- Stable isotope characterization of the ortho-oxygenated phenylpropanoids: Coumarin and melilotol
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The natural abundance 2H NMR spectra of extractive coumarin 10 and of its dihydroderivative melilotol 11 produced by baker's yeast reduction has been compared with synthetic materials. Diagnostic for the differentiation of 10 are the (D/H)β values, which are in the 128.1-133.6 ppm interval for the natural compounds but 258.5 and 189.8 ppm for the synthetic materials. Such a dramatic difference is also found for methyl cinnamate 12, which shows (D/H)β values of 127.2 and 515.8 ppm, respectively. In extractive 10, the ratio (D/H)4(para)/(D/H)6(ortho) = 1.24 is similar to that observed in structurally related salicin and methyl salicylate. Coumarin 10 is transformed in salicyl alcohol 9, providing diacetate 14, showing in the natural series the trend (D/H)3(meta) > (D/H)4(para) > (D/H)5(meta) ~ (D/H) 6(ortho). A similar trend is shown also by the synthetic 10. A clear distinction between extractive and synthetic 10 is obtained through δ18O determinations on 10 and on chroman 13. The bulk δ18O values in the extractive series of 10 are 20.3, 23.6, and 22.6‰, while those of the aromatic oxygen are 2.3, 0.5, and -0.5‰. In the synthetic sample, the values are 12.6 and 5.6‰, respectively. As a final product, the reduction of 10 leads to the dihydroderivative 11. Both the baker's yeast reduction and the catalytic hydrogenation lead to a marked decrease of the deuterium content of 11, which is stronger for the β-position than for the α-position.
- Brenna, Elisabetta,Fronza, Giovanni,Fuganti, Claudio,Gatti, Francesco G.,Grande, Valentina,Serra, Stefano,Guillou, Claude,Reniero, Fabiano,Serra, Francesca
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- Probing the Existence of a Metastable Binding Site at the β2-Adrenergic Receptor with Homobivalent Bitopic Ligands
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Herein, we report the development of bitopic ligands aimed at targeting the orthosteric binding site (OBS) and a metastable binding site (MBS) within the same receptor unit. Previous molecular dynamics studies on ligand binding to the β2-adrenergic receptor (β2AR) suggested that ligands pause at transient, less-conserved MBSs. We envisioned that MBSs can be regarded as allosteric binding sites and targeted by homobivalent bitopic ligands linking two identical pharmacophores. Such ligands were designed based on docking of the antagonist (S)-alprenolol into the OBS and an MBS and synthesized. Pharmacological characterization revealed ligands with similar potency and affinity, slightly increased β2/β1AR-selectivity, and/or substantially slower β2AR off-rates compared to (S)-alprenolol. Truncated bitopic ligands suggested the major contribution of the metastable pharmacophore to be a hydrophobic interaction with the β2AR, while the linkers alone decreased the potency of the orthosteric fragment. Altogether, the study underlines the potential of targeting MBSs for improving the pharmacological profiles of ligands.
- Gaiser, Birgit I.,Danielsen, Mia,Marcher-R?rsted, Emil,R?pke J?rgensen, Kira,Wróbel, Tomasz M.,Frykman, Mikael,Johansson, Henrik,Br?uner-Osborne, Hans,Gloriam, David E.,Mathiesen, Jesper Mosolff,Sejer Pedersen, Daniel
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p. 7806 - 7839
(2019/09/07)
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- Quinuclidyl benzoxepins as 5-HT3 antagonists
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Certain specific substituted 9-N-(1-azabicyclo-[2.2.2.]octan-3-yl)carboxamido-2,3,4,5-tetrahydro-1-benzoxepins and their valuable use as 5-HT3 antagonists having CNS and gastric prokinetic acticity and void of any significant D2 receptor binding properties are disclosed. Methods for their preparation also are described.
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- Methylase Models: Studies on General-Base vs. Nucleophilic Catalysis in the Intramolecular Alkylation of Phenols
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The ortho substituted phenols, 1 and 3, have been synthesized as models for the O-methylation of catecholamines, as catalyzed by catechol O-methyltransferase.The decomposition of 1 and 3 was studied at 40 deg C over a wide range of pH in both oxyanion and
- Knipe, Jay O.,Vasquez, Peter J.,Coward, James K.
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p. 3202 - 3209
(2007/10/02)
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