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A facile synthesis of bromodifluoromethylated selenides under metal-free conditions is described here. Commercially available Me3SiCF2Br and bench-stable selenosulfonates react smoothly to give a broad scope of alkyl- and aryl-substituted bromodifluoromethylated selenides in moderate to good yields via a difluorocarbene intermediate. This protocol features a short reaction time, the absence of toxic waste, good scalability, and successful late-stage modification of bioactive molecules. In addition, the title products can be easily converted to different fluorinated and 18F-labeled selenides.

Introduction Vesicular monoamine transporter 2 (VMAT2) has been associated with the risk of PD. Genetic reduction of VMAT2 level is reported to increase the vulnerability for dopaminergic neurodegeneration. In this study, by using in vivo microPET imaging with a VMAT2 radioligand [18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ), we investigated the enhanced role of inhibiting VMAT2 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced loss of dopaminergic neurons. Methods The (+)-α-dihydrotetrabenazine ((+)-DTBZ, an inhibitor of VMAT2, 5 mg/kg), or MPTP (low dose (ld): 10 mg/kg, high dose (hd): 30 mg/kg) or both of them were intraperitoneally injected into C57BL/6 mice for 5 or 10 consecutive days. MicroPET imaging with [18F]FP-(+)-DTBZ was performed to test the dopaminergic neuronal integrity. [18F]FP-(+)-DTBZ uptake in striatum was quantified as standardized uptake value (SUV). The pathological changes in the striata and substantia nigra were confirmed by measuring the DA contents and immunohistochemical staining of tyrosine hydroxylase (TH). Results In vivo imaging results showed that the striatal SUVs of both DTBZ&MPTPld and MPTPhd groups were substantially declined compared to the baseline. Moreover, the striatal uptakes of [18F]FP-(+)-DTBZ in DTBZ&MPTPld and MPTPhd groups were obviously lower than the control, DTBZ group and MPTPld group. Notably, the decrease of the striatal uptake in the DTBZ&MPTPld/10d group was more serious than the DTBZ&MPTPld/5d group and comparable to the MPTPhd group. Consistently, the ratios of DA metabolites to DA in DTBZ&MPTPld/10d and MPTPhd mice were significantly increased. The correlation analysis showed that SUVs were highly correlated to the striatal dopaminergic fiber density and TH-positive dopaminergic neuron number in the substantia nigra. Conclusions MicroPET brain imaging with [18F]FP-(+)-DTBZ noninvasively revealed that (+)-DTBZ co-administration significantly aggravated the neurotoxicity of MPTP to dopaminergic neurons, suggesting that inhibition of VMAT2 may be related to the pathogenesis of PD and tracing VMAT2 activity with PET imaging is of potential value in monitoring PD progression.

The aim of this study was to optimize the radiolabeling method of [18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ) to fulfill the demand of preclinical and clinical application. Optimized labeling conditions were performed by altering the molar ratio of precursor to base (P/B), base species, solvents, reaction temperature, reaction time, and precursor concentration through manual radiosynthesis of [18F]FP-(+)-DTBZ. The conditions with the highest radiochemical yield (RCY) were applied to automated radiosynthesis, and the crude product was purified with a Sep-Pak Plus C18 cartridge. Quality control and stability of [18F]FP-(+)-DTBZ were carried out by HPLC. In vitro cellular uptake and blocking assays were conducted in human neuroblastoma cell line SH-SY5Y. In vivo imaging with small animal positron emission tomography (microPET) was performed with Sprague–Dawley rats. Under the optimized conditions (P/K2CO3 = 1:8, heating at 120 °C for 3 min in dimethyl sulfoxide), an RCY of 88.7 % was obtained with 1.0 mg precursor. The optimized reaction conditions were successfully applied to an automated module and gave a high activity yield (AY) of 30–55 % in about 40 min with a > 99.0 % radiochemical purity (RCP) and a > 44.4 GBq/μmol molar activity (Am). Stability test displayed that the RCP retained > 98.0 % in 8 h in saline and in phosphate buffer saline (PBS, pH 7.4). In vitro cellular uptake assay showed accumulation of [18F]FP-(+)-DTBZ in SH-SY5Y cells, which could be significantly inhibited by vesicular monoamine transporter 2 (VMAT2) inhibitor DTBZ. MicroPET images of rat brain displayed that the striatum showed the highest uptake with a standardized uptake value (SUV) of 3.91 ± 0.30 at ~ 70 min. Co-injection with DTBZ (1.0 mg/kg) resulted in a 75 % decrease of the striatal SUV, confirming the specificity of [18F]FP-(+)-DTBZ to VMAT2. We obtained an optimized radiolabeling method of [18F]FP-(+)-DTBZ and successfully applied it to a commercial available module. The automated synthesis gave a high AY and RCP of [18F]FP-(+)-DTBZ with high and specific binding to VMAT2, facilitating its routine application for VMAT2 tracing.

In this study, polyvinylidene fluoride (PVDF) hollow fibers with interpenetrating network morphologies were fabricated via complex thermally induced phase separation (c-TIPS) by integration of non-solvent induced phase separation (NIPS) and thermally induced phase separation (TIPS) at 80 °C and then tested in membrane distillation (MD). The effects of solvents, additive and bore fluid on the membrane morphology, pore structure and MD performance were investigated. Direct-contact membrane distillation (DCMD) for desalination was carried out to evaluate membrane permeability and salt rejection. Using a weak solvent like triethylphosphate (TEP) and weak bore fluid like polyethylene glycol (PEG-200) in the c-TIPS favors the formation of an interpenetrating network morphology. In addition, PEG-200 increased the roughness and water contact angle of the inner skin. The hollow fibers fabricated via the c-TIPS at low temperature presented high permeability, mechanical strength and long-term stability. In desalination of formulated seawater, a distillate flux of 61.6 kg/m2h with NaCl rejection of 99.99% was achieved at feed temperature of 71 °C.

Objective To analyze the effects of escalating treatment strategy in children with severe chronic immune thrombocytopenia (SCITP). Methods This was a single-center, retrospective cohort study. Data from children with SCITP who received escalating treatment strategy in our center were collected between June 2017 and August 2019. The escalating strategy included three steps: Step I (six courses of high-dose dexamethasone [HDD]), Step II (HDD combined with low-dose rituximab), and Step III (eltrombopag). Results A total of 30 cases (18 males and 12 females) were included, with duration of immune thrombocytopenia (ITP) of 20.5 (12.0-96.0) months. After treatment, the remission rate was 36.7% (11/30) and the sustained response (SR) rate was 68.2% (15/22). The distribution (remission rates) from Step I to III was as follows: nine of 30 (33.3%, 3/9); four of 30 (50%, 2/4); 17/30 (29.4%, 5/17), respectively. In eltrombopag (Step III) cases, 47.5% (8/17) maintained a platelet count of ≥50 × 109 /L, 37.5% (3/8) had dose tapering, and 25% (2/8) have successfully discontinued the medication. The number of patients at 12, 24, and 36 months were 30, seven, and two, with a total response and remission rates of 80% (36.7%), 57.1% (28.6%), and 50% (50%), respectively. The total relapse rate was 26.7% (8/30), and three cases from Step II and five cases from Step III. Conclusion The escalating strategy for children SCITP showed an effective improvement rate with 36.7% remission and 68.2% SR, and 30% could benefit and retain SR from HDD treatment. Combined treatment with eltrombopag can reduce the relapse rate of low-dose rituximab.

A new radioiodinated tetrabenazine (TBZ) derivative containing an iodovinyl group at 9-position of TBZ (131I-IV-TBZ, 11a) and the corresponding cold compound IV-TBZ (11b) were synthesized and characterized. Analysis of in vitro autoradiography with rat brain slices showed 11a has a high uptake in the striatum and the uptake could be blocked by known vesicular monoamine transporter 2 (VMAT2) inhibitor. Furthermore, 11b has a competitive binding to VMAT2. These results suggest that 11a has ability to bind to VMAT2 and the binding is specific. Further studies are warranted to assess this radioiodinated TBZ derivative for VMAT2 imaging in vivo.

[18F]fluoropropyl-(+)-dihydrotetrabenazine ([18F]FP-(+)-DTBZ) is a rising positron tracer for imaging vesicular monoamine transporter II (VMAT2) in the central nervous system. The present work was to develop a novel chromatographic method capable of the molar activity (Am) determination of [18F]FP-(+)-DTBZ. As a complement work of the Am measurement, we also investigated the effect of Am on the quantitative analysis of VMAT2 autoradiography with [18F]FP-(+)-DTBZ. The Am determination was performed by high performance liquid chromatography (HPLC) using the non-radioactive standard (FP-(+)-DTBZ) for calibration plot of peak area against concentration. Based on this correlation, the Am of [18F]FP-(+)-DTBZ was calculated and corrected to the end of synthesis. In the quantitative analysis of in vitro VMAT2 autoradiography, the striatum radioactivity uptake together with the uptake ratio of striatum versus cortex reduced along with the decrease of Am and the increase of the FP-(+)-DTBZ content. Therefore, the Am and the corresponding FP-(+)-DTBZ content have a significant effect on the quantitative analysis of VMAT2 autoradiography using [18F]FP-(+)-DTBZ.

We studied on the structural requirement of C11b chirality of tetrabenazine (TBZ) analogs as vesicular monoamine transporter 2 (VMAT2) ligands. TBZ analogs (2, 6a, 6b) and 18F-radiolabeled [18F]6a and [18F]6b with eliminated C11b chirality were synthesized and characterized. Competition studies demonstrated that 2, 6a and 6b displayed much lower in vivo VMAT2 bindings than TBZ. MicroPET imaging studies of [18F]6a and [18F]6b showed negligible accumulation in VMAT2-enriched regions as compared with the known VMAT2 ligand 18F-FP-(+)-DTBZ. These results suggest that C11b chirality of TBZ analogs is essential for in vivo VMAT2 binding bioactivity.

A precise and sensitive HPLC method was developed for the determination of p-toluenesulfonoxypropyl-(+)-dihydrotetrabenazine [TsOP-(+)-DTBZ] enantiomeric purity. The effects of mobile phase composition and column temperature on the enantioresolution and analysis time of the enantiomers were investigated. The optimized chiral separation method was performed on a Phenomenex Chirex 3014 column (250 mm × 4.6 mm, particle size 5 μm) using a mobile phase consisting of n-hexane/1,2-dichloroethane/ethanol/trifluoroacetic acid/triethylamine (64/32/4/0.01/0.005 v/v/v/v/v) at a flow rate of 0.8 mL min−1 and a column temperature of 25 °C. The enantiomers were monitored with UV detection at 280 nm, and baseline separation with a resolution higher than 2.0 was achieved within 20 min. The method was validated in terms of linearity, precision, accuracy, robustness, limit of detection (LOD) and limit of quantification (LOQ). The linearity range for the determination of each enantiomer was 0.002–2.0 mg mL−1 (n = 6). Additionally, the LOD and LOQ of TsOP-(+)-DTBZ were 0.15 and 0.50 μg mL−1; those for its enantiomer were 0.18 and 0.60 μg mL−1, respectively. Furthermore, this validated method was successfully applied to analyze three different TsOP-(+)-DTBZ bulk samples. The results demonstrated that the proposed method was simple, rapid, accurate and robust for routine enantiopurity analysis of TsOP-(+)-DTBZ in pharmaceutical research.

Objectives The in vivo binding analysis of vesicular monoamine transporter type 2 (VMAT2) to radioligand has provided a means of investigating related disorders. Anesthesia is often inevitable when the investigations are performed in animals. In the present study, we tested effects of four commonly-used anesthetics: isoflurane, pentobarbital, chloral hydrate and ketamine, on in vivo VMAT2 binding to 18 F-FP-(+)-DTBZ, a specific VMAT2 radioligand, in rat brain. Methods The transient equilibrium time window for in vivo binding of 18 F-FP-(+)-DTBZ after a bolus injection was firstly determined. The brain biodistribution studies under anesthetized and awake rats were then performed at the equilibrium time. Standard uptake values (SUVs) of the interest brain regions: the striatum (ST), hippocampus (HP), cortex (CX) and cerebellum (CB) were obtained; and ratios of tissue to cerebellum were calculated. Results Isoflurane and pentobarbital did not alter distribution of 18 F-FP-(+)-DTBZ in the brain relative to the awake group; neither SUVs nor ratios of ST/CB and HP/CB were altered significantly. Chloral hydrate significantly increased SUVs of all the brain regions, but did not significantly alter ratios of ST/CB and HP/CB. Ketamine significantly increased SUVs of the striatum, hippocampus and cortex, and insignificantly increased the SUV of the cerebellum; consequently, ketamine significantly increased ratios of ST/CB and HP/CB. Conclusions It is concluded that in vivo VMAT2 binding to 18 F-FP-(+)-DTBZ are not altered by isoflurane and pentobarbital, but altered by chloral hydrate and ketamine. Isoflurane and pentobarbital may be promising anesthetic compounds for investigating in vivo VMAT2 binding. Further studies are warranted to investigate the interactions of anesthetics with VMAT2 binding potential with in vivo PET studies.

Magnetic resonance (MR) imaging is advantageous because it concurrently provides anatomic, functional, and molecular information. MR molecular imaging can combine the high spatial resolution of this established clinical modality with molecular profiling in vivo. However, as a result of the intrinsically low sensitivity of MR imaging, high local concentrations of biological targets are required to generate discernable MR contrast. We hypothesize that the prostate-specific membrane antigen (PSMA), an attractive target for imaging and therapy of prostate cancer, could serve as a suitable biomarker for MR-based molecular imaging. We have synthesized three new high-affinity, low-molecular-weight Gd(III) -based PSMA-targeted contrast agents containing one to three Gd(III) chelates per molecule. We evaluated the relaxometric properties of these agents in solution, in prostate cancer cells, and in an in vivo experimental model to demonstrate the feasibility of PSMA-based MR molecular imaging.

In this study, we synthesized a new carbon-11-labeled radiotracer, 10-(11) C-dihydrotetrabenazine (10-(11) C-DTBZ), and evaluated its potential as a vesicular monoamine transporter 2 (VMAT2) radioligand. The radiolabeled precursor 10-O-desmethyl-dihydrotetrabenazine (10-O-desmethyl-DTBZ) was prepared with a six-step reaction using 3-methoxy-4-benzyloxybenzaldehyde as starting material. 10-(11) C-DTBZ was synthesized by heating 1.0 mg of 10-hydroxy precursor and (11) C-methyl iodide in the presence of 0.3 mL of dimethyl sulfoxide and 4.0 µL of 3 N KOH at room temperature for 3 min. After purification by solid phase extraction using an alumina Sep-Pak cartridge, the final 10-(11) C-DTBZ product was obtained with a radiochemical purity of >99% and an uncorrected radiochemical yield of 18-26% (end of bombardment (EOB), n = 6). The overall synthesis time was approximately 20 min from the EOB to release of the product for quality control. Using small-animal positron emission tomography (microPET), the striatum of normal rats was found to exhibit symmetrical labeling (STR /STL = 0.98 ± 0.05, n = 3) and the highest uptake of radioactivity (striatum/cerebellum, ST/CB = 2.89 ± 0.31 at 30-60 min, n = 3). In contrast, rats with 6-hydroxydopamine unilateral lesions yielded asymmetrical striatal images with a higher 10-(11) C-DTBZ concentration on the unlesioned side (STunlesioned /CB = 2.53 ± 0.18, at 30-60 min, n = 3) compared with the lesioned side (STlesioned /CB = 1.26 ± 0.10, n = 3). These results suggest that 10-(11) C-DTBZ may represent a promising PET radiotracer for imaging VMAT2.

2β-Carbomethoxy-3β-(4-chlorophenyl)-8-(2-[18F]fluoroethyl)nortropane ([18F]-FECNT) is a potential dopamine transporter PET imaging agent. However, its current radio-synthesis is tedious and time consuming. In this article, we reported a fully automatic method for the synthesis of [18F] FECNT through only one step, using a TRACERlab FXN module, with decay corrected radiochemical yield of 25 ± 5 % (n = 5). The total synthesis time was 50–55 min. The synthesized [18F]FECNT was evaluated in vivo in Parkinson’s disease model rats.

This article reports, for the first time, on the absolute configuration of (+)-9-benzyloxy-α-dihydrotetrabenazine (8), as determined from the perspective of X-ray crystallography. Compound 8 was prepared by a six-step reaction using 3-benzyloxy-4-methoxybenzaldehyde (1) as a starting material. The X-ray crystal diffraction structure of two compounds, racemic 9-benzyloxy-tetrabenazine (5) and the diastereomeric salt of compound 8, is also described for the first time in this article. The X-ray results and the chiral HPLC helped elucidate that compound 8 has an absolute configuration as 2R,3R,11bR. The crystal structure of racemic compound 5 contains two symmetry- independent molecules in the unit cell. Interestingly, while they are structural isomers, they are enantiomers, too, i.e., in solution, because they are not mirror images of each other in the crystal lattice. In order to elucidate the intermolecular interaction mechanism of the diastereomeric salt of compound 8, its crystal packing was investigated with regard to the weak interactions, such as salt bridge, OH...O and CH...O hydrogen bonds, and intermolecular CH...π interaction. The results showed that the carbonyl-assisted salt bridges and the OH...O hydrogen bonds formed polar columns in the crystal structure of the diastereomeric salt of compound 8, resembling butterflies with open wings as viewed along the c-axis. These polar columns were extended to three-dimensional network by intermolecular CH...O hydrogen bonds and intermolecular CH...π interactions.

(68)Ga-labeled, low-molecular-weight imaging agents that target the prostate-specific membrane antigen (PSMA) are increasingly used clinically to detect prostate and other cancers with positron emission tomography (PET). The goal of this study was to compare the pharmacokinetics of three PSMA-targeted radiotracers: (68)Ga-1, using DOTA-monoamide as the chelating agent; (68)Ga-2, containing the macrocyclic chelating agent p-SCN-Bn-NOTA; and (68)Ga-DKFZ-PSMA-11, currently in clinical trials, which uses the acyclic chelating agent, HBED-CC. The PSMA-targeting scaffold for all three agents utilized a similar Glu-urea-Lys-linker construct. Each radiotracer enabled visualization of PSMA+ PC3 PIP tumor, kidney, and urinary bladder as early as 15 min post-injection using small animal PET/computed tomography (PET/CT). (68)Ga-2 demonstrated the fastest rate of clearance from all tissues in this series and displayed higher uptake in PSMA+ PC3 PIP tumor compared to (68)Ga-1 at 1 h post-injection. There was no significant difference in PSMA+ PC3 PIP tumor uptake for the three agents at 2 and 3 h post-injection. (68)Ga-DKFZ-PSMA-11 demonstrated the highest uptake and retention in normal tissues, including kidney, blood, spleen, and salivary glands and PSMA-negative PC3 flu tumors up to 3 h post-injection. In this preclinical evaluation (68)Ga-2 had the most advantageous characteristics for PSMA-targeted PET imaging.

The dihydrotetrabenazine (DTBZ) was synthesized by reduction of tetrabenazine with sodium borohydride in ethanol. Crystals suitable for X-ray analysis were obtained from a mixed solution of dichloromethane and ethanol in a five-to-one volume ratio. The crystal is monoclinic, space group P21/c with crystallographic parameters: a = 15.0129(14) , b = 12.5677(12) , c = 9.7715(9) , β = 98.556(2)°, μ = 0.078 mm−1, V = 1823.1(3) 3, Z = 4, Dc = 1.164 g/cm3, F(000) = 696, T = 296(2) K. The X-ray analysis and the chiral HPLC show that the DTBZ prepared by our method consists of (2R,3R,11bR) and (2S,3S,11bS) enantiomers.

The title compound tetrabenazine was synthesized by reaction of 3-dimethyl-aminomethylheptan-2-one and 6,7-dimethoxy-3,4-dihydroisoquinoline hydrochloride. This approach provides an efficient and concise way to the synthesis of the marketed drug tetrabenazine. The colorless single crystal of tetrabenazine suitable for X-ray analysis was obtained from saturated methanol solution. The X-ray results showed that tetrabenazine consists of (3R, 11bR) and (3S, 11bS) enantiomers. Two terminal methyl groups are disordered in the (3R, 11bR) enantiomer.

The title compound, 3-methyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole was synthesized by reaction of diphenylphosphazoanilide with N-acetyl-N′-(2-pyridoyl)hydrazine. Crystals suitable for X-ray analysis were obtained from a mixed solution of water and ethanol in a one-to-one volume ratio. The crystal is orthorhombic, space group P212121 with crystallographic parameters: a = 19.414(4) A, b = 17.172(3) A, c = 7.4850(15) A, β = 90.00°, μ = 0.079 mm−1, V = 2495.3(8) A3, Z = 8, Dc = 1.258 g/cm3, F(000) = 992, T = 295(2) K. The X-ray results showed that in the crystal structure of the title compound, the 1,2,4-triazole, pyridine and benzene rings are not coplanar. The title compound was synthesized by reaction of diphenylphosphazoanilide with N-acetyl-N′-(2-pyridoyl)hydrazine, and the crystal structure shows that its three aromatic rings (1,2,4-triazole, pyridine and benzene rings) do not share a common plane.

To provide a convenient and facile method to evaluate the radiochemical purity (RCP) of 99mTc-TRODAT-1 in quality control of routine clinical application, a simplified method of single-strip thin layer chromatography (TLC) was developed and validated by high performance liquid chromatography (HPLC). The RCP data of TLC correlated well with HPLC.

Until recently the opioid receptor family was thought to consist of only the mu-, delta- and kappa-receptors. The cloning of opioid receptor like receptor (ORL1) and its endogenous ligand nociceptin/orphanin FQ, which displayed anti-opioid properties, has raised the issue of functional co-operativity of this system with the classical opioid system. ORL1 receptor knockout mice have been successfully developed by homologous recombination to allow the issue of potential heterogeneity of this receptor and also of compensatory changes in mu-, delta- or kappa-receptors in the absence of ORL1 to be addressed. We have carried out quantitative autoradiographic mapping of these receptors in the brains of mice that are wild-type, heterozygous and homozygous for the deletion of the ORL1 receptor. ORL1, mu-, delta- and kappa-receptors were labelled with [(3)H] leucyl-nociceptin (0.4 nM), [(3)H] DAMGO (4 nM), [(3)H] deltorphin-I (7 nM), and [(3)H] CI-977 (2.5 nM) respectively. An approximately 50% decrease in [(3)H] leucyl-nociceptin binding was seen in heterozygous ORL1 mutant mice and there was a complete absence of binding in homozygous brains indicating the single gene encodes for the ORL1 receptor and any putative subtypes. No significant gross changes in the binding to other opioid receptors were seen across genotypes in the ORL1 mutant mice demonstrating a lack of major compensation of classical opioid receptors in the absence of ORL1. There were a small number of region specific changes in the expression of classical opioid receptors that may relate to interdependent function with ORL1.

In the title complex, [Cu(C3H4N2)(C10H11N3)2](ClO4)2, the CuII cation has a distorted trigonal-bipyramidal geometry defined by a CuN2N′2N′′ donor set. The imidazole ligand is disordered over two orientations of equal occupancy. Two of the perchlorate ion sites are located on a twofold rotation axis, and one of is disordered over two sites of equal occupancy. In the crystal structure there is a two-dimensional infinite network of hydrogen-bonded mol­ecules parallel to the ab plane.

In the title compound, C15H18ClNO2, the internal torsion angles of the tropane ring are comparable to those of tropane rings in the crystal structures reported for cocaine and its derivatives. There is an intramolecular hydrogen bond between the N atom in the tropane ring and the O atom of the carboxyl group. The crystal structure is further stabilized by many weak C—H...O interactions between the molecules in the ab plane, forming a two-dimensional supramolecular network.