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ABSTRACT: Cu supported catalysts (support: γ-Al2O3, Fe2O3, TiO2) have been conveniently prepared by deposition of Cu particles from acetone solvated Cu atoms. The catalysts have been characterized
by HRTEM analysis, showing a quite homogeneous Cu particle size distribution. They are active systems for the partial oxidation
of cyclohexane to cyclohexanol and cyclohexanone. After the catalytic experiment the Cu/γ-Al2O3 and Cu/TiO2 systems can be reused without valuable loss of activity, while the Cu/Fe2O3 system is quite inactive.
Catalysis Letters 05/2012; 116(1):57-62. · 2.24 Impact Factor
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ABSTRACT: Ln DOTA derivatives (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) are known to undergo relevant stereoisomeric equilibria in solution, which greatly modulate their chemical as well as their magnetic and optical properties. The subject is reviewed in terms of classical stereochemical description, with reference to conformational enthalpies. Yb is taken as the reference element because of its unique spectroscopic properties, namely, a small contact contribution to the paramagnetic shift and an intense near-infrared electronic circular dichroism, endowed with an easily recognizable fine structure.
ChemPhysChem 06/2011; 12(8):1490-7. · 3.41 Impact Factor
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ABSTRACT: A convenient route for the covalent immobilization of quinidine and hydroquinidine pyridazine ethers on insoluble polystyrene supports is described, which avoids the need of chromatographic purifications at any stage. The use of the heterogeneized alkaloid derivatives in the asymmetric organocatalytic dimerization of ketenes afforded high enantioselectivity values (90–97% ee) in the course of 20 reaction cycles.
Advanced Synthesis & Catalysis 05/2010; 352(9):1434. · 6.05 Impact Factor
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ABSTRACT: The interaction between quercetin, a popular antioxidant flavonoid, and human serum albumin (HSA) is investigated and characterized by means of induced circular dichroism and saturation transfer difference NMR. These techiques demonstrate the reversible binding of quercetin to the carrier protein, which is responsible for its dissolution in aqueous medium. Competition experiments with two classical probes for HSA binding sites, namely Ibuprofen and Warfarin (a common anticoagulant coumarin), demonstrate that quercetin has a primary binding site located in the subdomain IIA, where coumarins are hosted. The affinity for this site is large and we found that quercetin may effectively displace warfarin from HSA. This may have relevant consequences in rationalizing the interferences of common dietary compounds and food supplements to anticoagulant treatments.
Chirality 11/2009; 22(6):593-6. · 2.35 Impact Factor
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Andrea Dovio,
Eliana Roveda,
Chiara Sciolla,
Angela Montaruli,
Andrea Raffaelli,
Alessandro Saba,
Giovanna Calogiuri,
Silvia De Francia,
Paolo Borrione, Piero Salvadori,
Franca Carandente,
Alberto Angeli
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ABSTRACT: Intense physical exercise activates the hypothalamic-pituitary-adrenocortical axis but little is known about changes in glucocorticoid sensitivity at the target cell level. No data are available on the acute effects of exercise on 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 activity, which generates biologically active cortisol from inactive cortisone and is expressed also in skeletal muscle. Fifteen healthy, trained males (age mean +/- SE 28 +/- 1) were assessed on three non-consecutive days: at rest, during an endurance and strength sessions. During each session, between 1000 and 1600 hours, 6-h urine and four salivary samples were collected. Urinary total tetrahydrocortisol (THF) + alloTHF, tetrahydrocortisone (THE), cortisol (F) and cortisone (E) were measured with HPLC-tandem mass spectrometry; urinary-unconjugated F and E were measured by HPLC-UV. Salivary cortisol and interleukin (IL)-6 were measured by RIA and ELISA, respectively. Both endurance and strength exercises caused an increase in (THF + alloTHF)/THE ratio (mean +/- SE 1.90 +/- 0.07 and 1.82 +/- 0.05 vs. 1.63 +/- 0.06, P < 0.01 and P = 0.03, respectively), consistent with increased systemic 11beta-HSD type 1 activity. No relationship was found with age, BMI, VO(2max) maximal power load or perceived exertion. No significant change was apparent in F/E ratio, an index of 11beta-HSD type 2 activity. No effect of exercise on salivary cortisol and IL-6 was observed, whereas a significant effect of sampling time was found. Intense physical exercise acutely increases systemic 11beta-HSD type 1 activity in humans. Such an increase may lead to higher cortisol concentration in target tissues, notably in skeletal muscle where it could contribute to limit exercise-induced muscle inflammatory response.
Arbeitsphysiologie 11/2009; 108(4):681-7. · 2.15 Impact Factor
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ABSTRACT: Alteration of levels of glucocorticoids in plasma and urine can be related to several diseases. In particular, the determination of endogenous glucocorticoids in urine has been reported to provide information on cortisol and cortisone status, on the activities of steroid hormone enzymes and on glucocorticoid metabolism. In this study, the application of hyphenated mass spectrometry techniques (GC/MS without derivatization and LC/MS) for the simultaneous analysis of free urinary cortisol (F), cortisone (E), tetrahydrocortisol (THF), allo-tetrahydrocortisol (A-THF) and tetrahydrocortisone (THE) was evaluated. A sample preparation protocol by solid-phase extraction, mass spectrometry parameters and chromatographic conditions for both techniques were carefully optimized in terms of extracting phase and solvents, matrix effects, recovery, sensitivity and compound resolution. Baseline separation was achieved for the five underivatized analytes both in GC and LC. The LC/MS/MS technique was more suitable for the analysis of urine samples, being less influenced by matrix effects and showing excellent sensitivity and selectivity. A preliminary application of the reported method for the diagnosis of metabolic diseases was also described. The determination of each analyte in its free form, described for the first time in the paper, offers new perspectives in the application of glucocorticoid analysis for diagnostic purposes.
Rapid Communications in Mass Spectrometry 09/2009; 23(18):2975-82. · 2.79 Impact Factor
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Annalen der Chemie und Pharmacie 05/2009; 2009(19):3279 - 3284. · 3.10 Impact Factor
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ABSTRACT: Vitamin E derivatives bearing a carboxylic group have recently gained great attention because of their antitumoral properties. Garcinoic acid (trans-13'-carboxy-delta-tocotrienol) is a vitamin E analog extracted from Garcinia Kola seeds in which the carboxylic group is at the end of the aliphatic side chain and reported to be a racemate based on the optical rotation measurements. However, CD determination of a sample of the acid analyzed by us gave a positive peak at 208 nm, indicating that it is not a racemate. To assess the enantiomeric composition of garcinoic acid, it was thus transformed to alpha-tocopherol and analyzed by chiral HPLC on column OD-H. On the basis of the elution order of alpha-tocopherol stereoisomers, the garcinoic acid sample resulted to be enantiopure with R configuration at carbon 2 of the chroman ring. Moreover, in a preliminary test, the acid and some of its derivatives showed a marked antiproliferative effect on glioma C6 cancer cells.
Chirality 05/2009; 21(5):519-24. · 2.35 Impact Factor
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Annalen der Chemie und Pharmacie 03/2009; 2009(13):2063 - 2068. · 3.10 Impact Factor
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ABSTRACT: a b s t r a c t The growth of Pt particles in mesitylene-solvated metal atoms, obtained by metal vapour synthesis (MVS), has been followed at two temperatures (À40 and 25 °C) by NMR DOSY technique. The addition of 1,3-divinyltetramethyldisiloxane (DVS) at different time allows to quench the growth process and to make the resulting thermally stable solutions suitable for the evaluation of the Pt particles size at that moment. These solutions can be conveniently used to prepare supported Pt systems containing Pt parti-cles of tailored size.
Journal of Organometallic Chemistry 02/2009; · 2.38 Impact Factor
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Ines Kock,
Siegfried Draeger,
Barbara Schulz,
Brigitta Elsässer,
Tibor Kurtán,
Ágnes Kenéz,
Sándor Antus,
Gennaro Pescitelli, Piero Salvadori,
John-Bryan Speakman,
Joachim Rheinheimer,
Karsten Krohn
Annalen der Chemie und Pharmacie 02/2009; 2009(9):1427 - 1434. · 3.10 Impact Factor
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Annalen der Chemie und Pharmacie 01/2009; 2009(5):749 - 756. · 3.10 Impact Factor
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ABSTRACT: Six new metabolites, namely cycloepoxylactone (1a), cycloepoxytriol A (2), cycloepoxytriol B (3) and phomolactones A–C (4–6), were isolated from two cultures of the ethyl acetate soluble fraction of the endophytic fungus Phomopsis sp. (internal strain no. 7233). Their structures were determined by
means of spectroscopic data including HREIMS, 1 H NMR, 13 C NMR, and 2D NMR (HMQC, HMBC, and NOESY). The absolute configurations of 1a, 4 and 5 were determined by circular dichroism and comparison of solution CD spectra with TDDFT-calculated ones. Preliminary studies showed that cycloepoxylactone (1a) has good antibacterial, antifungal, and algicidal activity against Bacillus megaterium, Microbotryum violaceum, and Chlorella fusca, respectively, whereas cycloepoxytriol B (3) has good algicidal activity against Chlorella fusca
European Journal of Organic Chemistry 01/2009; · 3.33 Impact Factor
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ABSTRACT: A new insoluble polymer-bound bisoxazoline (IPB-box) was prepared by grafting a suitable chiral ligand
derivative onto a commercial Merrifield resin. The material obtained by this route was employed in the
asymmetric copper-catalyzed olefin cyclopropanation, obtaining good activity and enantioselectivity
values (54–84% yield, 71–93% ee) for a range of substrates. In addition, some key factors required for the
development of effective IPB-box systems are discussed, including the local ligand symmetry and the
influence of immobilization technique and catalyst loading.
Catalysis Today 01/2009; · 3.41 Impact Factor
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ABSTRACT: A previously reported method for the assessment of the ratio of tetrahydrocortisol (THF) + allo-tetrahydrocortisol (A-THF) to tetrahydrocortisone (THE) by HPLC-MS-MS has been significantly improved, in order to increase either ruggedness and reliability. That was achieved by the introduction of an on-line sample cleanup stage, which made use of a perfusion column as a solid phase microextraction (SPE) cartridge. The set of analytes was expanded, by introducing cortisol and cortisone, whose ratio supply additional diagnostic information. The response factors of both THF and A-THF has been checked, resulting almost identical, as well as the influence of the matrix on the calibration curves which, although different for water and urine, had similar effect on the ratios of interest. As a consequence, the calibration solutions can be prepared in pure water. The influence of several different storage procedures has also been tested, resulting in no substantial effect on the final result. Finally, the improved method has been used to run real samples from healthy volunteers, with satisfactory results.
Biological Mass Spectrometry 12/2008; 44(4):541-8. · 3.41 Impact Factor
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ABSTRACT: Four new alpha-methylene-gamma-lactone-bearing cembranoids, 20-acetylsinularolide B (6), presinularolide B (7), 3-dehydroxylpresinularolide B (8), and 3-dehydroxyl-20-acetylpresinularolide B (9), together with five known analogues, sinularolides B-E (1- 4) and 20-acetylsinularolide C (5), were isolated from a South China Sea soft coral Lobophytum crassum. Their structures and relative stereochemistry were established by a combination of detailed spectroscopic data analysis and chemical correlations. The structures of 1- 9 were further confirmed by an X-ray diffraction study on a single crystal of sinularolide B (1). The absolute configurations of sinularolide B (1) and presinularolide B (7) were determined by a novel solid-state CD/TDDFT approach and by a modified Mosher's method, respectively. This study also revealed that the coupling constant between the lactonic methine protons ((3) J 1,2) varies considerably with different functional groups on the cembrane ring and that the determination of the stereochemistry of lactone ring fusion based on this coupling constant is risky. In a bioassay, sinularolides B and C (1 and 2) and new cembranoids 7 and 8 showed in vitro cytotoxicity against the tumor cell lines A-549 and P-388.
Journal of Natural Products 07/2008; 71(6):961-6. · 3.13 Impact Factor
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ABSTRACT: Vitamin E is an essential nutrient of still increasing economic importance. Vitamin E derivatives include many nonracemic chiral compounds whose chirooptical characterization is scarcely described in the literature. We report the CD spectra of delta-tocopherol and its unsaturated analog delta-tocotrienol. TDDFT calculations demonstrate that the weak CD of delta-tocopherol is determined by the helicity of dihydropyrane ring. In addition, the moderate CD of delta-tocotrienol is due to the exciton interaction between the aromatic ring and the closest alkene group. Direct exciton-coupled CD calculations on structures generated by two different conformational sampling approaches reveal that, although such exciton coupling is expected to be weak, it is sufficient to explain the spectral differences between tocopherol and tocotrienol.
Chirality 07/2008; 21(1):35-43. · 2.35 Impact Factor
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ABSTRACT: The visible (alpha) and near-UV (beta) CD bands of rhodopsin have been studied extensively, but their source(s) have never been definitively established. Do they result from the intrinsic chirality of the polyene chromophore of the protonated Schiff base of retinal (retPSB) or from the coupling of the transitions of this chromophore with those of protein groups? We have calculated the contributions of these two mechanisms to the CD of rhodopsin. The intrinsic CD of the retPSB chromophore was calculated using time-dependent density functional theory (TDDFT) and, for comparison, the semiempirical ZINDO method. First-order perturbation theory was used to calculate the effects of coupling of the retPSB transitions with the pi pi* transitions of the aromatic chromophores and the pi pi* and n pi* transitions of the peptide groups in rhodopsin. Calculations were performed for eight structures based upon the two molecules in the asymmetric unit of four crystal structures. The most reliable results were obtained from TDDFT calculations on the structure of Okada et al. (J. Mol. Biol. 2004, 342, 571), PDB 1U19. Averaging over the two molecules in the asymmetric unit, the intrinsic rotational strengths are 0.62 +/- 0.00 DBM (Debye-Bohr magneton) and 0.90 +/- 0.03 DBM for the alpha- and beta-bands, respectively. The contributions from coupling with protein groups are, respectively, -0.32 +/- 0.05 and -0.01 +/- 0.03 DBM. Our results show that the visible/near-UV CD bands of rhodopsin are determined by the intrinsic chirality of the retPSB chromophore and that the contributions of coupling with the protein are significantly smaller for the alpha-band and negligible for the beta-band.
Journal of the American Chemical Society 06/2008; 130(19):6170-81. · 9.91 Impact Factor
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ABSTRACT: Pt nanoclusters have been generated by reaction of Pt vapour and mesitylene vapour and the role of the mesitylene/platinum ratio and the Pt particle size has been evaluated, quenching the resulting mesitylene solvated Pt atoms with 1,3-divinyltetramethyldisiloxane (DVS) as additional ligand. The Pt particle sizes have been estimated on the basis of DOSY (Diffusion-Ordered SpectroscopY) analysis and information on their structure features have been obtained by combined use of 2D NMR techniques.
Journal of Nanoscience and Nanotechnology 05/2008; 8(4):2096-101. · 1.56 Impact Factor
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ABSTRACT: The CD spectra of the series PhCH(Me)R, with R = Et (1), nPr (2), iPr (3), and tBu (4), are reported (1-3 for the first time) at room temperature in the 185-280 nm range and at 183 K. These purely hydrocarbon compounds represent the simplest chiral systems containing the phenyl chromophore and exhibit Cotton effects exclusively allied with the benzene transitions. The bands in 1La and 1Lb regions were checked against the available sector rules, with discordant outcomes. Time-dependent density-functional theory calculations, with various functionals and basis sets tested, correctly reproduced the prominent CD bands observed for 1-4.
Chirality 04/2008; 20(3-4):393-9. · 2.35 Impact Factor
