Some observations of various 1,8 naphthoquino-dimethane biradicals by electron spin resonance spectroscopy

Photolysis of 8-methyl-1-naphthyldiazomethane at 4 K gives the triplet ESR spectrum of 1,8-naphthoquinodimethane but not that of 8-methyl-1-naphthylcarbene. Photolysis of either 8-methyl-1-azido-naphthalene or 8-amino-1-azidonaththalene does produce the triplet biradical spectra of 8-imino-1-naphthoquinomethane and 1,8-diiminonaphthoquinodimethane, in addition to the triplet nitrene spectra of 8-methyl-1-nitreno-naphthalene and 8-amino-1-nitreno-naphthalene. Curie Law analyses demonstrate that these biradicals are all ground state triplets. Hückel and INDO calculations pertaining to the biradicals are reported. Large charge transfer interactions were observed in the ESR spectra of 8 substituted-1-naphthyl nitrenes.     

Phenolic Characterization and Neuroprotective Properties of Grape Pomace Extracts

Vitis vinifera (grape) contains various compounds with acknowledged phytochemical and pharmacological properties. Among the different parts of the plant, pomace is of particular interest as a winemaking industry by-product. A characterization of the water extract from grape pomace from Montepulciano d’Abruzzo variety (Villamagna doc) was conducted, and the bioactive phenolic compounds were quantified through HPLC-DAD-MS analysis. HypoE22, a hypothalamic cell line, was challenged with an oxidative stimulus and exposed to different concentrations (1 µg/mL⁻¹ mg/mL) of the pomace extract for 24, 48, and 72 h. In the same conditions, cells were exposed to the sole catechin, in a concentration range (5–500 ng/mL) consistent with the catechin level in the extract. Cell proliferation was investigated by MTT assay, dopamine release through HPLC-EC method, PGE₂ amount by an ELISA kit, and expressions of neurotrophin brain-derived neurotrophic factor (BDNF) and of cyclooxygenase-2 (COX-2) by RT-PCR. The extract reverted the cytotoxicity exerted by the oxidative stimulus at all the experimental times in a dose-dependent manner, whereas the catechin was able to revert the oxidative stress-induced depletion of dopamine 48 h and 72 h after the stimulus. The extract and the catechin were also effective in preventing the downregulation of BDNF and the concomitant upregulation of COX-2 gene expression. In accordance, PGE₂ release was augmented by the oxidative stress conditions and reverted by the administration of the water extract from grace pomace and catechin, which were equally effective. These results suggest that the neuroprotection induced by the extract could be ascribed, albeit partially, to its catechin content.     

Synthesis of soluble polymers for medicine that degrade by intramolecular acid catalysis

Aqueous soluble polymers designed to rapidly degrade by an intramolecular assisted acid catalysed mechanism were prepared. Degradation studies at pH 5.5 and 2.0 exhibited a rapid first phase followed by a slower phase and incomplete degradation to macromonomeric species. The fast phase was attributed to repeat units containing a carboxylic acid pendent chain cis to an amide bond in the polymer mainchain and the slow phase by the absence of this free carboxylic acid moiety.     

Two dimensional infrared (2D-IR) spectroscopic studies of the viscoelastic behavior of liquid crystalline polyurethanes

Dynamic infrared dichroism techniques have been used to study a complex side chain liquid crystalline segmented polyurethane. The obtained dynamic spectra were analyzed using two dimensional infrared techniques (2D-IR) that allow the easier interperation of the dynamic response of this system. Side chain mesogens are monitored by the cyano tag at the end of the molecule while the hard segments can be viewed in the carbonyl spectral region. A study of the different parts of the macromolecule leads to an understanding of the elastic and the viscous orientation behavior of the polymer. We find that the elastic component of the strain aligns smectic layers parallel and hard domains perpendicular to the direction of strain. The viscous strain component, on the other hand, induces a perpendicular smectic layer and parallel hard domain orientation behavior. These observations are consistent with a model proposed in earlier work that the hard segments and the smectic layers change orientation as the applied strain is increased from low to high strains. In addition, we show further evidence for the coupling of the mechanical deformation behavior of the smectic layers and the hard domains and identified two primary relaxation times in this system.