Characterisation and quantification of flavonoids in Iris germanica L. and Iris pallida Lam. resinoids from Morocco.

INTRODUCTION: Iris resinoid obtained from Iris germanica or Iris pallida rhizomes is widely used in the perfume industry but its chemical composition has not yet been reported. Nevertheless, very active compounds have been identified in iris rhizomes including iridals and isoflavones. OBJECTIVE: In this first study concerning iris resinoid composition, flavonoids were qualitatively and quantitatively investigated in I. germanica and I. pallida resinoids. METHODOLOGY: Resinoids were first fractionated by reverse-phase flash chromatography in order to obtain fractions containing all isoflavones. These fractions were analysed by HPLC-DAD (diode array detector) and the fractions containing isoflavones were analysed by HPLC-QTOF (quadrupole time of flight)-MS. Then, the main isoflavones were isolated and identified by NMR and high-resolution mass spectroscopy (HRMS). Finally, total and individual isoflavones were quantified by HPLC-DAD at 265 nm using an external calibration method with irigenin as the external standard. RESULTS: Eight isoflavones were identified in both resinoids (irigenin, iristectorigenin A, nigricin, nigricanin, irisflorentin, iriskumaonin methyl ether, irilone, iriflogenin), one isoflavone only was identified in I. germanica resinoid (irisolidone), whereas one isoflavone (8-hydroxyirigenin), one isoflavanone (2,3-dihydroirigenin) and one benzophenone (2,6,4'-trihydroxy-4-methoxybenzophenone) only were identified in I. pallida resinoid. Isoflavones were quantified in I. germanica and I. pallida resinoids at 180 ± 1.6 mg/g and 120 ± 3.3 mg/g respectively. CONCLUSION: The study shows that I. germanica and I. pallida resinoids are rich in flavonoids and that these two Iris species can be distinguished by simply analysing the polyphenol fraction.

Viral degradation of marine bacterial exopolysaccharides.

The identification of the mechanisms by which marine dissolved organic matter (DOM) is produced and regenerated is critical to develop robust prediction of ocean carbon cycling. Polysaccharides represent one of the main constituents of marine DOM and their degradation is mainly attributed to polysaccharidases derived from bacteria. Here, we report that marine viruses can depolymerize the exopolysaccharides (EPS) excreted by their hosts using five bacteriophages that infect the notable EPS producer, Cobetia marina DSMZ 4741. Degradation monitorings as assessed by gel electrophoresis and size exclusion chromatography showed that four out of five phages carry structural enzymes that depolymerize purified solution of Cobetia marina EPS. The depolymerization patterns suggest that these putative polysaccharidases are constitutive, endo-acting and functionally diverse. Viral adsorption kinetics indicate that the presence of these enzymes provides a significant advantage for phages to adsorb onto their hosts upon intense EPS production conditions. The experimental demonstration that marine phages can display polysaccharidases active on bacterial EPS lead us to question whether viruses could also contribute to the degradation of marine DOM and modify its bioavailability. Considering the prominence of phages in the ocean, such studies may unveil an important microbial process that affects the marine carbon cycle.

Production in vitro, on different solid culture media, of two distinct exopolysaccharides by a mucoid clinical strain of Burkholderia cepacia.

The production of exopolysaccharides (EPSs) by a mucoid clinical isolate of Burkholderia cepacia involved in infections in cystic fibrosis patients, was studied. Depending on the growth conditions, this strain was able to produce two different EPS, namely PS-I and PS-II, either alone or together. PS-I is composed of equimolar amounts of glucose and galactose with pyruvate as substituent, and was produced on all media tested. PS-II is constituted of rhamnose, mannose, galactose, glucose and glucuronic acid in the ratio 1:1:3:1:1, with acetate as substituent, and was produced on either complex or minimal media with high-salt concentrations (0.3 or 0.5 M NaCl). Although this behavior is strain-specific, and not cepacia-specific, the stimulation of production of PS-II in conditions that mimic those encountered by B. cepacia in the respiratory track of cystic fibrosis patients, suggests a putative role of this EPS in a pathologic context.

Exopolysaccharide production by mucoid and non-mucoid strains of Burkholderia cepacia.

Thirteen strains of Burkholderia cepacia from various origins with mucoid and non-mucoid phenotypes were assayed for exopolysaccharide (EPS) production. The EPS were characterized by glycosyl composition analysis and examination of the products resulting from lithium-ethylenediamine and Smith degradations. The results showed that all strains, including the non-mucoid strains, were able to produce EPS exhibiting the same structural features, i.e. presence of one rhamnosyl, three galactosyl, one mannosyl, one glucosyl and one glucuronosyl residues, suggesting that this EPS is representative of the B. cepacia species.

Structural studies of the acidic exopolysaccharide produced by a mucoid strain of Burkholderia cepacia, isolated from cystic fibrosis.

The acidic exopolysaccharide produced by a mucoid strain of Burkholderia cepacia isolated from a cystic fibrosis patient, was purified by cetyltrimethylammonium bromide precipitation and/or anion-exchange chromatography. Based on the sugar composition and permethylation analyses, supported by GLC-MS and NMR spectroscopy analyses, the repeating-unit of the polysaccharide was established as -->3)-beta-D-Glcp-(1-->3)-[4,6-O-(1-carboxyethylidene)]-alpha-D-Gal p-(1-->.

Evaluation of toxicological effects induced by tributyltin in clam Ruditapes decussatus using high-resolution magic angle spinning nuclear magnetic resonance spectroscopy: Study of metabolic responses in heart tissue and detection of a novel metabolite.

Tributyltin (TBT) is a highly toxic pollutant present in many aquatic ecosystems. Its toxicity in mollusks strongly affects their performance and survival. The main purpose of this study was to elucidate the mechanisms of TBT toxicity in clam Ruditapes decussatus by evaluating the metabolic responses of heart tissues, using high-resolution magic angle-spinning nuclear magnetic resonance (HRMAS NMR), after exposure to TBT (10-9, 10-6 and 10-4 M) during 24 h and 72 h. Results show that responses of clam heart tissue to TBT exposure are not dose dependent. Metabolic profile analyses indicated that TBT 10-6 M, contrary to the two other doses tested, led to a significant depletion of taurine and betaine. Glycine levels decreased in all clam groups treated with the organotin. It is suggested that TBT abolished the cytoprotective effect of taurine, betaine and glycine thereby inducing cardiomyopathie. Moreover, results also showed that TBT induced increase in the level of alanine and succinate suggesting the occurrence of anaerobiosis particularly in clam group exposed to the highest dose of TBT. Taken together, these results demonstrate that TBT is a potential toxin with a variety of deleterious effects on clam and this organotin may affect different pathways depending to the used dose. The main finding of this study was the appearance of an original metabolite after TBT treatment likely N-glycine-N'-alanine. It is the first time that this molecule has been identified as a natural compound. Its exact role is unknown and remains to be elucidated. We suppose that its formation could play an important role in clam defense response by attenuating Ca2+ dependent cell death induced by TBT. Therefore this compound could be a promising biomarker for TBT exposure.

HRMAS NMR as a tool to study metabolic responses in heart clam Ruditapes decussatus exposed to Roundup®.

The essence of this study was to investigate the metabolic responses of heart tissues of carpet-shell clam Ruditapes decussatus after exposure to two doses (0.2 and 1 g/L) of Roundup(®) during 24 and 72 h. The main metabolic changes after Roundup(®) exposure were related to disturbance in energy metabolism and metabolic biomarkers such as alanine, succinate, acetate and propionate, suggesting the occcurence of anaerobiosis and the impairment of oxydative metabolism. Results showed also that peak intensities of amino acids used as biomarker of anaerobiosis in molluscs are time and dose dependent. In the opposite, phosphoarginine and ATP level are dependent to Roundup(®) concentration rather than to the time of exposure. We suggest that changes in energy demands require adjustements in the forward arginine kinase reaction rate. Therefore, the results demonstrate the high applicability of HRMAS NMR to elucidate the mechanism of toxicity of Roundup(®). In addition, (31)P HRMAS NMR appeared to be an effective and simple method to follow bioaccumulation of Roundup(®) formulation.

Structural data on a bacterial exopolysaccharide produced by a deep-sea Alteromonas macleodii strain.

Some marine bacteria collected around deep-sea hydrothermal vents are able to produce, in laboratory conditions, complex and innovative exopolysaccharides. In a previous study, the mesophilic strain Alteromonas macleodii subsp. fijiensis biovar deepsane was collected on the East Pacific Rise at 2600 m depth. It was isolated from a polychaete annelid Alvinella pompejana and is able to synthesise and excrete the exopolysaccharide deepsane. Biological activities have been screened and some protective properties have been established. Deepsane is commercially available in cosmetics under the name of Abyssine(®) for soothing and reducing irritation of sensitive skin against chemical, mechanical and UVB aggression. This study presents structural data for this original and complex bacterial exopolysaccharide and highlights some structural similarities with other known EPS produced by marine Alteromonas strains.

Structural elucidation of two polysaccharides present in the lipopolysaccharide of a clinical isolate of Burkholderia cepacia.

Based on the sugar composition, methylation analyses and Smith degradation, supported by NMR spectroscopic analyses and fast-atom-bombardment MS experiments, the lipopolysaccharide produced by a clinical isolate of Burkholderia cepacia was shown to contain two distinct polymers, both with linear trisaccharide repeating units; a major, containing D-rhamnose and D-galactose residues (2:1) with the structure -->3)-alpha-D-Rhap(1-->3)-alpha-D-Rhap(1-->4)-alpha-D-Galp(1 --> (major), and a minor repeating unit, constituted by D-rhamnosyl residues, with the structure -->3)-alpha-D-Rhap(1-->3)-alpha-D-Rhap(1-->2)-alpha-D-Rha p(1--> (minor).

Structural elucidation of a novel exopolysaccharide produced by a mucoid clinical isolate of Burkholderia cepacia. Characterization of a trisubstituted glucuronic acid residue in a heptasaccharide repeating unit.

The structure of the exopolysaccharide (EPS) produced by a clinical isolate of Burkholderia cepacia isolated from a patient with fibrocystic lung disease has been investigated. By means of methylation analyses, carboxyl reduction, partial depolymerization by fuming HCl and chemical degradations such as Smith degradation, lithiumethylenediamine degradation and beta-elimination, supported by GC/MS and NMR spectroscopic analyses, the repeat unit of the EPS has been identified and was shown to correspond to the acidic branched heptasaccharide with the following structure: [formula: see text]. This partially acetylated acidic polymer, distinguished by the presence of the less usual D-isomer of rhamnose and of a trisubstituted glucuronic acid residue, could represent the main EPS produced by this bacterial species.