Physicochemical characterization and evaluation of the antioxidant potential of water-soluble polysaccharides from red microalgae, Rhodomonas salina

Rhodomonas salina is a red microalgal species belonging to the class cryptophyceae, which holds huge commercial value due to its rich biochemical composition, including proteins, fatty acids and pigments. However, detailed characterization on the chemical and physical properties of carbohydrates from R. salina are limited. The main objective of this study is to isolate water-soluble polysaccharides from Rhodomonas salina and investigate their physicochemical properties and in-vitro antioxidant activity. Investigation using chromatographic and spectroscopic techniques revealed that the major polysaccharide in R. salina is a α-glucan having (1 → 4) linked-d-Glucopyranose linkages. It is a semi-crystalline polysaccharide having thermal stability up to 245 °C and exhibits Newtonian fluid behaviour in an aqueous solution. The polysaccharide also exhibits moderate scavenging activities against DPPH free radicals and hydroxyl radicals. The findings provide a strong foundation for understanding the functional potential and scope of applications of this novel polysaccharide. Being a α-glucan, R. salina polysaccharide holds potential to be explored as a feedstock of bioethanol production in biotechnology and biorefinery industries.