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The selective HNO3 nitration of di-n-octylcrown-6 calix[4]arene using different conditions, studied with LC–MS and NMR (1H and 13C) spectroscopic techniques, lead to the identification of most of the expected nitro derivative isomeric compounds. The formation of these isomers under acidic and radiolytic conditions is discussed with the help of molecular modelling.Key words: calix crown compounds, nitration of calixarenes, NMR of isomeric nitrocalixarenes, LC-ESI-MS.

Crocin-a water soluble carotenoid-is found in the fruits of gardenia (Gardenia jasminoides Ellis) and in the stigmas of saffron (Crocus sativus Linne). For crocin purification, gardenia fruits are extracted with 50% acetone, followed by ether washing, ion exchange, and separation by preparative HPLC. Purified crocin with purity of >99.6% has an antioxidative activity at concentrations up to 40 ppm. At 20 ppm the antioxidative activity of crocin is comparable to that of BHA. The antioxidant property of crocin as evaluated by the thiocyanate method was better than with the thiobarbituric acid method. The adduct between the linoleic acid radical and crocin was detected by LC-MS. When crocin reacted with oxygen in the presence of FeSO(4), intermediates such as monohydroperoxides and dihydroperoxides of crocin were formed and detected by LC-MS.

Two novel compounds, celastroidine A (1) and B (2), were isolated from the roots of Hippocratea celastroides K. Their structures were elucidated by spectroscopical and X-ray diffraction studies. Celastroidine A (1) (C50H74O5) was identified as a Diels-Alder adduct of a triterpene plus a diterpene and celastroidine B (2) as a beyerane, a type of dimer of two diterpene (C40H60O4). Both compounds could be formed in vivo by a Diels-Alder reaction. Celastroidine A showed some antifeeding activity against the stored grain insect Sitophyllus zeamays.Key words: Hippocratea celastroides, Hippocrataceae, roots, Diels-Alder adducts, diterpenoids, triterpenoids, x-ray diffraction, insect antifeedants, stored grain insects, Sitophyllus zeamays, insecticidal plants, Diels-Alderase.

In this paper we report the synthesis and spectral analysis of new heterocyclic derivatives of 4-aryl thieno[3,2-c]pyridines. These functionalized compounds were obtained from heteroaromatic aldehyde derivative and a cyclisation via tandem aza–Wittig iminophosphorane reactions sequence. The assignment of the structures and conformation of the different derivatives were achieved using 1D and 2D NMR (NOESY, DEPT, HMQC and HMBC).

The revision of trinervinol (1) structure, a tricyclic diterpene isolated from Piqueria trinervia cav., led to the modification of the double bond position as well as to the inversion of configuration at glycol and possible hydroxymethylene moieties bearing asymetric carbons. the study was done using 1D and 2D high-resolution NMR.

X-ray structure analysis is discussed in order to probe the information about the conformational behaviour of compound 1.

The conformation of 1-phenyl-1-(1,2-dimethyl-5-pyrrolyl)-2-(2-methyl-5-benzoyl-1-pyrroly)ethanol, with characteristics of a molecular propeller, is stabilized by intramolecular hydrogen bonding as detected by 1H NMR, NOE difference experiments, 2D NMR, COSY, 13C NMR, HETCOR, HMBC and 1H NMR variable-temperature experiments.

High-field 2D NMR studies were performed on nine neo-clerodane diterpenoids. Unambiguous assignments of the 13 C signals and proton chemical shifts were achieved which led to the revision of some previous assignments

International audience; AIMS: To evaluate the immunosuppressive properties of the exopolysaccharide (EPS) from high-EPS producer Lactobacillus rhamnosus RW-9595M on inflammatory cytokines produced by macrophages. METHODS AND RESULTS: The conditioned media (CM) were produced by macrophages treated with parental Lact. rhamnosus ATCC 9595 and its isogenic variant, the high-EPS producer Lact. rhamnosus RW-9595M, and the levels of TNF-alpha, IL-6, IL-10 and IL-12 were evaluated. Results revealed that CM from parental Lact. rhamnosus induced higher levels of TNF-alpha, IL-6 and IL-12 but inhibited IL-10 production, whereas its mucous variant induced low or no TNF-alpha and IL-6. Addition of purified EPS to macrophages treated with parental Lact. rhamnosus decreased the inflammatory cytokines and inhibited the metabolic activity of lymphocytes. The intermediate polysaccharide chains (16-30 units) produced by time-controlled hydrolysis of EPS increased the IL-10 produced by macrophages. CONCLUSIONS: Polysaccharide chains of EPS induced immunosuppression by the production of macrophagic anti-inflammatory IL-10. SIGNIFICANCE AND IMPACT OF THE STUDY: These results indicate that the EPS from Lact. rhamnosus RW-9595M may be useful as a new immunosuppressive product in dairy food.

In the present study, analysis of 2H NMR line-shape and spin-lattice relaxation behavior has been used to investigate the dynamics of several glycolipid and phospholipid bilayers. The gel-phase spectra of these lipids labeled at the C3 position of the glycerol backbone are broad (approximately 90 kHz) and characteristic of fast-limit axially asymmetric motion. Moreover, anisotropic spin-lattice relaxation is observed in all of these systems. The line-shape and relaxation features of the lipids in the gel phase were best simulated by using a fast-limit three-site jump model, with relative site populations of 0.46, 0.34, and 0.20. This motion is associated with an internal jump about the C2-C3 bond of the glycerol backbone. A second motion, rotation about the long axis of the molecule, is needed to account for the observed temperature dependence of the quadrupolar echo amplitude and the spectral line shape above and below the gel to liquid-crystalline phase transition temperature. On the other hand, the gel-phase spectra of phospholipids labeled at the C2 position of the glycerol backbone are also characterized by a fast internal motion, which is simulated by a two-site librational jump. The results indicate that the glycerol backbone dynamics of the glycolipid and phospholipid systems investigatedmore » in this study can be described in terms of common fast internal motions and a slower whole molecule axial motion. These results are compared with previous dynamic studies of similar systems.« less

Selective isolation and HPLC–AAS protocols were developed to determine free selenomethionine (SeMet) in complex matrices such as nutritional supplements and mixtures of free amino acids. The selenoamino acid in alkaline solution was first derivatized with 1-fluoro-2,4-dinitrobenzene (FDNB, Sanger's reagent). After removal of excess of reagent by partitioning with diethyl ether, the N-dinitrophenyl (DNP)-derivatized SeMet was protonated by acidification and extracted with diethyl ether. DNP-SeMet was determined selectively by HPLC–thermochemical hydride generation (THG) AAS. A selective chromatographic mechanism based on π-electron interactions was optimized using a silica stationary phase derivatized with p-nitrophenyl moieties. Primary analytical validation parameters including stability, linearity and limit of detection were obtained using a purified DNP-SeMet standard which was characterized by 1H/13C/77Se NMR and fast atom bombardment MS techniques. The calibration graphs for sequential dilutions of this standard were linear (average r= 0.997) and the limit of detection from the resultant calibration graphs was estimated to be 17 ng as Se or 81 ng as DNP-SeMet. The standard was found to decompose slowly (0.08% h–1) via photolytic cleavage of a Se—C bond. MS and HPLC–THG-AAS studies demonstrated that the cleavage intermediates (CH3Se·) combined to form dimethyl diselenide. Ascorbic acid present in large amounts in nutritional supplements was revealed to be the major interferent during the DNP derivatization step. This interference was removed using a cation-exchange treatment of the crude extract prior to derivatization. The recovery of the SeMet from stock solutions and nutritional supplements was virtually quantitative (99 ± 4.5%). In the presence of a 500-fold excess of other amino acids, this recovery decreased (95 ± 2.6%), but remained in an acceptable range to allow the accurate determination of SeMet in a protein hydrolysate.