are less important as antioxidants in microalgae.