Antimicrobial activity of various 4- and 5-substituted 1-phenylnaphthalenes.

Bacterial cell division occurs in conjunction with the formation of a cytokinetic Z-ring structure comprised of FtsZ subunits. Agents that can disrupt Z-ring formation have the potential, through this unique mechanism, to be effective against several of the newly emerging multi-drug resistant strains of infectious bacteria. 1- and 12-Aryl substituted benzo[c]phenanthridines have been identified as antibacterial agents that could exert their activity by disruption of Z-ring formation. Substituted 4- and 5-amino-1-phenylnaphthalenes represent substructures within the pharmacophore of these benzo[c]phenanthridines. Several 4- and 5-substituted 1-phenylnaphthalenes were synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. The impact of select compounds on the polymerization dynamics of S. aureus FtsZ was also assessed.

3-Phenyl substituted 6,7-dimethoxyisoquinoline derivatives as FtsZ-targeting antibacterial agents.

The emergence of multidrug-resistant bacteria has created an urgent need for antibiotics with a novel mechanism of action. The bacterial cell division protein FtsZ is an attractive target for the development of novel antibiotics. The benzo[c]phenanthridinium sanguinarine and the dibenzo[a,g]quinolizin-7-ium berberine are two structurally similar plant alkaloids that alter FtsZ function. The presence of a hydrophobic functionality at either the 1-position of 5-methylbenzo[c]phenanthridinium derivatives or the 2-position of dibenzo[a,g]quinolizin-7-ium derivatives is associated with significantly enhanced antibacterial activity. 3-Phenylisoquinoline represents a subunit within the ring-systems of both of these alkaloids. Several 3-phenylisoquinolines and 3-phenylisoquinolinium derivatives have been synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis, including multidrug-resistant strains of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis (VRE). A number of derivatives were found to have activity against both MRSA and VRE. The binding of select compounds to S. aureus FtsZ (SaFtsZ) was demonstrated and characterized using fluorescence spectroscopy. In addition, the compounds were shown to act as stabilizers of SaFtsZ polymers and concomitant inhibitors of SaFtsZ GTPase activity. Toxicological assessment of select compounds revealed minimal cross-reaction mammalian ß-tubulin as well as little or no human cytotoxicity.

Antibacterial activity of substituted 5-methylbenzo[c]phenanthridinium derivatives.

Antibiotic resistance has prompted efforts to discover antibiotics with novel mechanisms of action. FtsZ is an essential protein for bacterial cell division, and has been viewed as an attractive target for the development of new antibiotics. Sanguinarine is a benzophenanthridine alkaloid that prevents cytokinesis in bacteria by inhibiting FtsZ self-assembly. In this study, a series of 5-methylbenzo[c]phenanthridinium derivatives were synthesized and evaluated for antibacterial activity against Staphylococcus aureus and Enterococcus faecalis. The data indicate that the presence of a 1- or 12-phenyl substituent on 2,3,8,9-tetramethoxy-5-methylbenzo[c]phenanthridinium chloride significantly enhances antibacterial activity relative to the parent compound or sanguinarine.

Antibacterial activity of substituted dibenzo[a,g]quinolizin-7-ium derivatives.

Berberine is a substituted dibenzo[a,g]quinolizin-7-ium derivative whose modest antibiotic activity is derived from its disruptive impact on the function of the essential bacterial cell division protein FtsZ. The present study reveals that the presence of a biphenyl substituent at either the 2- or 12-position of structurally-related dibenzo[a,g]quinolizin-7-ium derivatives significantly enhances antibacterial potency versus Staphylococcus aureus and Enterococcus faecalis. Studies with purified S. aureus FtsZ demonstrate that both 2- and 12-biphenyl dibenzo[a,g]quinolizin-7-ium derivatives act as enhancers of FtsZ self-polymerization.

Preclinical assessment of an adjunctive treatment approach for cognitive impairment associated with schizophrenia using the alpha7 nicotinic acetylcholine receptor agonist WYE-103914/SEN34625.

RATIONALE: α7 nicotinic acetylcholine receptor (nAChR) agonists are proposed as candidate agents for the adjunctive treatment of cognitive deficits associated with schizophrenia. Despite the pursuit of such an approach clinically, it is surprising that the preclinical profile of pro-cognitive agents in conjunction with antipsychotic drugs is currently unexplored. OBJECTIVES: We determined if the memory-enhancing effects of the selective α7 nAChR agonist WYE-103914 were preserved in the presence of the atypical antipsychotic drug risperidone, and if the antipsychotic-like profile of risperidone was preserved in the presence of WYE-103914. METHODS: Using the rat novel object recognition (NOR) paradigm, the maintenance of memory-enhancing activity of the α7 nAChR agonist WYE-103914 in the presence of risperidone was examined. Similarly, in the standard tests of antipsychotic-like activity, apomorphine-induced climbing (AIC) in mice and conditioned avoidance responding (CAR) in rats, the preservation of antipsychotic-like activity of risperidone was evaluated in the presence of WYE-103914. RESULTS: WYE-103914 exhibited memory-enhancing activity in rat NOR, and this effect of WYE-103914 was retained in the presence of risperidone. In AIC, the atypical antipsychotic profile of risperidone was not significantly altered by WYE-103914. In contrast, WYE-103914 moderately potentiated the efficacy profile of risperidone in CAR, an effect that did not appear to be convincingly linked to a pharmacokinetic interaction. CONCLUSIONS: These data underscore the value of a preclinical evaluation of the adjunctive profile of a memory-enhancing agent in combination with antipsychotics and provide further support to augmentation with α7 nAChR agonists to address the cognitive deficits associated with schizophrenia.

Phosphodiesterase 11A in brain is enriched in ventral hippocampus and deletion causes psychiatric disease-related phenotypes.

Phosphodiesterase 11A (PDE11A) is the most recently identified family of phosphodiesterases (PDEs), the only known enzymes to break down cyclic nucleotides. The tissue expression profile of this dual specificity PDE is controversial, and little is understood of its biological function, particularly in the brain. We seek here to determine if PDE11A is expressed in the brain and to understand its function, using PDE11A(-/-) knockout (KO) mice. We show that PDE11A mRNA and protein are largely restricted to hippocampus CA1, subiculum, and the amygdalohippocampal area, with a two- to threefold enrichment in the ventral vs. dorsal hippocampus, equal distribution between cytosolic and membrane fractions, and increasing levels of protein expression from postnatal day 7 through adulthood. Interestingly, PDE11A KO mice show subtle psychiatric-disease-related deficits, including hyperactivity in an open field, increased sensitivity to the glutamate N-methyl-D-aspartate receptor antagonist MK-801, as well as deficits in social behaviors (social odor recognition memory and social avoidance). In addition, PDE11A KO mice show enlarged lateral ventricles and increased activity in CA1 (as per increased Arc mRNA), phenotypes associated with psychiatric disease. The increased sensitivity to MK-801 exhibited by PDE11A KO mice may be explained by the biochemical dysregulation observed around the glutamate alpha-amino-3-hydroxy-5-methyl-4-isozazolepropionic (AMPA) receptor, including decreased levels of phosphorylated-GluR1 at Ser845 and the prototypical transmembrane AMPA-receptor-associated proteins stargazin (gamma2) and gamma8. Together, our data provide convincing evidence that PDE11A expression is restricted in the brain but plays a significant role in regulating brain function.

Benzimidazole- and indole-substituted 1,3'-bipyrrolidine benzamides as histamine H3 receptor antagonists.

Using a focused screen of biogenic amine compounds we identified a novel series of H(3)R antagonists. A preliminary SAR study led to reduction of MW while increasing binding affinity and potency. Optimization of the physical properties of the series led to (S)-6n, with improved brain to plasma exposure and efficacy in both water intake and novel object recognition models.

Phosphodiesterase 10A inhibitor activity in preclinical models of the positive, cognitive, and negative symptoms of schizophrenia.

Following several recent reports that suggest that dual cAMP and cGMP phosphodiesterase 10A (PDE10A) inhibitors may present a novel mechanism to treat positive symptoms of schizophrenia, we sought to extend the preclinical characterization of two such compounds, papaverine [1-(3,4-dimethoxybenzyl)-6,7-dimethoxyisoquinoline] and MP-10 [2-{[4-(1-methyl-4-pyridin-4-yl-1H-pyrazol-3-yl)phenoxy]methyl}quinoline], in a variety of in vivo and in vitro assays. Both of these compounds were active in a range of antipsychotic models, antagonizing apomorphine-induced climbing in mice, inhibiting conditioned avoidance responding in both rats and mice, and blocking N-methyl-D-aspartate antagonist-induced deficits in prepulse inhibition of acoustic startle response in rats, while improving baseline sensory gating in mice, all of which strengthen previously reported observations. These compounds also demonstrated activity in several assays intended to probe negative symptoms and cognitive deficits, two disease domains that are underserved by current treatments, with both compounds showing an ability to increase sociality in BALB/cJ mice in the social approach/social avoidance assay, enhance social odor recognition in mice and, in the case of papaverine, improve novel object recognition in rats. Biochemical characterization of these compounds has shown that PDE10A inhibitors modulate both the dopamine D1-direct and D2-indirect striatal pathways and regulate the phosphorylation status of a panel of glutamate receptor subunits in the striatum. It is striking that PDE10A inhibition increased the phosphorylation of the (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid receptor GluR1 subunit at residue serine 845 at the cell surface. Together, our results suggest that PDE10A inhibitors alleviate both dopaminergic and glutamatergic dysfunction thought to underlie schizophrenia, which may contribute to the broad-spectrum efficacy.

Procognitive and neuroprotective activity of a novel alpha7 nicotinic acetylcholine receptor agonist for treatment of neurodegenerative and cognitive disorders.

The alpha7 nicotinic acetylcholine receptor (nAChR) is a promising target for treatment of cognitive dysfunction associated with Alzheimer's disease and schizophrenia. Here, we report the pharmacological properties of 5-morpholin-4-yl-pentanoic acid (4-pyridin-3-yl-phenyl)-amide [SEN12333 (WAY-317538)], a novel selective agonist of alpha7 nAChR. SEN12333 shows high affinity for the rat alpha7 receptor expressed in GH4C1 cells (K(i) = 260 nM) and acts as full agonist in functional Ca(2+) flux studies (EC(50) = 1.6 microM). In whole-cell patch-clamp recordings, SEN12333 activated peak currents and maximal total charges similar to acetylcholine (EC(50) = 12 microM). The compound did not show agonist activity at other nicotinic receptors tested and acted as a weak antagonist at alpha3-containing receptors. SEN12333 treatment (3 mg/kg i.p.) improved episodic memory in a novel object recognition task in rats in conditions of spontaneous forgetting as well as cognitive disruptions induced via glutamatergic [5H-dibenzo[a,d]cyclohepten-5,10-imine (dizocilpine maleate); MK-801] or cholinergic (scopolamine) mechanisms. This improvement was blocked by the alpha7-selective antagonist methyllycaconitine, indicating that it is mediated by alpha7 activation. SEN12333 also prevented a scopolamine-induced deficit in a passive avoidance task. In models targeting other cognitive domains, including attention and perceptual processing, SEN12333 normalized the apomorphine-induced deficit of prepulse inhibition. Neuroprotection of SEN12333 was demonstrated in quisqualate-lesioned animals in which treatment with SEN12333 (3 mg/kg/day i.p.) resulted in a significant protection of choline acetyltransferase-positive neurons in the lesioned hemisphere. Cumulatively, our results demonstrate that the novel alpha7 nAChR agonist SEN12333 has procognitive and neuroprotective properties, further demonstrating utility of alpha7 agonists for treatment of neurodegenerative and cognitive disorders.

ADX47273 [S-(4-fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]-oxadiazol-5-yl]-piperidin-1-yl}-methanone]: a novel metabotropic glutamate receptor 5-selective positive allosteric modulator with preclinical antipsychotic-like and procognitive activities.

Positive allosteric modulators (PAMs) of metabotropic glutamate receptor subtype 5 (mGlu5) enhance N-methyl-d-aspartate receptor function and may represent a novel approach for the treatment of schizophrenia. ADX47273 [S-(4-fluoro-phenyl)-{3-[3-(4-fluoro-phenyl)-[1,2,4]oxadiazol-5-yl]-piperidin-1-yl}-methanone], a recently identified potent and selective mGlu5 PAM, increased (9-fold) the response to threshold concentration of glutamate (50 nM) in fluorometric Ca(2+) assays (EC(50) = 170 nM) in human embryonic kidney 293 cells expressing rat mGlu5. In the same system, ADX47273 dose-dependently shifted mGlu5 receptor glutamate response curve to the left (9-fold at 1 microM) and competed for binding of [(3)H]2-methyl-6-(phenylethynyl)pyridine (K(i) = 4.3 microM), but not [(3)H]quisqualate. In vivo, ADX47273 increased extracellular signal-regulated kinase and cAMP-responsive element-binding protein phosphorylation in hippocampus and prefrontal cortex, both of which are critical for glutamate-mediated signal transduction mechanisms. In models sensitive to antipsychotic drug treatment, ADX47273 reduced rat-conditioned avoidance responding [minimal effective dose (MED) = 30 mg/kg i.p.] and decreased mouse apomorphine-induced climbing (MED = 100 mg/kg i.p.), with little effect on stereotypy or catalepsy. Furthermore, ADX47273 blocked phencyclidine, apomorphine, and amphetamine-induced locomotor activities (MED = 100 mg/kg i.p.) in mice and decreased extracellular levels of dopamine in the nucleus accumbens, but not in the striatum, in rats. In cognition models, ADX47273 increased novel object recognition (MED = 1 mg/kg i.p.) and reduced impulsivity in the five-choice serial reaction time test (MED = 10 mg/kg i.p.) in rats. Taken together, these effects are consistent with the hypothesis that allosteric potentiation of mGlu5 may provide a novel approach for development of antipsychotic and procognitive agents.

Activation of estrogen receptor-beta regulates hippocampal synaptic plasticity and improves memory.

Estrogens have long been implicated in influencing cognitive processes, yet the molecular mechanisms underlying these effects and the roles of the estrogen receptors alpha (ERalpha) and beta (ERbeta) remain unclear. Using pharmacological, biochemical and behavioral techniques, we demonstrate that the effects of estrogen on hippocampal synaptic plasticity and memory are mediated through ERbeta. Selective ERbeta agonists increased key synaptic proteins in vivo, including PSD-95, synaptophysin and the AMPA-receptor subunit GluR1. These effects were absent in ERbeta knockout mice. In hippocampal slices, ERbeta activation enhanced long-term potentiation, an effect that was absent in slices from ERbeta knockout mice. ERbeta activation induced morphological changes in hippocampal neurons in vivo, including increased dendritic branching and increased density of mushroom-type spines. An ERbeta agonist, but not an ERalpha agonist, also improved performance in hippocampus-dependent memory tasks. Our data suggest that activation of ERbeta can regulate hippocampal synaptic plasticity and improve hippocampus-dependent cognition.