Sulfated polysaccharide from the red algae Gelidiella acerosa: Anticoagulant, antiplatelet and antithrombotic effects.

A sulfated polysaccharide from the red algae Gelidiella acerosa (GaSP) was obtained through enzymatic extraction and subjected to chemical characterization by HPSEC, elemental microanalysis, FT-IR and NMR spectroscopies. The GaSP anticoagulant activity was investigated through APTT and PT tests and platelet aggregation assessed by turbidimetry. The antithrombotic and hemorrhagic activities were evaluated by venous thrombosis and hemorrhagic tendency models, respectively. FT-IR and NMR demonstrated that GaSP is a sulfated agaran. HPSEC and elemental microanalysis revealed a peak molar mass of 284.8 kDa and a degree of sulfation of 0.63, respectively. This molecule prolonged the coagulation time in 2.1 times and inhibited the platelet aggregation by 45%. Furthermore, it showed significant dose-dependent antithrombotic effect of 40%, 64% and 80% at 0.1, 0.5 and 1 mg/kg, respectively, without hemorrhage. These results suggest that GaSP has promising antithrombotic.

Antidiarrheal activity of a novel sulfated polysaccharide from the red seaweed Gracilaria cervicornis.

ETHNOPHARMACOLOGICAL RELEVANCE: The use of marine seaweeds as a source of natural compounds with medicinal purposes is increasing in Western countries in the last decades, becoming an important alternative in the traditional medicine of many developing countries, where diarrhea still remains a severe public health problem, with high rates of mortality and morbidity. Sulfated polysaccharides (PLS) extracted from red seaweeds can exhibit therapeutic effects for the treatment of gastrointestinal disorders. Thus, the pharmacological properties of the PLS from Gracilaria cervicornis, an endemic seaweed found in the Brazilian northeast coast, was evaluated as an alternative natural medication for diarrhea. AIM OF THE STUDY: This study aimed to evaluate the antidiarrheal activity of sulfated polysaccharides (PLS) extracted from the red seaweed G. cervicornis in Swiss mice pre-treated with castor oil or cholera toxin. MATERIALS AND METHODS: The seaweed Gracilaria cervicornis was collected at Flecheiras beach (city of Trairí, State of Ceará, Brazil) and the PLS was obtained through enzymatic extraction and administered in mice (25-30 g) before diarrhea induction with castor oil or cholera toxin. For the evaluation of the total number of fecal output and diarrheal feces, the animals were placed in cages lined with adsorbent material. The evaluation of intestinal fluid accumulation (enteropooling) on castor oil-induced diarrhea in mice occurred by dissecting the small intestine and measuring its volume. The determination of Na+/K+-ATPase activity was measured in the small intestine supernatants by colorimetry, using commercial biochemistry kits. The gastrointestinal motility was evaluated utilizing an activated charcoal as a food tracer. The intestinal fluid secretion and chloride ion concentration were evaluated in intestinal closed loops in mice with cholera toxin-induced secretory diarrhea. The binding ability of PLS with GM1 and/or cholera toxin was evaluated by an Enzyme-Linked Immunosorbent Assay (ELISA). RESULTS: The G. cervicornis PLS showed antidiarrheal effects in both acute and secretory diarrhea, reducing the total number of fecal output, diarrheic stools, intestinal fluid accumulation, and increasing small intestine Na+/K+-ATPase activity on castor oil-induced diarrhea. However, the PLS did not affect gastrointestinal motility, indicating that this compound has a different action mechanism than loperamide. In secretory diarrhea, the PLS decreased intestinal fluid secretion and small intestine chloride excretion, binding with GM1 and/or cholera toxin and blocking their attachment to the enterocyte cell surface. CONCLUSIONS: In conclusion, PLS has a significant antidiarrheal effect in acute and secretory diarrhea. Further investigation is needed towards its use as a natural medicine to treat diarrhea.