Antioxidant activity of Ulva lactuca L. from different coastal locations of Lombok Island, Indonesia

Abstract

Green macroalgae Ulva lactuca is highly abundant in most coastal areas of Lombok, Indonesia. Previous studies have revealed Ulva contains valuable components, such as bioactive compounds, food or biofuel. In this study, we evaluated the antioxidant activity of Ulva lactuca found in different parts of Lombok Island coastal areas. The seaweeds were collected from Batu Layar (BL), Tanjung Aan (TA), and Seriwe (SW) in May 2019. Ethanol extracts of the seaweeds were determined for their antioxidant activity using DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging assay. Total phenolics were determined by colometric method with Folin-Ciocalteu reagent. Although they are the same species, all samples showed various antioxidant activities. Seaweed Ulva lactuca from TA (ULA) and Batu Layar (ULB) exhibited higher DPPH radical scavenging activity with a low IC50 522.23 ± 43 μg/mL and 534.76 ± 14 μg/mL respectively compared to Ulva lactuca from Seriwe (ULS; IC50 682.23 ± 23 μg/mL). However, positive control Ascorbic acid demonstrated significantly stronger antioxidant activity with IC50 of 67 ± 4.6 μg/mL). Furthermore, the total phenolic contents (TPC) of ULS, ULB, ULA were 2.675 ± 0.5 mgGAEg−1, 5.13 ± 0.8 mgGAEg−1, 5.33 ± 2.1 mgGAEg−1 respectively. Flavonoid contents were 19.031 ± 2.1 mgREg−1, 25.315 ± 2.6 mgREg−1, and 28. 053 ± 1.58 mgREg−1 respectively. Current data shows that different locations with different environmental conditions could result in different biological activity of the seaweeds. Green seaweed Ulva lactuca found in BL and TA with more extreme conditions could be considered as source for antioxidants and could be utilized in food and pharmaceutical industry.