Characterization of Alginate from Drifted Pelagic Sargassum natans and Sargassum fluitans Along the Moroccan Atlantic Coast

Abstract

The unprecedented influx of pelagic Sargassum represents both a serious ecological concern and a potential opportunity regarding biopolymer production. Assessing the quality, preservation status, and processing potential of these species is crucial to transforming this environmental challenge into a sustainable benefit for industrial valorization. In the present work, we investigated the alginate yields (21.2 ± 0.57% and 18.1 ± 0.11% dw) and the structural characteristics of sodium alginates extracted from Sargassum natans and Sargassum fluitans encountered drifting along Moroccan coasts, respectively. The FTIR analysis indicated that the extracted alginates from both species exhibited similar spectral profile of the commercial alginate obtained from Sigma-Aldrich. The 1H NMR spectra of the extracted alginates displayed characteristic signals for monads M and G and diads MM, GG, and MG/GM, consistent with M/G ratios above 1, with fairly abundant heteropolymeric fractions (FGM/FMG) accounting for more than 52% of the polymer diads. Intrinsic and molecular weight analyses revealed differences between S. natans ([η] = 1.39 dL/g; Mw = 0.65 × 10−5 g/mol) and S. fluitans ([η] = 0.80 dL/g; Mw = 0.37 × 10−5 g/mol). Both values are comparable to commercial alginate but remarkably lower in viscosity. Consequently, alginates from these species are foreseen to form elastic, flexible, and softer gels, making them suitable for applications such as drug delivery, cancer therapy, bioactive encapsulation, controlled nutrient release, and environmental remediation.