Biorefinery of Caribbean Pelagic Sargassum: Anticancer and Nutraceutical Potential of Multiple Extracts and Residue Valorization via Biomethane Production

Massive blooms of Sargassum spp. along Caribbean coasts have created an urgent need for sustainable valorization strategies. This study develops an integrated cascade biorefinery for biomass collected in Dominican Republic. First, bioactive compounds were extracted using methanol and high temperature/high pressure, followed by solvent-based fractionation according to molecular weight (x<3 kDa). Bioactivity testing against human medulloblastoma cell line (HDMB03) revealed a promising cell death effect, up to 60% at 8.0 mg/mL fraction concentration. Then, residual biomass underwent lipid extraction using chemical method, followed by compositional analysis (GC–MS) that highlighted nutritionally relevant fatty acids. Finally, the exhausted biomass was subjected to anaerobic digestion, where its biochemical methane potential (BMP) was determined using an Automatic Methane Potential Test System, yielding 102.9 ± 19.4 mL CH4 g−1 VS, demonstrating the feasibility of renewable energy production from the residual biomass. Overall, this study demonstrates the effectiveness of a cascade biorefinery approach for pelagic Sargassum spp., obtaining a set of extracts with potential for biomedical and nutraceutical sectors. In addition, we also valorize the residual, leftover biomass using biomethane production to enhance and advance circular bioeconomy solutions for affected Caribbean regions.