Acidic elements in histamine H(3) receptor antagonists.

Antagonists of the human histamine H(3) receptor (hH(3)R) often contain a second basic moiety, which is well known to boost affinity on this histamine receptor subtype. Here, we prepared compounds with acidic moieties of different pK(a) values to figure out that the hH(3)R tolerates these functionalities when added to a common pharmacophore blueprint. Depending on the acidic, electronic and steric features the designed ligands showed hH(3)R affinities in the nanomolar concentration range. Additionally, selected ligands were tested but failed as dual acting hH(3)R/hPPAR (human peroxisome proliferator-activated receptor) ligands.

Diether derivatives of homo- or substituted piperidines as non-imidazole histamine H3 receptor ligands.

Synthesis and biological activities of a series of homo- or substituted piperidine unsymmetrical diethers are described. The novel compounds were evaluated for histamine H(3) receptor binding affinities at recombinant human H(3) receptor stably expressed in HEK-293 cells. All diethers showed in vitro affinities in nanomolar concentration range. The most potent compounds are 1-[3-(3-(4-chlorophenoxy)propoxy)propyl]-3-methylpiperidine 11 (K(i)=3.2 nM) and 1-[3-(3-(4-chlorophenoxy)propoxy)propyl]azepane 13 (K(i)=3.5 nM).

A solid phase parallel synthesis of diverse amides as dopamine D3 receptor ligands.

A solid phase parallel synthesis using SynPhase technology was used to couple a series of 21 carboxylic with three different 4-(4-arylpiperazinyl)butanamines. The resulting library was evaluated as dopamine D(3) receptor ligands giving rise to several compounds with affinities in the low nanomolar concentration range (9e and 9n with binding affinities at D(3) receptors of 0.10 and 0.35 nM respectively).

Biomolecular interactions between human recombinant beta-MyHC and cMyBP-Cs implicated in familial hypertrophic cardiomyopathy.

OBJECTIVE: Cardiac myosin-binding protein C (cMyBP-C) is a component of sarcomere that contains at least three putative myosin-binding sites. Mutations in its gene are implicated in familial hypertrophic cardiomyopathy (FHC) and most of them are predicted to produce C-terminal truncated cMyBP-Cs. The aim of the present study was to analyze whether cMyBP-C truncated mutants resulting from FHC mutations interact in vitro with human beta-MyHC. METHODS: Recombinant proteins were produced using the baculovirus/insect cell system, and wild type and three truncated cMyBP-Cs were purified using metal affinity chromatography. The interaction between recombinant proteins was analyzed in real time using biosensor technology on immobilized anti-beta-MyHC antibodies. RESULTS: Biomolecular interaction with beta-MyHC was detected for both wild type cMyBP-C and a truncated mutant lacking half of the C-terminal C10 domain. In contrast, no interaction with beta-MyHC was found for two truncated cMyBP-Cs lacking at least the C5-C9 region. CONCLUSIONS: Biosensor technology allows in vitro analysis of the interaction between human beta-MyHC and cMyBP-C mutants resulting from FHC mutations. The data show that the interaction depends on the size of the truncation. This suggests that, in the context of FHC, impairment of suitable interaction between beta-MyHC and some of the truncated cMyBP-Cs may promote degradation of the truncated proteins and therefore contribute to the development of the disease.

First metal-containing histamine H3 receptor ligands.

Iron-containing ligands targeting the human histamine H(3) receptor (hH(3)R) were prepared. The compounds contain ferrocene sandwich complexes coupled via different linkers to a basic hH(3)R antagonist/inverse agonist pharmacophore. In a click chemistry approach, a triazole was successfully inserted as a new linking element. Two ferrocenylmethylamines and a ferrocenyltriazole were the most affine hH(3)R ligands within this series, showing receptor binding in the nano- and subnanomolar concentration range.

Highly potent fluorescence-tagged nonimidazole histamine H3 receptor ligands.

Different (3-phenoxypropyl)piperidine derivatives have been coupled to fluorescent moieties (5-dimethylaminonaphthalene-1-sulfonyl, carbazol-9-ylcarbonyl, 2-cyanoisoindol-1-yl, 2-cyanobenzo[f]isoindol-1-yl, 2,4-dinitrobenzen-1-yl, 2,4-diaminophenyl, 7-nitrobenzofurazan-4-yl, 7-aminosulfonylbenzofurazan-4-yl, 4-methylcoumarin-6-yl) as novel histamine H(3) receptor ligands. They have been synthesised starting from piperidine in a few steps. The compounds display good to excellent histamine hH(3) receptor affinities with K(i) values ranging from 13.4 to 0.048 nM. Some of the new compounds belong to the most potent ligands known so far and may act as tools for identification and understanding of the binding site on the histamine H(3) receptor. In vivo screening on selected derivatives of Sanger's reagent showed antagonist potencies with ED(50) values from 7.9 to 0.39 mg kg(-1), p.o.

Neuropeptide AF and FF modulation of adipocyte metabolism. Primary insights from functional genomics and effects on beta-adrenergic responsiveness.

The presence of a neuropeptide AF and FF receptor (NPFF-R2) mRNA in human adipose tissue (Elshourbagy, N. A., Ames, R. S., Fitzgerald, L. R., Foley, J. J., Chambers, J. K., Szekeres, P. G., Evans, N. A., Schmidt, D. B., Buckley, P. T., Dytko, G. M., Murdock, P. R., Tan, K. B., Shabon, U., Nuthulaganti, P., Wang, D. Y., Wilson, S., Bergsma, D. J., and Sarau, H. M. (2000) J. Biol. Chem. 275, 25965-25971) suggested these peptides, principally recognized for their pain modulating effects, may also impact on adipocyte metabolism, an aspect that has not been explored previously. Our aim was thus to obtain more insights into the actions of these peptides on adipocytes, an approach initially undertaken with a functional genomic assay. First we showed that 3T3-L1 adipocytes express both NPFF-R1 and NPFF-R2 transcripts, and that NPAF binds adipocyte membranes with a nanomolar affinity as assessed by surface plasmon resonance technology. Then, and following a 24-h treatment with NPFF or NPAF (1 microm), we have measured using real-time quantitative reverse transcriptase-PCR the mRNA steady state levels of already well characterized genes involved in key pathways of adipose metabolism. Among the 45 genes tested, few were modulated by NPFF ( approximately 10%) and a larger number by NPAF ( approximately 27%). Interestingly, NPAF increased the mRNA levels of beta2- and beta3-adrenergic receptors (AR), and to a lesser extent those of beta1-ARs. These variations in catecholamine receptor mRNAs correlated with a clear induction in the density of beta2- and beta3-AR proteins, and in the potency of beta-AR subtype-selective agonists to stimulate adenylyl cyclase activity. Altogether, these data show that NPFF-R1 and NPFF-R2 are functionally present in adipocytes and suggest that besides their well described pain modulation effects, NPAF and to a lesser extent NPFF, may have a global impact on body energy storage and utilization.