Optimization of Carrageenan Extraction From <i>Gracilaria edulis</i> and Determination of Its Antioxidant Activity

ABSTRACT The Red Seaweed Gracilaria eduli s polysaccharide extraction circumstances were augmented by means of Response Surface Methodology (RSM). The effect of different solvent concentrations on the yield of sulfated polysaccharide (SP) was examined utilizing several extract methods with varying effects of extraction pH, calcium chloride concentration, and solvent concentration. The optimal extraction conditions for SP were determined to be: an extraction pH of 8.5, a calcium chloride concentration of 1%, and a solvent concentration of 99%. The experimental extraction yield of SP was 8.4% under these conditions, which was quite near to the expected value. In vitro antioxidant tests revealed that SP has a high plummeting aptitude and scavenging activity against DPPH, Superoxide, Nitric oxide, and Iron‐reducing power. Where DPPH scavenging activity ranged from 8.4% to 66.6%; Superoxide radical scavenging tests ranged from 11.25% to 58.92%; Nitric oxide radical inhibition assays ranged from 7% to 51%; and Total iron‐reducing assays ranged from 14.46% to 57.45%. In all four studies, the highest scavenging effect was obtained at a concentration of 150 µg/mL of SP of G. edulis shows that G. edulis sulphated polysaccharides have the potential to be the natural antioxidant sources. The physical topographies of SP were investigated using FT‐IR spectra. In all four studies, the highest scavenging effect was observed at a concentration of 150 µg/mL of SP from G.edulis, indicating that G.edulis polysaccharides have the potential to serve as natural antioxidant sources. The physical topographies of SP were analyzed using FT‐IR spectra.