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Given the need for further improvements in anti-cocaine vaccination strategies, a chimeric hapten (GNET) was developed that combines chemically-stable structural features from steady-state haptens with the hydrolytic functionality present in transition-state mimetic haptens. Additionally, as a further investigation into the generation of an improved bifunctional antibody pool, sequential vaccination with steady-state and transition-state mimetic haptens was undertaken. While GNET induced the formation of catalytically-active antibodies, it did not improve overall behavioral efficacy. In contrast, the resulting pool of antibodies from GNE/GNT co-administration demonstrated intermediate efficacy as compared to antibodies developed from either hapten alone. Overall, improved antibody catalytic efficiency appears necessary to achieve the synergistic benefits of combining cocaine hydrolysis with peripheral sequestration.

Specific, sensitive, reverse-phase high-performance liquid chromatographic (HPLC) assays of cocaine (I) and its hydrolysis products, benzoylecgonine (II) and benzoic acid (III), have been devised with analytical sensitivities as low as 15 ng/ml of plasma for I using spectrophotometric detection at 232 nm. Cocaine can be separated from its hydrolysis products by extraction at pH 7.5 with haloalkanes. Benzoylecgonine and benzoic acid can be extracted at pH 3.0 with 1-butanol. The evaporated residues were reconstituted in acetonitrile-water for HPLC assay. The assay was used to determine the stabilities of I and II in aqueous solutions, to establish log k-pH profiles at various temperatures, and to evaluate Arrhenius' parameters. Hydrolyses were by specific acid-base catalysis. Cocaine showed hydrogen and hydroxyl ion attack on protonated I with 40 and 90% proceeding through the benzoylecgonine route, respectively, as well as hydroxyl ion attack on neutral cocaine, with only 6% proceeding through the benzoylecgonine route. Cocaine is relatively unstable in the neutral pH range with a half-life of 5 hr in buffer at pH 7.25 and 40°. Similar half-lives were observed in fresh dog plasma at 300 and 30 μg/ml, although one study at 0.5 μg/ml indicated a doubling of the rate.

Benzoylecgonine (BZE) is the major toxic metabolite of cocaine and is responsible for the long-term cocaine-induced toxicity owing to its long residence time in humans. BZE is also the main contaminant following cocaine consumption. Here, we identified the bacterial cocaine esterase (CocE) as a BZE-metabolizing enzyme (BZEase), which can degrade BZE into biological inactive metabolites (ecgonine and benzoic acid). CocE was redesigned by a reactant-state-based enzyme design theory. An encouraging mutant denoted as BZEase2, presented a >400-fold improved catalytic efficiency against BZE compared with wild-type (WT) CocE. In vivo, a single dose of BZEase2 (1 mg kg?1, IV) could eliminate nearly all BZE within only two minutes, suggesting the enzyme has the potential for cocaine overdose treatment and BZE elimination in the environment by accelerating BZE clearance. The crystal structure of a designed BZEase was also determined.

A concise and efficient method for the construction of N,C3-constrained tropane derivatives has been developed. The key step of the reaction sequence involves either a 6- or a 7-trig radical cyclization. (C) 2000 Published by Elsevier Science Ltd.

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The development of radiometal-labelled pharmaceuticals for neuroimaging could offer great potential due to easier handling during labelling and availability through radionuclide generator systems. Nonetheless, to date, no such tracers are available for positron emission tomography, primarily owing to the challenge of crossing the blood–brain barrier (BBB) and loss of affinity through chelator attachment. We have prepared a variety of 68Ga-labelled phenyltropanes showing that, through a simple hydrocarbon-linker, it is possible to introduce a chelator onto the lead structure while maintaining its high affinity for hDAT (human dopamine transporter) and simultaneously achieving adequate lipophilicity. One of the candidates, [68Ga]Ga-HBED-hexadiyne-tropane, showed an IC50 value of 66 nM, together with a log D7.4 of 0.96. A μPET study in a hemi-parkinsonian rat model showed a fast wash-out of the tracer, and no specific uptake in the brain, thus implying an inability to penetrate the BBB.

Bolaamphiphilic compounds are provided according to formula (I); where HG1, HG2 and L1 are as defined herein. Provided bolaamphiphilic compounds and the pharmaceutical compositions thereof are useful for delivering GDNF or NGF into animal or human brain.

The fluorine-18 labeled nortropane derivative 2β-carbomethoxy-3β- (4-chlorophenyl)-8-(2-fluoroethyl)-nortropane (FECNT) is a dopamine transporter (DAT) ligand. Currently, it is considered as reference for positron emission tomography imaging. Herein, the synthesis of novel precursors (N-tosyloxy-, chloro-, and bromo- analogues) for one-step radiosynthesis of [ 18F]FECNT is reported. Using the N-mesyloxy- precursor in a one-step radiosynthesis, the crude [18F]FECNT was obtained with the radiolabeling yield of 45 ± 10%, confirming the practical efficiency of this approach in the design of novel precursors for labeling. Copyright

Bolaamphiphilic compounds are provided according to formula (I): where HG1, HG2 and L1 are as defined herein. Provided bolaamphilphilic compounds and the pharmaceutical compositions thereof are useful for delivering GDNF or NGF into animal or human brain.

PR04.MZ was designed as a highly selective dopamine transporter inhibitor, derived from natural cocaine. Its binding profile indicates that [11C]PR04.MZ may be suited as a PET radioligand for the non-invasive exploration of striatal and extrastriatal DAT populations. As a key feature, its structural design facilitates both, labelling with fluorine-18 at its terminally fluorinated butynyl moiety and carbon-11 at its methyl ester function. The present report concerns the efficient [11C]MeI mediated synthesis of [11C]PR04.MZ from an O-desmethyl precursor trifluoroacetic acid salt with Rb2CO3 in DMF in up to 95 ± 5% labelling yield. A preliminary μPET-experiment demonstrates the reversible, highly specific binding of [11C]PR04.MZ in the brain of a male Sprague-Dawley rat.

A series of 2β-carbomethoxy-3β-phenyl tropanes with conformationally constrained nitrogen substituents were synthesized as potential selective dopamine transporter ligands. These novel compounds were examined for their monoamine uptake inhibition potency at the human dopamine transporter (hDAT), the human serotonin transporter (hSERT) and the human noradrenalin transporter (hNET), stably expressed in human embryonic kidney cells (HEK). A SAR-study was conducted to determine the contribution of extended, 4-fluorinated, conformationally constrained C4 chains at the tropane nitrogen to human monoamine transporter affinity and selectivity. The Royal Society of Chemistry 2009.

A series of 2β-isopropyl ester analogs of cocaine (7-11) was synthesised and evaluated in an in vitro dopamine transporter (DAT) binding assays. Ecgonine HCl (5) was obtained from (-)-cocaine (1) by hydrolysis using 1 N HCl. Acid catalysed esterification of 5 using 2-propanol and HCl gas afforded 2β-isopropyl ecgonine (6). Compounds 7-9 were obtained via esterification of the 3β-hydroxyl group of 6 using the appropriate acid chloride. Compound 10 was obtained via selective hydrolysis and re-esterification of 7 using 2-propanol and HCl gas. Compound 11 was obtained by reduction of 9 using H2/Pd-C. Compounds 7, 10 and 11 showed high binding affinity to the DAT (as indicated from the inhibition of the binding of [3H]WIN 35,428 (3)) with IC50 values (mean±S.E.M.) 208.5±9.5, 47.43±1.79 and 11.25±3.37 nM, respectively). Compound 7 is comparatively as active as cocaine, 10 is ca. fivefold more active than cocaine and 11 is ca. 20-fold more active than cocaine and even twice more active than the radioligand 3. Compound 11, like its methyl ester analog (2′ aminococaine), exhibited the highest affinity to the DAT. These results, along with previous results, emphasise the importance of a hydrogen-bond donor group at the 2′-position of cocaine and its isopropyl ester analogs to enhance binding affinity to the DAT.

3α-(Diphenylmethoxy)tropane (benztropine) and its analogues are tropane ring-containing dopamine uptake inhibitors that display binding and behavioral profiles that are distinct from cocaine. We previously prepared a benztropine-based photoaffinity label [125I]-(N-[4-(4′-azido-3′-iodophenyl)butyl]- 3α-[bis(4′-fluorophenyl)methoxy]tropane, [125I]1, that covalently attached to the 1-2 transmembrane spanning region of the dopamine transporter (DAT). This was in contrast to the 4-7 transmembrane spanning region labeled by a cocaine-based photoaffinity label, [125I] 2 (RTI 82). To characterize further these different binding domains, photoaffinity ligands that had the 4′-azido-3′-iodophenyl substituent extended from the same position on the tropane ring were desirable. Thus, identification of the optimal alkyl linker between this substituent and the tropane nitrogen in the benztropine series was investigated to ultimately prepare the identical N-substituted analogue of 2. In this pursuit, the N-[4-(4′-azido-3′-iodophenyl)propyl] analogue of 3α-[bis(4′-fluorophenyl)methoxy]tropane (9a) was synthesized as well as two isothiocyanate analogues that do not require photoactivation (10a,b) for irreversible binding. The synthesis of these target compounds was achieved using a modification of the strategy developed for 1. Evaluation of these compounds for displacing [3H]WIN 35 428 binding at DAT in rat caudate putamen revealed that the 4′-azido-3′-iodophenylbutyl substituent, found in 1, provided optimal binding affinity and was chosen to replace the N-CH3 group on 2. Both the 4′-azido-3′-iodophenyl- and the 4′-isothiocyanatophenylbutyl analogues of 2 (25 and 26, respectively) were synthesized. Both products bound to DAT with comparable potency (IC50 = 30 nM) to RTI 82 (2). In addition, compound 26 demonstrated wash-resistant displacement of [3H]WIN 35 428 in HEK 293 cells stably transfected with hDAT. These ligands will provide important tools for further characterizing the binding domains for tropane-based dopamine uptake inhibitors at the DAT.

A series of 11 novel 3β-substituted biphenyltropanes was synthesized and evaluated by selective radioligand binding assays for affinity to monoamine transporters. Both 5-HTT potency and selectivity for 5-HTT over DAT was greatest with electron withdrawing group at the 3-position. (C) 2000 Elsevier Science Ltd. All rights reserved.

The synthesis of (E)-N-(3-iodoprop-2-enyl)-2β-carbomethoxy-3β-(3',4'-dichlorophenyl) nortropane (β-CDIT) and its radioiodinated analogues is described. Three different synthetic methods are reported for the preparation of (E)-N-[3-(tributylstannyl)-2-enyl]-2β-carbomethoxy-3β-(3', 4'-dichlorophenyl) nortropane, which was iododestannylated for the preparation of the corresponding iodinated derivative. We also report the radiolabelling of β-CDIT with 125I or 123I that could be used for in vitro and in vivo exploration of the dopamine transporter.

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It is now accepted that (-)-cocaine binds to specific recognition sites associated with monoamine transporters in the mammalian brain. In this study, several analogs of 3β-phenyltropane-2β-carboxylic acid methyl ester were prepared and their potency for inhibiting the binding of -3β-(4-fluorophenyl)tropane-2β-carboxylic acid methyl ester to primate caudate-putamen was evaluated. The synthesis and binding affinity of 3β-(3,4-dichlorophenyl)tropane-2β-carboxylic acid methyl ester, one of the most potent cocaine congeners yet reported, is presented. The feasibility of synthesizing high-affinity ligands for cocaine recognition sites and their suitability as PET imaging ligands for cocaine receptors in vivo is demonstrated.

A series of modified retinals bearing nonconjugated positive charges along the polyene were synthesized.It was found that nonconjugated charges shifted the absorption maxima of retinal chromophore as well as protonated retinal Schiff bases.The magnitude of shift observed in bacteriorhodopsin (bR), 5170 cm-1, could be found in our models by the additivity of two factors: (1) interaction through space with a positive charge located in the vicinity of the ring operating in nonprotic solvents, provided that the interaction between the charge and its counteranion is weakened by a homoconjugation effect; (2) weakening the interaction of the Schiff base positively charged nitrogen with its counteranion.A shift of ca. 5000 cm-1 can also be achieved by interaction through space with two nonconjugated positive charges.The absorption maximum of protonated retinal Schiff base is influenced significantly by an interaction with a nonconjugated charge located in the vicinity of the ring moiety or carbon 9.The influence of a charge located in the vicinity of carbon 12 and carbon 14 is minor.Nonconjugated positive charges have a remarkable effect on C=C stretching frequencies as well.It is suggested that the different C=C stretching frequencies found in bR, visual pigments, as well as their photochemically induced intermediates, may originate from interaction with external charges, the C=N+ stretching frequency does no exhibit similar sensitivity to external nonconjugated charges, and it is practically unaffected by them.