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Food structure is an important factor in the nutritional quality of foods. With regard to dietary protein, it may have an impact on protein digestibility, proteolysis kinetics, gastric emptying and amino acid bioavailability, all with potential metabolic consequences. Egg white is an appropriate food model to investigate these issues, since very different structures and textures can be produced while keeping the chemical composition constant. Recently, we established that protein matrix structure impacts the extent of proteolysis and the nature ofthe peptides generated during in vitro digestion of egg white protein aggregates and gels. Our question here is “do such differences also exist in vivo, and do they have any biological consequences?” To address these questions, a smooth-rigid egg white gel, a granular-spongy gel and an intermediate gel were prepared. Each gel was fed to pigs (n=33) as a single meal, and gastric chyme samples were collected over a 6h-postprandial period in order to measure pH, proteolysis and particle size along digestion at 10 different stomach locations. Blood samples were also collected for plasma amino acid analyses.Acidification of the chyme started in the pylorus regin regardless of the type of gel, but acidification kinetics depended on the gel type, which suggested that gel structure impacts on HCl distribution in the chyme. In contrast, proteolysis commenced in the proximal region, consistent with the location of pepsinogen secretory cells. But from 1h-postprandial, proteolysis profiles greatly differed depending on the gels: the higher proteolysis was 2 observed in the pyloric region for the granular-spongy gel (acidity and proteolysis gradients were consistent), while maximum proteolysis was observed in the proximal region for the smooth-rigid and intermediate gels (acidity and proteolysis gradients were opposite), suggesting that pepsin diffusion profiles depend on the type of gel. Proteolysis kinetics weremore rapid with granular-spongy gel than with intermediate gel, while the smooth-rigid gel was the most resistant to proteolysis, which was consistent with the particle size observed during digestion. Finally, amino acid absorption was faster for the granular-spongy gel than for the two other gels.

Xanthomonas citri pv. citri is the pathogen responsible for the Asiatic citrus canker, one of the most serious diseases of citrus worldwide. The lipopolysaccharide (LPS) molecule was demonstrated to be involved in X. citri pv. citri virulence. Despite the enormous progress made in the investigation of molecular mechanisms responsible for bacterial pathogenicity, the determination of the detailed LPS structure-activity relationship still remains limited as the current knowledge is mainly based on structural determination of one X. citri pv. citri strain. Since X. citri pv. citri strains were distinguished into three main pathogenicity groups, we characterized the full structure of the LPS from two pathotypes differing in their host range specificity, revealing an intriguing different LPS O-chain structure. We also tested the LPSs and the isolated lipid A moieties for their capability to act as Microbe-Associated Molecular Patterns in Arabidopsis thaliana. We demonstrated that both LPS/lipid As were able to induce ROS accumulation but no differences were observed among the two pathotypes.

Novel fibers containing different ratios of PVA and d-limonene were fabricated using electrospinning for antibacterial active packaging applications. The PVA/d-limonene fibers were thoroughly characterized using a scanning electron microscope, fourier-transform infrared spectrometry, thermal gravimetry, differential scanning calorimetry, tensile tests, and oxygen permeability tests. The results of these analyses showed that the highest tensile strength and elongation at break values of 3.87 &plusmn, 0.25 MPa and 55.62 &plusmn, 2.93%, respectively, were achieved for a PVA/d-limonene ratio of 7:3 (v/v) and an ultrasonication time of 15 min during processing. This material also showed the lowest oxygen permeation and the best degradability and bacteriostatic properties of all samples.

International audience

Albicidin is produced by the sugarcane pathogenic bacterium Xanthomonas albilineans and is a potent antibiotic specifically targeting the bacterial DNA gyrase with an IC50 value in the nanomolar range. The structure of albicidin, which has remained unsolved for more than three decades since its first description, has been solved by a combination of extensive NMR and HR-MS/MS experiments. An inherent problem for the structure elucidation was the low amount of the albicidin production in cell culture. The low production forced us to cultivate several hundred liters in order to purify a few milligrams required for NMR experiments. In comparison, LC-HR-MS/MS has the great advantage of several orders of magnitude and high sensitivity. Thus, this approach requires much less material. But more importantly, purification of compounds is not necessary for structural analysis. Due to the application of targeted LC-MS/MS experiments, we were able to propose the structure of N-terminal carba- S158 moylated and b-methoxylated albicidin derivatives. Both of them are currently chemically synthesized and studied in a medicinal chemistry campaign. In order to search for more pharmaceutically relevant albicidin derivatives, we applied non-targeted LC-HR-MS/MS approaches combined with mass spectral networking, a recently introduced approach for non-targeted MS/MS data-analysis. However, as for the structural elucidation of albicidin, the even lower concentrated derivatives resulted in difficulties to obtain useful MS/ MS spectra. Since we typically operate the mass spectrometer in data-dependent acquisition mode (DDA), it inherently selects high abundant compounds of cell extracts for MS/ MS scans and possibly ignore low abundant compounds. The same goes for the network analysis which is based on similarity of MS/MS spectra and may not take potential ion species into account. To overcome this problem, we implemented a bioactivity-guided fractionation by solid phase extraction and semi-preparative HPLC. Fractions with antibacterial activity were subsequently submitted to several LC-MS/MS runs in DDA mode with shifted survey scan windows (stitched DDA). Besides the increased amount of MS/MS events per mass range, narrowing down the m/z range of the survey scan also increased the dynamic range of the orbitrap analyzer, which enabled us to significantly increase the method's sensitivity. Finally, we were able to detect a whole series of new albicidin derivatives and to propose their structures based on exact mass determination and MS/MS fragmentation patterns. These new compounds provide great opportunities in lead optimization of albicidin as a new anti-infective drug. Apart from the pharmaceutical relevance, some of the identified by-products give us important insights into the formation of albicidin and its intriguing biosynthetic machinery.

The pks genomic island of Escherichia coli encodes polyketide (PK) and nonribosomal peptide (NRP) synthases that allow assembly of a putative hybrid PK-NRP compound named colibactin that induces DNA double-strand breaks in eukaryotic cells. The pks-encoded machinery harbors an atypical essential protein, ClbP. ClbP crystal structure and mutagenesis experiments revealed a serine-active site and original structural features compatible with peptidase activity, which was detected by biochemical assays. Ten ClbP homologs were identified in silico in NRP genomic islands of closely and distantly related bacterial species. All tested ClbP homologs were able to complement a clbP-deficient E. coli mutant. ClbP is therefore a prototype of a new subfamily of extracytoplasmic peptidases probably involved in the maturation of NRP compounds. Such peptidases will be powerful tools for the manipulation of NRP biosynthetic pathways.

Fractionation of dichloromethane extracts from the leaves of Piper heterophyllum and P. aduncum afforded three prenylated hydroxybenzoic acids, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid, 3-[(2E,6E,10E)-11-carboxy-13-hydroxy-3,7,15-trimethyl-2,6,10,14-hexadecatetraenyl]-4,5-dihydroxybenzoic acid and 3-[(2E,6E,10E)-11-carboxy-14-hydroxy-3,7,15-trimethyl-2,6,10,15-hexadecatetraenyl]-4,5-dihydroxybenzoic acid, along with the known compounds, 4,5-dihydroxy-3-(E,E,E-11-formyl-3,7,15-trimethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid (arieianal), 3,4-dihydroxy-5-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 4-hydroxy-3-(E,E,E-3,7,11,15-tetramethyl-hexadeca-2,6,10,14-tetraenyl)benzoic acid, 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid, 4-hydroxy-3-(3,7-dimethyl-2,6-octadienyl)benzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid. Their structures were elucidated on the basis of spectroscopic data, including homo- and heteronuclear correlation NMR experiments (COSY, HSQC and HMBC) and comparison with data reported in the literature. Riguera ester reactions and optical rotation measurements established the compounds as racemates. The antiparasitic activity of the compounds were tested against three strains of Leishmania spp., Trypanosoma cruzi and Plasmodium falciparum. The results showed that 3-(3,7-dimethyl-2,6-octadienyl)-4-methoxy-benzoic acid exhibited potent and selective activity against L. braziliensis (IC(50) 6.5 microg/ml), higher that pentamidine used as control. Moreover, 3-[(2E,6E,10E)-11-carboxy-3,7,15-trimethyl- 2,6,10,14-hexadecatetraenyl)-4,5-dihydroxybenzoic acid and 4-hydroxy-3-(3-methyl-1-oxo-2-butenyl)-5-(3-methyl-2-butenyl)benzoic acid showed moderate antiplasmodial (IC(50) 3.2 microg/ml) and trypanocidal (16.5 microg/ml) activities, respectively.

Seven 2,5-diketopiperazines (DKPs) were isolated from the Fijian marine sponge Acanthella cavernosa. NMR and circular dichroism (CD) comparison with synthetic L-L DKPs allowed us to determine unambiguously the L-L absolute configuration of the natural DKPs. This work initiated the setting up of an optical properties database of natural DKPs, including specific rotation and CD. 2,5-Diketopiperazines (DKPs) are cyclic secondary metabolites directly resulted from the primary peptidic metabolites. They have been detected in beverages, foods and microorganisms. As the smallest cyclic peptides, DKPs provide interesting biological properties such as organoleptical, antitumoral, antifungal, antibacterial, antifouling and antiviral activities. 2 Many natural metabolites including alkaloids are biosynthetically derived from diketopiperazines by oxidation and rearrangement reactions. They represent an interesting tool for medicinal chemistry since their heterocyclic cores provide a good template for further chemical and stereochemical modification. Proline (Pro) and arginine (Arg) units are usually found in biologically active DKPs. Despite the increasing interest of DKPs, their stereochemical information was not well documented. DKP derivatives have attracted significant attention because of their potential rule as important class of multifunctional biomolecules. Their putative roles as signaling molecules in the chemical ecology context is more and more considered. Thus, determination of absolute configuration of cyclic dipeptides is of significant importance. As a part of our on-going research on bioactive natural compounds from Pacific Axinellidae marine sponges, a scrutinized study of secondary metabolites of a Fijian sample of the marine sponge Acanthella HETEROCYCLES, Vol. 90, No. 2, 2015 1351

Lactate is the product of fermentation of lactose in the digestive tract of milk consumers. The lactate has benef icial effect on health for the regulation of the milk protein digestion and calcium absorption. However, lactate has two stereoisomere named D and L form (for Dextrogyre and Levogyre). In dietetic, D form is not recommended because it could have negative effect on health, especially on young baby. The present study gives some preliminary results regarding the content of the D- and L-lactate in cow and camel milk. Twenty dromedary camel milk samples and 3 cow milk samples from Kazakhstan were analyzed to determine main composition, especially the lactates forms in order to compare these two species. The content of total lactate in camel milk was comparable to cow milk (1.82 – 2.49 g/l), but the quantity of L-Lactate was 100 times more in camel milk compared to cow milk - 2.21% of the total lactate vs 0.02% in camel and cow milk respectively. Further analyses are necessary to understand the role of the microflora present in each specific milk.

Albicidin is a potent DNA gyrase inhibitor produced by the sugarcane pathogenic bacterium Xanthomonas albilineans. Here we report the elucidation of the hitherto unknown structure of albicidin, revealing a unique polyaromatic oligopeptide mainly composed of p-aminobenzoic acids. In vitro studies provide further insights into the biosynthetic machinery of albicidin. These findings will enable structural investigations on the inhibition mechanism of albicidin and its assessment as a highly effective antibacterial drug.

Caffeic, ferulic, and coumaric acids were lipophilized with saturated fatty alcohols (C1?C20). The antioxidant properties of these hydroxycinnamic acids and their alkyl esters were evaluated in various assays. Furthermore, the antioxidant efficiency of the compounds was evaluated in a simple o/w microemulsion using the conjugated autoxidizable triene (CAT) assay. All evaluated phenolipids had radical scavenging, reducing power, and metal chelating properties. Only caffeic acid and caffeates were able to form a complex with iron via their catechol group in the phenolic ring. In the o/w emulsion, the medium chain phenolipids of the three homologues series were most efficient. The antioxidant properties and efficacies were dependent upon functional groups substituted to the ring structure and were in the following order: caffeic acid and caffeates > ferulic acid and ferulates > coumaric acid and coumarates. Moreover, the results demonstrated that the test system has an impact on the antioxidative properties measured.

This work, realized under the IUCr initiative, framework involves the structural study via X-ray diffraction, of some heteromolecular architectures formed by the association through non-covalent bonds, between the tris (oxalato) chromate (III) and tris (oxalato) ferrate (III) anions {[M(C2O4)3]3-, M = Cr, Fe} and the cationic complex of the 2-picolylamine (amp) and transition metal (Co2 +, Cu2 + and Mn2 +). Co2 + ion builds two-dimensional corrugated layers made of bimetallic chiral chains where the two different complex ions ([Cr(C2O4)3]3- and [Co(amp)3]3 +) are connected by hydrogen bonds. These layers, connected by weak hydrogen interactions, host between them, water molecules which build dodecameric clusters having new characteristics. The dehydrated compound has different structure and color and is able to quickly reabsorb water molecules from surrounding to regenerate the initial compound despite that it has no pores. Several cycles of this process do not seriously affect the crystalline quality of this compound. The compound obtained with the Cu2 + ion also has a two-dimensional framework. Their layers are formed between the dimeric cation [Cu2 (amp) 4Cl]3 + and the anion {[M(C2O4)3]3-,M = Cr, Fe}. Both compounds are iso-structural; their frameworks are formed via [pi] - - - [pi] interactions and build 1D channels which contain water molecules forming hexameric clusters. The compound undergoes a phase transition between 100 K and the dehydration temperature (341K). During this dehydration, a loss of symmetry of the compound is recorded and rehydration process is more difficult than for cobalt(III)-framework. The use of Mn2+ ions does not give the expected architecture but a new coordination polymer; Ce travail réalisé dans le cadre de l’initiative africaine de l’IUCr porte sur l’étude structurale par diffraction des rayons X de quelques architectures élaborées par association, via des interactions faibles, des anions {[M(C2O4)3]3-,M = Cr, Fe} et des cations complexes à base de la 2-picolylamine (amp) métaux de transition (Co2+, Cu2+ et Mn2+). L’architecture à base de l’ion Co2+ est bidimensionnelle et présente des feuillets ondulés constitués de chaines bimétalliques de chiralité différente où les deux ions complexes ([Cr(C2O4)3]3- et [Co(amp)3]3+ ) sont connectés par des liaisons hydrogène. Ces feuillets hébergent des molécules d’eau qui forment des clusters dodécamèriques aux caractéristiques nouvelles. Le composé déshydraté se réhydrate rapidement dans l’air ambiant et les deux états possèdent des couleurs différentes. Plusieurs cycles de déshydratation-réhydratation n’altèrent pas la qualité cristalline du composé. L’architecture à base des ions Cu2+ possède également des feuillets mais présente une ondulation plus forte que celle de l’architecture au cobalt. Ces couches sont constituées de chaines formées de cations dimériques [Cu2(amp)4Cl]3+ et d’anions {[M(C2O4)3]3-,M = Cr, Fe}. Les deux composés sont iso-structuraux et leur architecture présente des canaux monodimensionnels qui contiennent des molécules d’eau qui forment des clusters hexamèriques. Le composé subit des transitions de phase entre la basse température (100K) et la température de déshydratation (341K) avec une perte de la symétrie. Le composé se réhydrate plus difficilement que celui à base de l’ion cobalt(III). L’ion Mn2+ ne donne pas l’architecture escomptée mais un polymère de coordination nouveau

This work, realized under the IUCr initiative, framework involves the structural study via X-ray diffraction, of some heteromolecular architectures formed by the association through non-covalent bonds, between the tris (oxalato) chromate (III) and tris (oxalato) ferrate (III) anions {[M(C2O4)3]3-, M = Cr, Fe} and the cationic complex of the 2-picolylamine (amp) and transition metal (Co2 +, Cu2 + and Mn2 +). Co2 + ion builds two-dimensional corrugated layers made of bimetallic chiral chains where the two different complex ions ([Cr(C2O4)3]3- and [Co(amp)3]3 +) are connected by hydrogen bonds. These layers, connected by weak hydrogen interactions, host between them, water molecules which build dodecameric clusters having new characteristics. The dehydrated compound has different structure and color and is able to quickly reabsorb water molecules from surrounding to regenerate the initial compound despite that it has no pores. Several cycles of this process do not seriously affect the crystalline quality of this compound. The compound obtained with the Cu2 + ion also has a two-dimensional framework. Their layers are formed between the dimeric cation [Cu2 (amp) 4Cl]3 + and the anion {[M(C2O4)3]3-,M = Cr, Fe}. Both compounds are iso-structural; their frameworks are formed via [pi] - - - [pi] interactions and build 1D channels which contain water molecules forming hexameric clusters. The compound undergoes a phase transition between 100 K and the dehydration temperature (341K). During this dehydration, a loss of symmetry of the compound is recorded and rehydration process is more difficult than for cobalt(III)-framework. The use of Mn2+ ions does not give the expected architecture but a new coordination polymer, Ce travail réalisé dans le cadre de l’initiative africaine de l’IUCr porte sur l’étude structurale par diffraction des rayons X de quelques architectures élaborées par association, via des interactions faibles, des anions {[M(C2O4)3]3-,M = Cr, Fe} et des cations complexes à base de la 2-picolylamine (amp) métaux de transition (Co2+, Cu2+ et Mn2+). L’architecture à base de l’ion Co2+ est bidimensionnelle et présente des feuillets ondulés constitués de chaines bimétalliques de chiralité différente où les deux ions complexes ([Cr(C2O4)3]3- et [Co(amp)3]3+ ) sont connectés par des liaisons hydrogène. Ces feuillets hébergent des molécules d’eau qui forment des clusters dodécamèriques aux caractéristiques nouvelles. Le composé déshydraté se réhydrate rapidement dans l’air ambiant et les deux états possèdent des couleurs différentes. Plusieurs cycles de déshydratation-réhydratation n’altèrent pas la qualité cristalline du composé. L’architecture à base des ions Cu2+ possède également des feuillets mais présente une ondulation plus forte que celle de l’architecture au cobalt. Ces couches sont constituées de chaines formées de cations dimériques [Cu2(amp)4Cl]3+ et d’anions {[M(C2O4)3]3-,M = Cr, Fe}. Les deux composés sont iso-structuraux et leur architecture présente des canaux monodimensionnels qui contiennent des molécules d’eau qui forment des clusters hexamèriques. Le composé subit des transitions de phase entre la basse température (100K) et la température de déshydratation (341K) avec une perte de la symétrie. Le composé se réhydrate plus difficilement que celui à base de l’ion cobalt(III). L’ion Mn2+ ne donne pas l’architecture escomptée mais un polymère de coordination nouveau

The present invention relates to a antibiotically active compounds characterized by general formula (I), wherein X1, BB, BC, BD, BE and X2 are building blocks with D1, D2, D3, D4 or D5 being linkers which comprise carbon, sulphur, nitrogen, phosphor and/or oxygen atoms and which are covalently connecting the moities BA and BB, BB and BC, BC and BD, BD and BE and BE and BF, respectively, and wherein in particular the building block BC comprises an amino acid derivative. The invention relates further to said compounds for use in a method of treatment of diseases, in particular for use in a method of treatment of bacterial infections.

Stalked crinoids were, for a long time, known as fossils found in different quarries, and also from ocean depths since the great expeditions of the eighteenth century. The chemical analyses of fossils and also of living organisms led to the discovery of new bioactive pigments, and also confirmed that the core structures of these pigments had been preserved during the fossilization process. The existence of these quinoid pigments also leads to several interesting questions related to their stereochemistry and the photoactivation of their bioactivity.

Films were prepared by casting alkaline solutions of gliadin, a major wheat storage protein fraction. Their compositions and mechanical and surface properties were analyzed. Five polyols of the eth...

absent

International audience; : Human exposure to xenobiotics is usually estimated by indirect methods. Biological monitoring has emerged during the last decade to improve assessment of exposure. However, biomonitoring is still an analytical challenge, because the amounts of sample available are often very small yet analysis must be as thorough and sensitive as possible. The purpose of this work was to develop an untargeted "exposomics" approach by using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS), which was applied to the characterization of pesticide metabolites in urine from pregnant women from a French epidemiological cohort. An upgradable list of pesticides commonly used on different crops, with their metabolites (more than 400 substances) was produced. Raw MS data were then processed to extract signals from these substances. Metabolites were identified by tandem mass spectrometry; putative identifications were validated by comparison with standards and metabolites generated by experiments on animals. Finally, signals of identified compounds were statistically analyzed by use of multivariate methods. This enabled discrimination of exposure groups, defined by indirect methods, on the basis of four metabolites from two fungicides (azoxystrobin, fenpropimorph) used in cereal production. This original approach applied to pesticide exposure can be extended to a variety of contaminant families for upstream evaluation of exposure from food and the environment.

The synthesis of human milk fat substitutes (HMFS) which show a high degree of similarity to human milk fat (HFM) is of great interest to ensure a supply in infant nutrition with a triacylglyceride composition as close as possible to mothers milk. Biocatalyzed modifications of natural oils using microbial or plant-derived enzymes enable the production of high-value HMFS. Due to the mild reaction conditions and the exceptionally high sn-1,3-regioselectivity of these enzymes, they are preferred over chemical catalysis in the development of these lipids with desired nutritional and functional properties. In this article, research spanning over 20 years of lipase-catalysis for the production HMFS is reviewed. Specific attention is paid to the evaluation of the regiospecificity of the biocatalysts, choice of natural oils and acyl donors, production processes, purification of the HMFS, and analytical procedures for their characterization.

International audience; This work aimed to characterize the molecular structure and functional properties of starches isolated from wild Dioscorea yams grown at the Amazons, using conventional and up-to-date methodologies. Among the high purity starches isolated (>= 99%), the chain lengths were similar, whereas variations in gelatinization profile were observed. Starches have shown varied-shaped granules with monomodal distribution, and B-type crystallinity. Variations in amylose contents found by three analyses were hypothesized being related to intermediate material. Linear chain lengths were similar, and their amylopectins showed a dense, spherical conformation and similar molecular characteristics. The average molar mass and the radius of gyration of the chromatograms of the yam amylopectin, (M) over bar (W) and (R) over bar (G) were ranging between 174 x 10(6) g mol(-1) and 237 x 10(6) g mol(-1), and 201 nm and 233 nm, respectively. The white yams starches were more sensible to enzymes than the other two. All starches have shown a wide range of functional and nutritional properties. (C) 2013 Elsevier Ltd. All rights reserved.

International audience; The study of the EtOAc extract of the leaves of Dilobeia thouarsii led to the isolation and identification of seven new diprenylated dihydroxyflavonols named dilobenol A–G (1–7). Their structures were elucidated by spectroscopic analysis including UV, IR, 1D and 2D NMR and MS as well as by chemical hydrolysis. The isolated compounds were assessed for their antibacterial, antiplasmodial and cytotoxic activities. They exhibited moderate growth inhibitory activities against Staphylococcus aureus, Vibrio spp., Bacillus spp, and Plasmodium falciparum without significant toxicity against mammalian cell line L-6.

Leucascandrolide A ((+)-1), a doubly O-bridged 18-membered macrolide of a new type, i.e., showing little C1-branching vs. extensive 1,3-dioxygenation and a peculiar side chain, was isolated from a calcareous sponge of a new genus, Leucascandra caveolata BOROJEVIC and KLAUTAU from the Coral Sea. Transesterification of (+)-1 gave the methyl ester 3, derived from the side chain, and the 5-hydroxy derivative (+)-2, derived from the macrolide portion and with the natural configuration at C(5) (axial). Mosher's MTPA esters 4 and 5 obtained from (+)-2 showed scattered Δδ = (δ(S) − δ(R)) data. However, inversion of the configuration at C(5) led, via ketone (+)-6, to the less encumbered 5-equatorial hydroxy derivative (+)-7, whose MTPA esters 8 and 9 gave consistent Δδ data, allowing the assignment of the absolute configuration of (+)-7, and hence of (+)-1. The structural novelty of (+)-1 and its powerful antifungal and cytotoxic activities are likely to renew interest in calcareous sponges, previously limited to scarcely biologically active 2-aminoimidazoles.

Onchidin B (4) is a cyclic depsipeptide isolated from the pulmonate mollusc Onchidium sp. Its structure was determined by extensive 2D-NMR, FABMS, tandem FAB MS/MS, selective hydrolysis, and synthesis. It contains four α-amino acids [two units of N-methyl valine (MeVal), two units of proline (Pro)], four α-hydroxy acids [two 2-hydroxyisovaleric acids (Hiv), two 2-hydroxy-3-methylpentanoic acid moieties (Hmp)] and two units of the new β-hydroxy acid: 3-hydroxy-2-methyloct-7-ynoic acid (Hymo)]. Selective hydrolysis and direct comparison by chiral GC-MS with authentic samples of the α-amino and α-hydroxy acids allowed us the assignment of the entire absolute stereochemistry of onchidin B. In this way, the α-hydroxy acids were found to be (S)-Hiv and (S,S)-Hmp, and the α-amino acids (R)-proline, (S)-proline, and (R)-MeVal. In order to establish the absolute configuration of the new β-hydroxy acid, Hymo, its four possible stereoisomers were stereoselectively synthesized using chiral N-propionyl oxazolidinones...

From the cytotoxic extracts of the marine ascidian Leptoclinides dubius, N-(p-hydroxybenzoyl)-l-arginine (1), N-(1H-indolyl-3-carbonyl)-d-arginine (2), and N-(6-bromo-1H-indolyl-3-carbonyl)-R, where R is l-Arg (4), l-His (5), and the very rare amino acid l-enduracididine (3), have been isolated and identified by spectroscopic data, hydrolysis, and comparison with authentic samples.

Two phylogenetically and structurally unrelated families of NAD(P)-dependent aldehyde dehydrogenases (ALDH) catalyze the oxidation of aldehydes into activated or non-activated acids. These enzymes are known to be involved in many biological functions such as cellular differentiation, central metabolism, or detoxification pathways.The crystal structure of the bifunctional enzyme, 4-hydroxy-2-ketovalerate aldolase (DmpG)/acetaldehyde dehydrogenase (DpmF) from Pseudomonas sp. CF600, leads to the identification of a new ALDH family. The DmpF subunit exhibits a non-phosphorylating CoA-dependent aldehyde dehydrogenase activity while its structure belongs to the phosphorylating ALDH superfamily. The kinetics of the MhpEF orthologs from Escherichia coli and Thermomonospora curvata show that the kinetic parameters of MhpF do not depend of its oligomeric state, which is unique for an ALDH. In addition, the crystal structures of the enzyme with NAD+ or CoA, as well as the solution structure of the apoenzyme using SAXS, reveal the dynamics of the overall Rossmann fold between apo or cofactors-bound conformers, which is necessary to carry on the catalytic cycle. Finally, the catalytic mechanism and the structure of the thioacylenzyme intermediates indicate that MhpF is a hybrid between both ALDH families characterized to date, Deux familles d'aldéhyde déshydrogénases (ALDH) phylogénétiquement et structuralement distinctes catalysent l'oxydation des aldéhydes : les ALDH phosphorylantes et les ALDH non phosphorylantes. Ces enzymes jouent un rôle essentiel au niveau cellulaire en intervenant au niveau du métabolisme et dans des processus de détoxication. En 2003, la résolution de la structure tridimensionnelle de l'enzyme bifonctionnelle 4-hydroxy-2-cétovalérate aldolase/acétaldéhyde déshydrogénase (DmpFG) de Pseudomonas sp. CF600 a permis l'identification d'une nouvelle famille d'ALDH : la sous-unité DmpF étant structuralement apparentée aux ALDH phosphorylantes alors qu'elle présente une activité de type non phosphorylante CoA-dépendante. Par la caractérisation enzymatique et structurale des orthologues MhpEF issus d'Escherichia coli et de Thermomonospora curvata, nos travaux montrent que les paramètres cinétiques de MhpF ne dépendent pas de son état oligomérique, ce qui est cas unique pour les ALDH. De plus, la résolution des structures cristallographiques de l'enzyme complexée avec du NAD+ ou du CoA, couplée à la structure en solution de la forme apoenzyme obtenue par SAXS montrent que le Rossmann fold s'accomode de la présence des cofacteurs par un vaste changement conformationnel. Enfin, l'étude du mécanisme catalytique et la résolution de la structure thioacylenzyme permettent d'identifierla MhpF comme étant un hybride des deux familles d'ALDH caractérisées jusqu'à présent

Caledonin (1) is a modified peptide isolated from the marine tunicate Didemnun rodriguesi . Caledonin comprises a central L-phenylalanine residue connected via its amino group to ( S )-3-amino-5-mercaptopentanoic acid (a new sulfur-containing β-amino acid), and by its carboxyl group to a six membered cycloguanidine moiety, bearing an n -octyl chain. Caledonin is a natural bolaphile which strongly binds Zn II and Cu I ions.

International audience; Two known 13,28-epoxy-oleanane triterpene saponins (1) and (2), were isolated from the 95% ethanolic extract of the roots of Myrsine coriaceae and Myrsine andina. Their structures were deduced by combined spectral analysis and chemical evidences based on data reported in the literature. Compounds 1 and 2 were evaluated in vitro against different cellular models such as Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, six human cancer cell lines (Hs683, T98G, U251, HT29, MCF7, SKMEL28) and two murine cell lines (CT26 and B16F10). Compound 1 was found to exhibit antileishmanial activity (IC50 = 16 µg/mL) whereas compound 2 was inactive (IC50 > 50 µg/mL). Furthermore, compound 1 exhibited stronger inhibition activity on human cancer cells (IC50 = 15 µg/mL) and on murine cell lines (IC50 = 10 µg/mL) than compound 2 (IC50 > 82 and 42 µg/mL, respectively). As the only difference between 1 and 2 is due to a substitution of an aldehyde group by a hydroxymethyl moiety, these results showed the crucial role of the aldehyde function at C-30 for the cytotoxicity. In contrast, none of the tested compounds revealed activity against M. tuberculosis.; Dos saponinas triterpénicas de tipo 13,28-epoxi-oleanano (1) y (2), han sido aisladas a partir del extracto etanólico al 95% de las raíces de Myrsine coriaceae y Myrsine andina. Las estructuras fueron establecidas mediante la combinación de técnicas espectrales y evidencias químicas con datos reportados en la literatura. Los compuestos 1 y 2 fueron evaluados con ensayos biológicos in vitro frente a diferentes modelos celulares, tales como Mycobacterium tuberculosis, amastigotes axénicos de Leishmania amazonensis , macrófagos extraídos del peritoneo de ratón, seis líneas celulares de cáncer humano (Hs683, T98G, U251, HT29, MCF7, SKMEL28) y dos líneas de células murinas (CT26 y B16F10). El compuesto 1 mostró una buena actividad antileishmania (IC50 = 16 µg/mL) mientras que el compuesto 2 no mostró actividad alguna (IC50> 50 µg/mL). Por otra parte, el compuesto 1 mostró una mayor actividad de inhibición de las células cancerosas humanas (IC50 = 15 µg/mL) y en líneas celulares de ratón (IC50 = 10 µg/mL) que el compuesto 2 (IC50> 82 y 42 µg/mL, respectivamente). Como la única diferencia entre 1 y 2 se debe a una sustitución de un grupo aldehído por un grupo hidroximetilo, estos resultados demuestran el papel esencial de la función aldehído en C-30 para la citotoxicidad. En contraste, ninguno de los compuestos ensayados reveló actividad frente a M. tuberculosis.

International audience; Despite half a century of intensive research, the structure and presence of short-range ordered aluminosilicates in volcanic soils is still the focus of debate. Imogolite is easily distinguishable because of its tubular structure, whereas allophane compounds—usually described as spheres—are harder to identify, especially because of their variable structure and occurrence patterns. In addition, the local structure of allophanes can be very similar to that of proto-imogolite (imogolite precursor). Strangely, this similarity is seldom considered in most characterization studies. In this context, our study focuses on the structure of two Al-rich short range-ordered aluminosilicates of two different origins, from: (i) an Andosol B horizon (Andosol sample); and (ii) a weathered pumice grain (pumice sample). These natural samples were compared to a synthetic proto-imogolite. The three samples were analyzed using experimental tools that are commonly used for the identification of these nanophases (chemical composition, X-ray diffraction, nuclear magnetic resonance, Fourier transform infrared spectroscopy and transmission electron microscopy). The three samples exhibited the same local structure, but significant differences were observed at a larger scale. The pumice sample clearly showed ring-shaped particles, while the Andosol sample and the synthetic proto-imogolite were amorphous. Our results suggest that poorly ordered proto-imogolite, rather than Al-rich allophones and imogolites, is present in Andosol horizons. We believe that the mineralogy of these phases needs to be reassessed along with their growth mechanisms.

UMR IATE Axe 4 Biotechnologie microbienne et enzymatique des lipides et des agropolymères Contacts : stephane.dubascoux@supagro.inra.fr, frederic.bonfils@cirad.fr; Abstract: This paper presents results from the first analyses of the mesostructure of natural rubber (NR) by asymmetrical flow field flow fractionation (AF4). The results are compared with those obtained by size exclusion chromatography (SEC) in terms of average molar masses, radius of gyration and insoluble part (or gel quantity). Comparable results were obtained for the sample not containing gel. Conversely, for samples with gel, significant differences were found due to the presence of microaggregates. Contrary to SEC, AF4 fractionation enables partial fractionation of polyisoprene chains and microaggregates in a single run without preliminary treatment. The results presented here also highlight the special structure (very compact spheres) of microaggregates in NR compared to chemical crosslinked microaggregates in synthetic polyisoprene. The advantages and drawbacks of both techniques for analysing NR samples are also discussed.

Onchidin (1) is a cytotoxic depsipcptide isolatcd from thc pulmonate mollusc Onchidium sp. Its structure is cyclo (MeVal-Amo-Val-Hiv-Hiv-McVal-Amo-Val-Hiv-Hiv) made or two identical halves (C3OH49N307, MeVal-Amo-Val-Hiv-Hiv). Onchidin contains a new s-amino acid: 3-amino-2-methyl- oct-7-ynoic acid (Amo). It has C2-symmetry and this makcs one half homotopic to the other so only signals for a "monomer" can be seen in the NMR spectra. Thc structure and absolute stereochemistry' (all S) of onchidin was determined by extcnsivc spcctroscopic analysis, selective hydrolysis and chiral GCMS. Cyclic peptides with important pharmacological properties have been isolated from manne 0rganisms.l Frequently these metabolites contain D amino acids, hydroxy acids, new a-amino acids, new s-amino acids and thiazole and oxazole rings. In some cases, the cyclic structure incorporates elements of symmetry that complicate the structural determination due to the bonding possib es of the repeating fragments and the simplification of the spectra. The interest of these compounds is well illustrated by dolastatin- IO, the most potent antineoplastic agent known2 and by the didemnins,3 considered as some of the most promising antitumor compounds of marine origin. In this paper we describe the structure (including absolute configuration) of onchidin (1) a new cytoxic depsipeptide with C2 symmetry isolated from a pulmonate mollusc known to be a rich source of y- pyrone poIypropionates4. Onchidium sp. (Pulmonatu, order: Sryfommarophora) (3Kg. fresh weight) collected off New Caledonia was extracted with methanol. P-388 and Kb activity-guided fractioning by solvent partition followed by repeated chromatography (Sephadex, reverse phase HPLC) afforded 3 mg of a pure compound ((a)&'=-140.9'; P-388

A highly cytotoxic macrolide, superstolide A (1), has been isolated from the deep water marine sponge Neosiphonia superstes, collected off New Caledonia. The gross structure was determined by extensive 2D NMR experiments on the lactone 1 and on its opened-ring-derived methyl esters 2 and 3. The relative stereochemistries of the decaline moiety and of the C22-C26 fragment were determined by a combination of NMR data and acetonide analysis on 2. Absolute stereostructure of the decaline portion of 1 has been determined on the basis of GLC-modified Horeau's methodology applied to 4, whereas the results of the application of the modified Mosher's method to 1 and 3 allowed us to propose for the C22-C26 fragment the 22R, 23R, 24R, 25S, 26R configuration. We also propose the solution conformations of superstolide A (1) based on molecular dynamics and mechanics calculations using NMR-derived constraints.

Potent antileishmanial activity has recently been described in vivo when certain 2-substituted quinoline alkaloids are administered to mice with cutaneous leishmaniasis. We now report the antileishmanial activity of four 2-substituted quinoline alkaloids, namely chimanine D or 2-(1',2'-trans-epoxypropyl) quinoline (I), 2-n-propylquinoline (II), 2-styrylquinoline (III) and 2-(2'-hydroxypropyl) quinoline (IV), for experimental treatment of visceral leishmaniasis in infected BALB/c mice. Subcutaneous treatment with chimanine D for 10 days at 0.54 mmol/kg per day resulted in 86.6% parasite suppression in the liver. Oral administration of 0.54 mmol/kg of 2-n-propylquinoline once daily for 5 or 10 days to L. donovani-infected mice suppressed parasite burdens in liver by 87.8 and 99.9%, respectively. Cutaneous administration of meglumine antimonate for 10 days resulted in 97.4% parasite suppression in the liver. This study is, to our knowledge, the first to demonstrate the activity of 2-substituted quinoline alkaloids in experimental treatment of visceral leishmaniasis. Further biological and chemical studies of these products might yet prove helpful for the development of new antileishmanial drugs.

Three new manoalide-related sesterterpenes, fasciospongides A [1], B [2], and C [3], have been isolated from the sponge Fasciospongia sp. and their structures elucidated by spectral methods

Heating in dry state has gained a lot of interest in pharmaceutical and food industries for viral and microbial decontamination of thermo sensible products. In addition controlled dry heating is a common industrial process for improving the functional properties of food proteins (egg white proteins). Besides this improvement, chemical modifications in protein structures involving degradation of amino acids, new intra or inter-molecular disulfide bonds, isopeptide bonds, and some other links may occur. These chemical modifications are favored by severe heating under neutral or alkaline conditions, and except disulfide interchanges, are usually not predominant during heat treatments in solution and their occurrence is not well understood Understanding chemical modifications in protein structure that occur during dry heating of protein powders is a prerequisite for reproducible properties of final products at industrial scale. In the present work, we focused on how pH conditions for dry heating affects the chemical modifications and denaturation/aggregation reactions of whey proteins. Model whey protein powders obtained from freeze drying of a 15% w/w protein concentrates adjusted at three different pH‘s (2.5, 4.5 & 6.5) were adjusted to a fixed water activity (Aw 0.2). All the samples were dry heated at 100°C up to 24 hours and structural modifications induced during dry heating were followed. We showed that whatever the pH value for dry heating, proteins were characterized by irreversible mass losses of 18 Da. Such mass losses were increased at lower pH value and with extending time for dry-heating. Strikingly, at low pH value (2.5) intermolecular disulfide bonds were the predominant crosslinks between proteins while covalent crosslinks other than disulfide bonds were prevalent at higher pH’s (4.5 & 6.5). Protein hydrolysis was also detected at low pH. Whatever the pH, alpha-lactalbumin was more susceptible to dry heat induced chemical modifications as compared to beta-lactoglobulin. These results underline that chemical modifications in protein structures induced by dry heating are highly pH dependent. Hence, strict control of pH conditions for dry heating is indispensable to control the protein denaturation/aggregation process and having reproducible functionality in products where such modified proteins are incorporated as ingredient.

Since the discovery of carbon nanotubes (NTs), there has been great interest in the synthesis and characterization of similar shaped structures like inorganic nanotubes, nanorods, or nanowires. Imogolites (Al2SiO3(OH)4) are natural aluminosilicate single wall nanotubes. To date, only Ge-Al imogolite analogues have been successfully synthesized 100 times more concentrated than Si-Al imogolites. The growth mechanisms of imogolite-like aluminogermanate nanotubes were examined using a combination of local- (XAS at the Ge-Kedge and 27Al NMR) and semilocal scale techniques (in situ SAXS). A model is proposed for the precursors of the nanotubular structure and consist in rooftile-shaped particles, up to 5 nm in size, with ca. 26% of Ge vacancies and varying curvatures. These precursors assemble to form short nanotubes/nanorings observed during the aging process. The final products are most likely obtained by an edge-edge assembly of these short nanotube segments. Two structures are revealed by SAXS: at 0.25M of Al the Al-Ge imogolite are double-walled NTs whereas at 0.5 M single-walled NTs are obtained. First tests to reveal cyto and genotoxicity on various vertebrates cells (human fibroblasts and CHO-K1) are interesting. They show a genotoxicity for concentrations from 8 10-5 g/L and effects decreasing from proto-imogolite to long tubes. (Texte intégral)

Since the discovery of carbon nanotubes (NTs), there has been great interest in the synthesis and characterization of similar shaped structures like inorganic nanotubes, nanorods, or nanowires. Imogolites (Al2SiO3 (OH)4) are natural aluminosilicate single wall nanotubes. To date, only Ge-Al imogolite analogues have been successfully synthesized 100 times more concentrated than Si-Al imogolites. The growth mechanisms of imogolite-like aluminogermanate nanotubes were examined using a combination of local- (XAS at the Ge-Kedge and 27Al NMR) and semilocal scale techniques (in situ SAXS). A model is proposed for the precursors of the nanotubular structure and consist in rooftileshaped particles, up to 5 nm in size, with ca. 26% of Ge vacancies and varying curvatures. These precursors assemble to form short nanotubes/nanorings observed during the aging process. The final products are most likely obtained by an edge-edge assembly of these short nanotube segments. Two structures are revealed by SAXS: at 0.25M of Al the Al-Ge imogolite are double-walled NTs whereas at 0.5 M single-walled NTs are obtained. First tests to reveal cyto and genotoxicity on various vertebrates cells (human fibroblasts and CHO-K1) are interesting. They show a genotoxicity for concentrations from 8 10-5 g/L and effects decreasing from proto-imogolite to long tube. (Texte intégral)

Zanthoxylum chiloperone var. angustifolium Engl., Rutaceae, is used in traditional medicine to treat fungal and protozoal infections in the central area of South America. Considering the increasing resistance of Plasmodium falciparum in malarial ridden areas, we explored the anti-plasmodial effects of three compounds isolated from Z. chiloperone. The pyranocoumarin transavicennol and the canthinone alkaloids, canthin-6-one and 5-methoxycanthin-6-one, were found to have IC50 on chloroquine/mefloquine resistant and sensitive strains of P. falciparum of 0.5-2.7, 2.0-5.3 and 5.1-10.4 ƒÊg/mL, respectively. Moreover, the formation of heme adducts by these compounds is described by a novel alternative method based on MS-CID methods. The alkylamide sanshool was also identified, for first time in this plant, in the dichloromethanic and ethanolic extracts and the extracts were found to be notably non-toxic and displayed good anti-plasmodial effects.

International audience; The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 degrees C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from n(OH)/n(Al) = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: n(OH)/n(Al) = 1.5 for the formation of nanotubes with structural defects, n(OH)/n(Al) = 2 for the synthesis of a well crystallized Ge imogolite and n(OH)/n(Al) > 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube's crystallinity opens up interesting opportunities in regard to new potential applications.

L'industrie du malt tente actuellement de réduire les coûts énergétiques (touraillage) sans affecter la qualité de malt obtenu. Cette économie d’énergie passe nécessairement par une diminution de la teneur en eau du grain d’orge en fin de trempe et durant la germination.Nous avons choisi d'étudier des paramètres clés de la qualité brassicole des malts concernant leurs capacités diastasiques et pro-mousse. Ainsi la diffusion et les modifications de la TP1, protéine pro-mousse du malt, ont montré des résultats équivalents pour un malt faiblement hydraté comparé à un malt fortement hydraté.Par contre, le taux d’hydratation du grain affecte la diffusion et l'activité des β-glucanases et en conséquence la dégradation des β-glucanes. Ces effets sont liés à une différence dans la cinétique de diffusion et de synthèse de ces enzymes et peuvent être fortement réduits en augmentant la durée de germination.La migration de l’eau dans le grain suit un cheminement particulier lié au contournement des barrières hydrophobes du grain situées en surface du péricarpe et à l’interface entre aleurone et péricarpe (testa). Sur des variétés produisant, au niveau pilote industriel, des malts qualitativement différents suivant le taux d’hydratation,nous avons remarqué de faibles différences de composition et d’épaisseur entre les assises cuticulaires. En revanche, nous avons mis en évidence une très grande variabilité de composition des cuticules dans les différentes parties du grain, par exemple le scutellum, le sillon ou les glumelles, During kilning, reduction of energy costs without impacting significantly the malt quality, represents a major challenge of the malting industry. This energy reduction requires a reduction of barley grain water content at the end of steeping and during germination.In the present work, we focused on key malting quality parameters involved in diastatic power and foam promoting capacities of malt. When analysed in a low hydrated malt and a high hydrated malt, the LTP1 (a foam promoting protein) modifications and its diffusion from the aleurone layer to the starchy endosperm were similar. The hydration level of the grain affects however β-glucanase diffusion and activity, and consequently the β-glucan degradation. These effects are linked to a delay in the synthesis and the diffusion of these enzymes.An increase of the time of germination allows to sharply reduce these effects.According to grain hydrophobic barriers localized at the pericarp surface and at the interface of aleurone and pericarp (testa), water diffusion inside the grain follows a specific pathway. Only weak, although significant,differences in cuticular thickness and composition were observed between cultivars with different malt qualities according to their hydration levels. On the contrary, we observed a great variability in the cuticular composition of the various tissues of the grain e.g. scutellum, chalaza or husk

Chemical protein synthesis allows the generation of milligram quantities of correctly folded and previously inaccessible tyrosine-phosphorylated estrogen receptor a (ERa) and ß (ERß) ligand binding domains. By using this synthetic strategy, the crystal structure of a post-translationally modified nuclear receptor (pY488 ERß) could be obtained for the first time

Au cours de ce travail de thèse, nous nous sommes intéressés aux études taxonomiques des deux souches TN17 et Fr10 qui sont deux nouvelles espèces du genre Streptomyces dont nous avons proposé les nomenclatures suivantes : Streptomyces lilaceus sp. TN17 et Streptomyces microflavus sp. Fr10. A partir de la souche Streptomyces lilaceus sp. TN17, trois molécules on été purifiées et identifiées par le biais de plusieurs techniques spectroscopiques, il s’agit d’un dérivé de DKP (L-Leu, L-Arg), un dérivé de phtalate le di-(2-éthylhexyl) phtalate et un tértrapeptide cyclique : le 1 - [2 -(cyclopentanecarbonyl-3-phenylpropionyl] – pyrrolidine-2-carboxylique (1-carbamoyl-propyl)-amide. Ces trois molécules présentent des activités antibactériennes et antifongiques. Suite au criblage des souches de bactéries lactiques productrices de bactériocines de la collection de notre laboratoire et leurs caractérisations, nous avons identifié une nouvelle souche de Lactobacillus nommée Lactobacillus plantarum sp.TN635 qui produit une bactériocine « BacTN635 » de 3,8 KDa. Cette dernière a été purifiée à homogénéité, elle possède un spectre d’action très large contre les bactéries à Gram+, à Gram- et contre les champignons filamenteux et unicellulaires. BacTN635 a un effet bactéricide contre Listeria ivanovii BUG 496 et fongistatique contre Candida tropicalis R2 CIP203.

The growth mechanisms of imogolite-like aluminogermanate nanotubes have been examined at various stages of their formation. The accurate determination of the nucleation stage was examined using a combination of local- (XAS at the Ge−K edge and 27Al NMR) and semilocal scale technique (in situ SAXS). For the first time, a model is proposed for the precursors of the nanotubular structure and consist in rooftile-shaped particles, up to 5 nm in size, with ca. 26% of Ge vacancies and varying curvatures. These precursors assemble to form short nanotubes/nanorings observed during the aging process. The final products are most probably obtained by an edge−edge assembly of these short nanotube segments.