Mendes, Joana CorrêaValente, Joana F. A.Sousa, FaniBernardino, RaulBernardino, SusanaAfonso, CléliaChagas, Bárbara2026-01-242026-01-242026-02-01Mendes, J. C., Valente, J. F. A., Sousa, F., Bernardino, R., Bernardino, S., Afonso, C., & Chagas, B. (2026). Optimisation of Alginate Extraction and Characterisation of Polysaccharides from Brown Seaweed from the Portuguese Coast. Marine Drugs, 24(2), 60.1660-3397http://hdl.handle.net/10400.8/15644This work had the support of national funds through Fundação para a Ciência e Tecnologia (FCT, Portugal), within the scope of the projects: UIDB/00709/2020 (DOI 10.54499/UIDB/00709/2020); UIDP/00709/2020 (DOI 10.54499/UIDP/00709/2020); UIDB/04044/2020 (DOI 10.54499/UIDB/ 04044/2020); UIDP/04044/2020 (DOI 10.54499/UIDP/04044/2020); UID/PRR/04044/2025 (DOI 10.54499/UID/PRR/04044/2025); UID/04292/2025 (DOI 10.54499/UID/04292/2025); UID/50020/ 2025 (DOI: 10.54499/UID/50020/2025); UIDP/50020/2020 (DOI: 10.54499/UIDP/50020/2020); LA/P/0112/2020 (DOI 10.54499/LA/P/0112/2020); LA/P/0069/2020 (DOI 10.54499/LA/P/0069/ 2020); LA/P/0045/2020 (DOI: 10.54499/LA/P/0045/2020). The research work was also conducted under the PREDICTOS project, which received funding from the European Union’s Horizon Europe research and innovation program under Grant Agreement n. 101079372, and also by the project Programa de Recuperação e Resiliência-PRR: Packing of the future®, Green Agenda for Business Innovation, investment project n. 59, funded by the PRR, NextGenerationEU and the project Optimised additive biomanufacturing system to produce hierarchical multi-tissue scaffolds for the treatment of joint diseases (InnovaBIOMAS)—Ref. 2022. 10564.PTDC.Alginate is a widely used and versatile biopolymer with an ever-expanding range of applications in the pharmaceutical and biomedical industries. This highlights the importance of developing sustainable and renewable production sources. Conventional extraction methods, although effective, are often energy-intensive and rely on harsh chemicals. In this context, brown algae are a promising alternative due to their abundance and renewability. This study investigated the potential of Saccorhiza polyschides and Sargassum muticum as sources of sodium alginate (SA), thus optimising an extraction process that combines acid treatment with an alkaline step. The extracted biopolymers were characterised using FTIR, H-NMR, STA, SEM/EDX, viscosity measurements, dynamic light scattering, and spectrophotometric assays of residual polyphenols and proteins. The optimised extraction conditions produced yields above 20% of high-purity alginate. When compared with commercial SA, the extracted materials showed comparable quality while relying on a simplified, solvent-reduced protocol that improves process efficiency and reduces the environmental impact. These results demonstrate that S. polyschides and S. muticum are promising, locally available sources of high-quality sodium alginate, and that industrially relevant yields (>20%) can be achieved through an environmentally conscious two-step extraction process.engbrown seaweedsalginatepolysaccharidesextraction methodsSaccorhiza polyschidesSargassum muticumresearch article2026-02-05cv-prod-471452210.3390/md24020060