Optically pure (-)-4-[(N-allyl-3-methyl-4-piperidinyl)phenyl-amino]-N,N-diethylbenzami de displays selective binding and full agonist activity for the delta opioid receptor

The optical isomers of 4-[(N-allyl-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide+ ++ (3) have been prepared and tested in both binding and functional assays. The data show that (-)-3 is responsible for the delta opioid activity demonstrated by the racemic material. This compound displays a binding affinity of 5.5 nM for the delta opioid receptor as well as a 470-fold delta versus mu selectivity. Importantly, (-)-3 is a full agonist at the delta receptor in comparison with SNC-80 (2). Taken together, the data suggest that (-)-3 behaves more like the prototypical delta agonists, BW373U86 or SNC-80, and less like the peptidomimetic compound SL-3111 (5).     

(+/-)-4-[(N-allyl-cis-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzamide displays selective binding for the delta opioid receptor

Racemic 4-[(N-allyl-cis-3-methyl-4-piperidinyl)phenylamino]-N,N-diethylbenzam ide (3a) was synthesized and found to have good affinity and selectivity for the delta receptor. These compounds can be viewed as an analog of BW373U86 and SNC-80 where an internal piperazine nitrogen has been transposed with a benzylic carbon. Functionally, 3a behaves as an agonist at the delta receptor with no measurable stimulation of either the mu or kappa receptor subtypes and was found to be devoid of any measurable amount of antagonist activity for any opioid receptor. A comparison of 3a to SNC-80 and DPDPE in the [35S]GTPgammaS functional assay suggests that 3a may be more like the peptide DPDPE.     

Stereospecific synthesis of (2S)-2-methyl-3-(2',6'-dimethyl-4'-hydroxyphenyl)-propionic acid (Mdp) and its incorporation into an opioid peptide

To examine the effect of replacing the N-terminal amino group in opioid peptides with a methyl group on biological activity, a stereospecific synthesis of the tyrosine analogue (2S)-2-methyl-3-(2',6'-dimethyl-4'-hydroxyphenyl)-propionic acid (Mdp) was performed. The enkephalin analogue (2S)-Mdp-D-Ala-Gly-Phe-Leu-NH2 turned out to be a quite potent delta opioid antagonist and a somewhat less potent mu antagonist, indicating that a positively charged N-terminal amino group is not a conditio sine qua non for the binding of opioid peptides to delta and mu receptors but may be required for signal transduction.     

Use of S-Mosher acid as a chiral solvating agent for enantiomeric analysis of some trans-4-(4-fluorophenyl)-3-substituted-1-methylpiperidines by means of NMR spectroscopy.

S-Mosher acid 1 induced chemical-shift differences (Delta delta) in NMR spectra of chiral trans-4-fluorophenyl-3-substituted-1-methylpiperidines. The magnitude of Delta delta in (1)H and (19)F NMR spectra varied with the substituent at position 3 of the piperidine ring. The magnitudes of Delta delta observed for certain protons and for the fluorine in the 4-fluorophenyl group were sufficiently large to allow determination of enantiomeric composition.     

Identification of a domain in the delta subunit (S238-V264) of the alpha4beta3delta GABAA receptor that confers high agonist sensitivity

We have expressed the alpha4beta3delta and alpha4beta3gamma2L subtypes of the rat GABAA receptor in Xenopus oocytes and have investigated their agonist activation properties. GABA was a more potent agonist of the alpha4beta3delta receptor (EC50 approximately 1.4 micromol/L) than of the alpha4beta3gamma2L subtype (EC50 approximately 27.6 micromol/L). Other GABAA receptor agonists (muscimol, 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol, imidazole-4-amino acid) displayed similar subtype selectivity. The structural determinants underlying these differences have been investigated by co-expressing chimeric delta/gamma2L subunits with alpha4 and beta3 subunits. A stretch of amino acids in the delta subunit, S238-V264, is shown to play an important role in determining both agonist potency and the efficacies of full or partial agonists. This segment includes transmembrane domain 1 and the short intracellular loop that leads to the second transmembrane domain. The effects of the competitive antagonists, bicuculline and SR95531, and the channel blocker, picrotoxin, were not significantly affected by the incorporation of chimeric subunits. As the delta and gamma2L subunits have not been previously implicated directly in agonist binding, we suggest that the effects are likely to arise from changes in the transduction mechanisms that link agonist binding to channel activation.     

Derivatives of 17-(2-methylallyl)-substituted noroxymorphone: variation of the delta address and its effects on affinity and selectivity for the delta opioid receptor

In an effort to establish the importance of the N-(2-methylallyl) substituent in the noroxymorphone series, several derivatives have been synthesized, retaining that N-substituent and modifying the delta address moiety. A few compounds showed moderate binding affinity and selectivity for the delta receptor; none displayed a pharmacological profile as exceptional as N-(2-methylallyl)noroxymorphindole. A second study showed that 3-O-methylation of all derivatives decreases binding affinity. The present results indicate that only a combination of the N-(2-methylallyl) group and an indole delta address provided high selectivity for the delta receptor.     

A murine CD4-, CD8- T cell receptor-gamma delta T lymphocyte clone specific for herpes simplex virus glycoprotein I.

The role of TCR-gamma delta T lymphocytes in immune responses is currently not well understood. TCR-gamma delta cells have a limited repertoire suggesting that TCR-gamma delta T a limited number of evolutionarily conserved Ag such as nonpolymorphic MHC and heat shock proteins. TCR-gamma delta T lymphocytes appear in enhanced numbers in skin lesions produced by Mycobacterium leprae and in the synovial fluid of joints affected by rheumatoid arthritis, raising the possibility that this subset of T lymphocytes may play a role in control of infectious processes and in autoimmune diseases. We report the identification of a TCR-gamma delta T cell clone isolated from a HSV-infected mouse that recognizes glycoprotein I of HSV type 1. Clone recognition of glycoprotein I does not appear to require the expression of MHC class I or class II gene products. These data suggest that TCR-gamma delta lymphocytes may play an important role in the immune response to viral infections.     

(+)-4-phosphonophenylglycine (PPG) a new group III selective metabotropic glutamate receptor agonist

A new synthesis of (R,S)-PPG (4-phosphonophenylglycine) and the separation of the protected enantiomers leading after deprotection to (+)- and (-)-PPG are described. Pharmacological characterization at the group III metabotropic glutamate receptors hmGluR4a and hmGluR7b revealed (+)-PPG as the active enantiomer.     

Nucleotides -1 to -4 of hepatitis delta ribozyme substrate increase the specificity of ribozyme cleavage

In the past, the use of delta ribozyme as a therapeutic tool was limited because substrate specificity was thought to be determined by only 8 nucleotides. Recently, we have accumulated evidence suggesting that the substrate sequence upstream of the cleavage site, which is not involved in the binding with the delta ribozyme, appears to be essential in the selection of an appropriate cleavage site. To understand the role of this region in efficient cleavage, we synthesized a collection of small substrates that possessed single and multiple mutations in positions -1 to -4 and determined the kinetic parameters of their cleavage using a model antigenomic delta ribozyme. Some substrates were found to be uncleavage, whereas others showed >60-fold difference in relative specificity between the least and most efficiently cleaved substrates. The base at each position from -1 to -4 contributes differently to the ability of a substrate to be cleaved. An optimal sequence for positions -1 to -4 was determined to be -1HRHY(-4) (H = U, C, or A). These results shed light on new features that contribute to the substrate requirement of delta ribozyme cleavage and should increase interest in the use of this unique ribozyme.     

Subcellular distribution of steroid delta 4-5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase in the rat epididymis during sexual maturation

The curve of the specific activity of rat epididymal nuclear delta 4-5 alpha-reductase is bell shaped as a function of age, whereas that of cytoplasmic 3 alpha-hydroxysteroid dehydrogenase does not change significantly with age. The present study examines the subcellular distribution of delta 4-5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase in the caput-corpus and cauda epididymidis during development. A 5-step discontinuous sucrose gradient was developed for fractionation of epididymal homogenates. By using enzyme markers specific for different subcellular organelles, the five different subcellular fractions obtained were shown to be of cytoplasmic, microsomal, mitochondrial, nuclear and spermatozoal origin. 3 alpha-Hydroxysteroid dehydrogenase activity was associated only with the cytoplasmic fraction. The activity of the enzyme did not change significantly with age in either the caput-corpus or cauda epididymidis. delta 4-5 alpha-Reductase activity was found in fractions containing microsomal and nuclear markers. delta 4-5 alpha-Reductase activity in the nuclear fraction of the caput-corpus epididymidis was evident in the youngest age group (Day 25), increased 4-fold and peaked in the next age group (Day 35), and declined with each successive age group: Day 45 (60% of maximum), Day 60 (20% of maximum), Day 75 (15% of maximum) and Day 105 (10% of maximum). In contrast, microsomal delta 4-5 alpha-reductase activity increased successively from Day 25 to Day 105; enzyme activity doubled between these two ages. The ratio of nuclear to microsomal delta 4-5 alpha-reductase activity from the caput-corpus epididymidis thus changed markedly with age: Day 25:1.32; Day 35:3.76; Day 45:2.44; Day 60:1.03; Day 75:0.41; and Day 105:0.21. In the cauda epididymidis nuclear delta 4-5 alpha-reductase activity was only evident at Day 35 and Day 45; in microsomal fractions, activity was first found at Day 35 and did not subsequently change with age. These results demonstrate that: 1) epididymal 3 alpha-hydroxysteroid dehydrogenase activity is found only in the cytoplasmic fraction; 2) delta 4-5 alpha-reductase activity is found in nuclear and microsomal fractions; and 3) the subcellular distribution of delta 4-5 alpha-reductase activity changes markedly with age and epididymal section, suggesting differential regulation of nuclear and microsomal delta 4-5 alpha-reductase activities.     

Steroid delta 4-5 beta-reductase in human mammary tumors.

Steroid delta 4-5 alpha- and delta 4-5 beta-reductase activity was determined in 16 human mammary tumors and 8 DMBA-induced rat mammary tumors using a spectrophotometric assay. Steroid delta 4-5 alpha-reductase was present in all tumors investigated while delta 4-5 beta-reductase was detected in only 6 estrogen receptor negative human breast tumors and absent in all estrogen receptor positive human breast tumors as well as in all rat mammary tumors. Further support for the presence of delta 4-5 beta-reductase was established by using a dual-labelling technique consisting of incubating tumor slices with [14C] testosterone and adding [3H] etiocholanolone, [3H] testosterone and [3H]-5 alpha-dihydrotestosterone at the end of the reaction. Following extraction and chromic acid oxidation, 4-androstenedione, 5 beta-androstanedione and 5 alpha-androstanedione were isolated and purified, and the constancy of the 14C/3H ratio was used as proof of 5 alpha-reductase and 5 beta-reductase. These results were shown to be consistent with the data obtained using the spectrophotometric assay.     

Identification of amino acids in the nicotinic acetylcholine receptor agonist binding site and ion channel photolabeled by 4-[(3-trifluoromethyl)-3H-diazirin-3-yl]benzoylcholine,a novel photoaffinity antagonist

[(3)H]4-[(3-trifluoromethyl)-3H-diazirin-3-yl]benzoylcholine (TDBzcholine) was synthesized and used as a photoaffinity probe to map the orientation of an aromatic choline ester within the agonist binding sites of the Torpedo nicotinic acetylcholine receptor (nAChR). TDBzcholine acts as a nAChR competitive antagonist that binds at equilibrium with equal affinity to both agonist sites (K(D) approximately 10 microM). Upon UV irradiation (350 nm), nAChR-rich membranes equilibrated with [(3)H]TDBzcholine incorporate (3)H into the alpha, gamma, and delta subunits in an agonist-inhibitable manner. The specific residues labeled by [(3)H]TDBzcholine were determined by N-terminal sequence analysis of subunit fragments produced by enzymatic cleavage and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and/or reversed-phase high-performance liquid chromatography. For the alpha subunit, [(3)H]TDBzcholine photoincorporated into alphaCys-192, alphaCys-193, and alphaPro-194. For the gamma and delta subunits, [(3)H]TDBzcholine incorporated into homologous leucine residues, gammaLeu-109 and deltaLeu-111. The photolabeling of these amino acids suggests that when the antagonist TDBzcholine occupies the agonist binding sites, the Cys-192-193 disulfide and Pro-194 from the alpha subunit Segment C are oriented toward the agonist site and are in proximity to gammaLeu-109/deltaLeu-111 in Segment E, a conclusion consistent with the structure of the binding site in the molluscan acetylcholine binding protein, a soluble protein that is homologous to the nAChR extracellular domain.     

Functional and phenotypic differences between CD4+ and CD4- T cell receptor-gamma delta clones from peripheral blood.

CD4+ TCR-gamma delta+ T cells comprise a very small subset of TCR-gamma delta+ T cells. CD4+ TCR gamma delta+ T cell clones were established to study the phenotypical and functional characteristics of these cells. Thirty-four CD4+ TCR-gamma delta+ T cell clones were established after sorting CD4+ T cells from a pre-expanded TCR-gamma delta+ T cell population. These clones as well as the CD4- TCR-gamma delta+ T cells from the same donor used V gamma 2 and V delta 2. In a second cloning experiment CD4+ TCR-gamma delta+ T cells were cloned directly from freshly isolated TCR-gamma delta+ T cells using a cloning device coupled to a FACS sorter. Forty-three clones were obtained, which all expressed CD4 and TCR-gamma delta. Eleven of these clones used V delta 1 and three of them coexpressed V gamma 2. The other CD4+ TCR-gamma delta+ T cell clones used both V delta 2 and V gamma 2. CD4+ TCR-gamma delta+ T cell clones expressed CD28 irrespective of the V gamma or V delta usage, and were CD11b negative. Three CD4-CD8+ TCR-gamma delta+ clones expressed CD8 alpha but not CD8 beta and were CD11b positive. CD28 expression among CD4-CD8+ and CD4-CD8- was variable but lower than on CD4+ T cell clones. CD4- TCR-gamma delta+ T cell clones using V gamma 2 and V delta 2 specifically lyse the Burkitt lymphoma cell line Daudi and secrete low levels of IFN-gamma and granulocyte-macrophage-CSF upon stimulation with Daudi. In contrast, most CD4+ T cell clones that use V gamma 2 and V delta 2 had a very low lytic activity against Daudi cells and secrete high levels of IFN-gamma and granulocyte-macrophage-CSF after stimulation with Daudi cells. The NK-sensitive cell line K562 was killed efficiently by the CD4- TCR-gamma delta+ T cell clones, but not by CD4+ TCR-gamma delta+ T cell clones, and could not induce cytokine secretion in CD4+ or CD4- T cell clones. CD4+ TCR-gamma delta+ T cell clones, but not the CD4- clones, could provide bystander cognate T cell help for production of IgG, IgM, and IgA in the presence of IL-2 and IgE in the presence of IL-4. Thus, CD4+ TCR-gamma delta+ T cells are similar to CD4+ TCR-alpha beta+ T cells in their abilities to secrete high levels of cytokines and to provide T cell help in antibody production.(ABSTRACT TRUNCATED AT 400 WORDS)     

Synthesis and activity of 2-[4-(4-[3H]-2-cyanophenyl)piperazinyl]-N-(2,4,6-[3H]3-3-methylphenyl)acetamide: a selective dopamine D4 receptor agonist and radioligand

The first selective dopamine D4 agonist radioligand is described. The synthesis of these piperazine radioligands relied on the transformation of brominated precursors 4a and 4b with tritium gas in the presence of a sensitive cyano functional group. The specific activity of these two radioligands was measured and [3H]6b found to be suitable for use in D4 saturation and competition binding studies. The synthesis, biological, and radioactivity of this new agonist radioligand as well as preliminary SAR will be discussed.     

trans-3,4-dimethyl-4-(3-carboxamidophenyl)piperidines: a novel class of micro-selective opioid antagonists

trans-3,4-Dimethyl-4-(3-carboxamidophenyl)piperidines constitute a novel class of micro opioid receptor antagonists. The CONH(2) group was found to be an effective isostere of the phenolic OH moiety. Structure-activity relationships at the piperidine nitrogen position led to the identification of several ligands displaying high affinity toward the cloned human micro opioid receptors, good selectivity micro/delta, micro/kappa, and potent in vitro antagonist activity.     

SAR-oriented discovery of peroxisome proliferator-activated receptor pan agonist with a 4-adamantylphenyl group as a hydrophobic tail

3-(4-Alkoxyphenyl)propanoic acid derivatives were prepared as candidate peroxisome proliferator-activated receptor (PPAR) alpha/delta/gamma pan agonists, based on our previous SAR studies directed toward the development of subtype-selective PPAR agonists. Those studies indicated that the steric bulkiness of substituents introduced at the distal benzene ring had an important influence on PPAR activity. The finding that a 4-adamantyl derivative exhibited not only PPARalpha/delta activity but also significant PPARgamma activity prompted us to search for structurally novel phenylpropanoic acid derivatives with more potent adipocyte differentiation activity than the well-known PPARgamma agonist, rosiglitazone, as well as well-balanced PPARalpha and PPARdelta agonistic activities. A representative phenylpropanoic acid derivative (12) bearing a 4-adamantylphenyl substituent proved to be a well-balanced PPAR-pan agonist with activities to regulate the expression of genes involved in lipid and glucose homeostasis, and should be useful as a candidate drug for the treatment of altered PPAR function.     

The TIPP opioid peptide family: development of delta antagonists, delta agonists, and mixed mu agonist/delta antagonists

The discovery of the prototype delta opioid antagonists TIPP (H-Tyr-Tic-Phe-Phe-OH) and TIP (H-Tyr-Tic-Phe-OH) in 1992 was followed by extensive structure-activity relationship studies, leading to the development of analogues that are of interest as pharmacological tools or as potential therapeutic agents. Stable TIPP-derived delta opioid antagonists with subnanomolar delta receptor binding affinity and extraordinary delta receptor selectivity include TIPP[Psi] (H-Tyr-TicPsi[CH(2)NH]Phe-Phe-OH] and TICP[Psi] (H-Tyr-TicPsi[CH(2)NH]Cha-Phe-OH); Cha: cyclohexylalanine), which are widely used in opioid research. Theoretical conformational analyses in conjunction with the pharmacological characterization of conformationally constrained TIPP analogues led to a definitive model of the receptor-bound conformation of H-Tyr-Tic-(Phe-Phe)-OH-related delta opioid antagonists, which is characterized by all-trans peptide bonds. Further structure-activity studies revealed that the delta antagonist vs delta agonist behavior of TIP(P)-derived compounds depended on very subtle structural differences in diverse locations of the molecule and suggested a delta receptor model involving a number of different inactive receptor conformations. A further outcome of these studies was the identification of a new class of potent and very selective dipeptide delta agonists of the general formula H-Tyr-Tic-NH-X (X = arylalkyl), which are of interest for drug development because of their low molecular weight and lipophilic character. Most interestingly, TIPP analogues containing a C-terminal carboxamide group displayed a mixed mu agonist/delta antagonist profile, and thus were expected to be analgesics with a low propensity to produce tolerance and physical dependence. This turned out to be the case with the TIPP-derived mu agonist/delta antagonist DIPP-NH(2)[Psi] (H-Dmt-TicPsi[CH(2)NH]Phe-Phe-NH(2)); Dmt: 2',6'- dimethyltyrosine).     

4-N-Hydroxy-4-[1-(sulfonyl)piperidin-4-yl]-butyramides as HDAC inhibitors

A series of N-substituted 4-alkylpiperidine hydroxamic acids, corresponding to the basic structure of histone deacetylase (HDAC) inhibitors (zinc binding moiety-linker-capping group) has been previously reported by our group. Linker length and aromatic capping group connection were systematically varied to find the optimal geometric parameters. A new series of submicromolar inhibitors was thus identified, which showed antiproliferative activity on HCT-116 colon carcinoma cells. We report here the second part of the strategy used in our research group to find a new class of HDAC inhibitors, namely the SAR study for the compounds bearing a sulfonyl group on the piperidine nitrogen. In the present work, we have considered both sulfonamides and sulfonyl ureas.