An iota-carrageenan isolated from marine alga Agardhiella ramosissima negatively modulates the inflammatory response in arthritis conditions

The present study involves the structural characterization of an iota-carrageenan from Agardhiella ramosissima (IC-Ar) and its ability to suppress the inflammatory response in experimental arthritis. The IC-Ar was structurally characterized by Size Exclusion Chromatography (SEC) and Nuclear Magnetic Resonance (NMR) techniques. Experimentally, the mice were treated with IC-Ar (3, 10, or 30 mg/kg) e submitted to arthritis with zymosan and Complete Freund's Adjuvant (CFA). IC-Ar has a molecular mass of 730 KDa and contains 3,6 anhydro-alpha-Dgalactose-2 sulfate (DA2S), 8-D-galactose-4 sulfate (G4S) and glucose, structural characteristic typical of an iota carrageenan. IC-Ar treatment reduced zymosan-induced hypernociception, in a dose-dependent manner, accompanied by reduced edema, vascular permeability, and histopathological scores. Likewise, IC-Ar also significantly decreases MPO activity, leukocytes, neutrophils, IL-18, and nitrite levels in the synovial fluid. Therapeutically, IC-Ar inhibited the hypernociception, edema, and arthritic index in both acute, sub-chronic, and chronic phases of CFA-induced arthritis. In summary, we demonstrated the protective efficacy of an iotacarrageenan extracted from A. ramosissima in arthritis models by negatively modulating the inflammatory response and by reducing polymorphonuclear cell migration, IL-18, and nitrite levels, culminating in the inhibition of hypernociception and edema. Thus, IC-Ar could be a promising molecule to treat arthritis conditions.