Synthesis and crystal structures of chiral ferrocene and ruthenocene substituted aminomethylnaphthols obtained through Betti-condensation

Ferrocene- and ruthenocenecarboxaldehydes have been employed in Betti-type condensation reactions with 2-naphthol and (S)-phenylethylamine to give metallocenyl-substituted aminomethylnaphthols in a diastereoisomerically pure form. The absolute configurations of the new chiral compounds have been determined by means of NMR experiments and confirmed by X-ray crystallography. The chiral metallocenyl-aminomethylnaphthols have been tested as pre-catalysts for the addition of diethyl zinc to aldehydes, with enantioselectivities of up to 88% ee

Assessment of the botanical origin of Bulgarian honey samples using melissopalynological, DNA barcoding and NMR analyses

Polyfloral honey samples from Bulgaria were subject to parallel analyses of their botanical origin and composition using traditional melissopalynology, DNAbarcoding based on the plastid rbcL gene and NMR analysis. The obtained datasets were compared with each other to evaluate the information capacity of the applied experimental methods. The results from the melissopalynological and DNA-barcoding studies demonstrated a significantly higher resolution of the latter, revealing the presence of pollen from a total of 17 plant families, 21 plant genera and 5 plant species in comparison to pollen from only 7 plant families, 3 plant genera and 4 plant species identified by melissopalynology. The higher resolution of DNA barcoding allows a more detailed characterisation of the diet and foraging preferences of honey bees, including foraging on plant species growing in lower abundance in the area. The comparison of the quantitative data on floral honey composition for several plant genera and species reveals significant differences between the relative abundance of the pollen grains estimated by melissopalynological analysis and the relative abundance of rbcL clones in rbcL libraries determined after DNA barcoding. All three applied methods confirm the polyfloral botanical origin of the analysed samples and support routine NMR use for the assessment of the floral origin of honey

In vivo spectroscopy and NMR metabolite fingerprinting approaches to connect the dynamics of photosynthetic and metabolic phenotypes in resurrection plant Haberlea rhodopensis during desiccation and recovery.

International audienceThe resurrection plant Haberlea rhodopensis was used to study dynamics of drought response of photosynthetic machinery parallel with changes in primary metabolism. A relation between leaf water content and photosynthetic performance was established, enabling us to perform a non-destructive evaluation of the plant water status during stress. Spectroscopic analysis of photosynthesis indicated that, at variance with linear electron flow (LEF) involving photosystem (PS) I and II, cyclic electron flow around PSI remains active till almost full dry state at the expense of the LEF, due to the changed protein organization of photosynthetic apparatus. We suggest that, this activity could have a photoprotective role and prevent a complete drop in adenosine triphosphate (ATP), in the absence of LEF, to fuel specific energy-dependent processes necessary for the survival of the plant, during the late states of desiccation. The NMR fingerprint shows the significant metabolic changes in several pathways. Due to the declining of LEF accompanied by biosynthetic reactions during desiccation, a reduction of the ATP pool during drought was observed, which was fully and quickly recovered after plants rehydration. We found a decline of valine accompanied by lipid degradation during stress, likely to provide alternative carbon sources for sucrose accumulation at late stages of desiccation. This accumulation, as well as the increased levels of glycerophosphodiesters during drought stress could provide osmoprotection to the cells

Bioactive Constituents of Brazilian Red Propolis

In a new propolis type, red Brazilian propolis, 14 compounds were identified (six of them new for propolis), among them simple phenolics, triterepenoids, isoflavonoids, prenylated benzophenones and a naphthoquinone epoxide (isolated for the first time from a natural source). Three of the major components demonstrated significant antimicrobial activity, and two (obtained as inseparable mixture) possessed radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH)

Cd(II) and Pb(II) complexes of the polyether ionophorous antibiotic salinomycin

<p>Abstract</p> <p>Background</p> <p>The natural polyether ionophorous antibiotics are used for the treatment of coccidiosis in poultry and ruminants. They are effective agents against infections caused by Gram-positive microorganisms. On the other hand, it was found that some of these compounds selectively bind lead(II) ions in <it>in vivo </it>experiments, despite so far no Pb(II)-containing compounds of defined composition have been isolated and characterized. To assess the potential of polyether ionophores as possible antidotes in the agriculture, a detailed study on their <it>in vitro </it>complexation with toxic metal ions is required. In the present paper we report for the first time the preparation and the structure elucidation of salinomycin complexes with ions of cadmium(II) and lead(II).</p> <p>Results</p> <p>New metal(II) complexes of the polyether ionophorous antibiotic salinomycin with Cd(II) and Pb(II) ions were prepared and structurally characterized by IR, FAB-MS and NMR techniques. The spectroscopic information and elemental analysis data reveal that sodium salinomycin (SalNa) undergoes a reaction with heavy metal(II) ions to form [Cd(Sal)₂(H₂O)₂] (<b>1</b>) and [Pb(Sal)(NO₃)] (<b>2</b>), respectively. Abstraction of sodium ions from the cavity of the antibiotic is occurring during the complexation reaction. Salinomycin coordinates with cadmium(II) ions as a bidentate monoanionic ligand through the deprotonated carboxylic moiety and one of the hydroxyl groups to yield <b>1</b>. Two salinomycin anions occupy the equatorial plane of the Cd(II) center, while two water molecules take the axial positions of the inner coordination sphere of the metal(II) cation. Complex <b>2 </b>consists of monoanionic salinomycin acting in polydentate coordination mode in a molar ratio of 1: 1 to the metal ion with one nitrate ion for charge compensation.</p> <p>Conclusion</p> <p>The formation of the salinomycin heavy metal(II) complexes indicates a possible antidote activity of the ligand in case of chronic/acute intoxications likely to occur in the stock farming.</p

Optical Rotation—A Reliable Parameter for Authentication of Honey?

The controversial question of whether optical rotation data can be used to distinguish floral from honeydew honey was investigated. Specific optical rotation angles were determined for 41 honey samples, including floral, honeydew, and adulterated honey, indicating that moderate to high positive optical rotation angles were found for all adulterated samples measured. A strong correlation between the sugar profile and the specific optical rotation angle of honey was confirmed, and a method based on 13C NMR metabolomics was proposed to calculate specific optical rotation angles with good correlation with the experimental values. The results indicate that optical rotation is not a reliable method for distinguishing the origin of honey but could indicate adulteration

NMR analysis of weak molecular interactions using slice-selective experiments via study of concentration gradients in agar gels

Weak molecular interactions can be localized and quantified using a single NMR experiment analysing concentration gradients generated in agar gels. The spectra from various cross-sections along the gradient were obtained using a slice-selective pulse sequence realisable with standard NMR equipment

NMR Profiling of North Macedonian and Bulgarian Honeys for Detection of Botanical and Geographical Origin

Bulgaria and North Macedonia have a long history of the production and use of honey; however, there is an obvious lack of systematic and in-depth research on honey from both countries. The oak honeydew honey is of particular interest, as it is highly valued by consumers because of its health benefits. The aim of this study was to characterize honeydew and floral honeys from Bulgaria and North Macedonia based on their NMR profiles. The 1D and 2D 1H and 13C-NMR spectra were measured of 16 North Macedonian and 22 Bulgarian honey samples. A total of 25 individual substances were identified, including quinovose, which was found for the first time in honey. Chemometric methods (PCA&mdash;principal component analysis, PLS-DA&mdash;partial least squares discriminant analysis, ANOVA&mdash;analysis of variance) were used to detect similarities and differences between samples, as well as to determine their botanical and geographical origin. Semiquantitative data on individual sugars and some other constituents were obtained, which allowed for the reliable classification of honey samples by botanical and geographical origin, based on chemometric approaches. The results enabled us to distinguish oak honeydew honey from other honey types, and to determine the country of origin. NMR was a rapid and convenient method, avoiding the need for other more time-consuming analytical techniques