Marine macro alga are known to produce a plethora of bioactive metabolites with potential application in pharmaceutical and nutritional product development. In this study, the brown
algae <i>Sargassum wightii</i> was collected along the coast of Kovalam, Thiruvananthapuram and subjected to <i>in vitro</i> analysis to determine their bioactive properties. The chloroform-methanol extract of <i>S. wightii</i> was utilized to screen and quantify phytochemical components. Further, the
study examined the antioxidant potentials by lipid peroxidation inhibition, DPPH, and ABTS radical scavenging assays followed by an antibacterial activity. The capability of the extract to inhibit DNA damage and protein oxidation was also evaluated <i>in vitro</i>. Finally, the chemical characterization was
attained using UV-Visible, FTIR, and GC-MS spectral data. Alkaloids, coumarins, flavonoids, phenols, and tannins, were detected in preliminary qualitative phytochemical analysis and their quantitative estimation revealed a significant concentration of these phytocomponents. The extract
showed an IC<sub>50</sub> value of 310.53 ± 0.35 µg/mL and 242.85 ± 0.377 µg/mL for DPPH and ABTS free radicals respectively. Whereas an IC<sub>50</sub> of 205.42 ± 0.20 µg/mL was estimated for lipid peroxidation inhibition assay. A significant antimicrobial activity against four bacterial pathogens with a
maximum zone of inhibition of > 40 mm was also observed against <i>Staphylococcus aureus</i> 1.5 µg/mL). The extract also demonstrated a high capability for concentration-dependent prevention of DNA damage and protein oxidation. The GC-MS spectral peaks confirmed the occurence of 17 active components with reported biological activities. These findings suggest that the extract of <i>S. wightii</i>, can be a lead compound for the development of a promising pharmaceutical product.