- Effects of 18F-fluorinated neopentyl glycol side-chain on the biological characteristics of stilbene amyloid-β PET ligands
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Introduction: The 2,2-dihydroxymethyl-1-[18F]fluoropropane group, also called 18F-labelled neopentyl glycol side-chain, is a novel 18F-labelling group for positron emission tomography (PET) imaging agents. The aim of using this group is to develop simple purification with solid-phase extraction without high-performance liquid chromatography. However, the effects of the neopentyl 18F-labelling group on the characteristics of brain imaging agents are unknown. Here, we added this side-chain to compounds with an aminostilbene structure to evaluate their effects on the biological properties of aminostilbene as an amyloid-β (Aβ) radioligand. Methods: Biodistributions of four novel 18F-labelled stilbene compounds with different lengths of polyethylene glycol (PEG) linkers, called [18F]Cpd-0, -1, -2, and -4, (PEG = 0, 1, 2, and 4), and [18F]AV-1 in normal mice were evaluated. Metabolite analysis of [18F]Cpd-0 and -1 was performed with mouse plasma and brain. A competitive binding assay of [18F]AV-1 binding to Aβ1–42 fibrils was performed to determine the binding properties of the compounds. Results: [18F]Cpd-0, -1, and -2 demonstrated moderate initial brain uptake in mice (3.1–4.2% injected dose/g at 2 min post-injection) followed by fast clearance, and in vivo defluorination of these compounds was negligible. [18F]Cpd-4 exhibited low brain uptake and high bone uptake. Compared with [18F]Cpd-1, the percentage of [18F]Cpd-0 in mouse brain was high at 10 min post-injection. A competitive binding assay revealed partial interference effects by the neopentyl glycol side-chain on binding of stilbene compounds to Aβ1–42 fibrils. Conclusions: Aminostilbene compounds with two or fewer PEG linkers containing an 18F-labelled neopentyl glycol side-chain demonstrated preferable pharmacokinetic properties as a brain imaging radioligand in normal mice. These side-chains can be used as an alternative labelling group for imaging agents targeting the brain.
- Tago, Tetsuro,Toyohara, Jun,Fujimaki, Ryo,Tatsuta, Maho,Song, Ruichong,Hirano, Keiichi,Iwai, Kumiko,Tanaka, Hiroshi
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- Copper-free Sandmeyer-type Reaction for the Synthesis of Sulfonyl Fluorides
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A copper-free Sandmeyer-type fluorosulfonylation reaction is reported. Utilizing Na2S2O5 and Selectfluor as the sulfur dioxide and fluorine sources, respectively, aryldiazonium salts were transformed into sulfonyl fluorides. The one-pot direct synthesis of sulfonyl fluorides from aromatic amines was also realized via in situ diazotization. The practicality of this method was demonstrated by the broad functional group tolerance, gram-scale synthesis, and late-stage fluorosulfonylation of natural products and pharmaceuticals.
- Zhong, Tao,Pang, Meng-Ke,Chen, Zhi-Da,Zhang, Bin,Weng, Jiang,Lu, Gui
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p. 3072 - 3078
(2020/04/10)
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- Development of Covalent Ligands for G Protein-Coupled Receptors: A Case for the Human Adenosine A3 Receptor
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The development of covalent ligands for G protein-coupled receptors (GPCRs) is not a trivial process. Here, we report a streamlined workflow thereto from synthesis to validation, exemplified by the discovery of a covalent antagonist for the human adenosine A3 receptor (hA3AR). Based on the 1H,3H-pyrido[2,1-f]purine-2,4-dione scaffold, a series of ligands bearing a fluorosulfonyl warhead and a varying linker was synthesized. This series was subjected to an affinity screen, revealing compound 17b as the most potent antagonist. In addition, a nonreactive methylsulfonyl derivative 19 was developed as a reversible control compound. A series of assays, comprising time-dependent affinity determination, washout experiments, and [35S]GTPγS binding assays, then validated 17b as the covalent antagonist. A combined in silico hA3AR-homology model and site-directed mutagenesis study was performed to demonstrate that amino acid residue Y2657.36 was the unique anchor point of the covalent interaction. This workflow might be applied to other GPCRs to guide the discovery of covalent ligands.
- Yang, Xue,Van Veldhoven, Jacobus P. D.,Offringa, Jelle,Kuiper, Boaz J.,Lenselink, Eelke B.,Heitman, Laura H.,Van Der Es, Daan,Ijzerman, Adriaan P.
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p. 3539 - 3552
(2019/04/16)
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- Phosphoramidite containing sulfonyl fluoride group
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The invention provides phosphoramidite containing a sulfonyl fluoride group. The structure of phosphoramidite containing the sulfonyl fluoride group is shown as a formula I, and R1, R2 and R3 in the formula are defined in the claims and description. Phosphoramidite can be used as a solid phase synthesis reagent for synthesis to obtain oligomeric nucleic acid containing the sulfonyl fluoride group.The formula I is shown in the description.
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Paragraph 0023; 0024; 0025
(2018/07/30)
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- Irreversible Cysteine-Selective Protein Labeling Employing Modular Electrophilic Tetrafluoroethylation Reagents
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Fluoroalkylation reagents based on hypervalent iodine are widely used to transfer fluoroalkyl moieties to various nucleophiles. However, the transferred groups have so far been limited to simple structural motifs. We herein report a reagent featuring a secondary amine that can be converted to amide, sulfonamide, and tertiary amine derivatives in one step. The resulting reagents bear manifold functional groups, many of which would not be compatible with the original synthetic pathway. Exploiting this structural versatility and the known high reactivity toward thiols, the new-generation reagents were used in bioconjugation with an artificial retro-aldolase, containing an exposed cysteine and a reactive catalytic lysine. Whereas commercial reagents based on maleimide and iodoacetamide labeled both sites, the iodanes exclusively modified the cysteine residue. The study thus demonstrates that modular fluoroalkylation reagents can be used as tools for cysteine-selective bioconjugation.
- Václavík, Ji?í,Zschoche, Reinhard,Klimánková, Iveta,Matou?ek, Václav,Beier, Petr,Hilvert, Donald,Togni, Antonio
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supporting information
p. 6490 - 6494
(2017/05/15)
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- RADIOACTIVE FLUORINE LABELING PRECURSOR COMPOUND AND METHOD FOR MANUFACTURING RADIOACTIVE FLUORINE LABELED COMPOUND USING THE SAME
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There is provided a labeling precursor compound represented by the following general formula (2): wherein R1 represents an alkynyl group, an alkynyloxy group, an azide group, an azidoalkyl group, an arylazide group, a monocyclic or condensed polycyclic aryl group or a nitrogen-containing heterocycle; R2 and R3 each independently represent an alkyl group or a hydroxyalkyl group which hydroxy group may be protected with a protecting group, and n is an integer of 1 or 2; R6 represents an alkyl group or —CONR11R12 wherein R11 and R12 each independently represent an alkyl group or a monocyclic or condensed polycyclic aryl group; and R4, R5, R7 and R8 each independently represent a hydrogen atom, an alkyl group or an alkoxy group.
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Paragraph 0039; 0040
(2017/03/28)
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- Aromatic sulfonyl fluorides covalently kinetically stabilize transthyretin to prevent amyloidogenesis while affording a fluorescent conjugate
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Molecules that bind selectively to a given protein and then undergo a rapid chemoselective reaction to form a covalent conjugate have utility in drug development. Herein a library of 1,3,4-oxadiazoles substituted at the 2 position with an aryl sulfonyl fluoride and at the 5 position with a substituted aryl known to have high affinity for the inner thyroxine binding subsite of transthyretin (TTR) was conceived of by structure-based design principles and was chemically synthesized. When bound in the thyroxine binding site, most of the aryl sulfonyl fluorides react rapidly and chemoselectively with the pK a-perturbed K15 residue, kinetically stabilizing TTR and thus preventing amyloid fibril formation, known to cause polyneuropathy. Conjugation t50s range from 1 to 4 min, ~1400 times faster than the hydrolysis reaction outside the thyroxine binding site. X-ray crystallography confirms the anticipated binding orientation and sheds light on the sulfonyl fluoride activation leading to the sulfonamide linkage to TTR. A few of the aryl sulfonyl fluorides efficiently form conjugates with TTR in plasma. Eleven of the TTR covalent kinetic stabilizers synthesized exhibit fluorescence upon conjugation and therefore could have imaging applications as a consequence of the environment sensitive fluorescence of the chromophore.
- Grimster, Neil P.,Connelly, Stephen,Baranczak, Aleksandra,Dong, Jiajia,Krasnova, Larissa B.,Sharpless, K. Barry,Powers, Evan T.,Wilson, Ian A.,Kelly, Jeffery W.
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supporting information
p. 5656 - 5668
(2013/06/04)
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