Head space (HS) solid phase microextraction (SPME) followed by gas chromatography with mass spectrometry detection (GC-MS) is the most widespread technique to study the volatile profile of honey samples. In this paper, the experimental SPME conditions were optimized by a multivariate strategy. Both sensitivity and repeatability were optimized by experimental design techniques considering three factors: extraction temperature (from 50 ∘ C to 70 ∘ C), time of exposition of the fiber (from 20 min to 60 min), and amount of salt added (from 0 to 27.50%). Each experiment was evaluated by Principal Component Analysis (PCA) that allows to take into consideration all the analytes at the same time, preserving the information about their different characteristics. Optimal extraction conditions were identified independently for signal intensity (extraction temperature: 70 ∘ C; extraction time: 60 min; salt percentage: 27.50% w/w) and repeatability (extraction temperature: 50 ∘ C; extraction time: 60 min; salt percentage: 27.50% w/w) and a final global compromise (extraction temperature: 70 ∘ C; extraction time: 60 min; salt percentage: 27.50% w/w) was also reached. Considerations about the choice of the best internal standards were also drawn. The whole optimized procedure was than applied to the analysis of a multiflower honey sample and more than 100 compounds were identified.
Two new HA derivatives bearing carborane rings were synthesized by click chemistry. The optimal conditions were assessed for the preparation of biocompatible boron carriers, potentially suitable for application in BNCT and capable of targeting the CD44 antigen. The new polymeric samples were characterized by means of NMR-spectroscopy techniques that gave degrees of 17 and 8% for HAAACB and HapACB, respectively. Both HAAACB and HApACB turned out to be nontoxic for colorectal, ovarian and bladder tumor cell lines, to disclose a specific interaction with the CD44 antigen as the native hyaluronan moiety, and to deliver boron-atom concentrations largely sufficient for BNCT therapy when accumulated in cancer cells.
The synthesis of a carba-analogue corresponding to the trisaccharide repeating unit of Streptococcus pneumoniae type 19F capsular polysaccharide, where a residue of carba-L-rhamnose has been inserted into the natural trisaccharide in place of L-rhamnose, is described. The conformational properties of the analogue were investigated with the aid of molecular dynamics simulations and were strictly analogous to those of the natural compound. The biological activity of the carba-analogue was comparable to that of the corresponding natural repeating unit, thus suggesting that this compound, more stable to hydrolysis, is a good mimic of the natural structure.
Flash column chromatography was performed on Merck silica gel 60 (0.040-0.063 mm), following a literature procedure. 1 Reactions were monitored by TLC on Merk silica gel 60 F 254 plates, and the compounds were detected by examination under UV light and by charring with phosphomolybdate based reagent. Solvents were removed under reduced pressure below 40 °C. CH 2 Cl 2 was dried and stored over 4 Å molecular sieves. All reactions (if not specifically including water as a reactant, solvent, or co-solvent) were performed under an Ar atmosphere, in oven-dried glassware. 1 H NMR spectra were recorded in CDCl 3 at 300 MHz, 13 C NMR spectra at 75 MHz as an internal reference.Chemical shifts (δ) are given in parts per million; multiplicities are indicated as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet), and br (broad). Coupling constants (J) are reported in hertz.
Synthesis of 9-hydroxynonanoic acid (1)1,18-octadec-9-enedioic acid (4)Compound 4 was prepared according to a literature procedure. 2 Oleic acid (89 g (90%), 0.315 mol) was transferred into a 250-mL three-necked round-bottomed flask via syringe and outgassed with N 2 for 0.5 h. 1,3-Bis-(2,4,6-trimethylphenyl)-2-(imidazolidinylidene) (dichlorophenylmethylene)tricyclohexylphosphine) ruthenium (267 mg, 0.315 mmol), 2 nd generation Grubbs catalyst, was then added. The reaction mixture was stirred with a mechanical stirrer and heated at 45°C, and after ~5 min the diacid began to precipitate from the reaction mixture. After 3 days stirring the crude product was quenched with ethyl vinyl ether (40 mL), and excess ether was removed under reduced pressure. The residue was recrystallized several times from a mixture of hexane (300 mL) and ethyl acetate (50 mL) to give pure 4 as a white solid (
The preparation of anomeric tetrabutylammonium sulphates of glucose and galactose derivatives is reported and their role as donors in glycosylation reactions is studied. Metal triflates showed good performance in activating...
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