84877-52-1Relevant articles and documents
Tuning the emission of a water-soluble 3-hydroxyflavone derivative by host-guest complexation
Li, Dahua,Xing, Yuzhi,Ding, Lan,Wu, Chengfeng,Hou, Guangliang,Song, Bo
, p. 4231 - 4237 (2018/06/07)
3-Hydroxyflavone derivatives have great potential as fluorescent probes for bio-labeling in aqueous medium. They were extensively studied in various organic solvents for the "excited state intramolecular proton transfer" process, but seldom addressed in aqueous solution due to the poor water solubility. Herein, an amphiphilic molecule bearing 3-hydroxyflavone and oligo(ethylene oxide) (denoted as 3HF-EO) was designed and synthesized. Different from the fluorescence in organic solvents, 3HF-EO in aqueous solution showed a remarkable single fluorescence emission, which is ascribed to the fluorescence of its anionic species. We found that the fluorescence intensity could be efficiently tuned via host-guest complexation. α-CD has little effect on the emission, while β-CD and γ-CD lead to enhanced and reduced emissions of 3HF-EO, respectively. The 1H NMR and 2D NOESY NMR spectra indicate that α-CD barely had any interaction with 3HF-EO, while β-CD and γ-CD formed complexes with one and two 3HF-EO molecules, respectively. These results provide a sound explanation for the modulated fluorescence intensity.
Reversal of aryl bromide reactivity in Pd-catalysed aryl amination reactions promoted by a hemilabile aminophosphine ligand
Parisel, Sebastien L.,Adrio, Luis Angel,Pereira, Adriana Amoedo,Pérez, Marta Marino,Vila, José M.,Hii, King Kuok
, p. 9822 - 9826 (2007/10/03)
Incorporation of a hemilabile amino group with a bulky, electron-rich phosphorus ligand led to a reversal in the order of aryl bromide reactivity in Pd-catalysed aryl amination reactions.
Mechanistic Studies on Dopamine β-Monooxygenase Catalysis: N-Dealkylation and Mechanism-Based Inhibition by Benzylic-Nitrogen-Containing Compounds. Evidence for a Single-Electron-Transfer Mechanism
Wimalasena, Kandatege,May, Sheldon W.
, p. 4036 - 4046 (2007/10/02)
Dopamine β-monooxygenase (DBM) readily catalyzes oxidative N-dealkylation of N-phenylethylenediamine (PEDA) and N-methyl-N-phenylethylenediamine (N-MePEDA) with the reaction characteriscics expected for a monooxygenase-catalyzed process.The products of this reaction have been quantitatively identified as aniline (or N-methylaniline for N-MePEDA) and 2-aminoacetaldehyde, the latter compound being successfully trapped by using NaBH4 reduction followed by N-succinimidyl p-nitriphenylacetate (SNPA) derivatization, and identified by HPLC and mass spectroscopy.In contrast, either analogues of PEDA, i.e. phenyl 2-aminoethyl ether (PAEE) and its p-hydroxy derivative (p-OHPAEE), as well as 2-phenoxycycloprpylamine are not substrates but are competitive inhibitors.Furthermore, 2-methyl-2-anilino-1-aminoethane (β-MePEDA) did not exhibit measurable substrate activity with DBM, in contrast to the excellent substrate activity of the sulfur analogue of β-MePEDA, 2-methyl-2-(phenylthio)-1-aminoethane (β-MePAES).DBM is inactivated during the N-dealkylation reaction in a time- and concentration-dependent manner, a phenomenon that has not, to our knowledge, been observed for any other oxygenase-catalyzed N-dealkylation reaction.Both PEDA and N-MePEDA, as well as β-MePEDA, inactivate DBM under turnover conditions.The inactivation exhibited pseudo-first-order saturable kinetics and expected protection by the DBM substrate, tyramine.No reappearance of enzyme activity was observed after extensive dialysis.Radioactive labeling experiments with ring-tritiated PEDA showed incorporation of nondialyzable radioactivity into DBM in the expected amount, consistent with covalent attachment of a reactive species derivd from PEDA to the DBM active site during enzyme inactivation.Although aniline, N-ethylaniline, N-(2-fluoroethyl)aniline, m- and p-anisidine, p-toluidine, and 5-hydroxyindole were found not to exhibit detectable DBM substrate activity, all of these inactivated the enzyme under turnover conditions.The isotope effect on partition ratio measured for dideuteriated PEDA was found to be a reflection of an isotope effect on Vmax and not on kinact.Our results provide a strong support for the conclusion that the initial nitrogen cation radical species is responsible for enzyme inactivation.Results with ring-deuteriated and ring-tritiated PEDA revealed that the amount of radioactivity incorporated into covalently inactivated DBM by ring-tritiated PEDA is in agreement with that expected for covalent attachment of the para carbon to the protein.An 18O labeling study was carried out to test for oxygen rebound into the aminoacetaldehyde product, and results demonstrated that the aldehyde oxygen of enzymatically produced 2-aminoacetaldehyde exchanges very rapidly with solvent water, in agreement with literature reports.On the basis ...
