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BACKGROUND: The essential oil from Eucalyptus radiata leaves collected in Tunisia was extracted by steam distillation and analysed by gas chromatography/flame ionisation detection and gas chromatography/mass spectrometry. Its antioxidant and antiradical properties were evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The antimicrobial activity of the oil was examined in vitro against two plant-pathogenic bacteria (four strains each of Agrobacterium tumefaciens and Pseudomonas savastanoi pv. savastanoi) and two plant-pathogenic fungi (Fusarium solani and Rhizoctonia solani). RESULTS: Thirty-five compounds were identified and quantified in the essential oil, the major ones being 1,8-cineole (69.53%), α-pinene (11.94%) and trans-pinocarveol (4.81%). Medium antioxidant activity was found in the ABTS assay (IC50 = 484.3 ± 17.3 mg L−1), whereas no significant free radical-scavenging activity was detected in the DPPH assay (IC50 > 10 000 mg L−1). The antimicrobial assays showed that the oil exhibited a high level of activity against A. tumefaciens and R. solani, with minimum inhibitory concentrations ranging between 750 and 1000 µL L−1. However, it was less efficient against P. savastanoi pv. savastanoi and F. solani. CONCLUSION: The results indicate that the essential oil of E. radiata, with a high content of terpenic compounds, exhibits significant antimicrobial activity against strains of A. tumefaciens and the fungus R. solani and may therefore be useful for their control. Copyright © 2009 Society of Chemical Industry

Rhizobial lipochitooligosaccharide (LCO) signal molecules induce various plant responses, leading to nodule development. We report here the LCO structures of the broad-host range strain Rhizobium sp. BR816. The LCOs produced are all pentamers, carrying common C18:1 or C18:0 fatty acyl chains, N-methylated and C-6 carbamoylated on the nonreducing terminal N-acetylglucosamine and sulfated on the reducing/terminal residue. A second acetyl group can be present on the penultimate N-acetylglu-cosamine from the nonreducing terminus. Two novel characteristics were observed: the reducing/terminal residue can be a glucosaminitol (open structure) and the degree of acetylation of this glucosaminitol or of the reducing residue can vary.

We have isolated and characterized the extracellular Nod factors of Rhizobium fredii USDA257, a nitrogen-fixing symbiont of soybean [Glycine max (L.) Merr.] and several other legume species. These signals are produced upon exposure to the isoflavone genistein and consist of a series of substituted, beta 1,4-linked tri-, tetra-, and pentamers of N-acetylglucosamine. N-Vaccenic acid replaces acetate on the nonreducing residue, and the reducing residue contains alpha-linked 2-O-methylfucose on carbon 6. Small amounts of a fucose-containing tetramer also were present. The Nod factors elicit root-hair deformations on soybean and two other plants at concentrations ranging from 10(-6) to 10(-12) M.

Tesis (Profesor de Educación Física, Licenciado en Educación) Elaborar un programa de ejercicios para prevenir las malformaciones en la columna vertebral de los niños de NB l Conocer y reconocer las malformaciones en la columna vertebral de los niños. Identificar las causas de las malformaciones de la columna vertebral. Entender la importancia de adquirir una postura adecuada. Crear conciencia de la gravedad de una inadecuada posición postural en la columna vertebral. Conocer los test posturales que sirven para el diagnostico de las malformaciones de la columna vertebral. Identificar y practicar los ejercicios pertinentes para las distintas malformaciones de la columna vertebral

Rhizobia synthesize mono-N-acylated chitooligosaccharide signals, called Nod factors, that are required for the specific infection and nodulation of their legume hosts. The biosynthesis of Nod factors is under the control of nodulation (nod) genes, including the nodABC genes present in all rhizobial species. The N-acyl substitution can vary between species and can play a role in host specificity. In Rhizobium meliloti, an alfalfa symbiont, the acyl chain is a C16 unsaturated or a (omega-1) hydroxylated fatty acid, whereas in Rhizobium tropici, a bean symbiont, it is vaccenic acid (C18:1). We constructed R. meliloti derivatives having a non-polar deletion of nodA, and carrying a plasmid with either the R. meliloti or the R. tropici nodA gene. The strain with the R. tropici nodA gene produced Nod factors acylated by vaccenic acid, instead of the C16 unsaturated or hydroxylated fatty acids characteristic of R. meliloti Nod factors, and infected and nodulated alfalfa with a significant delay. These results show that NodA proteins of R. meliloti and R. tropici specify the N-acylation of Nod factors by different fatty acids, and that allelic variation of the common nodA gene can contribute to the determination of host range.

Flavonoid cues from the plant host cause symbiotic, nitrogen-fixing rhizobia to synthesize lipochitooligosaccharides (LCOs), which act as return signals to initiate the nodulation process. Rhizobium fredii strain USDA257 is known to produce four LCOs, all substituted with vaccenic acid (C18:1). We show here that a mutant strain can replace vaccenic acid with a C16:0 side chain, and that strain USDA191 synthesizes additional LCOs that differ from one another in the length and unsaturation of their fatty acyl substituents. USDA191 and 257DH4 both produce a novel LCO with glucose substituted for N-acetyl-d-glucosamine in the backbone of the molecule.

New methyl-branched fatty acids were isolated from the lipids of Mycobacterium aurum, belonging to both saturated and non-saturated series. The most abundant component of the former series was identified as a C22-mycosanoic acid (2-L, 4-L-dimethyleicosanoic acid). The unsaturated fraction contained a mixture of 2-L, 4-L-dimethyl-11-eicosenoic acid and 2-L, 4-L-dimethyl-14-eicosenoic acid. The biosynthetic precursors of these, according to the hypothesis of elongation by propionate units, were found in the non-branched hexadecenoic fraction. The lipidic fraction containing mycosanoic acid was a partially acylated oligosaccharide devoid of sulfate or phosphate groups.

The isolation of a ‘palmitone lipid’ from Corynebacterium diphtheriae is described. The use of a temporary hydrophobic protecting group allows the obtaining of the lipid in free and pure form. Structural studies by chemical degradation and mass spectrometry allow one to propose structure Ic for this compound, namely 6-(2-tetradecyl 3-keto octadecanoyl)-α-D-trehalose. This structure was confirmed by chemical synthesis.

Separation and Structural Studies of the Molecular Species of Monomycolates and Dinzycolates of α-d-Trehalose present in Mycobacterium phlei Mixtures of dimycolates of α-d-trehalose (cord factor) and monomycolates have been isolated from Mycobacterium phlei and separated as trimethylsilyl derivatives according to the polarity of the fatty acid residues. The free glycolipids can be recovered by mild hydrolysis. Silylation and desilylation reactions did not induce any isomerisation. The structure of these trehalose esters has been determined by using a series of reactions elaborated on synthetic acyl-sugar models. Free hydroxyl groups are transformed into tetrahydropyran ethers, deacylated by dimsyl sodium, methylated and the sugar derivatives are hydrolyzed. The O-methylsugars obtained contain a methyl ether group located at the position where the acyl group was present initially. Identification by gas chromatography of the 0-methyl-sugars thus allows the location of the fatty acid residues in the glycolipid. It has been demonstrated that no migration occurs. Two types of 6-monomycoloyl-α-d-trehalose have been isolated, differing by the nature of the mycolic acid residues. One of them, called MA, contains “α-phlei mycolic acid”. The other one, called MB, contains “α-phlei mycolic acid” which is the,ester of 2-eicosanol with the α-carboxyl function of a dicarboxylic mycolic acid. Three types of 6,6′-dimycoloyl-α-d-trehalose (cord factor) have been obtained. Two of them are symmetrical diesters, containing either two residues of mycolic acid, or two residues of α-mycolic acid. The last one is an unsymmetrical diester, the hydrolysis of which gives one mole of a-mycolic acid and one mole of α-mycolic acid. The ratio of the different diesters in the cord factor fraction might be explained by some equilibration between the different 6-ester groups or by a transformation in situ of one species into another one by biochemical modification of the mycolic acid residues

The collision-induced remote site fragmentation process of closed-shell ions, such as carboxylate anions, is a very potent analytical tool for the structural determination of fatty acids. This leads to an easy location of branch points, double bonds, cyclopropane rings and other functional groups. Although corynomycolic acid mixtures from Corynebacterium diphtheriae can be directly analyzed by negative-ion fast atom bombardment combined with collisionally activated decomposition spectra, mycolic acid mixtures from mycobacteria need a preliminary chemical cleavage. They are oxidized to β-keto esters and then submitted to a retro-Claisen reaction. The resulting fatty acids were then converted into pentafluorobenzyl derivatives and introduced directly into a high pressure ion source working in the negative ion mode. The resulting gas phase carboxylate anions are activated to decompose by collision with helium atoms. When applied to M3-mycolic acids from Mycobacterium fallax, this method allows for the characterization of a new tri-unsaturated mycolic acid, which has the middle and the remote double bonds separated by two methylene groups.

Mycobacterium phlei synthesizes an homologous series of polyunsaturated fatty acids, the main member of which is hexatriaconta-4,8,12,16,20-pentaenoic acid. These acids will be refered to as “phleic acids”. Natural derivatives of these acids and their subcellular localization are studied in this paper. A series of esters of trehalose and phleic acids, called “lipids P”, have been isolated from Mycobacterium phlei. They differ by their number of esterified hydroxyl groups. Because of their low stability, it is difficult to make a distinction between natural product and artefact. The main member of this series, lipid P1, has been isolated in an homogeneous form by chromatographic procedures. Saponification of lipid P1 gives only phleic acids and trehalose. Quantitative estimation by gas chromatography, as methyl phleate and trehalose trimethylsilyl ether, and examination of infrared and nuclear magnetic resonance spectra of the whole lipid P1 suggest the structure of octaphleate of trehalose for this lipid. Then lipid P1 is a glycolipid having a strong lipidic character, that differs from most other natural lipid compounds by its high molecular weight (4400) and its high unsaturation (40 double bonds). Lipids P appear to be the main form of phleic acid derivatives. They are located in the outer part of the cell, and can be extracted by a simple washing of the bacteria with hexane; bacterial cells are still living after this treatment. Phleic acids are not obligatory components of mycobacteria, as they have been found in two saprophytic strains (Mycobacterium phlei and Mycobacterium smegmatis), but not in two strains of Mycobacterium tuberculosis and one strain of Mycobacterium bovis (BOG). On the basis of chemical structure, subcellular localization and species distribution, lipids P exhibit analogies with other kinds of esters of trehalose found in some strains of mycobacteria devoid of phleic acids. Although the content of phleic acids in a culture of Mycobacterium phlei reaches a constant value long before the end of the logarithmic phase of growth, phleic acids do not appear to be simple excretion products. They are not storage compounds: unlike common fatty acids, they are neither used when no carbon source is supplied to the medium, nor accumulated when the main nitrogen source of the medium (asparagin) is omitted. An important decrease of the content of phleic acids is observed when the medium is supplemented with a surfactant, which prevents bacterial aggregation.

Mixtures of dimycolates of alpha-D-trehalose (cord factor) and monomycolates have been isolated from Mycobacterium phlei and separated as trimethylsilyl derivatives according to the polarity of the fatty acid residues. The free glycolipids can be recovered by mild hydrolysis. Silylation and disilylation reactions did not induce any isomerisation. The structure of these trehalose esters has been determined by using a series of reactions elaborated on synthetic acyl-sugar models. Free hydroxyl groups are transformed into tetrahydropyran ethers, deacylated by dimsyl sodium, methylated and the sugar derivatives are hydrolyzed. The O-methyl-sugars obtained contain a methyl ether group located at the position where the acyl group was present initially. Identification by gas chromatography of the O-methyl-sugars thus allows the location of the fatty acid residues in the glycolipid. It has been demonstrated that no migration occurs. Two types of 6-monomycoloyl-alpha-D-trehalose have been isolated, differing by the nature of the mycolic acid residues. One of them, called MA, contains "alpha-phlei mycolic acid". The other one, called MB, contains "gamma-phlei mycolic acid" which is the ester of 2-eicosanol with the omega-carboxyl function of a dicarboxylic mycolic acid. Three types of 6,6'-dimycoloyl-alpha-D-trehalose (cord factor) have been obtained. Two of them are symmetrical diesters, containing either two residues of alpha-mycolic acid, or two residues of gamma-mycolic acid. The last one is an unsymmetrical diester, the hydrolysis of which gives one mole of alpha-mycolic acid and one mole of gamma-mycolic acid. The ratio of the different diesters in the cord factor fraction might be explained by some equilibrium between the different 6-ester groups or by a transformation in situ of one species into another one by biochemical modification of the mycolic acid residues.

The analysis of a complex mixture of monounsaturated fatty acids from mycobacterium phlei is achieved by capillary gas chromatographic separation of their pentafluorobenzyl esters, formation of gas-phase carboxylate anions by electron capture ionization and decomposition of these anions by collision activation. This method allows the structural determination of fatty acid isomers by examination of their collisionally activated dissociation mass-analysed ion kinetic energy spectra. A good correlation is observed between the structure of the unsaturated fatty acids ranging from C24 to C27 and the methyl terminal part of the main chain of diunsaturated mycolic acids.

Rhizobia are symbiotic bacteria that synthesize lipochitooligosaccharide Nod factors (NFs), which act as signal molecules in the nodulation of specific legume hosts. Based on the structure of their N-acyl chain, NFs can be classified into two categories: (i) those that are acylated with fatty acids from the general lipid metabolism; and (ii) those (= alphaU-NFs) that are acylated by specific alpha,beta-unsaturated fatty acids (containing carbonyl-conjugated unsaturation(s)). Previous work has described how rhizobia that nodulate legumes of the Trifolieae and Vicieae tribes produce alphaU-NFs. Here, we have studied the structure of NFs from two rhizobial species that nodulate important genera of the Galegeae tribe, related to Trifolieae and Vicieae. Three strains of Mesorhizobium huakuii, symbionts of Astragalus sinicus, produced as major NFs, pentameric lipochitooligosaccharides O-sulphated and partially N-glycolylated at the reducing end and N-acylated, at the non-reducing end, by a C18:4 fatty acid. Two strains of Rhizobium galegae, symbionts of Galega sp., produced as major NFs, tetrameric O-carbamoylated NFs that could be O-acetylated on the glucosamine residue next to the non-reducing terminal glucosamine and were N-acylated by C18 and C20 alpha,beta-unsaturated fatty acids. These results suggest that legumes nodulated by rhizobia synthesizing alphaU-NFs constitute a phylogenetic cluster in the Galegoid phylum.

BACKGROUND:Juniperus phoenicea is an important medicinal plant. In the present study, essential oils (18 samples) from leaves and berries of Juniperus phoenicea L. (Cupressaceae), obtained by various drying methods and in different collection months, were analysed by gas chromatography–mass spectrometry and also evaluated for in vitro antimicrobial and antioxidant activities. Correlations were studied between antimicrobial activity and the chemical composition of essential oils. RESULTS: Sixty-seven compounds were identified in essential oils, representing 97.7–100%. Essential oils were dominated by monoterpenes and sesquiterpenes, which presented 35.0–93.3% and 6.7–62.0%, respectively, depending of organ, season and drying method. Antimicrobial tests showed that essential oils strongly inhibited the growth of Gram-positive microorganisms and Mucor ramamnianus, but was inactive against Gram-negative strains. Antioxidant activity was tested using the ABTS radical-scavenging assay. Most samples showed good activity (the best IC50 = 41.7 ± 1.5 mg L−1). CONCLUSIONS: It could be concluded that drying of leaves of J. phoenicea in the sun and berries in oven-drying was more suitable and was recommended for obtaining higher essential oil yield, but for a higher percentage of some special components such as α-pinene and δ-3-carene shade-drying was more suitable. Copyright © 2009 Society of Chemical Industry