RÉSUMÉ
In this present study, four brown seaweeds viz Sargassum wightii Greville, Padina tetrastromatica Hauck, Chnoospora minima, Hormophysa triquetra (C. Ag.) Kutz, collected from Mandapam region of Gulf of Mannar were analyzed for its bioactive potentials. High protein content was observed in Hormophysa triquetra (15.34±0.01%) and carbohydrate (59.30±0.66%); lipid (0.55±0.002%) were recorded in Padina tetrastromatica. Total phenolic content (20±3.46 mg GAE /g) was found to be high in Sargassum wightii, whereas antioxidant activity (34.66±5.77 mg AAE /g) in Padina tetrastromatica. Flavonoid content (66.3±1.43 mg QE /g), DPPH radical scavenging activity (85.08±1.17%) and alginic acid yield (26.70%) was found to be high in Hormophysa triquetra. The viscosity of sodium alginate was found to be high in 5 hours of extraction period in all the seaweeds.