Search results for "AROMA"
showing 10 items of 1006 documents
Retene, pyrene and phenanthrene cause distinct molecular-level changes in the cardiac tissue of rainbow trout (Oncorhynchus mykiss) larvae, Part 2 – …
2020
Polycyclic aromatic hydrocarbons (PAHs) are global contaminants of concern. Despite several decades of research, their mechanisms of toxicity are not very well understood. Early life stages of fish are particularly sensitive with the developing cardiac tissue being a main target of PAHs toxicity. The mechanisms of cardiotoxicity of the three widespread model polycyclic aromatic hydrocarbons (PAHs) retene, pyrene and phenanthrene were explored in rainbow trout (Oncorhynchus mykiss) early life stages. Newly hatched larvae were exposed to sublethal doses of each individual PAH causing no detectable morphometric alterations. Changes in the cardiac proteome and metabolome were assessed after 7 o…
How nitrogen modifies the nuclear magnetic shielding in tetraazanaphthalenes
2009
Although for planar conjugated hydrocarbons the out-of-plane component of proton magnetic shielding is an unquestionable quantitative aromaticity indicator, the same is not true for tetraazanaphthalenes. As in these compounds the (core + sigma)-currents associated to the nitrogen nuclei diminish the perpendicular component of shielding, abnormal values of (1)H NMR sigma(zz) are obtained. Therefore, a consistent aromaticity measure must be based only on the pi-contribution to the out-of-plane component of proton magnetic shielding. Otherwise, the behavior of these compounds in presence of an external magnetic field parallels that of naphthalene, with the nitrogen nuclei contributing to the r…
Aromaticity of the most stable adenine and purine tautomers in terms of Hückel's 4N+2 principle
2019
Abstract Electron structures of the fused rings in 7H and 9H tautomers of purine and adenine follow the 4N + 2 rule; the values of pEDA, HOMA, NICS and FLU indices document their aromatic character. In the 1H and 3H tautomers, these rings contain five or seven π electrons, hence they do not follow this rule and consequently exhibit lower aromaticity. This also applies to the aromaticity of whole molecules.
Dimethylpyridin-4-ylamine-Catalysed Alcoholysis of 2-Amino-N,N,N-Trimethyl-9H-purine-6-ylammonium Chloride: An Effective Route to O6-Substituted Guan…
2002
Dimethylpyridin-4-ylamine (DMAP)-catalysed reactions of 2-amino-N,N,N-trimethyl-9H-purine-6-ylammonium chloride with fluoropyridine methoxides and various other alkoxides in DMSO at 60 °C gave the corresponding coupling products in moderate to good yields between 20-87%. Under these reaction conditions, fluorinated O 6 -substituted Guanine derivatives have been synthesized which could not be obtained via known analogous literature procedures. The respective yields of known O 6 -substituted guanine derivatives could be significantly improved by using this method. The efficient use of DMAP as an excellent nucleophilic catalyst in the syntheses of O 6 -substituted Guanine derivatives has thus …
Surface-Enhanced Raman Study of the Interactions between Tripodal Cationic Polyamines and Polynucleotides
2011
Raman and surface-enhanced Raman spectra of new DNA/RNA-binding compounds consisting of three imidazole (Im) and three pyridine (Py) rings connected by tripodal polyaminomethylene linkages were obtained by the near-infrared excitation at 1064 nm. Study of interactions of Im and Py polyamines with single-stranded RNA polynucleotides (poly A, poly G, poly C, poly U), double-stranded DNA polynucleotides (poly dAdT-poly dAdT, poly dGdC-poly dGdC) and calf thymus DNA (ct-DNA) by surface-enhanced Raman spectroscopy (SERS) reveals unambiguous enhancement of the Raman scattering from the small molecules as well as appearance of new bands in spectra associated mainly with nucleobases. The SERS exper…
Synthesis and electronic aspects of tetrahydrobenzothienopyrimidine derivatives
2015
Abstract The chemistry of thiophenes, pyrimidines, triazolopyrimidines and benzothiophenes has drawn much attention because of their biological activities. Their interesting properties are connected with their complex π-electron delocalisation effects. Herein the synthesis, crystal and molecular structures at 100 K and DFT calculated structures of three tetrahydrobenzothienopyrimidine derivatives are reported i.e. 4-hydrazino-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidine which was a substrate for 2-phenyl-8,9,10,11-tetrahydro[1]benzothieno[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine and 3-methyl-9,10,11,12-tetrahydro-2H-[1]benzothieno[2′,3′:4,5]pyrimido[1,6-b][1,2,4]triazin-2-one. Moreover t…
Study of relationships between the structure of aroma compounds and their retention-release between vapour phase and dairy gels
2010
An integrated approach physicochemistry and structures activity relationships has been carried out to study the aroma compounds retention-release phenomenon in a fat free dairy gel added with pectin. This study aimed to identify the molecular properties that govern this phenomenon assuming that modifying the structure leads automatically to a change in the retention-release of aroma compounds. For this purpose, we have determined the partition coefficients of 28 aroma compounds in water, in pectin gels and in dairy gels supplemented or not supplemented with pectin, at equilibrium conditions using the PRV method (Phase Ratio Variation). Then, we have performed a structure-retention relations…
Assessment of polycyclic aromatic hydrocarbons (PAHs) in soil of a Natural Reserve (Isola delle Femmine) (Italy) located in front of a plant for the …
2009
Isola delle Femmine Natural Reserve is a very little isle about 15 km from the centre of Palermo, in front of a plant for the production of cement and about 600 m from coast. In the present research, profiles soil PAHs were obtained for 16 sites within the reserve and for 8 stations on the rural soil taken as reference. summation Sigma PAHs, in the soil of investigated area, ranged from 35 to 545 microg/kg. With the aim to find the origin of PAHs in the soil of Isola delle Femmine, we compare the distribution of single analytes in the investigated area with those of the reference rural area (Monte Raffo Rosso), with those of atmospheric urban particulate collected at Palermo along with repo…
Interaction between flavour compounds and beta-lactoglobulin: approach by NMR and 2D/3D-QSAR studies of ligands
2004
author cannot archive publisher's version/PDF; International audience; Interactions between flavour compounds and beta-lactoglobulin (BLG) have been the subject of several studies, but there are no unanimous binding site explanations. In our laboratory, interactions between BLG, and two flavour compounds, beta-ionone and gamma-decalactone, were studied by 2D-NMR spectroscopy. It appears that several amino acids affected by binding of gamma-decalactone are buried in the central cavity, whereas binding of beta-ionone affects amino acids located in a groove near the outer surface of the protein. 2D/3D-QSAR studies were performed using QSAR+ module of Cerius2 and Catalyst. The QSAR equation pr…
2D- and 3D-QSAR Models of Interaction between Flavor Compounds and beta-Lactoglobulin Using Catalyst and Cerius2
2004
The present paper describes an application of Catalyst to three aroma sets (35, 24 and 21 compounds respectively) to generate activities-based alignments, using the best significant generated hypotheses. The obtained Catalyst models confirmed the existence of at least two binding sites on the BLG.