From Tonic-cups to Bitter-cups: Kwasi bita beker from Suriname Determination, past and present use of an ancient galenic artefact

In the main markets of Paramaribo (Suriname), many stands offer what is locally called "Bitter-cups", or "Kwasi bita beker", small footed-cups, roughly carved from a whitish wood. The use of these cups is strictly medicinal and it seems to be restricted to Suriname, as they are not found in neighbouring countries (Guyana, French Guiana). The aim of this study was to identify the botanical origin of Bitter-cups still in use in the Saramaka traditional medicine (as information from field people was controversial), and document the ethnopharmacology of this original galenical artefact. Microscopic and high performance liquid chromatography (HPLC) analyses were carried out on Bitter-cup, and anatomical criteria (marginal parenchyma band, size of intervessel and vessel-ray pits, rays width and rays composition, vessels clustering, frequency and size of parenchyma pits) together with HPLC profiles of the macerates showed that the wood cup was similar to Quassia amara L. (Simaroubaceae) wood. Ethnopharmacological investigation indicates that the use of these cups is simply due to the pharmacological properties attributed to "bitters", and is strongly linked to tradition and cultural attitudes. This study also emphasizes the long lasting use of these cups, now restricted to Suriname only, with almost no variation over one century.

Simalikalactone D is responsible for the antimalarial properties of an Amazonian traditional remedy made with Quassia amara L. (Simaroubaceae)

French Guiana (North-East Amazonia) records high malaria incidence rates. The traditional antimalarial remedy most widespread there is a simple tea made out from Quassia amara L. leaves (Simaroubaceae). This herbal tea displays an excellent antimalarial activity both in vitro and in vivo. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC(50) value of 10nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro. Lastly, it inhibits 50% of Plasmodium yoelii yoelii rodent malaria parasite at 3.7 mg/kg/day in vivo by oral route. These findings confirm the traditional use of this herbal tea.

Regioselective desulfation of sulfated L-fucopyranoside by a new sulfoesterase from the marine mollusk Pecten maximus: application to the structural study of algal fucoidan (Ascophyllum nodosum)

The study of the structural bases of the biological properties of algal fucoidan (Ascophyllum nodosum) led us to look for enzymes able to modify this sulfated polysaccharide. In this context, we found a sulfoesterase activity in the digestive glands of the common marine mollusk Pecten maximus, which is active on fucoidan. This sulfoesterase activity was shown by capillary electrophoresis and 13C-1H NMR (500 MHz) analysis of the enzymatic hydrolysis of the fucoidan, of fucoidan oligosaccharides and of sulfated fucose isomers. We report the exhaustive list of all proton and carbon chemical shifts for each of the three isomers of sulfated-l-fucose (including of their alpha/beta anomers), i.e. the 2-O-, 3-O- and 4-O-sulfated fucose, which have been useful reference values for the assignments of NMR spectra of fucoidan oligosaccharides upon enzymatic desulfation. Our results demonstrated a high regioselectivity for this sulfoesterase, which hydrolyzes only the sulfate group at the 2-O position of the fucopyranoside. Therefore, this sulfoesterase is a helpful tool in the structure-activity study of the fucoidan, as the literature data suggest that the 2-O-sulfation level play a central role in the biological properties of the polysaccharide.

Characterization, chemical modifications and in vitro anticoagulant properties of an exopolysaccharide produced by Alteromonas infernus

A new low-molecular-weight 'heparin-like' component was obtained from an exopolysaccharide produced by a mesophilic strain found in deep-sea hydrothermal vents. Data concerning the structure of the native high-molecular-weight exopolysaccharide (10(6) g/mol, 10% sulfate content) are reported for the first time. Two depolymerization processes were used to obtain low-molecular-weight (24-35x10(3) g/mol) oversulfated fractions (sulfate content 20 or 40%). Nuclear magnetic resonance studies indicated that after sulfation (40%), the low-molecular-weight fraction obtained by free radical depolymerization was less sulfated in the 6-O-position than the fraction depolymerized by acid hydrolysis. The free radical depolymerized product also had sulfated residues in the 4-O-position and disulfated ones in the 2,3-O-positions. Moreover, the compounds generated by the free radical process were more homogeneous with respect to molecular mass. Also for the first time, the anticoagulant activity of the low-molecular-weight exopolysaccharide fractions is reported. When the fractions obtained after sulfation and depolymerization were compared with heparins, anticoagulant activity was detected in oversulfated fractions, but not in native exopolysaccharide. The free radical depolymerized fraction inhibited thrombin generation in both contact-activated and thromboplastin-activated plasma, showing a prolonged lag phase only in the contact-activated assay. Affinity co-electrophoresis studies suggested that a single population of polysaccharide chains binds to antithrombin and that only a subpopulation strongly interacts with heparin cofactor II.

A disaccharide repeat unit is the major structure in fucoidans from two species of brown algae

The predominant repeating structure of a fraction of the fucoidan from Ascophyllum nodosum prepared by acid hydrolysis and centrifugal partition chromatography (LMWF) was established as: [-->3)-alpha-L-Fuc(2SO3-)-(1-->4)-alpha-L-Fuc(2,3diSO3-)-(1]n by NMR spectroscopy and methylation analysis. The proton and carbon NMR spectra of this unit have been assigned and found to correspond with features in the spectra of the whole purified fucan from A. nodosum which account for most of the integrated intensity. The same structure has also been recognised in the fucoidan of Fucus vesiculosus. The fraction LMWF has in vitro anticoagulant activity, indicating that the above structure may be partly responsible for biological activity in the native fucoidan.

Determination of cadmium partitioning in microalgae and oysters: contribution to the assessment of trophic transfer

Alternative methodologies have been applied to the study of cadmium transfer in a food chain: water, microalgae (Skeletonema costatum and Tetraselmis suecica), oysters (Crassostrea gigas). The potential bioavailability of Cd in organisms was assessed through partitioning at the cell or tissue levels, and the predictive value of this method was evaluated by determining directly the metal transfer in an experimental food chain model. Cd concentrations were lower in S. costatum than T. suecica, in controls as well as in contaminated algae. In both algal species, Cd was firmly bound to the cell wall or had entered the cell. Cytosolic Cd was bound to intracellular ligands, the biochemical characteristics of which were not consistent with the hypothesis of detoxification via phytochelatins. In both algal species, Cd was predominantly present in the insoluble fraction, but at pHs such as those existing in the digestive tract of bivalves, it was easily extracted from the cells. Thus, exposure to Cd through phytoplanktonic food induced a significant uptake of this metal in soft tissues of bivalves. Due to the difference in Cd accumulation in algae, Cd doses associated with S. costatum were lower than those bound to T. suecica. Moreover, oysters retained a lower percentage of the metal associated with S. costatum compared to T. suecica (9 and 20%, respectively, after 21 days of exposure). Cd doses potentially available to oysters exposed directly in sea water were considerably higher, and direct uptake induced the highest levels of Cd incorporation but only 2% of dissolved Cd was actually retained by oysters over 21 days of exposure. In the soft tissues of oysters, Cd was distributed equally between soluble and insoluble fractions. Cytosolic Cd was present predominantly in the heat-stable fraction and mainly bound to compounds of molecular weight equal to 13.5 kDa. Moreover, a positive correlation was observed between metallothionein-like protein (MTLP) levels and gross concentrations of Cd in the soft tissues of oysters. These data are consistent with the hypothesis of an important role of metallothioneins in Cd metabolism in oysters and suggest a potential availability of MT-bound fraction of Cd to the consumers. These data are in agreement with the response of oysters exposed to Cd in the field.

Improvement purification of sulfated oligofucan by ion-exchange displacement centrifugal partition chromatography

Centrifugal partition chromatography in ion-exchange displacement mode was used to fractionate mixtures of sulfated oligofucans obtained by partial depolymerization of brown seaweed fucoidans. Diluted (10%, v/v) protonated LA2 (a lipophilic secondary amine) is used as a weak exchanger. In an attempt to improve this method, several solvents (methyl isobutyl ketone, methyl tert.-butyl ether, BuOH) were tested to dissolve LA2H+. MtBE produced less bleeding than MiBK, whereas BuOH proved unsuitable. The sample injected needs to be highly diluted in water to ensure participation in the chromatographic process. A comparison of data (NMR, composition, molecular mass) indicated the homogeneity of the fractions obtained as well as the differences between them.

Further data on the structure of brown seaweed fucans: relationships with anticoagulant activity

The composition, molecular weight (MW), anticoagulant activity and nuclear magnetic resonance spectra of various low-molecular-weight fucans (LMWFs) obtained by partial hydrolysis or radical depolymerization of a crude fucoidan extracted from the brown seaweed Ascophyllum nodosum are compared. Fucose units were found mainly sulfated at O-2, to a lesser extent at O-3, and only slightly at O-4, contrary to previously published results for fucoidans from other brown seaweeds, and fucose 2, 3-O-disulfate residues were observed for the first time. As the sulfation pattern excluded an alpha-(1-->2)-linked fucose backbone and a high proportion of alpha-(1-->4) linkages was found, it would appear that the concept of fucoidan structure needs to be revised. Anticoagulant activity is apparently related not only to MW and sulfation content, as previously determined, but also (and more precisely) to 2-O-sulfation and 2,3-O-disulfation levels.

Monitoring of labile zinc in cultures of Skeletonema costatum using a salt groundwater

Labile Zn concentration was monitored by differential pulse anodic stripping voltammetry (DPASV) throughout the exponential growth phase of the marine diatom Skeletonema costatum (Grev.) Cleve. Algal blooms were induced both under natural conditions and in laboratory experiments using a salt groundwater (salinity 33) from the Bay of Bourgneuf, northwest coast of France. Salt groundwater is a very complex medium containing high concentrations of dissolved organic matter and other trace metal adsorbents, such as phosphate, iron oxyhydroxides, and manganese and silicon oxides, which can bind metal ions, reducing their availability and toxicity to algae. Besides metal uptake by algae and complexation of Zn by algal exudates, the rapid decrease in the labile Zn concentration during the algal blooms was ascribed mainly to the adsorption or coprecipitation of Zn ion onto freshly formed iron hydroxides.

Preliminary report on fractionation of fucans by ion-exchange displacement centrifugal partition chromatography

A new method combining ion-exchange displacement chromatography with centrifugal partition chromatography (CPC) was used for the fractionation of partially depolymerized fucans (polysulphated polysaccharides). The ion-exchanger was Amberlite LA2, a high-molecular-mass liquid secondary amine miscible with most common organic solvents and immiscible with aqueous solutions. Ion-exchange displacement centrifugal partition chromatography was performed with LA2 in methyl isobutyl ketone (MiBK) as the stationary phase, water as the mobile phase, Cl- as the carrier and OH- as the displacer. A complex mixture of partially depolymerized fucans was resolved into adjacent families characterized by their peak molecular mass and polydispersity. The Dubois test (sugar) and the azur A test (SO3-) confirmed the displacement mode of the process, and size-exclusion chromatographic controls confirmed its efficiency.