Bioactive Metabolites from Portuguese Atlantic Seaweeds: Diversity, Chemical Profiles, and Emerging Biotechnological Applications

The Portuguese Atlantic coast harbors a remarkably diverse macroalgal flora, shaped by the intersection of Lusitanian, Mediterranean, and boreal biogeographic influences. This diversity is reflected in the rich repertoire of secondary metabolites produced by local seaweeds, including halogenated compounds, terpenoids, phlorotannins, mycosporine like amino acids, sulfated polysaccharides, and unique phenolic structures. These metabolites exhibit a wide range of bioactivities, antioxidant, anti-inflammatory, antimicrobial, antiviral, antifouling, antitumoral, and neuroprotective, positioning Portuguese seaweeds as promising sources of novel bioactive agents. This review synthesizes the current state of knowledge on the chemical diversity and biological properties of metabolites isolated from seaweeds along the Portuguese Atlantic coast. We examine species-specific metabolite profiles, ecological drivers of chemical variability, and advances in extraction, purification, and structural elucidation. Emerging applications in pharmaceuticals, nutraceuticals, cosmeceuticals, and sustainable biomaterials are discussed, alongside the potential of seaweed derived compounds to support blue bioeconomy development. Finally, we identify research gaps and propose future directions for bioprospecting, metabolomics, and biotechnological exploitation of this underexplored marine resource.