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[Display omitted] • 9-Amino-quinolimide based fluorescent labelling reagents have been prepared. • 9-Amino-quinolimide-labelled peptides derived from CDK5 have been obtained. • CDK5 labelled peptides behave as p25 fluorescence sensors in vitro and in cellulo. • In cellulo imaging FRET response to a CDK5 labelled peptide correlates with p25 level. CDK5 kinase is activated through interactions with different partners including the p35/p25 regulators. Active CDK5 plays a key role in several neuronal functions and its hyperactivity contributes to a variety of neurodegenerative processes and several human cancers, in particular glioblastomas and neuroblastomas. In order to probe partners that interact with CDK5, we designed and synthesized fluorescent quinolimide-labelled peptides derived from the C-helix of CDK5, which were implemented to probe CDK5 partners in vitro and by in cellulo imaging in U87 glioblastoma and N2a neuroblastoma cells. Ectopic expression of a NIR fluorescent protein miRFP670 fusion with p25 (p25-miRFP670) in N2a cells induced FRET between a quinolimide-labelled peptide biosensor and p25-miRFP670, and fluorescence intensity was proportional to the expression level of p25, thereby demonstrating the potential of the quinolimide-labelled peptide biosensor to report on p25 relative abundance. [ABSTRACT FROM AUTHOR]

Presents studies on the synthesis of cyanomethyleneamino pseudopeptides. Preparation of various cyanomethyleneamino pseudopeptides; Lewis acid catalyzed addition of trimethylsilyl cyanide to unstable aldimine intermediates; Absolute configurations of the alpha-amino aldehyde and the amino acid.

Lanthanides have unique photoluminescence (PL) emission properties, including very long PL lifetimes. This makes them ideal for biological imaging applications, especially using PL lifetime imaging microscopy (PLIM). PLIM is an inherently multidimensional technique with exceptional advantages for quantitative biological imaging. Unfortunately, due to the required prolonged acquisitions times, photobleaching of lanthanide PL emission currently constitutes one of the main drawbacks of PLIM. In this study, we report a small aqueous‐soluble, lanthanide antenna, 8‐methoxy‐2‐oxo‐1,2,4,5‐tetrahydrocyclopenta[de]quinoline‐3‐phosphonic acid, PAnt, specifically designed to dynamically interact with lanthanide ions, serving as exchangeable dye aimed at mitigating photobleaching in PLIM microscopy in cellulo. Thus, self‐assembled lanthanide complexes that may be photobleached during image acquisition are continuously replenished by intact lanthanide antennas from a large reservoir. Remarkably, our self‐assembled lanthanide complex clearly demonstrated a significant reduction of PL photobleaching when compared to well‐established lanthanide cryptates, used for bioimaging. This concept of exchangeable lanthanide antennas opens new possibilities for quantitative PLIM bioimaging. [ABSTRACT FROM AUTHOR]

Lanthanides have unique photoluminescence (PL) emission properties, including very long PL lifetimes. This makes them ideal for biological imaging applications, especially using PL lifetime imaging microscopy (PLIM). PLIM is an inherently multidimensional technique with exceptional advantages for quantitative biological imaging. Unfortunately, due to the required prolonged acquisitions times, photobleaching of lanthanide PL emission currently constitutes one of the main drawbacks of PLIM. In this study, we report a small aqueous‐soluble, lanthanide antenna, 8‐methoxy‐2‐oxo‐1,2,4,5‐tetrahydrocyclopenta[de]quinoline‐3‐phosphonic acid, PAnt, specifically designed to dynamically interact with lanthanide ions, serving as exchangeable dye aimed at mitigating photobleaching in PLIM microscopy in cellulo. Thus, self‐assembled lanthanide complexes that may be photobleached during image acquisition are continuously replenished by intact lanthanide antennas from a large reservoir. Remarkably, our self‐assembled lanthanide complex clearly demonstrated a significant reduction of PL photobleaching when compared to well‐established lanthanide cryptates, used for bioimaging. This concept of exchangeable lanthanide antennas opens new possibilities for quantitative PLIM bioimaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lanthanide exhibit long PL lifetimes, facilitating time-resolved applications. • Water-stable lanthanide luminophores are scarce. • Despite water quenching, PAnt dynamically coordinates with Tb(III) and Eu(III) • Spectroscopy and TD–DFT unveil sensitization mechanisms for Eu(III) and Tb(III) Lanthanide photoluminescence (PL) emission has attracted much attention for technological and bioimaging applications because of its particularly interesting features, such as narrow emission bands and very long PL lifetimes. However, this emission process necessitates a preceding step of energy transfer from suitable antennas. While biocompatible applications require luminophores that are stable in aqueous media, most lanthanide-based emitters are quenched by water molecules. Previously, we described a small luminophore, 8-methoxy-2-oxo-1,2,4,5-tetrahydrocyclopenta[ de ]quinoline-3-phosphonic acid (PAnt), which is capable of dynamically coordinating with Tb(III) and Eu(III), and its exchangeable behavior improved their performance in PL lifetime imaging microscopy (PLIM) compared with conventional lanthanide cryptate imaging agents. Herein, we report an in-depth photophysical and time-dependent density functional theory (TD–DFT) computational study that reveals different sensitization mechanisms for Eu(III) and Tb(III) in stable complexes formed in water. Understanding this unique behavior in aqueous media enables the exploration of different applications in bioimaging or novel emitting materials. [ABSTRACT FROM AUTHOR]

Abstract: Diverse basic amino acid-derived α-amino nitriles have been synthesized via a modified Strecker reaction, using TMSCN as the cyanide source. It has been found that this synthesis is a slow thermodynamically controlled reaction, where it was difficult to induce stereocontrol. Moderate selectivity was induced by thermodynamic control of the reaction in MeOH. The absolute configuration at the stereogenic center generated was assigned by chemical correlation with 2-oxopiperazine derivatives. [Copyright &y& Elsevier]

Abstract: New indole alkaloid analogues, containing a 10b-methyl- or a 10b-hydroxy-1,2,4,5,10b,10c-hexahydropyrrolo[1′,2′,3′:1,9a,9]imidazo[1,2-a]indole skeleton, have been obtained by highly stereoselective electrophile addition–cyclization reactions of a tryptophan-derived α-amino nitriles. [Copyright &y& Elsevier]

The synthesis of new indole alkaloid analogues, containing a 1,2,4,5,10b,10c-hexahydropyrrolo[1′,2′,3′:1,9a,9]imidazo-[1,2-a]indole skeleton, via highly stereoselective novel domino cyclative halogenation or prenylation reactions of tryptophan-derived α-amino nitriles, is described. [ABSTRACT FROM AUTHOR]

The scope and stereoselectivity of the acid-promoted cyclization of new tryptophan-based α-amino nitriles derived from either ketones or aldehydes to novel hexahydropyrrolo[1′,2′,3′:1,9a,9]imidazo[1,2-a]indoles is described. This cyclization involves the generation of two or three stereogenic centers. The time and stereoselectivity of this reaction mostly depended on both the steric volume of the substituents at the amino nitrile and its stereochemistry. Unhindered amino nitriles gave exclusively 2-exo-isomers, while hindered amino nitriles, which required higher reaction times, provided also these isomers under kinetic control. Under thermodynamic control, the 2-endo-isomer was the main reaction product, except for the benzaldehyde-derived a-amino nitriles, where a favorable electronic interaction between the phenyl and methoxycarbonyl groups in a relative cis-disposition might be responsible of the formation of the 2-exo-isomer as the only cyclization product. [ABSTRACT FROM AUTHOR]

Chiral spirocyclic 2,6-dioxopiperazines were synthesized from amino acid derived α-quaternary α-amino nitriles via H2SO4-promoted cyano hydration, followed by base-mediated cyclization and N-alkylation. This methodology, requiring the previous preparation of the amino nitrile by a modified Strecker reaction, was applied to Phe, Trp, Pro, Asp, Glu, and Ser derivatives. In the case of the Trp-derived amino nitrile the major product of the treatment with H2SO4 was not the expected carboxamide, but a new tetracyclic indoline derivative containing the novel heterocyclic system hexahydropyrrolo[1′,2′,3′: 1,9a,9]imidazo[1,2-α]indole, as a result of a domino tautomerization. The treatment of this indoline derivative with refluxing 1 N HCl led to a Trp-derived 2,6-dioxopiperazine. The 2,6-dioxopiperazine ring opened under the reaction conditions of methyl ester saponification, giving N-(carboxyalkyl)amino acid derivatives. Therefore, the synthesis of 2,6-dioxopiperazines containing free carboxylic acids from the respective methyl esters required transesterification to benzyl esters, followed by hydrogenolysis. [ABSTRACT FROM AUTHOR]

An efficient synthesis of [4.4]-spirolactam restricted derivatives of the didemnin side chain dipeptide l-Pro-N-Me-d-Leu is described. This methodology involves: (a) peptide coupling of N-Boc-2-allylproline with d-Leu-OBn; (b) OsO4/NaIO4 mediated allyl oxidation and intramolecular cyclization to the corresponding cyclic hemiaminals; and (c) NaBH4 mediated reduction of an intermediate N-acyliminium ion. This synthetic strategy gave significant better results than the previously reported strategies for the synthesis of [4.4]-spirolactam β-turn mimetics. [Copyright &y& Elsevier]

An efficient and stereocontrolled synthesis of phenylalanine- and tryptophan-derived 5-phenyl-1,4-benzodiazepines is described. This new methodology involves, as a key step, the synthesis of 5-phenyl-2,3-dihydro-lH-1,4-benzodiazepines by a one-pot cyano reduction and reductive cyclization of the appropriate amino nitrile, which were obtained via a modified Strecker reaction of N-protected α-amino aldehydes with 2-aminobenzophenone and trimethylsilyl cyanide. The subsequent reduction of these 2,3-dihydro-1H-1,4-benzodiazepines, followed by regio-selective alkylation or acylation at position 4, led to 2,4-disubstituted5-phenyl-2,3,4,5-tetrahydro-1H-1,4-benzodiazepine. [ABSTRACT FROM AUTHOR]

Discusses the synthesis of 3-unsubstituted 4-alkyl-4-carboxy-2-azetidinone amino acid derivatives via an intramolecular N[sup alpha]-C[sup alpha]-cyclization strategy. Stereoselective formation of 1,4,4-trisubstituted 2-azetidinones; Asymmetric methylation of (S)-Phe derivatives and chiral intermediates.

Two new families of lanthanide antennas are described. 8-Methoxy-4,5-dihydrocyclopenta[de]quinolin-2(1H)-one phosphonates or carboxylates behave as selective antennas exhibiting Eu3+ luminescence in organic solvents, while quinolin-2(1H)-one analogues selectively sensitize the Tb3+ emission. These emissions are quenched by H2O addition. Based on this behaviour, the new lanthanide antennas can be used as highly sensitive water sensors. [ABSTRACT FROM AUTHOR]

In this work, we describe the application of the self-assembled europium complex 1 :Eu(III) (where 1 : diethyl 8-methoxy-2-oxo-1,2,4,5-tetrahydro-cyclopenta[ de ]quinolin-3-yl)phosphonate) for the analysis of water content of wheat flour. The methodology herein described represents a robust and accurate way for the detection of small amounts of water in food, providing comparing results with well-established methods such as thermogravimetry and Karl-Fischer titration. Interestingly, as an advantage over other methods, our luminescence-based approach can be implemented in lab-on-a-chip microfluidic devices for real-time and on-line detection of water content of food samples. Additionally, the remarkably long luminescence lifetime of Eu(III) allows the use of state-of-the-art imaging strategies based on PLIM microscopy for the direct visualization of unique water content maps of wheat flour particles. [Display omitted] • Self-assembled europium complex 1 :Eu(III) detects water in wheat flour with accuracy. • Robust method provides comparable results to established techniques. • Luminescence-based approach is advantageous as it can be implemented in lab-on-a-chip devices for real-time detection. • The long luminescence lifetime of Eu(III) allows visualization of water content maps via PLIM microscopy. [ABSTRACT FROM AUTHOR]

The article discusses a significant advancement in quantitative PLIM bioimaging called PAnt (phosphonic acid antenna). PAnt is a small water-soluble lanthanide antenna that can self-assemble with lanthanide ions, serving as an exchangeable probe to overcome photobleaching in PLIM microscopy in cellulo. This allows for continuous replenishment of lanthanide complexes that may be photobleached during acquisition, resulting in remarkable photostability compared to traditional lanthanide cryptates. The research was conducted by Angel Orte, Juan A. González-Vera, and their team, and the article includes artwork by M. Eugenio Vázquez from the University of Santiago de Compostela. [Extracted from the article]

The article discusses a significant advancement in quantitative PLIM bioimaging called PAnt (phosphonic acid antenna). PAnt is a small water-soluble lanthanide antenna that can self-assemble with lanthanide ions, serving as an exchangeable probe to overcome photobleaching in PLIM microscopy in cellulo. The use of PAnt allows for continuous replenishment of lanthanide complexes that may be photobleached during acquisition, resulting in remarkable photostability compared to traditional lanthanide cryptates. The research was conducted by Angel Orte, Juan A. González-Vera, and their colleagues. [Extracted from the article]

Novel 4,5-quinolimide-based fluorophores are more solvatochromic and red-shifted than known naphthalimide analogues. Conjugation of one of these fluorophores to a peptide derived from CDK5 kinase demonstrated its sensitivity for monitoring the interaction with its regulatory partner p25. Introduction of the quinolimide-labelled peptide into living glioblastoma cells probed the interaction with endogenous p25. [ABSTRACT FROM AUTHOR]

Abstract: The potential of α-amino nitrile-derived ureas for the synthesis of imidazolidin-2-one derivatives has been studied in the context of a medicinal chemistry project focused on the search of antagonists of the thrombin receptor PAR1. In this study α-amino nitrile-derived ureas have shown chameleonic reactivity. Thus, under neutral, basic or mild acid media they cyclize to 4-iminoimidazolidin-2-one derivatives, which tautomerize to 4-amino-2,3-dihydro-1H-imidazol-2-ones. This tautomerism triggers epimerization at the C5 of the imidazolidine ring, as well as its oxidation. However, they give stable highly functionalized hydantoin derivatives under strong acid media, by a no-epimerizing two-step hydrolysis. [Copyright &y& Elsevier]

A series of Phe-Gly dipeptide-derived piperazinones containing an aromatic urea moiety and a basic amino acid has been synthesized and evaluated as inhibitors of human platelet aggregation induced by the PAR1 agonist SFLLRN and as cytotoxic agents in human cancer cells. The synthetic strategy involves coupling of a protected basic amino acid benzyl amide to 1,2- and 1,2,4-substituted-piperazinone derivatives, through a carbonylmethyl group at the N1-position, followed by formation of an aromatic urea at the exocyclic moiety linked at the C2 position of the piperazine ring and removal of protecting groups. None of the compounds showed activity in the biological evaluation. [ABSTRACT FROM AUTHOR]

Abstract: A series of pseudodipeptide-based chiral 1,3,4,5-tetrasubstituted-2-oxopiperazines has been designed and synthesized as potential PAR1 antagonists. These highly functionalized piperazines were synthesized from aromatic and basic amino acid derived Ψ[CH(CN)NH]pseudodipeptides through a four step pathway that involves reduction of the cyano group to build the 2-oxopiperazine ring, followed by selective functionalization at the N4-, N1-positions, and at the exocyclic moiety at position C5. This regioselective functionalization required the fine tuning of reaction conditions. All new compounds were screened as inhibitors of human platelet aggregation induced by the PAR1 agonist SFLLRN and as cytotoxic agents in human cancer cell lines. Some of the compounds displayed moderate PAR1 antagonist activity, while, others were cytotoxic at μM concentration. No correlation was observed between both types of activities. [Copyright &y& Elsevier]

The synthesis of 1,4-unsubstituted piperazin-2-ones by one-pot reductive cyclization of PheΨ[CH(CN)NH]Gly pseudodipeptides is described. Studies on the reactivity of the piperazin-2-one ring showed a higher reactivity at the N4 position than at the N1 position. The stepwise regioselective functionalization of piperazin-2-one derivatives showed great potential for molecular diversity generation. [ABSTRACT FROM AUTHOR]

Abstract: By applying a diversity oriented synthesis strategy for the search of new antagonists of the thrombin receptor PAR1, a series of peptide-based ureas and thioureas, including analogues of the PAR1 reference antagonist RWJ-58259, has been designed and synthesized. The general synthetic scheme involves reduction of basic amino acid-derived amino nitriles by hydrogen transfer from hydrazine monohydrate in the presence of Raney Ni, followed by reaction with diverse isocyanates and isothiocyanates, and protecting group removal. All new compounds have been evaluated as inhibitors of human platelet aggregation induced by the PAR1 agonist SFLLRN. Some protected peptide-based ureas displayed significant antagonist activity. [Copyright &y& Elsevier]

Background: Extending the therapeutic window of intravenous thrombolysis for acute ischemic stroke beyond the established 4.5-hour limit is of critical importance in order to increase the proportion of thrombolysed stroke patients. In this setting, the capacity of MRI to select acute stroke patients for reperfusion therapies in delayed time windows has been and is being tested in clinical trials. However, whether the more available and cost-effective perfusion computed tomography (PCT) may be useful to select candidates for delayed intravenous thrombolysis remains largely unexplored. We aimed to evaluate the safety and efficacy of PCT-guided intravenous thrombolysis beyond 4.5 h after stroke onset. Methods: We prospectively studied all consecutive acute ischemic stroke patients treated with intravenous tissue plasminogen activator (tPA) in our stroke unit between January 2008 and December 2010. Patients treated within 0- 4.5 h were treated according to non-contrast CT (NCCT) criteria. Beyond 4.5 h, patients received intravenous tPA according to PCT criteria, i.e. an infarct core on cerebral blood volume (CBV) maps not exceeding one third of the middle cerebral artery (MCA) territory and tissue at risk as defined by mean transit time-CBV mismatch greater than 20%. Predetermined primary endpoints were symptomatic hemorrhagic transformation and favorable long-term outcome, while early neurological improvement and MCA recanalization were considered secondary endpoints. Statistical analysis included bivariate comparisons between the two groups for each endpoint and logistic regression models when significance was found in bivariate analyses. This study was approved by our local ethics committee. Results: A total of 245 patients received intravenous thrombolysis. After the groups were matched by baseline National Institutes of Health Stroke Scale score, 172 patients treated at <4.5 h and 43 patients treated at >4.5 h were finally included. Early and late groups were comparable regarding baseline variables; only cardioembolic etiology was more frequent in the >4.5 h group. Rates of symptomatic hemorrhagic transformation (2.9% in the <4.5 h group vs. 2.3% in the >4.5 h group; p = 1.0) and good long-term outcome (64.5 vs. 60.5%, respectively; p = 0.620) were similar between the groups. However, delayed intravenous thrombolysis was independently associated with a worse early clinical course [odds ratio (OR) 2.07, 95% confidence interval (CI) 1.04-4.1; p = 0.038] and lower 2-hour MCA recanalization rates (OR 0.4, 95% CI 0.17-0.92; p = 0.03). Conclusion: Primary safety and efficacy endpoints were comparable between the early and delayed thrombolysis groups. The results of our exploratory study may justify a randomized clinical trial to test the safety and efficacy of PCT-guided intravenous thrombolysis in acute ischemic stroke patients presenting beyond 4.5 h from symptom onset. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Extending the therapeutic window of intravenous thrombolysis for acute ischemic stroke beyond the established 4.5-hour limit is of critical importance in order to increase the proportion of thrombolysed stroke patients. In this setting, the capacity of MRI to select acute stroke patients for reperfusion therapies in delayed time windows has been and is being tested in clinical trials. However, whether the more available and cost-effective perfusion computed tomography (PCT) may be useful to select candidates for delayed intravenous thrombolysis remains largely unexplored. We aimed to evaluate the safety and efficacy of PCI-guided intravenous thrombolysis beyond 4.5 h after stroke onset. Methods: We prospectively studied all consecutive acute ischemic stroke patients treated with intravenous tissue plasminogen activator (tPA) in our stroke unit between January 2008 and December 2010. Patients treated within 0-4.5 h were treated according to non-contrast CI (NCCI) criteria. Beyond 4.5 h, patients received intravenous tPA according to PCT criteria, i.e. an infarct core on cerebral blood volume (CBV) maps not exceeding ore third of the middle cerebral artery (MCA) territory and tissue at risk as defined by mean transit time-CBV mismatch greater than 20%. Pre-determined primary endpoints were symptomatic hemorrhagic transformation and favorable long-term outcome, while early neurological improvement and MCA recanalization were considered secondary endpoints. Statistical analysis included bivariate comparisons between the two groups for each endpoint and logistic regression models when significance was found in bivariate analyses. This study was approved by our local ethics committee. Results: A total of 245 patients received intravenous thrombolysis. After the groups were matched by baseline National Institutes of Health Stroke Scale score, 172 patients treated at <4.5 hand 43 patients treated at >4.5 h were finally included. Early and late groups were comparable regarding baseline variables; only cardioembolic etiology was more frequent in the >4.5 h group. Rates of symptomatic hemorrhagic transformation (2.9% in the <4.5 h group vs. 2.3% in the >4.5 h group; p = 1.0) and good long-term outcome (64.5 vs. 60.5%, respectively; p = 0.620) were similar between the groups. However, delayed intravenous thrombolysis was independently associated with a worse early clinical course [odds ratio (OR) 2.07, 95% confidence interval (Cl) 1.04-4.1; p = 0.038] and lower 2-hour MCA recanalization rates (OR 0.4, 95% Cl 0.1 7-0.92; p = 0.03). Conclusion: Primary safety and efficacy endpoints were comparable between the early and delayed thrombolysis groups. The results of our exploratory study may justify a randomized clinical trial to test the safety and efficacy of PCT-guided intravenous thrombolysis in acute ischemic stroke patients presenting beyond 4.5 h from symptom onset. [ABSTRACT FROM AUTHOR]

The protective effects of insulin-like growth factor I on the somatostatin (SRIF) system in the temporal cortex after β-amyloid (Aβ) injury may be mediated through its N-terminal tripeptide glycine-proline-glutamate (GPE). GPE is cleaved to cyclo[Pro-Gly] (cPG), a metabolite suggested to mediate in neuroprotective actions. We evaluated the effects of GPE and cPG in the temporal cortex of Aβ25–35-treated rats on SRIF and SRIF receptor protein and mRNA levels, adenylyl cyclase activity, cell death, Aβ25–35 accumulation, cytosolic calcium levels ([Ca2+]c) and the intracellular signaling mechanisms involved. GPE and cPG did not change Aβ25–35 levels, but GPE partially restored SRIF and SRIF receptor 2 protein content and mRNA levels and protected against cell death after Aβ25–35 insult, which was coincident with Akt activation and glycogen synthase kinase 3β inhibition. In addition, GPE displaced glutamate from NMDA receptors and blocked the glutamate induced rise in cytosolic calcium in isolated rat neurons and moderately increased Ca2+ influx per se. Our findings suggest that GPE, but not its metabolite, mimics insulin-like growth factor I effects on the SRIF system through a mechanism independent of Aβ clearance that involves modulation of calcium and glycogen synthase kinase 3β signaling. [ABSTRACT FROM AUTHOR]

The presence of neuritic plaques and amyloid fibrils arising from the misfolding of certain proteins is the principal molecular indicator of neurodegenerative diseases such as Alzheimer's and Parkinson's disease. Methodologies for studying the early stages of amyloid aggregation are rapidly arising to provide a better understanding of the mechanism of fibrillization and cytotoxicity and to identify potential targets for diagnosis and therapy. The method presented here involves the simultaneous use of two different fluorophores, a quinolimide derivative and Nile Blue A. These are capable of interacting with and reporting on the formation of preamyloid aggregates and fibrils of apoferritin through fluorescence resonance energy transfer (FRET), which occurs between them, thus maximizing the contrast in detection and quantitative information of such amyloid species by using multidimensional fluorescence lifetime imaging microscopy (FLIM). • A pair of dyes interact with pre-amyloid aggregates with different affinities. • FRET between the dyes allow sensitive detection of different types of aggregates. • The aggregates are characterized by multiparametric FLIM and superresolution STED microscopies. [ABSTRACT FROM AUTHOR]

Abstract: The scope of acid-mediated cyclative additions of electrophiles to tryptophan-derived α-amino nitriles for the synthesis of 10b-substituted-1,2,4,5,10b,10c-hexahydropyrrolo[1′,2′,3′:1,9a,9]imidazo[1,2-a]indoles analogues of indole alkaloids has been studied. The results demonstrate the high potential of the methodology for the synthesis of 10b-bromo-derivatives, by bromination with NBS, 10b-allyl-derivatives, by bromo-allyl exchange, and 10b-prenyl-derivatives, by reaction with prenyl bromide in the presence of Mg(NO3)2·6H20. Some of the new pyrroloimidazoindole derivatives displayed moderate μM cytotoxicities in human cancer cell lines and at 10μg/mL inhibited more than 50% EGFR or HIF-1α. [Copyright &y& Elsevier]

Abstract: The regio- and diastereoselective reduction and reductive alkylation of 3-spiro-2,6-dioxopiperazines are described via a two-step process, which involves addition of NaBH4 or Grignard reagents, followed by TFA-mediated dehydration with a second NaBH4 addition. The results show that the reactivity of 2,6-dioxopiperazines is limited by their steric hindrance and by the volume of the nucleophile, which preferably add to the C6 carbonylic carbon with complete diastereoselectivity. The diastereoselectivity of the first step is mainly governed by electronic factors, which direct the addition of the nucleophile from the most hindered face, while in the second step, the NaBH4 attacks from the less crowded face. This second step proceeds with partial or complete racemization. [Copyright &y& Elsevier]

Abstract: The influence of several modifications on the GPE tripeptide structure upon the binding to GluRs and on their neuroprotective effects has been studied. The results indicated that the prevention of neuronal death showed by GPE and some analogues is not directly related to their affinity at glutamate receptors. [Copyright &y& Elsevier]

Abstract: A suitable solid-phase approach, based on Fmoc/ t Bu methodology and on the use of 2-chlorotrityl resin, allowed a rapid and efficient preparation of new GPE analogues. Most of the synthesized tripeptides displayed glutamate receptor binding affinity comparable to that of GPE, but only a few derivatives showed significant neuroprotective activity. [Copyright &y& Elsevier]

Abstract: A series of GPE analogues, including modifications at the Pro and/or Glu residues, was prepared and evaluated for their NMDA binding and neuroprotective effects. Main results suggest that the pyrrolidine ring puckering of the Pro residue plays a key role in the biological responses, while the preference for cis or trans rotamers around the Gly-Pro peptide bond is not important. [Copyright &y& Elsevier]

The stereocontrolled synthesis of phenylalanine and tryptophan derived 5-oxo-1,2,3,4-tetrahydro-5H-1,4-benzodiazepine derivatives is described. This new methodology involves a modified Strecker reaction of N-Boc protected amino aldehydes and methyl anthranilate, reduction of the resulting α-amino nitriles, and lactamization. The resulting 2-substituted-5-oxo-1,2,3,4-tetrahydro-5H-1,4-benzodiazepines were further functionalized at position 4 by alkylation or acylation reactions. One of these new tryptophan-derived 1,4-benzodiazepines showed significant selective binding affinity at cholecystokinin CCK1 receptors (IC50=156.5±33.2 nM). [Copyright &y& Elsevier]

The synthesis of novel chiral 4,7-disubstituted- and 2,4,7-trisubstituted-1,6,8-trioxoperhydropyrazino[1,2-c]pyrimidines from suitably protected TrpΨ[CH(CN)NH]Asp pseudodipeptides is described. This synthesis involves the cyclization of the Ψ[CH(CN)NH] pseudodipeptides, via catalytic hydrogenation and in situ lactamization, to give 3,5-disubstituted-2-oxopiperazine derivatives, which upon reaction with isocyanates, followed by base-catalyzed cyclization lead to the target 4,7-disubstituted-1,6,8-trioxoperhydropyrazino[1,2-c]-pyrimidines. The alkylation of these bicyclic heterocycles gives their corresponding 2,4,7-trisubstituted derivatives. [Copyright &y& Elsevier]

Examines the use of 2-Oxopiperazine as mimetics of γ-turn conformationally constrained tripeptides. Synthetic pathway for the preparation of epimers; Analog synthesis of tetrapeptide compounds; Effect of conformational restriction on the affinity of CCK receptors.

The synthesis of branched peptides from cyanomethylenamino pseudopeptides, via catalytic hydrogenation in the presence of amino acid derivatives, is described. When the inserted amino acid was a glycine derivative, the resulting branched peptide lactamized in situ to 2-oxopiperazine derivatives. This new C-backbone peptide branching approach is compatible with the diversity of amino acid side chains. [Copyright &y& Elsevier]

Abstract: Current safety recommendations for multiple sclerosis (MS) patients who are considered for natalizumab do not specify how to screen for latent tuberculosis (LTB). Only chest X-ray is recommended as a routine, and follow-up depends on its results. The incidence of TB in Spain is high and the risk of a LTB reactivation due to natalizumab is unknown. Our objective is to describe in our clinical practice if following the current recommendations for the MS population on natalizumab allows identifying patients with a LTB, as well as the risk for TB reactivation. Our study demonstrated that, in our environment, current recommendations are not sensitive enough to identify cases of LTB, though no cases of active TB were observed. Considering the lack of documented active TB cases worldwide among natalizumab patients, we suggest that these safety measures are probably unnecessary, even in countries with a high TB incidence. [Copyright &y& Elsevier]

The photophysical properties of naphthalimide-based fluorophores can be easily tuned by chemical manipulation of the substituents on that privileged scaffold. Replacement of a OMe group at position 6 in 2-(hydroxyl)ethyl-naphthalimide derivatives by diverse amines, including 2-(hydroxyl)ethylamine, trans -(4-acetamido)cyclohexylamine and azetidine increases the solvatochromic (ICT) character, while this replacement in 2-(dimethylamino)ethyl-naphthalimide analogues (PET fluorophores) decrease their solvent polarity sensitivity or even reversed them to solvatochromic fluorophores. These fluorophores resulted macrophage nucleus imaging probes, which bind DNA as intercalants and showed low cytotoxicity in human cancer cells. Image 1 • New naphthalimide and quinolimide-based fluorophores are described. • Properties of naphthalimide-based fluorophores have been tuned by substituent manipulation. • DNA intercalating properties provide macrophage nucleus fluorescence imaging. [ABSTRACT FROM AUTHOR]

The lack of polarity sensing fluorophores with OFF-ON features when increasing the environment polarity has limited the monitoring of biological processes that involve an increase in local hydrophilicity. In this work, replacement of a hydroxyl group by a dimethylamino group transformed solvatochromic ICT naphthalimide- and quinolimide-based fluorophores into reversed solvatochromic ones, with higher emission in polar than in apolar environments. Excited-state dynamics studies, TD-DFT calculations, X-ray and NMR support the existence of a folded conformation for the 2-(dimethylamino)ethyl chain upon the imide ring in apolar solvents, where the dimethylamino group would quench the fluorescence by a PET effect, while in polar solvents the chain has an extended conformation, where the PET is hindered. These PET fluorophores have given rise to H 2 O and pH sensors in organic solvents as well as to bright macrophage cytoplasm imaging probes. OFF-ON polarity sensing PET fluorophores were obtained by simple substituent manipulation of solvatochromic (ICT) fluorophores. This switching led to H 2 O and pH sensors and cell cytoplasm imaging probes. Image 1 • Naphthalimide and quinolimide-based fluorophores have been prepared. • ICT fluorophores are switched to OFF-ON polarity sensing PET fluorophores. • TRES, TD-DFT calculations, X-ray and NMR support a PET fluorescence mechanism. • The dyes behave as OFF-ON H 2 O and pH fluorescence sensors. • Macrophage cytoplasm fluorescence imaging probes are obtained. [ABSTRACT FROM AUTHOR]

DREAM, a neuronal calcium sensor protein, has multiple cellular roles including the regulation of Ca2+ and protein homeostasis. We recently showed that reduced DREAM expression or blockade of DREAM activity by repaglinide is neuroprotective in Huntington's disease (HD). Here we used structure-based drug design to guide the identification of IQM-PC330, which was more potent and had longer lasting effects than repaglinide to inhibit DREAM in cellular and in vivo HD models. We disclosed and validated an unexplored ligand binding site, showing Tyr118 and Tyr130 as critical residues for binding and modulation of DREAM activity. IQM-PC330 binding de-repressed c-fos gene expression, silenced the DREAM effect on KV4.3 channel gating and blocked the ATF6/DREAM interaction. Our results validate DREAM as a valuable target and propose more effective molecules for HD treatment. [ABSTRACT FROM AUTHOR]

Neutral, basic or mild acidic reaction conditions are evaluated for N-cyanoalkyl-substituted ureas of type (I) and (III) resulting in cyclization to imidazolidine derivatives. [ABSTRACT FROM AUTHOR]

The reaction of aminonitriles (I) with isocyanates leads to desired ureas (III) in high isolated yields, whilst crude ureas derived from aminonitriles (IV) are prone to a cyclization during chromatographic purification affording hydantoins (V). [ABSTRACT FROM AUTHOR]