Synthesis of [3H], [13C215N] and [14C]Sch 66336 (Sarasar™)

[³H]Sch 66336 was prepared at a specific activity of 1.35 Ci/mmol by Ru(Ph₃P)₃Cl₂ catalysed exchange with tritiated water. [¹³CN]Sch 66336 was synthesized from potassium [¹³C]cyanide and [¹³C¹⁵N₂]urea in 29% overall yield from potassium [¹³C]cyanide. [¹⁴C]Sch 66336 was synthesized from potassium [¹⁴C]cyanide in 31% yield. A second synthesis, from N‐Boc‐4‐hydroxy[¹⁴C]piperidine, gave [¹⁴C]Sch 66336 labelled in a different site in 19% overall yield. Copyright © 2004 John Wiley & Sons, Ltd.     

The synthesis and use of [14C]carbon monoxide in Pd‐catalyzed carbonylation reactions

The [¹⁴C]carbonylation reaction is a very powerful method of incorporating C‐14 into a drug molecule late in a radiochemical synthesis. The first and perhaps most critical step in [¹⁴C]carbonylation reactions is the generation of ¹⁴CO and its subsequent delivery to the reaction flask. There are three published methods for generating ¹⁴CO: conversion of ¹⁴CO₂ with Zn at 400°C, pyrolysis of Ca¹⁴CO_3, and dehydration of NaOCH. Additionally, a newly published method for the in situ carbonylation of aryl and vinyl halides to give acids has been investigated using NaOCH as the labeled precursor. Finally, the application of ¹⁴CO in Pd‐catalyzed [¹⁴C]carbonylation reactions will be discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and biological evaluation of a lipophilic,fluorine‐18‐labeled 5‐ethynyl‐2′‐deoxyuridine derivative

The synthesis and preliminary biological evaluation of a lipophilic, fluorine‐18‐labeled 5‐ethynyl‐2′‐deoxyuridine derivative [¹⁸F]‐ 3 is described. Initially, 5‐ethynyl‐2′‐deoxyuridine 5 was synthesized by coupling trimethylsilyl protected acetylene to 5‐iodo‐2′‐deoxyuridine 4 , followed by deprotection in alkaline conditions. Compound 5 was then reacted with 4‐(4′‐iodophenyl)phenol to give 5‐[4(4′‐hydroxyphenyl)phenyl]ethynyl‐2′‐deoxyuridine 6 . Compound 6 was reacted with BrCH₂CHF as alkylating agent to give stable or radiolabeled 3 . The crude products were purified using reversed phase‐high performance liquid chromatography to obtain compound 3 and [¹⁸F]‐ 3 in 33 and 7.4% yield (decay corrected), respectively. The synthesis time to obtain pure [¹⁸F]‐ 3 was about 60 min (starting from BrCH₂CHF). The specific radioactivity of the tracer was between 74 and 222 GBq/µmol. The log P_7.4 of [¹⁸F]‐ 3 was found to be 2.4. However, biodistribution study in normal mice showed low uptake of the tracer in the brain. The affinity of compounds 6 and 3 for varicella‐zoster virus thymidine kinase enzyme (VZV‐TK) was examined in vitro and the results revealed that the fluorinated analog 3 has a poor affinity for the enzyme in contrast to the phenol precursor 6 . Copyright © 2007 John Wiley & Sons, Ltd.     

Selective [15N] labelling of an NG‐propionylated arginine derivative

A straightforward convergent synthesis of [¹⁵N]‐Bz‐Arg(N^η‐propionyl)‐OEt^*TFA is presented. In this approach, the guanidinylation reagent [¹⁵N₂]‐N(boc)‐N′(propionyl)‐S‐methylisothiourea is reacted with the side chain amino group of the title compound's ornithine precursor. The guanidinylation step is promoted by stoichiometric addition of HgCl₂ to force completion. This method leads directly to the N^G‐acylated product and the acyl residue is principally modifiable in the last synthetic step of the guanidinylation reagent. Copyright © 2008 John Wiley & Sons, Ltd.     

Application of 99Mo/99mTc alumina generator in the labeling of metoprolol for diagnostic purposes

Labeling of metoprolol by technetium‐99m in pertechnetate form (^99mTcO) eluted from a ⁹⁹Mo/^99mTc alumina generator in the presence of stannous chloride dihydrate was carried out via chelation reaction. The reaction parameters that affect the labeling yield such as metoprolol concentration, stannous chloride dihydrate concentration, reaction temperature, and pH of the reaction mixture were studied to optimize the labeling conditions. Using 1 GBq ^99mTcO, 500 µg metoprolol as substrate dissolved in 500 µL phosphate buffer at pH 9 and 50 µL of stannous chloride as reducing agent (1 mg/mL) at 25°C for 30 min reaction time, a maximum radiochemical yield of ^99mTc‐metoprolol (92%) was obtained. ^99mTc‐metoprolol was characterized by thin layer chromatography (TLC) and by high pressure liquid chromatography (HPLC). The specific activity of ^99mTc‐metoprolol obtained was 888 MBq/1.88 mmol. The biological distribution in normal mice showed that ^99mTc‐metoprolol is rapidly concentrated after injection in the heart, which indicates its suitability for heart imaging. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and biodistribution in mice of 99mTcN–DBODC–DMSEt

Nitrido technetium(V)‐mixed ligand complex of ^99mTcN–DBODC – DMSEt [DMSEt: Monoethyl ester of (meso) 2,3‐dimercaptosuccinic acid, DBODC: bis(2‐ethoxyethyl)carbamodithioate] has been prepared in a two‐step procedure by first reaction of ^99mTcO with succinic dihydrazede in the presence of stannous chloride as a reducing agent and propylenediamine tetraacetic acid as a complexant, followed by the addition of DMSEt and DBODC. The complex was stable over 6 h at room temperature. The partition coefficient indicated that it was a hydrophilic complex. Biodistribution in mice demonstrated that the complex accumulated mainly in liver, lungs and kidneys. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and biodistribution in mice of a new 99mTc nitrido complex for brain imaging

The bis(N‐cyclopentyl dithiocarbamato) nitrido technetium‐99m complex ^99mTcN(CPEDTC)₂ was synthesized by the reduction of ^99mTcO into [^99mTc≡N]²⁺ with stannous chloride in the presence of succinic dihydrazide and propylenediamine tetraacetic acid, followed by the addition of sodium N‐cyclopentyl dithiocarbamate monohydrate. The radiochemical purity (RCP) of the product was over 90% as measured by thin layer chromatography(TLC) and high performance liquid chromatography(HPLC). In vitro studies showed that the complex possessed good stability under physiological conditions. Its partition coefficient studies indicated it was a good lipophilic complex. The electrophoresis results showed the complex was neutral. The biodistribution results in mice indicated that ^99mTcN(CPEDTC)₂ was significantly retained into the brain. The brain uptake(ID%/g) was 3.58, 5.26, 3.73 and 2.72 and the brain/blood ratios were 0.79, 1.69, 1.59 and 1.58 at 5, 30, 60 and 90 min post‐injection, respectively. These results suggested potential usefulness of the complex as a new brain perfusion imaging agent. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation and biological evaluation of 99mTcN‐4‐(cyclohexylpiperazin‐1‐yl)‐dithioformate as a potential sigma receptor imaging agent

The goal of this study is to develop a novel ^99mTc‐labeled σ receptor imaging agent. Potassium 4‐(cyclohexylpiperazin‐1‐yl)‐dithioformate, 2 , and the corresponding rhenium complex, ReN‐2 , were synthesized and characterized. ReN‐2 possessed moderate affinity toward σ₁ (K_i = 1.94 ± 0.60 µmol/L) and σ₂ (K_i = 2.83 ± 1.39 µmol/L) receptors. The radiolabeled complex ^99m TcN‐2 was prepared in high yield (> 95%) through the [^99mTcN] precursor and characterized by HPLC. ^99m TcN‐2 was found to be a lipophilic and neutral complex with good stability. The biodistribution in tumor‐bearing mice showed that ^99m TcN‐2 had good tumor uptake (2.12 ± 0.01 %ID/g at 2 h p.i.) and moderate brain uptake (0.27 ± 0.05 %ID/g at 2 h p.i.). After blocking with haloperidol, the uptakes by tumor and brain were lower than control. The results indicated that the complex has specific binding to the σ receptors in vivo. Further structural modifications of this complex are needed to obtain ^99mTc‐based σ receptor imaging agents with high affinity and subtype selectivity. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,radio‐LC–MS analysis and biodistribution in mice of 99mTc–NIM–BAT

S,S′‐bis‐trityl‐N‐BOC‐1,2‐ethylenedicysteamine (S,S′‐bis‐trityl‐N‐BOC–BAT) was conjugated to 2‐nitroimidazole (NIM) through a propylene spacer in order to provide a precursor for a potential technetium‐99 m labelled hypoxia tracer. For labelling with technetium‐99 m, a two‐step one‐pot procedure was developed consisting of deprotection of the ligand by heating in mild acidic conditions and subsequent exchange labelling in the presence of SnCl₂, tartrate and ^99mTcO. The labelling reaction mixture was analyzed using electrospray radio‐LC–MS and the observed mass spectrum corresponding to the main radiometric peak was in accordance with the predicted structure of oxo–Tc(V)–NIM–BAT. ^99mTc–NIM–BAT was purified using RP–HPLC and its biodistribution was evaluated in normal mice at 10 min and 4 h p.i. ^99mTc–NIM–BAT was cleared from plasma mainly by hepatobiliary excretion. Copyright © 2003 John Wiley & Sons, Ltd.     

Optimizing [13N]N2 radiochemistry for nitrogen‐fixation in root nodules of legumes

Here we explored the conditions for synthesizing [¹³N]N₂ in a state that is suitable for the administration to plant root nodules enabling studies of nitrogen fixation. [¹³N]N₂ was prepared batchwise, starting with [¹³N]NO from the ¹⁶O(p,α)¹³N nuclear reaction on a liquid water target. [¹³N]NO was first reduced to [¹³N]NH₃ using Devarda's alloy, and then the [¹³N]NH₃ was oxidized to [¹³N]N₂ by hypobromite using carrier‐added NH₄Cl. The amounts of carrier NH₄Cl and hypobromite were varied to determine the effects these parameters had on the radiochemical yield, and on the radiotracer specific activity. As expected, increasing the amount of carrier NH₄Cl improved the radiochemical yield. Unexpectedly, increasing the amount of excess hypobromite from 1.6‐fold to 6‐fold molar equivalents (relative to NH₄Cl) improved the radiochemical yield and radiotracer specific activity under all conditions of carrier NH₄Cl. As a comparison, we measured [¹³N]N₂ specific activity derived from in‐target production based on a 50 µA min irradiation driving the ¹⁴N(p,pn)¹³N reaction on a gaseous N₂ target. The ‘wet’ radiochemistry approach afforded two advantages over the in‐target approach with a ～600‐fold improvement in specific activity, and the ability to collect the tracer in a small volume of gas (～20 mL at STP). Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of heavy metals on the biology of a N2-fixing cyanobacterium Anabaena doliolum

The effects of copper, nickel, and iron on survival, growth, nutrient uptake (NH, NO, and PO), carbon fixation, nitrate reductase, nitrogenase (CH₂ reduction assay), glutamine synthetase (transferase), and alkaline phophatase activities of Anabaena doliolum were studied. About 50% survival of the test alga was scored at 8.0 × 10^?3, 8.6 × 10^?3, and 0.36 mM of Cu, Ni, and Fe, respectively. However 45, 59, and 57% reductions in final yield were scored, respectively, at LD₅₀ concentrations of Cu, Ni, and Fe. On the basis of the LD₅₀ of the test metals, Ni was the most inhibitory for nutrient uptake. However, the LD₅₀ concentrations of Cu, Ni, and Fe showed different levels of inhibition for different processes. Although metal concentrations higher than LD₅₀ were found to be more inhibitory, 0.54 mM iron generated maximum inhibitory effect as compared to Cu and Ni. The present study demonstrates that the test cyanobacterium exhibits metal and dose-specific responses toward different physiological and biochemical processes.     

Effects of a new 1,3,4‐thiadiazolium mesoionic compound,MI‐D,on the acute inflammatory response

A new mesoionic compound, 4‐phenyl‐5‐(4‐nitro‐cinnamoyl)‐1,3,4‐thiadiazolium‐2‐phenylamine (MI‐D), is described along with some of its biological properties. Its effects on hepatic metabolism, on O and nitric oxide (NO) production, and in in vivo models for potential antinociceptive, antipyretic, and antiinflammatory activities were determined. In perfused rat liver, MI‐D (25 µM) stimulated glycogenolysis (95%), and inhibited oxygen uptake (37%) with affecting glycolysis. In phorbol 12‐myristate 13‐acetate‐stimulated macrophages, O generation was reduced (95%) by MI‐D (15 µM), whereas the production of NO was unaffected. MI‐D (2 mg/kg) inhibited (55%) the number of abdominal writhings induced by acetic acid. At 1 mg/kg, MI‐D inhibited the febrile response (5 h) induced by lipopolysaccharide (LPS) and was also effective against a preexisting febrile response. Treatment with MI‐D (1 mg/kg) reduced by 67% prostaglandin (PGE₂) levels in the cerebrospinal fluid of LPS‐exposed mice, and at a higher dose (8 mg/kg) MI‐D inhibited paw edema formation (2 h) induced by carrageenan. MI‐D has a spectrum of activities similar to other nonsteroidal antiinflammatory drugs, qualifying it as a potential anti‐inflammatory drug. Drug Dev. Res. 61:207–217, 2004. © 2004 Wiley‐Liss, Inc.     

Synthesis and biodistribution of novel 99mTc‐nitrido methylpiperidine dithioformate derivatives as potential brain imaging agents

Three dithioformate ligands with methyl substituted on the piperidine rings, potassium 1‐(2‐methylpiperidine‐1‐yl)‐dithioformate (2‐mp), potassium 1‐(3‐methylpiperidine‐1‐yl)‐dithioformate (3‐mp) and potassium 1‐(4‐methylpiperidine‐1‐yl)‐dithioformate (4‐mp) were synthesized. The corresponding ^99mTc‐nitrido complexes were prepared in high yield (>95%) through the [^99mTcN] intermediate and characterized by thin layer chromatography and high‐performance liquid chromatography. All the neutral ^99mTc‐nitrido complexes were stable under physiological conditions and lipophilic with log P values between 1.40 and 1.58. In vivo biodistribution results showed that all the ^99mTc‐nitrido complexes displayed high brain uptakes and long retention times. Among them, ^99mTcN‐4mp, demonstrated the best properties for brain imaging with the brain uptake 3.40±0.24, 3.22±0.31, 2.72±0.28 and 2.22±0.18% ID/g at 5, 30, 60 and 120 min p.i., respectively. Moreover, the influence of stereochemistry of the ^99mTcN complexes with methyl substitution on ortho, meta and para positions on piperidine ring on the biodistribution properties were investigated with B3LYP/6‐31G*(LANL2DZ for Tc) method using the Gaussian 03 program package. Copyright © 2009 John Wiley & Sons, Ltd.     

Recombinant coagulation factor VIIa labelled with the fac‐99 mTc(CO)3‐core: synthesis and in vitro evaluation of a putative new radiopharmaceutical for imaging in acute bleeding lesion

Coagulation in blood is initiated when coagulation factor VII (FVII) binds to exposed TF and is activated to FVIIa, and the TF/FVIIa complex may therefore provide a marker of vascular injury potentially applicable in diagnostic imaging of acute gastrointestinal (GI) bleeding. Methods: Recombinant FVIIa (rFVIIa) was radiolabeled with technetium‐99 m in a direct labeling reaction using the ‘carbonyl approach’ using the IsoLink^® carbonyl labeling agent. The properties of ^{99 m}Tc(CO)₃‐rFVIIa complex was analyzed by TCA precipitation, HPLC and FVIIa functional integrity was tested in in vitro assays. Results: Labeling of rFVIIa was possible without tagging with a chelater. Incorporation of radioactivity depended strongly on rFVIIa concentration and temperature. More than 95% incorporation was achieved after 30 min at 45°C with 0.76 mg/ml rFVIIa. ^{99 m}Tc(CO)₃‐rFVIIa was obtained in 46% radiochemical yield and in >95% radiochemical purity. Pull down experiments showed that the biological activity (binding to tissue factor and to anti‐FVII antibody) of the radiolabelled product remained intact in the formulation mixture as well as in human serum. By computer modeling analysis, two candidate sites for stabilizing the ^{99 m}Tc(CO)‐ligand structure in FVIIa were identified. Conclusion: Radiolabelled rFVIIa derivatives may represent a novel tool for the diagnosis of acute gastrointestinal bleeding lesions. Copyright © 2010 John Wiley & Sons, Ltd.     

Repeated dose pharmacokinetics of pancopride in human volunteers

The aim of this study was to assess the pharmacokinetic profile of pancopride after repeated oral dose administration of 20 mg pancopride in tablet form once a day for 5 d in 12 healthy male volunteers. Plasma levels were measured by HPLC using a solid phase extraction method and automated injection. The minimum quantification limit of pancopride in plasma was 2 ng mL^?1. The maximum plasma concentration (mean ± SD) after the first dose was 92.5 ± 41.5 ng mL^?1 and t_max was 1.7 ± 0.9 h. The elimination half-life (t_1/2) was 14.3 ± 6.9 h. The area under the concentration-time curve from zero to infinity (AUC) was 997 ± 396 ng h mL^?1. The maximum plasma concentration (mean ± SD) at steady state (day 5) was 101.8 ± 36.9 ng mL^?1 and t_max was 2.2 ± 1.2 h. The elimination half-life (t_1/2) was 16.3 ± 2.7 h and the minimum plasma concentration (C) was 16.6 ± 6.9 ng mL^?1. The area under the concentration-time curve during the dosing interval (AUC) was 995 ± 389 ng h mL^?1. The average plasma concentration at steady state (C) was 43.3 ± 16.1 ng mL^?1 and the experimental accumulation ratio (R_AUC) was 1.34 ± 0.19, whereas the mean theoretical value (R) was 1.40 ± 0.29. The results obtained showed a good correlation between the experimental plasma levels and the expected values calculated using a repeated dose two-compartment model assessed by means of the Akaike value. It is concluded that the pharmacokinetics of pancopride are not modified after repeated dose administration. The safety parameters showed no clinically relevant alterations.     

Kit with technetium‐99m labelled antimicrobial peptide UBI 29‐41 for specific infection detection

The purpose of this study was to investigate radiochemical and biological characteristics of an instant kit for the preparation of ^99mTc‐labelled UBI 29‐41 for specific detection of infections. The kit is based on ^99mTc‐labelling via HYNIC conjugated to the terminal amine of the peptide, producing a well‐understood labelled compound. One hour after the addition of fresh ^99mTcO to the kit ITLC and HPLC reverse‐phase analysis was performed. Stability of the labelled complex was challenged and the binding to bacterial pellets was assessed. Finally, the biodistribution and accumulation in MRSA‐infected tissues were studied using scintigraphy and ex vivo countings. Data were compared to a non‐kit control method. Radiochemical analysis indicated >96% labelling, stability for 24 h and the preparation was used without purification. In vitro studies showed 41% of radioactivity was bound to bacteria. After injection into mice with a bacterial infection the site of infection was visualized within 30 min. Kit prepared ^99mTc‐HYNIC‐UBI 29‐41 was rapidly (half‐life 113 min) cleared via the kidneys and urinary bladder, essentially slower than control peptide (half‐life 74 min). This slower clearance results in higher activities in blood and other tissues. Nevertheless, ^99mTc‐HYNIC‐UBI 29‐41 shows favourable radiochemical characteristics and deserves further evaluation in a clinical setting. Copyright © 2005 John Wiley & Sons, Ltd.     

Comparative evaluation of [99mTc(H2O)3(CO)3]+ precursor synthesized by conventional method and by using carbonyl kit

A comparison of the preparation of Tc carbonyl complexes of a few ligands of interest through the conventional method as well as by using the recently introduced carbonyl kit method is described. Synthesis of [^99mTc(OH₂)₃(CO)₃]⁺ precursor was carried out by the conventional method in which ^99mTcO was reduced with sodium borohydride and carbonylated by purging CO gas. Tricarbonyl complexes of MIBI, TBI, isoniazid and mebrofenin were prepared using the above precursor under optimized conditions. [^99mTc(OH₂)₃(CO)₃]⁺ precursor was also synthesized by using the carbonyl kit and its utility for the synthesis of tricarbonyl complexes was studied by carrying out synthesis of complexes with the above ligands. For comparison, these complexes were first prepared under similar conditions optimized with conventional precursor in order to see the variation in the yields in the two different procedures. Characterization of the precursors as well as the respective tricarbonyl complexes was carried out by reverse phase HPLC using C18 column. It was observed that [^99mTc(OH₂)₃(CO)₃]⁺ precursor could be synthesized in high yields using the carbonyl kit, however, the reaction kinetics was found to be slow while using the kit precursor. In the case of TBI and MIBI, it was observed that increase in reaction time was essential to achieve good yields. A five‐fold increase in the ligand concentration was needed while using the carbonyl kit in order to get good complexation yields with isoniazid and mebrofenin. Copyright © 2004 John Wiley & Sons, Ltd.     

Stabile Pyridophenanthridiniumsalze mit Acyliminium-Partialstruktur, 1. Mitt

Stable Pyridophenanthridinium-Salts with Acyliminium Partial Structure, 1. Comm Stable crystalline acyliminiumfluoroborates 7a – c·BF₄ ^? are synthesized from tetracyclic lactams 6a – c by NOBF-dehydrogenation. Treatment of 6b , c with bromine affords less stable bromides 7b – c·Br ^?. On reaction with NaHCO₃-solution the salts 7 are converted into carbinolamides 8 , from which the salts 7a – c·BF₄ ^? and 7a – c·Br ^? can be regenerated with BF₃·Et₂O and SOBr₂. α-Amidoalkylation reactions of the acyliminiumsalts 7 and carbinolamides 8 with O- and C-nucleophiles are described.     

Synthesis of labeled BCX‐4208, a potent inhibitor of purine nucleoside phosphorylase

BCX‐4208, a novel inhibitor of the enzyme purine nucleoside phosphorylase, mimics the charged ribosyl oxocarbenium ion formed during the transition state of the enzyme‐catalyzed C‐N bond cleavage of nucleosides. A slow‐onset, tight‐binding inhibitor with a of 16 ± 1.4 pM, BCX‐4208 is one of the most potent inhibitors known for the enzyme. In support of our BCX‐4208 clinical program, a mass spectrometric assay has been developed that required labeled BCX‐4208 as an internal standard. The synthesis of [²H]₂‐BCX‐4208 and [¹³C]‐BCX‐4208 is described in this report. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,Cytotoxicity, and Apoptosis Induction Study of Antitumor Dinuclear Platinum(II) Complexes

Five novel dinuclear platinum(II) complexes with a new chiral ligand, 3‐(2‐amino‐cyclohexylamino)‐propionic acid (HP), were designed, prepared and spectrally characterized. The in vitro cytotoxicities of these compounds were evaluated against the HepG‐2, MCF‐7, A549, and HCT‐116 cell lines. The results indicated that all compounds showed cytotoxicity towards the HepG‐2 cell line. Particularly, complex X5 , which has SO as a bridge, exhibited better cytotoxicity than carboplatin or oxaliplatin against all selected cell lines. Moreover, double dyeing flow cytometric resection indicated that the target compounds inhibited tumor cell growth by inducing apoptosis.