Antioxidant Activity, Nutritional Composition, and Proximate Analysis of the Moroccan Alga Ulva Lactuca from the Mehdia Coast

The investigation of seaweeds to identify their bioactive metabolites and potential broader applications has gained significant relevance. This study aimed to analyze the proximate composition, mineral content, fatty acid profiles, water and oil-holding capacities, and antioxidant activity of various solvent extracts of Ulva lactuca. The results indicated that Ulva lactuca is characterized by its fiber content (12.68 ± 0.5%), carbohydrates (61.12 ± 1.42%), proteins (22.15 ± 1.7%), and lipids (1.3 ± 0.1%). It has a higher proportion of unsaturated fatty acids, an excellent ω-3/ω-6 ratio, and a high nutritional value. Additionally, it serves as a significant source of essential minerals, particularly potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), and phosphorus (P). The methanolic extract exhibited higher levels of phenolics (45.69 ± 3.24mg gallic acid equivalents/g DM), flavonoids (15.49 ± 0.064 mg quercetin equivalents/g DM), and tannins (22.52 ± 8.23mg catechin equivalents/g DM) compared to other extracts. Using total antioxidant capacity, DPPH (2,2-Diphenyl-1-picrylhydrazyl), and reducing power assays, the results demonstrated that all three examined extracts possessed antioxidant properties. Notably, the methanolic extract showed the highest antioxidant activity, with a half-inhibitory concentration of 33.6 ± 1.31µg/ mL in the DPPH radical scavenging assay. The study also revealed that the water and oil-holding capacities of Ulva lactuca varied with temperature and were comparable to those of many commercial fiber-rich products. Sourced from the coastal waters of Kenitra, Ulva lactuca presents a viable option for applications in nutrition, pharmaceuticals, and the agri-food industry due to its biochemical composition, functional characteristics, and antioxidant properties.