Potentiel antioxydant des algues des côtes de l’est Algérien.

Abstract

The number of studies of marine algae extracts from the Algerian species Ulva lactuca is so little. This study aims to examine the biological potential of polyphenoles, polysaccharide and lectins fractions of the species U. lactuca collected from eastern Algeria (Jijel). The polyphenoles fractions was evaluated by testing the antioxidant activity in vitro, the carrageenin-induced anti-inflammatory activity in the Albino wistar rat, and the immunomodulatory effect in vivo by assessing the index of phagocytosis. U. lactuca metabolites (polysaccharide and lectins) are also investigated for their ability to inhibit TNF-α synthesis and NO release in LPS-stimulated RAW 264.7 macrophages. The gastroprotective effect of the polysaccharide phase on inflammatory and ulcerative lesions of the gastric mucosa was estimated by the animal model of gastric alterations induced by intra- gastric administration of the gastric mucosa of absolute ethanol. All of these studies was supported by minute microscopic and macroscopic examinations. The results show that the polyphenol phase has proved an antioxidant potential in vitro. The polysaccharide and lectin phases showed a significant antiedema effect. Decreases in MPO activity and MDA levels in inflammatory rat foot tissues were significant in the case polysaccharide phase compared to lectins. Both phases increased the phagocytic activity of macrophages in vivo, although this increase was more pronounced in groups treated with the lectin phase. Both phases exerted a protective effect against LPS-induced inflammation in RAW264 cells and revealed a significant dependent dose down regulating the production of NO by macrophages, TNF-α release; these effects were more obvious in the case of the polysaccharide phase. The results of this study showed that Algerian U. lactuca has an important immunomodulatory activity due specifically to the lectin fraction and an anti- inflammatory effect due specifically to the polysaccharide fraction. The pre-treatment of mice with polysaccharide extract preserves biomarkers of altered gastric mucosa and compensate the deficiency of antioxidant defense mechanisms, GSH, CAT, SOD and GST, and eliminates lipid peroxidation. The histological study similarly confirmed an important restoration of the architecture of the gastric mucosa. Thus, the Algerian U. lactuca is endowed with an antioxidant, anti-inflammatory and gastroprotective potential, these properties could be due to the synergistic effects of its constituents including specifically lectins and polysaccharides.