Antioxidant and anti-inflammatory potential of the aqueous extract and polysaccharide fraction from brown marine macroalgae Padina sp. from Gulf of Mannar of Peninsular India

Objective: To evaluate the antioxidant and anti-inflammatory potential of the aqueous extract and polysaccharide fraction from two brown marine macroalga, Padina gymnospora (P. gymnospora) and Padina tetrastomatica (P. tetrastomatica) harvested from Gulf of Mannar of peninsular India. Methods: The antioxidant activity was evaluated using different in vitro systems, viz., 1,1- diphenyl-2-picrylhydrazyl (DPPH), 2, 2′-azino-bis-3ethylbenzothiozoline-6-sulfonic acid diammonium salt (ABTS), H2O2/ HO. radical scavenging, Fe2+ ion chelating ability, and reducing potential. Folin–Ciocalteu method was used to determine the total phenolic content, and the results were expressed as mg of gallic acid equivalents (GE). Thiobarbituric acid-reactive substance formation inhibition assay was employed to assess the ability of the samples to inhibit lipid oxidation in a model system. COXII and LOXV inhibition assays were employed to assess the anti-inflammatory potential of aqueous extract and polysaccharide fraction. Results: The aqueous extract fraction of P. tetrastomatica realized high total phenolic content (288 mg GE/g), and its activity towards scavenging short-lived radicals (OH. and H2O2) (27.8% and 68.3%, respectively; 0.6 mg/mL) are higher than those registered for Padina gymnospora. Aqueous extract and polysaccharide fractions of P. gymnospora showed higher anti-inflammatory activities against LOXV (56% and 53%, respectively) and COXII (30% and 35%, respectively; 1 mg/mL) enzymes. The correlation studies confirmed that polysaccharides present with the Padina sp. are responsible for their anti-inflammatory potential. IR spectral data of polysaccharide fraction revealed the presence of polysaccharide in alginate form and also confirmed the presence of sulphated polysaccharides as principle bioactive constituents. Conclusions: The study revealed that these seaweeds possess beneficial value as human food or health additives and can be used as a natural green remedy against oxidative stress induced inflammatory diseases.