Aggregation properties of bis(salicylaldiminato)zinc(II) Schiff-base complexes and their Lewis acidic character

The synthesis, characterization, (1)H NMR, optical absorption and fluorescent properties of a series of amphiphilic Schiff-base bis(salicylaldiminato)zinc(II) complexes are reported. Detailed (1)H NMR, DOSY NMR, optical absorption and fluorescence spectroscopy studies indicate the existence of aggregate species in solutions of non-coordinating solvents. The degree of aggregation is related to the nature of the bridging diamine. Chloroform solutions of complexes where the bridging diamine contains a naphthalene or the pyridine nucleus are always characterized by the presence of defined dimer aggregates, whereas oligomeric aggregates are likely formed by complexes where the bridging diamine contains a benzene ring. In coordinating solvents or in the presence of coordinating species, a complete deaggregation of the complexes occurs, because of the axial coordination to the Zn(II) ion, accompanied by considerable changes in the (1)H NMR and optical absorption spectra. The effect of the alkyl chains length seems to play a minor role in the aggregation properties, as noticed by (1)H NMR data, optical absorption and fluorescence spectra, which remain almost unaltered on changing the chain length.     

Tri-partite complex for axonal transport drug delivery achieves pharmacological effect

Background

Targeted delivery of pharmaceutical agents into selected populations of CNS (Central Nervous System) neurons is an extremely compelling goal. Currently, systemic methods are generally used for delivery of pain medications, anti-virals for treatment of dermatomal infections, anti-spasmodics, and neuroprotectants. Systemic side effects or undesirable effects on parts of the CNS that are not involved in the pathology limit efficacy and limit clinical utility for many classes of pharmaceuticals. Axonal transport from the periphery offers a possible selective route, but there has been little progress towards design of agents that can accomplish targeted delivery via this intraneural route. To achieve this goal, we developed a tripartite molecular construction concept involving an axonal transport facilitator molecule, a polymer linker, and a large number of drug molecules conjugated to the linker, then sought to evaluate its neurobiology and pharmacological behavior.

Results

We developed chemical synthesis methodologies for assembling these tripartite complexes using a variety of axonal transport facilitators including nerve growth factor, wheat germ agglutinin, and synthetic facilitators derived from phage display work. Loading of up to 100 drug molecules per complex was achieved. Conjugation methods were used that allowed the drugs to be released in active form inside the cell body after transport. Intramuscular and intradermal injection proved effective for introducing pharmacologically effective doses into selected populations of CNS neurons. Pharmacological efficacy with gabapentin in a paw withdrawal latency model revealed a ten fold increase in half life and a 300 fold decrease in necessary dose relative to systemic administration for gabapentin when the drug was delivered by axonal transport using the tripartite vehicle.

Conclusion

Specific targeting of selected subpopulations of CNS neurons for drug delivery by axonal transport holds great promise. The data shown here provide a basic framework for the intraneural pharmacology of this tripartite complex. The pharmacologically efficacious drug delivery demonstrated here verify the fundamental feasibility of using axonal transport for targeted drug delivery.     

Comparison of four extraction/methylation analytical methods to measure fatty acid composition by gas chromatography in meat

Four different extraction-derivatization methods commonly used for fatty acid analysis in meat (in situ or one-step method, saponification method, classic method and a combination of classic extraction and saponification derivatization) were tested. The in situ method had low recovery and variation. The saponification method showed the best balance between recovery, precision, repeatability and reproducibility. The classic method had high recovery and acceptable variation values, except for the polyunsaturated fatty acids, showing higher variation than the former methods. The combination of extraction and methylation steps had great recovery values, but the precision, repeatability and reproducibility were not acceptable. Therefore the saponification method would be more convenient for polyunsaturated fatty acid analysis, whereas the in situ method would be an alternative for fast analysis. However the classic method would be the method of choice for the determination of the different lipid classes.     

Synthesis ofN,N′-ditosyl-8, 19-dimethoxy-2,5-diaza-[6.1]-naphthyl-cyclophane: crystal and molecular structure of its 1∶1 chloroform solvate

The title compound, C₄₁H₄₀N₂O₆S₂, has been synthesised in good yield and was found to form a 11 inclusion compound with CHCl₃ and other organic solvents. The crystal and molecular structure of the CHCl₃ solvate has been determined by single crystal X-ray analysis and refined to anR-value of 0.034 for 3229 reflections. The compound is monoclinic, space groupP2₁/c, witha=15.316(1),b=14.515(1),c=18.720(3) Å, =101.98(1)^o, andZ=4. One molecule of chloroform is included in the crystal lattice. Supplementary data relevant to this article have been deposited with the British Library as Supplementary Publication No. SUP 82146 (9 pp.).     

Natural control of bacteria affecting meat quality by a neem (Azadirachta indica A. Juss) cake extract

The antibacterial activity of an ethylacetate neem cake extract (NCE) against bacteria that affect meat quality, namely Campylobacter jejuni, Carnobacterium spp., Lactobacillus curvatus, Lactobacillus sakei and Leuconostoc sp., is reported. The antibacterial activity was detected using standardised disc diffusion and macrodilution methods. The bacterial growth inhibition zone ranged from 11.33 ± 0.58 to 22.67 ± 0.58 mm (100 μL NCE). There is significant difference between the growth inhibition zone of NCE and the control (ciprofloxacin 100 μg). The percent of bacterial growth reduction range was 79.75 ± 1.53 to 90.73 ± 1.53 (100 μg NCE) as compared with control (without NCE). NCE in different amounts counteracted the growth of all tested bacteria.     

An interval framework for uncertain frequency response of multi-cracked beams with application to vibration reduction via tuned mass dampers

Meccanica - The paper addresses the frequency response of beams in presence of open cracks with interval parameters. On adopting the standard Euler–Bernoulli beam theory, every crack is...     

Conformationally Rigid Hosts Containing Phosphonic Units

We present here a new class of cleft-like receptor molecules containing two or four phosphonates anions, tailored for multipoint binding of their substrates. Depending on the accessibility of the cleft, these hosts are water soluble and selective for short or long f , y -diammonium compounds. Due to their inherent chirality, we found that only those host-guest combinations which allow a three-point-interaction were effective.     

Synthesis and NMR Spectroscopic Study of a New Bis(aminophosphonate) with Terminal Furyl Groups

1,3-Bis[ N -methyl(diethoxyphosphonyl)-1-(2-furyl)]diaminobenzene has been synthesized through the addition of diethyl phosphite to the Schiff base N , N '-difurfurylidene- m -phenylenediamine. The compound has been characterized by elemental analysis, TLC, IR, and 1 H, 13 C, and 31 P NMR spectra. The NMR studies show that the reaction product is a mixture of two diastereomers ( meso and racemic forms). The 31 P NMR data revealed 61% content for the predominant and 39% for the minor form.