Bioactive polysaccharides from seaweeds: applications, mechanisms, and toxicological insights.

Seaweeds, or marine macroalgae, are valuable renewable resources widely used in the food, pharmaceutical, and cosmetic industries due to their rich content of structurally diverse polysaccharides and bioactive compounds. This review highlights major polysaccharides from red (agar, carrageenan, porphyran), brown (alginate, fucoidan, laminarin, mannitol), and green (ulvan) seaweeds, emphasizing structural characteristics, and functional properties. Advances in analytical techniques, including FTIR, NMR, and chromatographic-mass spectrometric methods (HPLC, GC-MS, LC-MS), have greatly improved the characterization of these complex biopolymers. Safety and toxicological aspects are also addressed, particularly concerning potential contaminants. Furthermore, emerging challenges such as the need for standardized extraction procedures, environmentally friendly processing technologies, and deeper insight into molecular mechanisms underlying biological activities are discussed. Overall, this review provides an integrated perspective on the chemistry, biofunctionality, applications, and safety of seaweed polysaccharides, highlighting their growing importance as sustainable multifunctional biomaterials.