New Insights in Adriatic Seaweed (Ulva spp.): Nutraceutical and Bioactive Potential and Green Extraction Techniques for Pigments, Antioxidants, and Phenolic Compounds.

Seaweeds, particularly those from the genus Ulva, have gained increasing attention due to their health benefits for humans and their promising bioactive properties, which are applicable as pharmaceuticals and nutraceuticals. However, the potential of Ulva species from the Adriatic Sea (Boka Kotorska Bay) remains largely unexploited. This study aimed to optimize the extraction protocol for key bioactive compounds to maximize their utilization. The chemical composition, physicochemical characteristics, antioxidant capacity, and antimicrobial properties of Ulva spp. were evaluated. Dried seaweed contained 108.51 mg GAE/100 g of polyphenolics, along with chlorophyll a (19.57 mg/100 g) and chlorophyll b (24.02 mg/100 g) as natural green pigments. The antioxidant activity, assessed by DPPH, RP, and ABTS assays, exhibited the IC50 values of 1.727, 1.167, and 0.932 mg/mL, respectively. However, the antimicrobial activity against pathogens such as S. aureus, B. cereus, E. coli, and P. aeruginosa demonstrated low potency. FTIR analysis revealed various significant peaks of characteristic alcoholic and phenolic functional groups, indicating the presence of major phytochemical compounds, while thermal analysis confirmed the good stability of the dried macroalga up to 142 °C. Among the tested extraction methods, maceration (50% ethanol, 1:20 solid-to-solvent ratio) proved to be the most effective. Dried Ulva powder demonstrated a balanced n-6/n-3 ratio and a comprehensive profile of essential and non-essential amino acids beneficial for human nutrition. All of these findings support the potential of Ulva as a valuable marine resource, promoting and contributing to the development of sustainable seaweed-based industries.