Uncovering the nutraceutical and biorefinery applications of two different marine macroalgae Sargassum polycystum and Rosenvingea intricata

The marine ecosystem provides resources for various food products and nutraceuticals with multiple benefits to human health. In this study, two underexploited seaweeds such as Sargassum polycystum (Sp) and Rosenvingea intricata (Ri) were used to investigate their biological potentials. The seaweeds underwent for washing and the washed water was examined to identify the bioactive compounds by Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The fucoxanthin was extracted from both seaweeds using Ultrasound-Assisted Extraction (UAE) with 100% of absolute ethanol and acetone, which resulted in higher fucoxanthin from unwashed Ri (0.8 ± 0.12 mg/g) and unwashed Sp (0.59 ± 0.03 mg/g). Further, the remnant biomass of both washed and unwashed forms was used for the fucoidan extraction by employing UAE and Microwave-Assisted Extraction (MAE). Among these, the MAE process had yielded 1.86 folds higher fucoidan after fucoxanthin extraction from unwashed Sp compared to the washed. Finally, the relic seaweed residue of Sp underwent separate hydrolysis and batch fermentation (SHF) for the production of bioethanol, which was quantified by GC-MS. Thus, this study suggests that the entire biomass of seaweed would be a plausible feedstock for producing bioproducts.