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Bis(diamido)-bridged basket resorcin[4]arene (all-S)-1 and its (all-R)-1 enantiomer proved able to interact with 2'-deoxycytidine (2) and pyrimidine nucleoside analogs in dimethyl sulfoxide (DMSO) solution. In such a solvent, the resorcinarene hosts adopt a preferential 1,3-alternate-like conformation, with a larger cavity delimited by two syn 3,5-dimethoxyphenyl moieties, and two external pockets, each delimited by the other 3,5-dimethoxyphenyl group and its diamido arm (the wing). Complexation phenomena were investigated by nuclear magnetic resonance (NMR) methods, including 1H NMR DOSY and 1D ROESY experiments, and molecular modeling. Heteroassociation constants of [(all-S)-1·2] and [(all-R)-1·2] diastereoisomeric complexes were obtained from diffusion data by single point measurements, and from nonlinear fitting of 1H NMR chemical shifts. Selective proton relaxation rate measurements allowed us to significantly discriminate the two complexes by identifying two different interaction sites of the guest in the resorcin[4]arene host, depending on its configuration. Chirality 25:840–851, 2013. © 2013 Wiley Periodicals, Inc.

A pharmacophore represents a simple and intuitive concept that can be used in many different drug discovery applications. Ligand-based and structure-based pharmacophore models continue to play a pivotal role in hit discovery and may guide lead optimization. Moreover, owing to the versatility of the pharmacophore concept, pharmacophore modelling has been routinely used in combination with other molecular modelling techniques. The synergistic use of different tools in drug discovery workflows may allow to fully exploit the advantages, while compensating for some of the intrinsic limitations, of each methodology. This review will focus on the synergistic combination of pharmacophore modelling with other molecular modelling approaches such as the hot spot analysis of protein binding sites, molecular dynamics, and docking.

The catalytic mechanism of Burkholderia cepacia lipase (BCL), which catalyzes the enantioselective hydrolysis of racemic esters of primary alcohols, was investigated by modeling the first stage of ...

We recently described the synthesis of 1-benzyl-3-propyl-1H,8H-imidazo[2,1-f]purine-2,4-diones, new potent and selective A3 adenosine receptor antagonists containing a xanthine core. The present work can be considered an extension of our SAR studies on related structures in which the effect of different kind of substitutions at the 1-, 3- and 8-positions has been evaluated in order to improve both the potency and the hydrophilicity of the originally synthesised molecules. The A3 binding disposition of these compounds was also investigated through docking and 3D-QSAR studies.

New 1-[(3-aryloxy-3-aryl)propyl]-1 H-imidazoles were synthesized and evaluated against Candida albicans and dermatophytes in order to develop structure-activity relationships (SARs). Against C. albicans the new imidazoles showed minimal inhibitory concentrations (MICs) comparable to those of ketoconazole, miconazole, and econazole, and were more potent than fluconazole. Several derivatives ( 10, 12, 14, 18- 20, 24, 28, 29, 30, and 34) turned out to be potent inhibitors of C. albicans strains resistant to fluconazole, with MIC values less than 10 microg/mL. Against dermatophytes strains, compounds 20, 25, and 33 (MICor= 5 microg/mL) were equipotent to ketoconazole, econazole, and miconazole. SARs of imidazoles 10- 44 were rationalized with reasonable accuracy by a previously developed quantitative pharmacophore for antifungal agents.

This review is aimed at providing an overview of the up-to-now published literature on resorc[4]arene macrocycles exploited as artificial receptors for the molecular recognition of some classes of natural products. A concise illustration of the main synthetic strategies developed to afford the resorc[4]arene scaffold is followed by a report on the principles of the gas-phase investigation of recognition phenomena by mass spectrometry (MS). Emphasis is placed on gas-phase studies of diastereoisomeric complexes generated inside a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer by resorc[4]arene receptors towards a series of natural products, namely amino acids, amphetamine, ethanolamine neurotransmitters, dipeptides, vinca alkaloids and nucleosides. The literature outcomes discussed here, taken largely from our own revisited work, have been completed by references to other studies, in order to draw a broader picture of this rapidly evolving field of research.

Some N-Boc ynamides bearing a terminal ester or aryl group are treated with azides to produce the desired triazoles with complete regiocontrol.

During the course of our investigations in the field of azole antimicrobial agents, we have identified BM 212, a pyrrole derivative with good in vitro activity against mycobacteria and candidae. These findings prompted us to prepare new pyrrole derivatives 1-10 in the hope of increasing the activity. The microbiological data showed interesting in vitro activity against Mycobacterium tuberculosis and atypical mycobacteria.

In the last few years, molecular modeling studies have been published that are devoted to a better understanding of the structural flexibility of hyaluronan (HA). Further conformational investigations, however, are needed on this polysaccharide, such as the application of statistical methods to perform enhanced one-step conformational analyses of its subunits. Moreover, the adjustment of assisted model building and energy refinement (AMBER) force field could provide the appropriate computational tool to study the interactions of HA and its derivatives with proteins. The present paper reports a combined Monte Carlo (MC) and molecular dynamics (MD) approach applied to the conformational study of HA, using an adjusted version of AMBER force field and the generalized Born solvent-accessible surface area (GB/SA) continuum solvation model. The MC approach turned out to be extremely effective to outline a conformational survey of the disaccharides constituting HA. Complete sets of conformations of the monomers were provided for the first time, some of which had never been predicted. MD technique, integrating the MC results, correctly reproduced the unusual stiffness of HA and predicted the existence of a minor skew-boat conformation of the β-d-glucuronic moiety. The computational approach, as a whole, improved the comprehension of the dynamic behavior of HA and offered a clear causal explanation of the relative dynamics of the glycosidic linkages.

The 5-amino-1,2,3-triazole-4-carboxylic acid is a suitable molecule for the preparation of collections of peptidomimetics or biologically active compounds based on the triazole scaffold. However, its chemistry may be influenced by the possibility of undergoing the Dimroth rearrangement. To overcome this problem, a protocol based on the ruthenium-catalyzed cycloaddition of N-Boc ynamides with azides has been developed to give a protected version of this triazole amino acid. When aryl or alkyl azides are reacted with N-Boc-aminopropiolates or arylynamides, the cycloaddition occurs with complete regiocontrol, while N-Boc-alkyl ynamides yield a mixture of regioisomers. The prepared amino acids were employed for the preparation of triazole-containing dipeptides having the structural motives typical of turn inducers. In addition, triazoles active as HSP90 inhibitors (as compound 41, IC50 = 29 nM) were synthesized.

Prokineticins are angiogenic hormones that activate two G protein-coupled receptors: PKR1 and PKR2. PKR1 has emerged as a critical mediator of cardiovascular homeostasis and cardioprotection. Identification of non-peptide PKR1 agonists that contribute to myocardial repair and collateral vessel growth hold promises for treatment of heart diseases. Through a combination of in silico studies, medicinal chemistry, and pharmacological profiling approaches, we designed, synthesized, and characterized the first PKR1 agonists, demonstrating their cardioprotective activity against myocardial infarction (MI) in mice. Based on high throughput docking protocol, 250,000 compounds were computationally screened for putative PKR1 agonistic activity, using a homology model, and 10 virtual hits were pharmacologically evaluated. One hit internalizes PKR1, increases calcium release and activates ERK and Akt kinases. Among the 30 derivatives of the hit compound, the most potent derivative, IS20, was confirmed for its selectivity and specificity through genetic gain- and loss-of-function of PKR1. Importantly, IS20 prevented cardiac lesion formation and improved cardiac function after MI in mice, promoting proliferation of cardiac progenitor cells and neovasculogenesis. The preclinical investigation of the first PKR1 agonists provides a novel approach to promote cardiac neovasculogenesis after MI.

A novel series of 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesised and investigated for the ability to inhibit selectively monoamine oxidases, swine kidney oxidase, and bovine serum amine oxidase. The newly synthesised compounds 1 – 6 proved to be reversible and non-competitive inhibitors of all types of the assayed amine oxidases. Compounds inhibit monoamine oxidases potently, displaying low I 50 values of particular interest. In particular 1-acetyl-3-(2,4-dihydroxyphenyl)-5-(3-methylphenyl)-4,5-dihydro-(1H)-pyrazole 6 showed to be a potent monoamine oxidase inhibitor with a K i of about 10 −8 M. Further insights in the theoretical evaluation of the possible interactions between the compounds and monoamine oxidase B have been developed through a computational approach.

In the present review we summarize recent work, aimed at a better understanding of the interactions in macromolecule–ligand complexes, performed by means of computational tools such as pseudoreceptor generation, molecular docking, conformational search and energy minimization. While the first approach has been applied when the three-dimensional structural properties of the biological target were unknown, the remaining protocols exploited the knowledge of the overall structure of the involved macromolecules and their active sites. Molecular modeling techniques were used in the cases reported to study and propose macromolecular binding sites and to predict their interactions with bioactive conformers of the ligands.

Following our studies on resorcin[4]arenes, we synthesized new macrocycles containing cyanomethyl and aminomethyl side chains. Three stereoisomers (2a−c) of the former were obtained by BF3·Et2O tetramerization of the corresponding trans-cinnamic acid derivative and were shown to be in the 1,2-alternate, cone, and 1,3-alternate conformations. Conversely, the tetraamino derivative 6a in the cone conformation was prepared from the corresponding tetrabromide 3a. The interactions with CuII cations of the new compounds were analyzed by measurements of 1H NMR and EPR spectra in parallel with molecular modeling calculations.

Molecular mechanics calculations and experimental 1 H NMR data are in close agreement and show that the epimerization equilibrium at C 3 of 3,7-dimethylbicyclo[3.3.1]nonan-2,9-diones is shifted toward the 3- endo -epimer in order to reach the lowest energy chair–boat conformation. Introduction of a 1,3-dioxolane moiety at C 9 results in reversal of the equilibrium, in protic solvents, leading mainly to the 3- exo -epimer in the most stable chair–chair conformation. These results have been applied to the stereocontrolled synthesis of the title compounds.

Synthetic routes to highly functionalized 1,4-thiazepinones 2 and 3 have been developed. S-Ac-N-Boc-L-Cys-D(L)-ThrOMe 7a,b have been prepared and, after transformation into the corresponding mesylates, used as the cyclization substrates. Treatment of these compounds with LiAlH(OMe)(3) in THF results in mesylate elimination and thiolacetate reduction, giving rise to both a Michael acceptor (alpha,beta-unsaturated ester) and Michael donor (thiol anion), which undergo in situ intramolecular conjugate addition leading to the stereoselective formation of only two of the four possible stereoisomers of 2. On the other hand, PCC/CaCO(3) oxidation of 7a gave in 80% yield the corresponding ketone 11, which was in turn transformed into the enol triflate 15. Cleavage of the thiolacetate moiety, simultaneous elimination of trifluoromethanesulfonic acid to generate an allene system, and addition of the thiol group to the central carbon of the allene to provide the enantiomerically pure cyclic compound 3 in 85% yield was effected via a one-pot reaction by means of MeONa/MeOH. Thiazepinone 3 is an interesting intermediate for the preparation of conformationally restricted dipeptide mimetics, and its elaboration into the dual ACE/NEP inhibitor 4 is reported.

Objective Prokineticins are potent angiogenic peptides that bind to two G protein-coupled receptors to initiate their biological effects. We previously have shown that prokineticin receptor-1 (PKR1) signaling contributes to cardiomyocyte survival or repair in myocardial infarction. Here, we discovered the first non-peptidic PKR1 agonists and examined their effects in mice model of heart diseases. Methods and results Herein we identify a selective PKR1 agonist both in vitro and in vivo, utilizing GPCR structure-based virtual screening approach. High Throughput Docking was carried out by GOLD using homology model of PKR1. Asinex gold collection 3D chemical databese (250,000 compounds) was screened by the docking protocol. We provided a strategy with a high potential for in silico identifying one agonist hit. We present here IS20, the first synthetic PKR1 agonist that induces angiogenesis in the presence of PKR1 on the endothelial cells seeded on matrigel. IS20 reduced doxorubicin cytotoxicity in H9C2 cells. IS20 promotes mouse epicardial progenitor cell differentiation into endothelial cells. In vivo IS20 activates Akt in mice heart. IS20 treatment of mice after coronary ligation reduces mortality by 30%. Conclusion This study identifies a non-peptidic PKR1 agonist as therapeutic target holding promise for treatment of heart diseases.

G protein-coupled receptors (GPCRs) are seven integral transmembrane proteins that are the primary targets of almost 30% of approved drugs and continue to represent a major focus of pharmaceutical research. All of GPCR targeted medicines were discovered by classical medicinal chemistry approaches. After the first GPCR crystal structures were determined, the docking screens using these structures lead to discovery of more novel and potent ligands. There are over 360 pharmaceutically relevant GPCRs in the human genome and to date about only 30 of structures have been determined. For these reasons, computational techniques such as homology modeling and molecular dynamics simulations have proven their usefulness to explore the structure and function of GPCRs. Furthermore, structure-based drug design and in silico screening (High Throughput Docking) are still the most common computational procedures in GPCRs drug discovery. Moreover, ligand-based methods such as three-dimensional quantitative structure–selectivity relationships, are the ideal molecular modeling approaches to rationalize the activity of tested GPCR ligands and identify novel GPCR ligands. In this review, we discuss the most recent advances for the computational approaches to effectively guide selectivity and affinity of ligands. We also describe novel approaches in medicinal chemistry, such as the development of biased agonists, allosteric modulators, and bivalent ligands for class A GPCRs. Furthermore, we highlight some knockout mice models in discovering biased signaling selectivity.

The development of a novel approach for the prediction of antiestrogenic activity is described, bringing up to date a previous pharmacophore study. Software Phase has been used to derive a 3D-QSAR model based, as alignment rule, on a pharmacophore built on three compounds highly active against MCF-7 cell line. Five features comprised the pharmacophore: two hydrogen-bond acceptors, one hydrogen-bond donor, and two aromatic rings. The sequential 3D-QSAR yielded a test set q2 equal to 0.73 and proved to be predictive with respect to an external test set of 21 compounds (r2 = 0.69). The model was used to detect new MCF-7 inhibitors through 3D-database searching and identified fourteen compounds that were subsequently tested in vitro against the MCF-7 human breast adenocarcinoma cell line. Eleven out of the fourteen compounds exhibited inhibitory activity with IC50 values ranging between 30 and 186 μM. The results of the study confirmed the fundamental validity of the chosen approach as a hit discovery tool.

A mild chlorination reaction of alcohols was developed using the classical thionyl chloride reagent but with added catalytic titanium(IV) chloride. These reactions proceeded rapidly to afford chlorination products in excellent yields and with preference for retention of configuration. Stereoselectivities were high for a variety of chiral cyclic secondary substrates including sterically hindered systems. Chlorosulfites were first generated in situ and converted to alkyl chlorides by the action of titanium tetrachloride which is thought to chelate the chlorosulfite leaving group and deliver the halogen nucleophile from the front face. To better understand this novel reaction pathway, an ab initio study was undertaken at the DFT level of theory using two different computational approaches. This computational evidence suggests that while the reaction proceeds through a carbocation intermediate, this charged species likely retains pyramidal geometry existing as a conformational isomer stabilized through hyperconjugation (hyperconjomers). These carbocations are then essentially "frozen" in their original configurations at the time of nucleophilic capture.

Bis(diamido)-bridged basket resorcin[4]arene (all-S)-1 and its (all-R)-1 enantiomer proved able to interact with 2'-deoxycytidine (2) and pyrimidine nucleoside analogs in dimethyl sulfoxide (DMSO) solution. In such a solvent, the resorcinarene hosts adopt a preferential 1,3-alternate-like conformation, with a larger cavity delimited by two syn 3,5-dimethoxyphenyl moieties, and two external pockets, each delimited by the other 3,5-dimethoxyphenyl group and its diamido arm (the wing). Complexation phenomena were investigated by nuclear magnetic resonance (NMR) methods, including (1)H NMR DOSY and 1D ROESY experiments, and molecular modeling. Heteroassociation constants of [(all-S)-1·2] and [(all-R)-1·2] diastereoisomeric complexes were obtained from diffusion data by single point measurements, and from nonlinear fitting of 1H NMR chemical shifts. Selective proton relaxation rate measurements allowed us to significantly discriminate the two complexes by identifying two different interaction sites of the guest in the resorcin[4]arene host, depending on its configuration.

The synthesis and pharmacological evaluation of a series of pyrrolo[1,4]benzothiazine derivatives are described. These compounds, related to diltiazem, have been shown to be representative of a novel series of calcium channel antagonists. The IC 50 s for inhibition of [ 3 H]nitrendipine binding calculated by radioreceptor assay on rat cortex and rat heart homogenates showed that some of the described compounds possess an affinity equal to or higher than those of the reference calcium antagonists verapamil and cis-(+)-diltiazem. Furthermore, the alteration of the benzothiazepinone system of diltiazem to the pyrrolo[1,4]benzothiazine system of the title compounds resulted in a clear-cut selectivity for cardiac over vascular tissue, as shown in functional studies. In fact comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using an isolated guinea pig left atrium, revealed that the compounds examined displayed higher selectivity than the reference standard, within a wide variation of data. A number of structure-activity relationship trends have been identified, and possible explanation is advanced in order to account for the observed differences in selectivity. Prerequisite for in vitro calcium channel-blocking activity is the presence of two pharmacophores, namely, the substitution at C-4 and the substitution on the pyrrole ring. Two of the tested compounds, 8b and 28a, were identified as potent calcium antagonists selective for cardiac over vascular tissue.

In our search for new cannabinoid receptor modulators, we describe herein the design and synthesis of three sets of indole-based ligands characterized by an acetamide, oxalylamide, or carboxamide chain, respectively. Most of the compounds showed affinity for CB2 receptors in the nanomolar range, with K(i) values spanning 3 orders of magnitude (377-0.37 nM), and moderate to good selectivity over CB1 receptors. Their in vitro functional activity as inverse agonists was confirmed in vivo in the formalin test of acute peripheral and inflammatory pain in mice, in which compounds 10a and 11e proved to be able to reverse the effect of the CB2 selective agonist COR167.

The potential efficacy of GABA(B) receptor agonists in the treatment of pain, drug addiction, epilepsy, cognitive dysfunctions, and anxiety disorders is supported by extensive preclinical and clinical evidence. However, the numerous side effects produced by the GABA(B) receptor agonist baclofen considerably limit the therapeutic use of this compound. The identification of positive allosteric modulators (PAMs) of the GABA(B) receptor may constitute a novel approach in the pharmacological manipulation of the GABA(B) receptor, leading to fewer side effects. The present study reports the identification of two novel compounds, methyl 2-(1-adamantanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR627) and methyl 2-(cyclohexanecarboxamido)-4-ethyl-5-methylthiophene-3-carboxylate (COR628), which act as GABA(B) PAMs in 1) rat cortical membranes and 2) in vivo assay. Both compounds potentiated GABA- and baclofen-stimulated guanosine 5'-O-(3-[(35)S]thio)-triphosphate binding to native GABA(B) receptors, while producing no effect when given alone. GABA concentration-response curves in the presence of fixed concentrations of COR627 and COR628 revealed an increase of potency of GABA rather than its maximal efficacy. In radioligand binding experiments [displacement of the GABA(B) receptor antagonist, 3-N-[1-((S)-3,4dichlorophenyl)-ethylaminol]-2-(S)hydroxypropyl cyclo-hexylmethyl phosphinic acid ([(3)H]CGP54626)], both COR627 and COR628 increased the affinity of high- and low-affinity binding sites for GABA, producing no effect when administered alone up to a concentration of 1 mM. In vivo experiments indicated that pretreatment with per se ineffective doses of COR627 and COR628 potentiated the sedative/hypnotic effect of baclofen. In conclusion, COR627 and COR628 may represent two additional tools for use in investigating the roles and functions of positive allosteric modulatory binding sites of the GABA(B) receptor.

Three heterocyclic systems were selected as potential bioisosteres of the amide linker for a series of 1,6-disubstituted-4-quinolone-3-carboxamides, which are potent and selective CB2 ligands that exhibit poor water solubility, with the aim of improving their physicochemical profile and also of clarifying properties of importance for amide bond mimicry. Among the newly synthesized compounds, a 1,2,3-triazole derivative (1-(adamantan-1-yl)-4-[6-(furan-2-yl)-1,4-dihydro-4-oxo-1-pentylquinolin-3-yl]-1H-1,2,3-triazole) emerged as the most promising in terms of both physicochemical and pharmacodynamic properties. When assayed in vitro, this derivative exhibited inverse agonist activity, whereas, in the formalin test in mice, it produced analgesic effects antagonized by a well-established inverse agonist. Metabolic studies allowed the identification of a side chain hydroxylated derivative as its only metabolite, which, in its racemic form, still showed appreciable CB2 selectivity, but was 150-fold less potent than the parent compound.

This paper deals with the design, synthesis, and evaluation of a new series of receptors for protein surface recognition. The design of these agents is based around the attachment of four constrained dipeptide chains onto a central resorc[4]arene scaffold. By varying the sequence, nature, and stereochemistry of the chains we prepared anionically functionalized N-linked peptidoresorc[4]arenes 12, 13, and 17 by Pd/C-catalyzed hydrogenation of the corresponding benzyl esters 10, 11, and 16. From this family of receptors we have identified noncompetitive inhibitors of α-chymotrypsin (ChT), which function by binding to the surface of the enzyme in the neighborhood of the active site cleft (K(i) values ranging from 12.4 ± 5.1 μM for free carboxylic acid (+)-12b to 0.76 ± 0.14 μM for benzyl ester (-)-16a). For anionically functionalized receptors 12, 13, and 17 the ChT inhibition is based essentially on electrostatic interaction, and the bound enzyme can be released from the resorcarene surface by increasing the ionic strength, with its activity almost completely restored. For receptors with terminal benzyl ester groups (10 and 16) a hydrophobic network can be suggested.

The synthesis and the pharmacological characterization of novel heterocyclic systems 1 and 2 is described. On radioreceptor assay 1a showed higher affinity for Calcium Channel Receptors (CCRs) and in functional studies higher potency and efficacy as negative inotropic agent than Diltiazem, without relevant calcium antagonist activity on vascular smooth muscle, revealing a clear-cut selectivity for cardiac over vascular tissue.

The synthesis and pharmacological evaluation of a series of pyrrolo[1,4]benzothiazine derivatives are described. These compounds, related to diltiazem, have been shown to be representative of a novel series of calcium channel antagonists. The IC 50 s for inhibition of [ 3 H]nitrendipine binding calculated by radioreceptor assay on rat cortex and rat heart homogenates showed that some of the described compounds possess an affinity equal to or higher than those of the reference calcium antagonists verapamil and cis-(+)-diltiazem. Furthermore, the alteration of the benzothiazepinone system of diltiazem to the pyrrolo[1,4]benzothiazine system of the title compounds resulted in a clear-cut selectivity for cardiac over vascular tissue, as shown in functional studies. In fact comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using an isolated guinea pig left atrium, revealed that the compounds examined displayed higher selectivity than the reference standard, within a wide variation of data. A number of structure-activity relationship trends have been identified, and possible explanation is advanced in order to account for the observed differences in selectivity. Prerequisite for in vitro calcium channel-blocking activity is the presence of two pharmacophores, namely, the substitution at C-4 and the substitution on the pyrrole ring. Two of the tested compounds, 8b and 28a, were identified as potent calcium antagonists selective for cardiac over vascular tissue.

This paper describes a three-dimensional quantitative structure–selectivity relationships (3D-QSSR) study for selectivity of a series of ligands for cannabinoid CB1 and CB2 receptors. 3D-QSSR exploration was expected to provide design information for drugs with high selectivity toward the CB2 receptor. The proposed 3D computational model was performed by Phase and generated taking into account a number of structurally diverse compounds characterized by a wide range of selectivity index values. The model proved to be predictive, with r2 of 0.95 and Q2 of 0.63. In order to get prospective experimental validation, the selectivity of an external data set of 39 compounds reported in the literature was predicted. The correlation coefficient (r2 = 0.56) obtained on this unrelated test set provided evidence that the correlation shown by the model was not a chance result. Subsequently, we essayed the ability of our approach to help the design of new CB2-selective ligands. Accordingly, based on our interest in studying the cannabinergic properties of quinolones, the N-(adamantan-1-yl)-4-oxo-8-methyl-1-pentyl-1,4-dihydroquinoline-3-carboxamide (65) was considered as a potential synthetic target. The log(SI) value predicted by using our model was indicative of high CB2 selectivity for such a compound, thus spurring us to synthesize it and to evaluate its CB1 and CB2 receptor affinity. Compound 65 was found to be an extremely selective CB2 ligand as it displayed high CB2 affinity (Ki = 4.9 nM), while being devoid of CB1 affinity (Ki > 10,000 nM). The identification of a new selective CB2 receptor ligand lends support for the practicability of quantitative ligand-based selectivity models for cannabinoid receptors. These drug discovery tools might represent a valuable complementary approach to docking studies performed on homology models of the receptors.

The preparation of 3-cyano-4,6-diaryl-pyridin-2(1H)-ones 4a – h , calcium entry blockers related to diltiazem, is described starting from 1,3-diaryl-2-propen-1-ones 5 . On preliminary pharmacological tests all compounds are active and some of them show calcium antagonistic activity superior or comparable to diltiazem.

Fourier-Transform Ion Cyclotron Resonance (FT-ICR) kinetic experiments, supported by molecular mechanics calculations and molecular dynamics simulations, indicate that the relative stability of the diastereomeric proton-bound adducts between some ethanolamine neurotransmitters and a chiral amido[4]resorcinarene receptor depends on the relative position and orientation of the hydroxyl and amino functionalities on the neurotransmitter side chain, on the presence of the methyl substituent on its N center, as well as on the specific group of the receptor proton-bonded to the amino group of the ethanolamine. These factors strongly influence the nature and the intensity of the noncovalent interactions in the ethanolamine/amido[4]resorcinarene adducts and, therefore, their reactivity towards 2-aminobutane enantiomers.

A dynamic target-based pharmacophoric model mapping the CD4 binding site on HIV-1 gp120 was built and used to identify new hits able to inhibit gp120-CD4 protein-protein interactions. Two compounds showed micromolar inhibition of HIV-1 replication in cells attributable to an interference with the entry step of infection, by direct interaction with gp120. Inactivity of compounds toward a M475I strain suggested specific contacts with the Phe43 cavity of gp120.

The intramolecular version of the Huisgen cycloaddition is a potentially useful reaction for the stereocontrolled preparation of 1,5-disubstituted and 1,4,5-trisubstiututed triazoles. When α-azido propargyl esters derived from α-amino acids are submitted to [3 + 2] cycloaddition, the expected 4H-[1,2,3]triazolo[5,1-c][1,4]oxazin-6-ones are not formed; rather, an oligomeric cyclic polyester is obtained via a prevailing intermolecular cycloaddition. We have discovered that propargyl α-azido amides undergo metal-free intramolecular Huisgen cycloaddition in MeCN/H2O under microwave dielectric heating. This reaction provides access to new condensed triazoles that can be considered as conformationally constrained peptidomimetics. Moreover, the following microwave-assisted lactam ring opening provides 1,4-disubstituted and 1,4,5-trisubstituted triazole amino acids. The same kind of compounds are obtained from the ester cycloadduct by reaction with primary amines in the presence of AlMe3. In order to interpretate...

The intramolecular version of the Huisgen cycloaddition is a potentially useful reaction for the stereocontrolled preparation of 1,5-disubstituted and 1,4,5-trisubstiututed triazoles. When alpha-azido propargyl esters derived from alpha-amino acids are submitted to [3 + 2] cycloaddition, the expected 4H-[1,2,3]triazolo[5,1-c][1,4]oxazin-6-ones are not formed; rather, an oligomeric cyclic polyester is obtained via a prevailing intermolecular cycloaddition. We have discovered that propargyl alpha-azido amides undergo metal-free intramolecular Huisgen cycloaddition in MeCN/H(2)O under microwave dielectric heating. This reaction provides access to new condensed triazoles that can be considered as conformationally constrained peptidomimetics. Moreover, the following microwave-assisted lactam ring opening provides 1,4-disubstituted and 1,4,5-trisubstituted triazole amino acids. The same kind of compounds are obtained from the ester cycloadduct by reaction with primary amines in the presence of AlMe(3). In order to interpretate this unpredictable behavior, an ab initio study of the reaction pathway was undertaken using GAMESS(US) at the B3LYP/6-31G** level of theory. Different relaxed potential energy profiles were obtained for esters and amides, suggesting that the cis-arrangement of the -CO=N- could account for the amide reactivity.

International audience; The role played by stereochemistry in the C2-substituent (left part) on the S-DABO scaffold for anti-HIV-1 activity has been investigated for the first time. A series of S-DABO analogues, where the double bond in the C2-substituent is replaced by an enantiopure isosteric cyclopropyl moiety, has been synthesized, leading to the identification of a potent lead compound endowed with picomolar activity against RT (wt) and nanomolar activity against selected drug-resistant mutants. Molecular modeling calculation, enzymatic studies, and surface plasmon resonance experiments allowed us to rationalize the biological behavior of the synthesized compounds, which act as mixed-type inhibitors of HIV-1 RT K103N, with a preferential association to the enzyme-substrate complex. Taken together, our data show that the right combination of stereochemistry on the left and right parts (C6-substituent) of the S-DABO scaffold plays a key role in the inhibition of both wild-type and drug-resistant enzymes, especially the K103N mutant.

Five new C(15) acetogenin en-ynes (1-5) with a rare tetrahydrofuran moiety and a linear biosynthetic precursor (6) were isolated from an organic extract of Laurencia glandulifera, collected from the island of Crete in the south Aegean Sea. The structures of the new natural products, as well as their relative configuration, were established by means of spectroscopic data analysis. The cytotoxicity of the isolated natural products was evaluated against five human tumor cell lines.

Carbapenem-hydrolyzing class D beta-lactamases (CHDLs) are enzymes found in important Gram-negative pathogens (mainly Acinetobacter baumannii and Enterobacteriaceae) that confer resistance to beta-lactam antibiotics, and notably carbapenems. The crystal structure of the OXA-48 carbapenemase was determined at pH 7.5 and at a resolution of 1.9 A. Surprisingly, and by contrast with OXA-24, the only other CHDL of known crystal structure, the structure of OXA-48 was similar to OXA-10, an enzyme devoid of carbapenemase activity, indicating that the hydrolysis of these compounds could depend on subtle changes in the active site region. Moreover, the active site groove of OXA-48 was different from that of OXA-24 in shape, dimensions, and charge distribution. Molecular dynamics pointed to the functional relevance of residues located in or close to the beta5-beta6 loop and allowed us to propose a mechanism for carbapenem hydrolysis by OXA-48.

The stereoselectivity of the reaction between (R)-(-)-2-butylamine and the diastereomeric proton-bound complexes of (+)-catharanthine (C) or (-)-vindoline (V) with some chiral amido[4]resorcinarenes has been investigated in the gas phase by ESI-FT-ICR-MS. The reaction stereoselectivity (0.56 < k(homo)/k(hetero) < 16.9) is found to depend critically on the functional groups present in the chiral pendants of the hosts. Rationalisation of the kinetic results is based on careful computational and spectroscopic studies of the most stable conformations of (+)-catharanthine and its protonated form in the isolated state and in water, as well as in a representative host structure. The emerging picture points to the relevant diastereomeric proton-bound complexes as quasi-degenerate, thus suggesting that their stereoselectivity in the guest exchange reaction is mostly due to kinetic factors. The results of this study may represent a starting point for a deeper comprehension of the intrinsic factors that endow these molecules, and their dimeric forms, with their biochemical properties.