Variation of chemical composition of essential oils in wild populations of Thymus algeriensis Boiss. et Reut., a North African endemic Species

<p>Abstract</p> <p>Background</p> <p><it>Thymus algeriensis </it>is an endemic aromatic plant to Tunisia largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location and the phase of the plant development. Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of <it>T. algeriensis </it>collected during the vegetative and the flowering phases and from eight different geographical regions. Besides, influence of population location and phenological stage on yield and metal chelating activity of essential oils is also assessed.</p> <p>Methods</p> <p>The essential oil composition of <it>Thymus algeriensis </it>was determined mainly by GC/FID and GC/MS. The chemical differentiation among populations performed on all compounds was assessed by linear discriminate analysis and cluster analysis based on Euclidean distance.</p> <p>Results</p> <p>A total of 71 compounds, representing 88.99 to 99.76% of the total oil, were identified. A significant effect of the population location on the chemical composition variability of <it>T. algeriensis </it>oil was observed. Only 18 out of 71 compounds showed a statistically significant variation among population locations and phenological stages. Chemical differentiation among populations was high. Minor compounds play an important role to distinguish between chemical groups. Five chemotypes according to the major compounds have been distinguished. Chemotypes distribution is linked to the population location and not to bioclimate, indicating that local selective environmental factors acted on the chemotype diversity.</p> <p>Conclusions</p> <p>The major compounds at the species level were α-pinene (7.41-13.94%), 1,8-cineole (7.55-22.07%), <it>cis</it>-sabinene hydrate (0.10-12.95%), camphor (6.8-19.93%), 4-terpineol (1.55-11.86%), terpenyl acetate (0-14.92%) and viridiflorol (0-11.49%). Based on major compounds, the populations were represented by (α-pinene/1,8-cineole/<it>cis</it>-sabinene hydrate/camphor/viridiflorol), (1,8-cineole/camphor/terpenyl acetate), (α-pinene/1,8-cineole/camphor), (1,8-cineole/camphor/4-terpineol) and (α-pinene/1,8-cineole/<it>cis</it>-sabinene hydrate/camphor/4-terpineol) chemotypes. Variation of phenological stage did not have a statistically significant effect on the yield and metal chelating activity of the essential oil. These results can be used to investigate the geographical location and the harvesting time of this plant for relevant industries.</p

Pyrene bisiminopyridine ligand and its zinc complex

The synthesis of a pyrene bisiminopyridine ligand L was successfully accomplished by condensation between 1-aminopyrene and 2,6-pyridinecarboxaldehyde. The complexation of L with zinc triflate afforded a neutral metal complex formulated as [Zn(H2O)LCF3SO3)2].2Et2O. In the complex, the ligand is coordinated to zinc(II) through its three nitrogen atoms which form a distorted octahedral environment together with three oxygen atoms, two from the triflate anions and one from aqua ligand. Both compounds have been characterized using NMR, elemental analysis, mass spectrometry, electronic absorption (UV-Vis) and infrared. Luminescence properties of these compounds show an emission maxima at 412 nm, indicating a pyrene monomer emission

Expression by Streptomyces lividans of the Rat α Integrin CD11b A-Domain as a Secreted and Soluble Recombinant Protein

We already reported the use of a long synthetic signal peptide (LSSP) to secrete the Streptomyces sp. TO1 amylase by Streptomyces lividans strain. We herein report the expression and secretion of the rat CD11b A-domain using the same LSSP and S. lividans as host strain. We have used the Escherichia coli/Streptomyces shuttle vector pIJ699 for the cloning of the A-domain DNA sequence downstream of LSSP and under the control of the constitutive ermE-up promoter of Streptomyces erythraeus. Using this construct and S. lividans as a host strain, we achieved the expression of 8 mg/L of soluble secreted recombinant form of the A-domain of the rat leukocyte β2 integrin CD11/CD18 alpha M subunit (CD11b). This secreted recombinant CD11b A-domain reacted with a function blocking antibody showing that this protein is properly folded and probably functional. These data support the capability of Streptomyces to produce heterologous recombinant proteins as soluble secreted form using the “LSSP” synthetic signal peptide

Modulation des propriétés ONL de ligands azobenzéniques par coordination de cations métalliques

National audienc

Metal Complexes of a Pyrene based iminopyridine ligand: Synthesis, X-ray structures and Optical properties

National audienc

Effects of Physical Ripening Conditions and Churning Temperature on the Butter-Making Process and the Physical Characteristics of Camel Milk Butter

peer reviewe

Microstructure and chemical composition of camel and cow milk powders’ surface

This study aimed at investigating the chemical composition and microstructure of spray dried camel and cowmilk powders' surfaces with two different milk-fat contents (1 and 20g 100 g−1). The SEM (Scanning ElectronMicroscopy) micrographs showed that spherical particles with a ‘brain’-type surface for both milk powders wereproduced. The surface roughness (Ra) of whole (WDMP) and skimmed (SDMP) camel milk powders(Ra=7.6 ± 0.4 nm and 5.6 ± 0.7 nm, respectively) were significantly lower as compared with the partiallyskimmed (PSCMP) and skimmed (SCMP) cow milk powders. The XPS (X-ray Photoelectron Spectroscopy)analysis highlighted that the surface of skimmed camel milk powders contained twice the lactose amount(17.7 ± 0.8%) as compared to cow milk powders (8.7 ± 0.4%). Furthermore, both milk powders showed theoverexposure of proteins and fats at their surfaces regardless of the fat content. The CLSM (Confocal LaserScattering Microscopy) micrographs highlighted that most of the camel milk fat globules were encapsulated bythe proteins near the powder surface. Camel milk fat behavior during particle formation was attributed to theirlower size distribution and their higher crystallization temperature

Azo-based iminopyridine ligands: synthesis, optical properties, theoretical calculations and complexation studies

We describe herein the full characterization of azobenzene based iminopyridine ligands (L1–L4) synthesized by a condensation reaction between N,N-Dimethyl-4,4′-azodianiline or 4-(4-nitrophenylazo)aniline and 2-pyridinecarboxaldehyde or 2,6-pyridinedicarboxaldehyde. The UV–visible absorption bands of these ligands were fully assigned using DFT and TD-DFT computations. The complexation of ligand L1 and ligand L2 with AgNO3 afforded two neutral silver metal complexes formulated as [AgL1NO3] and [AgL2NO3], respectively. The crystal structure analysis of the two complexes indicate the presence of a Y-shaped tricoordinated silver (I) ion for [AgL1NO3] and a tetracoordinated silver(I) ion displaying rather rare and distorted square planar geometry for [AgL2NO3]. In solid state, for both complexes, a 3D supramolecular architecture is generated via hydrogen bonds of type C–HċO and C–Hċπ. The UV–visible spectrophotometric titration studies of ligands L1–L4, by increasing amount of AgNO3 or of ZnCl2 indicates the possibility of forming transition metal complexes with these ligands

Variation of Grain Yield, Grain Protein Content and Nitrogen Use Efficiency Components under Different Nitrogen Rates in Mediterranean Durum Wheat Genotypes

Nitrogen (N) is a crucial nutrient for plant growth and development. To optimize agricultural environments, N fertilizers represent a critical tool to regulate crop productivity. The improvement of nitrogen use efficiency (NUE) represents a promising tool that may enable cereal production to meet future food demand. Wheat reported contrasting behaviors in N utilization showing specific abilities depending on genotype. This study selected two landraces and two improved genotypes from Northern Africa to investigate grain yield (GY), grain protein content (GPC) and NUE. Plants were grown under three levels of N supply: 0, 75, 150 kg N ha−1 and for two consecutive years. Results reported a better NUE (0.40 kg.kg N−1) obtained under 150 kg N ha−1, while N utilization efficiency (NUtE) showed a 13% increase using 75 kg N ha−1 compared with 150 kg N ha−1. Under low nitrogen rate (0 N), crop N supply (CNS) and N uptake efficiency (NUpE) were shown as determinant factors for improved genotypes GY (R2 = 0.72), while NUtE represented the most determinant component for GPC in landraces (R2 = 0.92). Multivariate regression models explained the dependence in GPC on NUE, NUpE, and NUtE. In conclusion, our results recognize GPC and NUtE as suitable selection traits to identify durum wheat with higher NUE