One-Pot Synthesis of 6-Substituted Amino-2,4-diaminopyrimidine Derivatives Using Ketene Dithioacetals with Amines and Guanidine Carbonate

6-Substituted amino-2,4-diaminopyrimidine derivatives were prepared by one-pot synthesis using ketene dithioacetals, amine compounds, and guanidine carbonate in pyridine. These pyrimidine products displayed blue fluorescence in the solid state

Synthesis of a Novel Pyrazine-Pyridone Biheteroaryl-Based Fluorescence Sensor and Detection of Endogenous Labile Zinc Ions in Lung Cancer Cells

A small extent of endogenous labile zinc is involved in many vital physiological roles in living systems. However, its detailed functions have not been fully elucidated. In this study, we developed a novel biheteroaryl-based low molecular weight fluorescent sensor, 3-(phenylsulfonyl)-pyrazine-pyridone (5b), and applied it for the detection of endogenous labile zinc ions from lung cancer cells during apoptosis. The electron-withdrawing property of the sulfonyl group between the phenyl ring as an electron donor and the pyridone ring as a fluorophore inhibited the intramolecular charge transfer state, and the background fluorescence of the sensor was decreased in aqueous media. From the structure-fluorescence relationship analysis of the substituent effects with/without Zn 2+ , compound 5b acting as a sensor possessed favorable properties, including a longer emission wavelength, a large Stokes shift (over 100 nm),a large fluorescence enhancement in response to Zn 2+ under physical conditions, and good cell membrane permeability in living cells. Fluorescence imaging studies of human lung adenocarcinoma cells (A549) undergoing apoptosis revealed that compound 5b could detect endogenous labile zinc ions. These experiments suggested that the low molecular weight compound 5b is a potential fluorescence sensor for Zn 2+ toward understanding its functions in living systems

An open-label continuation trial of tocilizumab for familial Mediterranean fever with colchicine ineffective or intolerance

Background:Colchicine is the first-line treatment for familial Mediterranean fever (FMF), but secondary amyloidosis resulting from persistent inflammation is a concern in patients with colchicine-resistant or colchicine-intolerant FMF. Although tocilizumab (TCZ), which is a recombinant, humanized, anti-human interleukin 6 receptor monoclonal antibody, has been reported to prevent FMF attacks, the long-term safety and efficacy of TCZ on individuals with colchicine-resistant or colchicine-intolerant FMF have not been evaluated.Methods/design:In this investigator-initiated, multicenter, open-label trial, the long-term safety of TCZ will be evaluated in patients participating in a placebo-controlled, randomized, double-blind, parallel-group trial on colchicine-resistant or colchicine-intolerant FMF. The study will be conducted in 9 centers in Japan. After the evaluation and examination for 24 weeks in the preceding study, this trial will be started promptly. The trial will be completed by the time the drug is approved for FMF treatment in Japan. The primary endpoint is the incidence of adverse events, and the secondary endpoints include the number of FMF attacks, number of occurrences of accompanying symptoms during attacks, serum C-reactive protein and amyloid A levels, general evaluation by a physician (100mm visual analog scale [VAS]), general evaluation by a patient (100mm VAS), and body temperature.Discussion:The study is expected to obtain evidence regarding the long-term safety of TCZ as a potential new therapeutic agent for patients with colchicine-resistant or colchicine-intolerant FMF.Trial registration:This study was registered with the University Hospital Medical Information Network Clinical Trials Registry (https://upload.umin.ac.jp/cgi-open-bin/ctr-e/ctr-view.cgi?recptno=R000037116) as UMIN000032557 on May 30 2018

Synthesis, photophysical evaluation, and computational study of 2-methoxy- and 2-morpholino pyridine compounds as highly emissive fluorophores in solution and the solid state

Two 2-pyridone tautomeric analogs, methoxypyridine 4 and N-methylpyridone 5, were synthesized, and their spectroscopic properties were investigated both experimentally and computationally. A detailed photophysical study reveals that 4 shows high fluorescence quantum yields not only in chloroform but also in ethanol, and the strong fluorescence in solution might be attributed to the enol form (pyridine) of the 2-pyridone. Furthermore, we designed and synthesized novel 2-substitued pyridines to achieve more intense emissions in both solution and the solid state. Substituent modification with phenylsulfonyl,morpholino, and 4-diethylamino groups greatly affected the fluorescence properties, and methoxypyridine 7 and morpholinopyridine compound 8 showed fluorescence in various solvents (Ф = 0.59-0.95) and the solid state (Ф = 0.12-0.15). A hypsochromic shift in the emission maximum wavelength and strong fluorescence in the solid state (Ф = 0.39) were observed for dimorpholinopyridine 9. Morpholinopyridine 11 showed intense fluorescence in all nonpolar and polar solvents. Systematic time-dependent density functional theory calculations were performed for the compounds whose electronic and fluorescent maxima were computationally reproduced with good agreement to those from experiment. In detail, the drastic difference in the emission intensity between 4 and 5 in solution was successfully explained using CASSCF calculations, which revealed the presence of conical intersections between the ground and the excited states

High-Affinity Ratiometric Fluorescence Probe Based on 6-Amino-2,2′-Bipyridine Scaffold for Endogenous Zn²⁺ and Its Application to Living Cells

Zinc is an essential trace element involved in many biological activities; however, its functions are not fully understood. To elucidate the role of endogenous labile Zn2+, we developed a novel ratiometric fluorescence probe, 5-(4-methoxyphenyl)-4-(methylsulfanyl)-[2,2′-bipyridin]-6-amine (6 (rBpyZ)) based on the 6-amino-2,2′-bipyridine scaffold, which acts as both the chelating agent for Zn2+ and the fluorescent moiety. The methoxy group acted as an electron donor, enabling the intramolecular charge transfer state of 6 (rBpyZ), and a ratiometric fluorescence response consisting of a decrease at the emission wavelength of 438 nm and a corresponding increase at the emission wavelength of 465 nm was observed. The ratiometric probe 6 (rBpyZ) exhibited a nanomolar-level dissociation constant (Kd = 0.77 nM), a large Stokes shift (139 nm), and an excellent detection limit (0.10 nM) under physiological conditions. Moreover, fluorescence imaging using A549 human lung adenocarcinoma cells revealed that 6 (rBpyZ) had good cell membrane permeability and could clearly visualize endogenous labile Zn2+. These results suggest that the ratiometric fluorescence probe 6 (rBpyZ) has considerable potential as a valuable tool for understanding the role of Zn2+ in living systems

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

New fluorescent compounds, benzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides (3a–g), 2-amino-4-methylsulfanylbenzo[4,5]thieno[3,2-d]pyrimidine (6), and 2-amino-4-methylsulfanyl-7-methoxybenzo[4,5]furo[3,2-d]pyrimidine (7), were synthesized in good yields from heterocyclic ketene dithioacetals (1a–c) and guanidine carbonate (2a) or (S)-methylisothiourea sulfate (2b) in pyridine under reflux. Among the fused pyrimidine derivatives, compound 3c, which has an amino group at the 2-position and a benzylamino group at the 4-position of the pyrimidine ring, showed the strongest solid-state fluorescence. The absorption and emission properties of the compounds were quantitatively reproduced by a series of ab initio quantum-chemical calculations