Multifaceted bioactivity of brown seaweed-derived fucoidan from the Indian Coastline: A natural health product candidate

Brown seaweeds are rich in bioactive constituents, among which fucoidan a sulphated polysaccharide is particularly noted for its broad-spectrum therapeutic properties. This study explores the multifaceted bioactivity of fucoidan extracted from six brown seaweed species (Sargassum wightii, Sargassum tenerrimum, Sargassum cinereum, Turbinaria conoides, Padina boergesenii, and Padina tetrastromatica) collected from the Pudumadam coast, Gulf of mannar region, Tamil Nadu, India. Fucoidan was isolated and structurally characterized using Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The antioxidant capacity of the extracts was assessed through 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity (HRSA), and ferric reducing antioxidant power (FRAP) assays, with Sargassum cinereum showing the highest antioxidant activity (IC₅₀: 0.342 ± 0.01 mg/ml for DPPH; 1.26 ± 0.02 mg/ml for HRSA; 33.17 ± 0.02 mM Fe (II)/g for FRAP). In vitro antidiabetic assays demonstrated that fucoidan from Sargassum wightii exhibited the strongest inhibition of α-amylase and α-D-glucosidase (IC₅₀: 0.042 ± 0.02 mg/ml). Additionally, fucoidan from S. wightii displayed significant cytotoxic activity against MCF-7 human breast cancer cells. These findings underscore the therapeutic promise of brown seaweed-derived fucoidan as a multifunctional agent, supporting its potential application in the formulation of natural health products.