Preparation and Biological Evaluation of [99mTc]Tc-CNGU as a PSMA-Targeted Radiotracer for the Imaging of Prostate Cancer

Prostate-specific membrane antigen (PSMA) is a well-established biological target that is overexpressed on the surface of prostate cancer lesions. Radionuclide-labeled small-molecule PSMA inhibitors have been shown to be promising PSMA-specific agents for the diagnosis and therapy of prostate cancer. In this study, a glutamate-urea-based PSMA-targeted ligand containing an isonitrile (CNGU) was synthesized and labeled with ^99mTc to prepare [^99mTc]Tc-CNGU with a high radiochemical purity (RCP). The CNGU ligand showed a high affinity toward PSMA (K_i value is 8.79 nM) in LNCaP cells. The [^99mTc]Tc-CNGU exhibited a good stability in vitro and hydrophilicity (log P = −1.97 ± 0.03). In biodistribution studies, BALB/c nude mice bearing LNCaP xenografts showed that the complex had a high tumor uptake with 4.86 ± 1.19% ID/g, which decreased to 1.74 ± 0.90% ID/g after a pre-injection of the selective PSMA inhibitor ZJ-43, suggesting that it was a PSMA-specific agent. Micro-SPECT imaging demonstrated that the [^99mTc]Tc-CNGU had a tumor uptake and that the uptake was reduced in the image after blocking with ZJ-43, further confirming its PSMA specificity. All of the results in this work indicated that [^99mTc]Tc-CNGU is a promising PSMA-specific tracer for the imaging of prostate cancer.     

Effects of partial anion substitution on the thermoelectric properties of silver(I) chalcogenide halides in the system Ag5Q2X with Q=Te, Se and S and X=Br and Cl

A selection of mixed conducting silver chalcogenide halides of the general formula Ag₅Q₂X with Q=sulfur, selenium and tellurium and X=chlorine and bromine has been investigated due to their thermoelectric properties. Recently, the ternary counterpart Ag₅Te₂Cl showed a defined d¹⁰-d¹⁰ interaction in the disordered cation substructure at elevated temperatures where Ag₅Te₂Cl is present in its high temperature α-phase. A significant drop of the thermal diffusivity has been observed during the β−α phase transition reducing the values from 0.12 close to 0.08 mm² s⁻¹. At the same transition the thermopower reacts on the increasing silver mobility and jumps towards less negative values.Thermal conductivities, thermopower and thermal diffusivity of selected compounds with various grades of anion substitution in Ag₅Q₂X were determined around the silver-order/disorder β−α phase transition. A formation of attractive interactions could be observed for selenium substituted phases while no effect was detected for bromide and sulfide samples. Depending on the grade and type of substitution the thermopower changes significantly at and after the β−α phase transition. Thermal conductivities are low reaching values around 0.2-0.3 W m⁻¹ K⁻¹ at 299 K. Partial anion exchange can substantially tune the thermoelectric properties in Ag₅Q₂X phases.     

Synthesis and in vitro studies of Gd-DTPA derivatives as new potential MRI contrast agents

A new type of dendritic molecules, Gd-DTPA derivatives, which work as a functionalized ligand coordinating gadolinium(III) ion at the center of their frameworks with different terminal moieties on the molecular surfaces, was readily synthesized with high yield. The structures were established by ¹H, ¹³C NMR, and mass spectral studies. In vitro studies showed them to have enhanced r₁ value in albumin medium and good potentiality as MRI contrast agent.     

A N NMR study of tautomerism in dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate

Dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate can exist either in 1,2- or 1,4-dihydro tautomeric forms. The ¹⁵N NMR spectra of dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate were measured at the ¹⁵N natural abundance level as well as in ¹⁵N doubly labelled selectively and in ¹⁵N completely labelled compounds (20% ¹⁵N). The J(¹⁵N,¹⁵N) value was determined in ¹⁵N completely labelled compounds (20% ¹⁵N) using 1D ¹⁵N INADEQUATE and was found to be 12.2 ± 0.2 Hz in deuteriochloroform, acetonitrile-d₃, DMSO-d₆ and CD₃OH. Very similar ¹⁵N chemical shifts and ¹J(¹⁵N,¹H) values were also observed in all the solvents. This indicates that compound 1 exists completely in the 1,4-dihydro tautomeric form (i.e., as dimethyl 1,4-dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate) in all the solvents tested.     

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 (K_d = 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.     

An Improved Synthesis of N-(4-[18F]Fluorobenzoyl)-Interleukin-2 for the Preclinical PET Imaging of Tumour-Infiltrating T-cells in CT26 and MC38 Colon Cancer Models

Positron emission tomography (PET) imaging of activated T-cells with N-(4-[¹⁸F]fluorobenzoyl)-interleukin-2 ([¹⁸F]FB-IL-2) may be a promising tool for patient management to aid in the assessment of clinical responses to immune therapeutics. Unfortunately, existing radiosynthetic methods are very low yielding due to complex and time-consuming chemical processes. Herein, we report an improved method for the synthesis of [¹⁸F]FB-IL-2, which reduces synthesis time and improves radiochemical yield. With this optimized approach, [¹⁸F]FB-IL-2 was prepared with a non-decay-corrected radiochemical yield of 3.8 ± 0.7% from [¹⁸F]fluoride, 3.8 times higher than previously reported methods. In vitro experiments showed that the radiotracer was stable with good radiochemical purity (>95%), confirmed its identity and showed preferential binding to activated mouse peripheral blood mononuclear cells. Dynamic PET imaging and ex vivo biodistribution studies in naïve Balb/c mice showed organ distribution and kinetics comparable to earlier published data on [¹⁸F]FB-IL-2. Significant improvements in the radiochemical manufacture of [¹⁸F]FB-IL-2 facilitates access to this promising PET imaging radiopharmaceutical, which may, in turn, provide useful insights into different tumour phenotypes and a greater understanding of the cellular nature and differential immune microenvironments that are critical to understand and develop new treatments for cancers.     

Novel fluoro-substituted benzo- and benzothieno fused pyrano[2,3-c]pyrazol-4(1H)-ones

A straightforward, two-step synthesis of fluoro substituted chromeno[2,3-c]pyrazol- and [1]benzothieno[2′,3′:5,6]pyrano[2,3-c]pyrazol-4(1H)-ones, respectively, is presented. Hence, treatment of 1-substituted or 1,3-disubstituted 2-pyrazolin-5-ones with fluoro substituted 2-fluorobenzoyl chlorides or 3-chloro-6-fluoro-1-benzothiophene-2-carbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-aroylpyrazol-5-ols, which were cyclized into the fused ring systems. 5-Fluorochromeno[2,3-c]pyrazol-4(1H)-one was obtained upon treatment of the 1-(4-methoxybenzyl) protected congener with trifluoroacetic acid. Treatment of 5-fluorochromeno[2,3-c]pyrazol-4(1H)-ones with methylhydrazine afforded novel tetracyclic ring systems such as 2-methyl-7-phenyl-2,7-dihydropyrazolo[4′,3′:5,6]pyrano[4,3,2-cd]indazole. Detailed NMR spectroscopic investigations (¹H, ¹³C, ¹⁵N, ¹⁹F) with the obtained compounds were undertaken.     

A practical synthesis of [C4] N-benzylpiperazine from [C2] glycine

A high yielding gram-scale synthesis of [¹³C₄] N-benzylpiperazine for use as a convenient and versatile building block in isotope labeling studies of clinical drug candidates is reported.     

The Chemical Constituents from Fruits of Catalpa bignonioides Walt. and Their α-Glucosidase Inhibitory Activity and Insulin Secretion Effect

Catalpa pod has been used in traditional medicine for the treatment of diabetes mellitus in South America. Studies on the constituents of Catalpa species have shown that it is rich in iridoids. In the present study, three previously undescribed compounds (2–4), including two secoiridoid derivatives along with twelve known compounds, were isolated from the fruits of Catalpa bignonioides Walt. In addition, fully assigned ¹³C-NMR of 5,6-dihydroxy-7,4’-dimethoxyflavone-6-O-sophoroside (1) is reported for the first time in the present study. The structures of compounds were determined on the basis of extensive spectroscopic methods, including UV, IR, 1D, and 2D NMR, mass spectroscopy, and CD spectroscopic data. All the isolated compounds were evaluated for α-glucosidase inhibitory activity. Among the tested compounds, compounds 2, 3, and 9 exhibited significant inhibitory activity against α-glucosidase enzyme assay. Meanwhile, the effect of compounds 2, 3, and 9 on glucose-stimulated insulin secretion (GSIS) was measured using pancreatic β-cells. Compounds 2, 3, and 9 exhibited non-cytotoxicity-stimulated insulin secretion in INS-1 cells. The expression levels of proteins associated with β-cell function and insulin secretion such as phosphorylation of total insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), Akt, activated pancreatic duodenal homeobox-1 (PDX-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) were increased in INS-1 cells after treatment with compounds 2, 3, and 9. The findings of the present study could provide a scientific warrant for their application as a potential antidiabetic agent.     

基于NaYF4:Yb3+,Er3+上转换发光纳米晶的复合微球组装及其光动力活性研究

采用微乳液法,以NaYF₄:Yb³⁺,Er³⁺纳米晶为发光基元,肽菁锌(ZnPc)光敏分子与十八碳烯-马来酸酐共聚物(PMAO)为功能分子,一步组装获得了NaYF₄-ZnPc-PMAO复合微球,此微球同时具备成像与光动力活性功能,NaYF₄可作为低生物背景的荧光成像剂,同时其上转换发光可以敏化ZnPc用于光动力活性研究,PMAO分子经过简单的水解反应即可实现表面羧基功能化。TEM,Zeta电位与PL测试证实了微球的结构与性能。利用荧光共聚焦成像技术实现了对Hela细胞的发光成像;进一步通过单线态氧监测及980 nm光照下的MTT法细胞活性测试表明微球具有光动力活性功能。     

Preparation of the novel fluorine-18-labeled VIP analog for PET imaging studies using two different synthesis methods

Vasoactive intestinal peptide (VIP) receptors are expressed on various tumor cells in much higher density than somatostatin receptors, which provides the basis for radiolabeling VIP as tumor diagnostic agent. However, fast proteolytic degradation of VIP in vivo limits its clinical application. With the aim to develop and evaluate new ligands for depicting the VIP receptors with positron emission tomography (PET), the structure modified [R^8,15,21, L¹⁷]-VIP analog was radiolabeled with ¹⁸F using two different methods. With the first method, N-4-[¹⁸F]fluorobenzoyl-[R^8,15,21, L¹⁷]-VIP ([¹⁸F]FB-[R^8,15,21, L¹⁷]-VIP 7) was produced in a decay-corrected radiochemical yield (RCY) of 33.6 ± 3%, a specific radioactivity of 255 GBq/μmol (n = 5) within 100 min in four steps. Similarly, N-4-[¹⁸F](fluoromethyl)-benzoyl-[R^8,15,21, L¹⁷]-VIP ([¹⁸F]FMB-[R^8,15,21, L¹⁷]-VIP 8) was synthesized in a RCY of 34.85 ± 5%, a specific radioactivity of 180 GBq/μmol (n = 5) within 60 min in only one step. The two products 7 and 8 were both shown good stability in HSA. Moreover, the low bone uptakes of 7 and 8 in vivo of mice showed good defluorination stability.     

Synthesis of gemini surfactants with twelve symmetric fluorine atoms and one singlet F MR signal as novel F MRI agents

A family of fluorinated gemini surfactants derived from perfluoropinacol has been synthesized as novel ¹⁹F magnetic resonance imaging (¹⁹F MRI) agents. These fluorinated surfactants with 12 symmetric fluorine atoms and one singlet ¹⁹F MR peak can be conveniently prepared from perfluoropinacol and oligo(ethylene glycols) on multi-gram scales. Solubility, hydrophilicity (log P), and critical micelle concentration (CMC) measurements of these fluorinated surfactants indicated that high aqueous solubility can be achieved by introducing oligo(ethylene glycols) with appropriate length into perfluoropinacol, i.e., manipulating the fluorine content (F%). One of these fluorinated surfactants with high aqueous solubility and excellent ¹⁹F MR properties has been identified by ¹⁹F MRI phantom experiments as a promising ¹⁹F MRI agent.     

Syntheses and characterization of Cu,Ni and Zn binding capability of histidinehydroxamic acid derivatives

Two histidinehydroxamic acid derivatives (N-methyl-histidinehydroxamic acid, N-Me-Hisha and Z-histidinehydroxamic acid, Z-Hisha) have been synthesized and their complexation with Cu²⁺-, Ni²⁺- and Zn²⁺-ions has been studied by using pH-potentiometric, UV–Vis, CD, ¹H NMR, EPR and ESI-MS methods. Both of the two new derivatives contain one donor atom less compared to the histidinehydroxamic acid (Hisha). In the case of N-Me-Hisha the hydroxamate-N as donor is eliminated, while the coordination of the amino-N of Z-Hisha is not possible at all.     

Mononuclear hydridocarbonyl ruthenium complexes incorporating N2O2 bis-chelating ligands

The reactions of [RuH(CO)Cl(PPh₃)₃] with N,N^′-bis(salicylidine)-hydrazine (H₂bsh) and N,N^′-bis(salicylidine)-p-phenylene diammine (H₂bsp) in presence of KOH in methanol led in the formation of neutral mononuclear complexes with the formulations [RuH(CO)(PPh₃)₂(L)] (LHbsh or Hbsp). These present the first examples where the ligands H₂bsh or H₂bsp provide only two of its available donor sites for interaction with the metal centre. The complexes have been characterized by elemental analyses, FAB-MS, IR, ¹H, ¹³C, ³¹P NMR and electronic spectral studies. Molecular structure of the representative complex [RuH(CO)(PPh₃)₂(Hbsh)] have been determined by single crystal X-ray analysis.     

A New Coumarin-Acridone Compound as a Fluorescence Probe for Fe3+ and Its Application in Living Cells and Zebrafish

A new coumarin-acridone fluorescent probe S was designed and synthesized, and the structure was confirmed with ¹H/¹³C NMR spectrometry, single-crystal X-ray diffraction, and high-resolution mass spectrometry. This probe has high sensitivity and selectivity for Fe³⁺ over other testing metal ions at 420 or 436 nm in acetonitrile–MOPS (3-Morpholinopropanesulfonic Acid) buffer solution (20.0 μM, pH = 6.9, 8:2 (v/v)). Under physiological conditions, the probe displayed satisfying time stability with a detection limit of 1.77 µM. In addition, probe S was successfully used to detect intracellular iron changes through a fluorescence-off mode, and the imaging results of cells and zebrafish confirmed their low cytotoxicity and satisfactory cell membrane permeability, as well as their potential biological applications.     

LC/ESI-MS n and 1H HR-MAS NMR analytical methods as useful taxonomical tools within the genus Cystoseira C. Agardh (Fucales; Phaeophyceae)

Species of the genus Cystoseira are particularly hard to discriminate, due to the complexity of their morphology, which can be influenced by their phenological state and ecological parameters. Our study emphasized on the relevance of two kinds of analytical tools, (1) LC/ESI-MSⁿ and (2) ¹H HR-MAS NMR, also called in vivo NMR, to identify Cystoseira specimens at the specific level and discuss their taxonomy. For these analyses, samples were collected at several locations in Brittany (France), where Cystoseira baccata, C. foeniculacea, C. humilis, C. nodicaulis and C. tamariscifolia were previously reported. To validate our chemical procedure, the sequence of the ITS2 has been obtained for each species to investigate their phylogenetic relationships at a molecular level. Our study highlighted the consistency of the two physico-chemical methods, compared to “classical” molecular approach, in studying taxonomy within the genus Cystoseira. Especially, LC/ESI-MSⁿ and phylogenetic analyses converged into the discrimination of two taxonomical groups among the 5 species. The occurrence of some specific signals in the ¹H HR-MAS NMR spectra and/or some characteristic chemical compounds during LC/ESI-MSⁿ analysis could be regarded as discriminating factors. LC/ESI-MSⁿ and ¹H HR-MAS NMR turned out to be two relevant and innovative techniques to discriminate taxonomically this complex genus.     

基于NaYF_4∶Yb~(3+),Er~(3+)上转换发光纳米晶的复合微球组装及其光动力活性

采用微乳液法,以NaYF4∶Yb3+,Er3+纳米晶为发光基元,肽菁锌(Zn Pc)光敏分子与十八碳烯-马来酸酐共聚物(PMAO)为功能分子,一步组装获得了NaYF4-Zn Pc-PMAO复合微球,此微球同时具备成像与光动力活性功能,NaYF4可作为低生物背景的荧光成像剂,同时其上转换发光可以敏化Zn Pc用于光动力活性研究,PMAO分子经过简单的水解反应即可实现表面羧基功能化。TEM,Zeta电位与PL测试证实了微球的结构与性能。利用荧光共聚焦成像技术实现了对Hela细胞的发光成像;进一步通过单线态氧监测及980 nm光照下的MTT法细胞活性测试表明微球具有光动力活性功能。     

Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes—evidence for steric and spatial hyperconjugative interactions

The syn and anti isomers of cis,cis-tricyclo[5.3.0.0^2,6]dec-3-ene derivatives have been synthesized and their ¹H and ¹³C NMR spectra unequivocally analyzed. Both their structures and their ¹H and ¹³C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions.     

Identification of polyoxypregnane glycosides from the stems of Marsdenia tenacissima by high-performance liquid chromatography/tandem mass spectrometry

A facile method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/(+)ESI-MSⁿ) has been established for the analysis of polyoxypregnane glycosides in the stems of Marsdenia tenacissima. The data reveals the ability of MSⁿ in the structural elucidation of polyoxypregnane glycosides including the nature of the polyoxypregnane core, the kinds of the substituents and the types of sugar residues. Offline Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is also performed to assign accurate elemental compositions. In this study, eighteen polyoxypregnane glycosides have been investigated. Among these components, five compounds are unambiguously identified as Marsdenoside K, Tencissoside A, B, C and D; two compounds are established as novel compounds based on mass spectral data; and the other eleven compound's structures are tentatively proposed. Furthermore, breakdown curves are constructed to distinguish five pairs of isomers among these eighteen compounds. As far as our knowledge, this is the first report on identification of polyoxypregnane glycosides in the stems of M. tenacissima by HPLC/ESI-MSⁿ directly, which could save time and material consuming efforts in traditional phytochemistry analyses.