Recent increased interest in seaweed is motivated by attention generated in their bioactive components that have potential applications in the functional food and nutraceutical industries. In the present study, nutritional composition, metabolite profiles, phytochemical screening and physicochemical properties of freeze-dried brown seaweed, Sargassum polycystum were evaluated. Results showed that the S. polycystum had protein content of 8.65 ± 1.06%, lipid of 3.42 ± 0.01%, carbohydrate of 36.55 ± 1.09% and total dietary fibre content of 2.75 ± 0.58% on dry weight basis. The mineral content of S. polycystum including Na, K, Ca, Mg Fe, Se and Mn were 8876.45 ± 0.47, 1711.05 ± 0.07, 1079.75 ± 0.30, 213.85 ± 0.02, 277.6 ± 0.12, 4.70 ± 0.00 and 4.45 ± 0.00 mg 100/g DW, respectively. Total carotenoid, chlorophyll a and b content in S. polycystum were detected at 45.28 ± 1.77, 141.98 ± 1.18 and 111.29 µg/g respectively. The total amino acid content was 74.90 ± 1.45%. The study revealed various secondary metabolites and major constituents of S. polycystum fibre to include fucose, mannose, galactose, xylose and rhamnose. The metabolites extracted from the seaweeds comprised n-hexadecanoic acid, 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester, benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy- methyl ester, 1-dodecanol, 3,7,11-trimethyl-, which were the most abundant. The physicochemical properties of S. polycystum such as water-holding and swelling capacity were comparable to several commercial fibre-rich products. In conclusion, results of this study indicate that S. polycystum is a potential candidate as functional food sources for human consumption and its cultivation needs to be encouraged.

Seaweed has tremendous potentials as an alternative source of high‐quality food products that have attracted research in recent times, due to their abundance and diversity. In the present study, three selected seaweed species commonly found in the Malaysian Peninsular, Ulva intestinalis, Halimeda macroloba, and Sargassum ilicifolium, were subjected to preliminary chemical screening and evaluated for α‐glucosidase inhibitory and cytotoxic activities against five cancer cell lines. Chemical composition of U. intestinalis, H. macroloba, and S. ilicifolium methanolic extracts was evaluated by Gas Chromatography‐Mass Spectrometry (GC‐MS) analysis. Our results revealed the highest total carotenoids (162.00 μg g⁻¹ DW), chlorophyll a (313.09 ± 2.53 μg g⁻¹ DW), and chlorophyll b (292.52 ± 8.84 μg g⁻¹ DW) concentrations in U. intestinalis. In the α‐glucosidase inhibitory activity, S. ilicifolium demonstrated the lowest efficacy with an IC₅₀ value of 38.491 ppm compared to other species of seaweed. H. macroloba extract, on the other hand, was found to be the most cytotoxic toward MCF‐7 and HT 29 cells with IC₅₀ of 37.25 ± 0.58 and 21.32 ± 0.25 μg/mL, respectively, compared to other cell lines evaluated. Furthermore, H. macroloba extract was also found to be less toxic to normal cell (3T3) with IC₅₀ of 48.80 ± 0.11 μg/mL. U. intestinalis extract exhibited the highest cytotoxicity toward Hep G2 cells with IC₅₀ of 23.21 ± 0.11 μg/mL, whereas S. ilicifolium was less toxic to MDA‐ MB231 cell with IC₅₀ of 25.23 ± 0.11 μg/mL. Subsequently, the GC‐MS analysis of the methanolic extracts of these seaweed samples led to the identification of 27 metabolites in U. intestinalis, 22 metabolites in H. macroloba, and 24 metabolites in S. ilicifolium. Taken together, the results of this present study indicated that all the seaweed species evaluated are good seaweed candidates that exhibit potential for cultivation as functional food sources for human consumption and need to be promoted.