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.
