Collagen metabolism and antioxidant status in the paw tissue of type II collagen-induced arthritic rats—protective role of alginic acid isolated from Sargassum wightii

Abstract

The aim of the present study was to evaluate the effects of alginic acid isolated from the brown algae, Sargassum wightii, on collagen metabolism and antioxidant status in the paw tissue of rats in experimental arthritis. To induce arthritis, rats were immunized with type II collagen (2 mg/ml) intradermally. Alginic acid (100 mg/kg) and indomethacin (3 mg/kg) were administered orally for 21 days. The severity of arthritis was assessed by measuring paw edema volume and histology of hind paw tissue. Markers of oxidative stress, protein-bound carbohydrates in plasma, and urine and degradative collagen levels were analyzed in all the rats. Alginic acid treatment significantly reduced the oxidative stress in the paw tissue of arthritic rats and modulated the altered level of collagen metabolism along with reduction in serum inducible nitric oxide synthase (iNOS) activity, prostaglandins E2 level, and paw edema volume in arthritic rats. Histopathology of hind paw tissue showed that arthritic rats receiving alginic acid exhibited the dermis and hypodermis free from inflammatory cell infiltration with mild edema and proliferation of collageneous tissue. The overall results show that alginic acid offers protection against arthritis via reducing oxidative stress, modulating collagen metabolism, and downregulating the activities of iNOS and prostaglandin E2.