Structural characterization of anticoagulant and antithrombotic polysaccharides isolated from Caesalpinia ferrea stem barks.

This study aimed to isolate, characterize chemical-structurally and evaluate the effects of polysaccharides from Caesalpinia (Libidibia) ferrea stem barks in the haemostatic system. The deproteinated-polysaccharide extract (PE-Cf) after being fractionated by ion exchange chromatography-DEAE-cellulose resulted in three fractions (FI, FII, FIII) containing total carbohydrates (14.3-38%), including uronic acid (5-16%), and polyphenols (0.94-1.7 mg/g GAE). The polysaccharide fractions presented polydisperse profile in polyacrylamide gel electrophoresis (detected by Stains-All) and molecular masses (9.5 × 104 Da-1.5 × 105 Da) identified by gel permeation chromatography. FT-IR showed absorption bands (1630 cm-1, 1396-1331 cm-1), indicative of uronic acid, and a band at 1071 cm-1, typical of COO- groups of galacturonic acid. The NMR spectra of C. ferrea polysaccharides revealed a central core composed mainly by 5-linked α-Araf and minority components as α-Rhap and α-GalAp. UV spectra of fractions revealed discrete shoulders at 269-275 nm, characteristic of polyphenolic compounds. In vitro, polysaccharides inhibited the intrinsic and/or common coagulation pathway (aPTT test) (2.0-3.7 fold) and the platelet aggregation induced by 3 µM adenosine diphosphate (25-48%) and 5 µg/mL collagen (24%), but not that induced by arachidonic acid. In vivo, the polysaccharides inhibited (36-69%) venous thrombosis induced by hypercoagulability and stasis, showing discrete hemorrhagic effect. In conclusion, the polysaccharides of C. ferrea barks, containing arabinose, galactose, rhamnose and uronic acid, possess anticoagulant, antiplatelet and antithrombotic properties of low hemorrhagic risk, suggesting potential applicability in thromboembolic disorders.

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.