Synthesis and receptor binding affinity of new selective GluR5 ligands

Two hybrid analogues of the kainic acid receptor agonists, 2-amino-3-(5-tert-butyl-3-hydroxy-4-isoxazolyl)propionic acid (ATPA) and (2S,4R)-4-methylglutamic acid ((2S,4R)-4-Me-Glu), were designed, synthesized, and characterized in radioligand binding assays using cloned ionotropic and metabotropic glutamic acid receptors. The (S)-enantiomers of E-4-(2,2-dimethylpropylidene)glutamic acid ((S)-1) and E-4-(3,3-dimethylbutylidene)glutamic acid ((S)-2) were shown to be selective and high affinity GluR5 ligands, with Ki values of 0.024 and 0.39 microM, respectively, compared to Ki values at GluR2 of 3.0 and 2.0 microM. respectively. Their affinities in the [3H]AMPA binding assay on native cortical receptors were shown to correlate with their GluR2 affinity rather than their GluR5 affinity. No affinity for GluR6 was detected (IC50 > 100 microM).     

Synthesis and adenosine receptor affinity and potency of 8-alkynyl derivatives of adenosine

Adenosine derivatives bearing different (ar)alkynyl chains at the 8-position were synthesized and tested at human adenosine receptors. Binding studies showed that all compounds possess affinity for the A3 subtype in the high nM range. Moreover, guanosine 5'-O-(3-[35S]thio)triphosphate binding assay indicated that the 8-alkynyl adenosines behaved as antagonists of NECA at A3 receptors.     

Synthesis and structure--activity relationship of novel aminotetralin derivatives with high micro selective opioid affinity

Several novel racemic aminotetralin derivatives have been prepared using a stereoselective aziridine ring opening reactions and were evaluated for their micro-opioid receptor binding affinity. Selectivity index towards other opioid receptors and antinociceptive activity in mice have been evaluated for the most potent derivatives.     

Synthesis and binding affinity of new pyrazole and isoxazole derivatives as potential atypical antipsychotics

We describe the synthesis and binding affinities on D(2), 5-HT(2A) and 5-HT(2C) receptors of 6-aminomethyl-6,7-dihydro-1H-indazol-4(5H)-ones and 6-aminomethyl-6,7-dihydro-3-methyl-benzo[d]isoxazol-4(5H)-ones, as conformationally constrained butyrophenone analogues. One of the new compounds showed good in vitro binding features, and a Meltzer's ratio characteristic of an atypical antipsychotic profile.     

Synthesis and NMDA-receptor affinity of 4-oxo-dexoxadrol derivatives

A synthesis of novel dexoxadrol analogues is described, which allows modifications of the piperidine substructure. The key step of the synthesis is a hetero Diels-Alder reaction of the imine 12 with Danishefsky's diene 6. After separation of the diastereomeric piperidones 14a and 14b, the relative configuration of the unlike configured piperidone 15b was determined by X-ray crystal structure analysis. In receptor binding studies the like configured secondary amine 15a (racemate) showed considerable affinity toward the phencyclidine binding site of the NMDA receptor (Ki=470 nM).     

Synthesis of dopamine transporter selective 3-diarylmethoxymethyl-8-arylalkyl-8-azabicyclo[3.2.1]octane derivatives

A series of diarylmethoxymethyltropane-GBR hybrid analogues with all three possible stereochemical orientations at C3 were synthesized and evaluated at dopamine and serotonin transporters. The 3alpha derivatives were found to be the most potent compounds with the 3alpha-di(4-fluorophenyl)methoxymethyl-8-(3-phenylpropyl)-8-azabicyclo[3.2.1]octane 15b (Ki = 5 nM) being the most potent compound of the series. The corresponding 3-di(4-fluorophenyl)-methoxymethyl-8-(3-phenylpropyl)-8-azabicyclo[3.2.1]oct-2-ene 12b (Ki = 12 nM) was slightly less potent than the 3alpha-analogue, while the 3beta-di(4-fluorophenyl)methoxymethyl-8-(3-phenylpropyl)-8-azabicyclo[3.2.1]octane 23b (Ki = 78 nM) exhibited only modest affinity for the dopamine transporter. Only the 3alpha-analogue 15b (SERT/DAT = 48) exhibited higher SERT/DAT selectivity than GBR 12909. These results indicate that the dopamine transporter can tolerate some variability in proximity of the benzhydryl ether to the basic nitrogen atom of the tropane without loss in potency. In addition, the structure-activity data for these tropane-GBR 12909 hybrid analogues support previous findings that the stereochemical and conformational effects imparted by unsaturation at C3 are important for dopamine transporter selectivity over the serotonin transporter.     

Synthesis of polyamine derivatives for the preparation of affinity chromatography columns for the search of new Trypanosoma cruzi targets.

The most potent trypanocidal compound of a series of symmetrically substituted 1,4-bis(3-aminopropylpiperazines) which displayed an IC50 value of 5 microM on Trypanosoma cruzi trypomastigotes, was inactive on trypanothione reductase. Two derivatives 6 and 12 of this compound, one symmetrical and one dissymmetrical, were synthesized via a reductive amination reaction, to prepare affinity chromatography columns, which allowed us to isolate three parasitic proteins. Among these, the major ligand 6- and 12-binding protein having an apparent molecular weight of 52 kDa has been identified as the thiol-disulfide oxido-reductase Tc52, previously characterized in Trypanosoma cruzi.     

Synthesis of thiazole and selenazole derivatives with affinity for the odorant-binding protein.

Three new ligands for odorant-binding proteins (OBPs) have been prepared, to be used in protein structure studies: the photoaffinity label 2-azido-4-butyl-5-propylthiazole, the NMR probe 2-trifluoromethyl-4-butyl-5-propylthiazole and the X-ray probe 2-amino-4-butyl-5-propylselenazole. All three compounds bind the bovine OBP with dissociation constants in the micromolar range.     

Synthesis of new pyridazinone derivatives and their affinity towards alpha1-alpha2-adrenoceptors.

A series of 3(2H)-pyridazinone derivatives was evaluated for their affinity in vitro towards alpha1-alpha2-adrenoceptors by radioligand receptor binding assays. All target compounds showed good affinities for the alpha1-adrenoceptor (with Ki values in the subnanomolar range), and a gradual increase in affinity was observed by increasing the polymethylene chain length of this series up to a maximum of six and seven carbon atoms, when the fragment 4-[2-(2-methoxyphenoxy)-ethyl]-1-piperazinyl is linked in 5 position of the 3(2H)-pyridazinone ring, while a slight decrease was found for the higher homologues. Increasing the chain length when the 4-[2-(2-methoxyphenoxy)-ethyl]-1-piperazinyl group is linked in 6 position of the 3(2H)-pyridazinone ring, had a different effect: there is the highest affinity when the polymethylene chain is of four carbon atoms. The alkylic chain, a spacer between the two major constituents of the molecule, can influence the affinity and the selectivity.     

Synthesis,binding affinity and SAR of new benzolactam derivatives as dopamine D3 receptor ligands

A series of new benzolactam derivatives was synthesized and the derivatives were evaluated for their affinities at the dopamine D₁, D₂, and D₃ receptors. Some of these compounds showed high D₂ and/or D₃ affinity and selectivity over the D₁ receptor. The SAR study of these compounds revealed structural characteristics that decisively influenced their D₂ and D₃ affinities. Structural models of the complexes between some of the most representative compounds of this series and the D₂ and D₃ receptors were obtained with the aim of rationalizing the observed experimental results. Moreover, selected compounds showed moderate binding affinity on 5-HT_2A which could contribute to reducing the occurrence of extrapyramidal side effects as potential antipsychotics.     

Synthesis and BZR affinity of pyrazolo[1,5-a]pyrimidine derivatives. Part 1: study of the structural features for BZR recognition

Examination of the pharmacophoric points of the pyrazolo[1,5-a]pyrimidine derivatives, ligands for BZR, previously published led us to the design of a novel class of 3,6-diaryl-4,7-dihydro-pyrazolo[1,5-a]pyrimidin-7-ones and to determine the groups involved in the BZR recognition.     

A new bacterial mannosidase for the selective modification of ramoplanin and its derivatives

Ramoplanin is a lipoglycodepsipeptide produced by Actinoplanes sp. ATCC 33076 and active on bacterial cell wall biosynthesis by binding to Lipid II. A screening of an actinomycetes collection was performed to select enzymatic activities able to introduce specific modifications in the ramoplanin molecule. An extracellular mannosidase from Streptomyces GE 91081 was found to selectively remove one mannose unit from ramoplanin and tetrahydroramoplanin to give the corresponding mannosyl aglycones. These molecules show an improved microbiological activity versus some resistant staphylococci and streptococci, and are useful intermediates in the synthesis of novel ramoplanin-like antibiotics. The biotransformation of ramoplanin has been optimised to improve molar conversion and the transformation reaction rate.     

A new bacterial mannosidase for the selective modification of ramoplanin and its derivatives

Ramoplanin is a lipoglycodepsipeptide produced by Actinoplanes sp. ATCC 33076 and active on bacterial cell wall biosynthesis by binding to Lipid II. A screening of an actinomycetes collection was performed to select enzymatic activities able to introduce specific modifications in the ramoplanin molecule. An extracellular mannosidase from Streptomyces GE 91081 was found to selectively remove one mannose unit from ramoplanin and tetrahydroramoplanin to give the corresponding mannosyl aglycones. These molecules show an improved microbiological activity versus some resistant staphylococci and streptococci, and are useful intermediates in the synthesis of novel ramoplanin-like antibiotics. The biotransformation of ramoplanin has been optimised to improve molar conversion and the transformation reaction rate.     

Synthesis of 3-phenylnaphthalenic derivatives as new selective MT(2) melatoninergic ligands

A series of naphthalenic analogues of melatonin were prepared and evaluated as melatonin receptor MT(2) selective ligands. Activity and MT(2) selectivity can be modulated with suitable variations of the C-3 phenyl and the acyl group on the C-1 side chain. Surprisingly, in contrast with what had been previously described in other series (2-benzylindoles, 2-benzylbenzofurans and 3-phenyltetralins), the presence of a C-3 phenyl with a functional group on the meta position seems to be primordial for MT(2) affinity and selectivity. Indeed, N-[2-(3-(3-hydroxymethylphenyl)-7-methoxynaphth-1-yl)ethyl]acetamide (21) is one of the best MT(2) selective ligands described until now and behaves as an antagonist.     

Synthesis and first in vivo evaluation of new selective high affinity beta1-adrenoceptor radioligands for SPECT based on ICI 89,406

The results of cardiac biopsies suggest that myocardial beta1-adrenoceptor (AR) density is reduced in patients with chronic heart failure, while changes in cardiac beta2-ARs vary. A technique for visualization and quantification of beta1-AR populations rather than total beta-AR densities in the human heart would be of great clinical interest. Molecular imaging techniques, either single photon emission computed tomography (SPECT) or positron emission tomography (PET), with appropriate radiopharmaceuticals offer the possibility to assess beta-AR density noninvasively in humans, but to date, neither a SPECT nor a PET-radioligand is clinically established for the selective imaging of cardiac beta1-ARs. The aim of this study was to design a high affinity selective beta1-AR radioligand for the noninvasive in vivo imaging of cardiac beta1-AR density in man using SPECT. Based on the well-known selective beta1-AR antagonist, ICI 89,406, both the racemic iodinated target compound 11a and the (S)-enantiomer 15a were synthesized. Competition studies using the nonselective AR ligand, [(125)I]iodocyanopindolol ([(125)I]ICYP), and ventricular membrane preparations from mice showed that 11a and 15a possess higher beta1-AR affinities (up to 265-fold) and beta1-AR selectivities (up to 245-fold) than ICI 89,406. Encouraged by these results, the radioiodinated counterparts of racemic 11a (11b: (125)I, 11c: (123)I) and (S)-configurated 15a (15b: (125)I, 15c: (123)I) were synthesized. The target compounds were evaluated in rats. Biodistribution and metabolism studies in rats indicated that there is a specific heart uptake of 11b-c and especially 15b-c accompanied by rapid metabolism of the radioligands. Therefore, radioiodinated 11c and 15c appeared to be unpromising SPECT-radioligands for assessing beta1-ARs in vivo in the rat. However, the rat may metabolize beta-AR ligands more rapidly than other species as demonstrated for (S)-[(11)C]CGP 12177, a radioligand structurally related to 11a-c and 15a-c. Therefore further studies in a different animal model will be carried out.     

Synthesis and characterization of metal ion imprinted nano-porous polymer for the selective recognition of copper

Selective recognition of metal ions utilizing metal ion-imprinted polymers (MIIPs) received much importance in diverse fields owing to their high selectivity for the target metal ions. In the present study, a copper ion imprinted polymer was synthesized without an additional complexing ligand or complex with a broad aim to avoid the conventional extra metal ion complexing ligand during the synthesis of MIIP. The complete removal of the copper metal ion from the MIIP was confirmed by AAS and SEM–EDX. SEM image of the MIIP exhibited nano-patterns and it was also found to be entirely different from that of non-imprinted polymer and polymer with copper metal ions. BET surface area analysis revealed more surface area (47.96 m²/g) for the Cu(II)-MIIP than non-imprinted control polymer (41.43 m²/g). TGA result of polymer with copper metal ion indicated more char yield (18.41%) when compared to non-imprinted control polymer (8.3%) and Cu(II)-MIIP (less than 1%). FTIR study confirmed the complexation between Cu(II)-MIIP and Cu(II) metal ion through carbonyl oxygen of acryl amide. The Cu(II)-MIIP exhibited an imprinting efficiency of 2.0 and it was showing 8% interference from a mixture of Zn, Ni and Co ions. A potentiometric ion selective electrode devised with Cu(II)-MIIP showed more potential response for Cu(II) ion than that was fabricated from non-imprinted polymer.     

Designed calix[8]arene-based ligands for selective tryptase surface recognition

Basic amino acid calix[8]arene receptors for tryptase surface recognition have been synthesized. The tetrameric arrangement and the negative charge distribution close to the active sites of the enzyme, have suggested the design of complementary multifunctional receptors that might bind to the active region of the protein blocking the approach of the substrate. Kinetic inhibition analysis on recombinant lung tryptase have showed a time-dependent competitive inhibition with both initial and steady-state rate constants in the nanomolar range.     

Towards a better understanding of agronomic and soil basis for possible charcoal root rot control and production improvement in bean

Abstract

Macrophomina phaseolina causes charcoal root rot (CRR) in numerous crops worldwide. However, structural progression of CRR epidemics in association with bean agro-ecosystems is little understood. Thus, progression of CRR epidemics in interaction with 13 agro-ecological variables was characterised in 48 commercial bean fields. Frequency of pathogen isolated from root was assessed at vegetative (V3), flowering-podding (R6-7) and pod maturity (R9) growth stages. Two principal factors accounting for 89% of total data variance characterised CRR epidemics. Rhizobial nodulation and cultivation–depth, clay–pH, date–preceding crop, urea–bean class and urea–herbicide interactions accounted for 50% CRR epidemic dynamics. Sixty-five percent of production variance was explained by soil clay, bean class, colonisation, planting date and depth, cultivation method, preceding crop, nodulation, herbicide and urea application. The present findings enabled us to explain a noticeable part of variations in productivity among the bean CRR pathosystems with the help of certain agricultural and environmental events for sustainable agriculture purposes.     

Synthesis and properties of new rubomycin derivatives

Condensation of rubomycin (daunorubicin) with respective hydrazides yielded novel substituted hydrazones: 13-cyanoacetyl hydrazone rubomycin, 13-L-phenylalanyl hydrazone rubomycin, 13-BOC-3-(uracilyl-1)-DL-alanyl hydrazone rubomycin and 13-BOC-3-(adenylyl-9)-DL-alanyl hydrazone rubomycin. With successive treatment of rubomycin with hydrazine hydrate and respective ketones novel asymmetric azines were prepared: 13-cyclopentylidene hydrazone rubomycin, 13-alpha,alpha'-dimethyl-cyclopentylidene hydrazone rubomycin and 13-(1-phenylethylidene-1) hydrazone rubomycin. 14-Adenylyl-N9-rubomycin was synthesized by interaction of 14-bromorubomycin with adenine and hydrogenation of its analog, 14-N-imidazolyl rubomycin by sodium borhydrite yielded 13-dihydro-14-N-imidazolyl rubomycin. There was observed correlation between the antimicrobial activity of the derivatives against B. mycoides and their cytostatic effect on the cells of murine leukemia NK/LI. The high in vitro activity of 13-cyclopentylidene hydrazone rubomycin showed satisfactory correlation with the results of the study on the antitumor effect in animals.     

Bioinformatic strategies for better understanding of immune function

Novartis Foundation sponsored a Symposium which brought together a group of experimental immunologists, theoretical immunologists, and bioinformaticians to discuss the new field of immunoinformatics. The discussion focused on immunological databases, antigen processing and presentation, immunogenomics, host-pathogen interactions, and mathematical modelling of the immune system. A main conclusion of the meeting is the critical role played by immunoinformatics in current immunology research. In particular, immunoinformatics provides a foundation for the emerging fields of systems immunology and immunogenomics.