Evaluation of antioxidant properties of different extracts of Ulva fasciata Delile and Sargassum vulgare C. Agardh in winter and spring

Seaweed is a rich source of natural antioxidants. There are large populations of Ulva and Sargassum on the southern coasts of Iran. In this study, populations of green alga U. fasciata Delile and brown alga S. vulgare C. Agardh were collected from Bushehr coasts in winter and spring, and their total phenols and flavonoids were evaluated. Various extracts of these species were prepared and their antioxidant activities were investigated by ABTS and DPPH methods. The results showed that S. vulgare had the highest phenols and the lowest flavonoids contents in spring at 0.62±0.065 and 0.83±0.088 mg g-1 of algae, respectively, and U. fasciata contained the highest flavonoids and the lowest phenols in winter (1.65±0.21 and 0.28±0.04 mg g-1 of algae, respectively. In all extracts, S. vulgare showed higher antioxidant activity than U. fasciata. Both species did not show significant differences in antioxidant activity in winter and spring. The 80% ethanolic, methanolic and boiling water extracts showed higher antioxidant properties than the pure ethanolic, methanolic and distilled water extracts, respectively. The highest and the lowest antioxidant activities were mostly observed in the acidic and ethanolic extracts, respectively. The results will greatly help in the selection and application of algae in the food and pharmaceutical industries.