Development of potent dopamine-norepinephrine uptake inhibitors (DNRIs) based on a (2S,4R,5R)-2-benzhydryl-5-((4-methoxybenzyl)amino)tetrahydro-2H-pyran-4-ol molecular template.

Current therapy of depression is less than ideal with remission rates of only 25-35% and response rates of 45-60%. It has been hypothesized that a dysfunctional dopaminergic system in the mesocorticolimbic pathway in depressive disorder may lead to development of anhedonia associated with loss of pleasure and interest along with loss of motivation. The current antidepressants do not address dopamine dysfunction which might explain their low efficacy. In this report, we have described an SAR study on our pyran-based triple reuptake inhibitors (TRIs) which are being investigated as the next-generation antidepressants. In the present work we demonstrate that our lead TRIs can be modified with appropriate aromatic substitutions to display a highly potent SSRI profile for compounds 2a and 4a (Ki (SERT); 0.71 and 2.68nM, respectively) or a potent DNRI profile for compounds 6b and 6h (Ki (DAT/NET); 8.94/4.76 and 13/7.37nM, respectively). Compounds 4g-4i exhibited potencies at all three monoamine transporters. The results provide insights into the structural requirements for developing selective dual- and triple-uptake inhibitors from a unique pyran molecular template for an effective management of depression and related disorders.

Flexible and biomimetic analogs of triple uptake inhibitor 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol: Synthesis, biological characterization, and development of a pharmacophore model.

In this study we have generated a pharmacophore model of triple uptake inhibitor compounds based on novel asymmetric pyran derivatives and the newly developed asymmetric furan derivatives. The model revealed features important for inhibitors to exhibit a balanced activity against dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). In particular, a 'folded' conformation was found common to the active pyran compounds in the training set and was crucial to triple uptake inhibitory activity. Furthermore, the distances between the benzhydryl moiety and the N-benzyl group as well as the orientation of the secondary nitrogen were also important for TUI activity. We have validated our findings by synthesizing and testing novel asymmetric pyran analogs. The present work has also resulted in the discovery of a new series of asymmetric tetrahydrofuran derivatives as novel TUIs. Lead compounds 41 and 42 exhibited moderate TUI activity. Interestingly, the highest TUI activity by lead tetrahydrofuran compounds for example, 41 and 42, was exhibited in a stereochemical preference similar to pyran TUI for example, D-161.

Recent Progress in Chemical Modification of the Natural Polysaccharide Guar Gum.

Guar gum (GG) is a natural heteropolysaccharide. Due to its non-toxic, eco-friendly, and biodegradable nature, GG has found wide applications in many areas, in particular food, paper, textile, petroleum, and pharmaceutical industries. Therefore, GG is often called "Black Gold" as well. Due to the presence of hydroxyl groups, GG can be modified by various methods. The physical and biological properties of GG can be modulated by chemical modifications. In this manuscript, various methods for the chemical modifications of GG have been discussed according to the type of modifications. Mechanistic insights have also been provided whenever possible. In addition, potential applications of new GG derivatives have also been briefly mentioned.

Application of Guar Gum and its Derivatives as Green Binder/Separator for Advanced Lithium-Ion Batteries.

Since their first commercialization in the 1990s,lithium-ion batteries (LIBs) have become an indispensible part of our everyday life in particular for portable electronic devices. LIBs have been considered as the most promising sustainable high energy density storage device. In recent years, there is a strong demand of LIBs for hybrid electric and electric vehicles to lower carbon footprint and mitigate climate change. However, LIBs have several issues, for example, high cost and safety issues such as over discharge, intolerance to overcharge, high temperature operation etc. To address these issues several new types of electrodes are being studied. Traditional binder PVDF is costly, difficult to recyle, undergoes side reactions at high temperature and cannot stabilize high energy density electrodes. To overcome these challenges, diiferent binders have been introduced with these electrodes. This minireview is focused on the application of guar gum as a binder for different electrodes and separator. The electrochemical performance of electrodes with guar gum has been compared with other binders.

A rapid, one-pot, microwave-influenced synthesis of spiro-2,5-diketopiperazines via a cascade Ugi/6-exo-trig aza-Michael reaction.

A rapid, cascade reaction process has been developed to access biologically validated spiro-2,5-diketopiperazines. The facile and environmentally benign method capitalizes on commercially available starting reagents for a sequential Ugi/6-exo-trig aza-Michael reaction, water as a solvent, and microwave irradiation without any extraneous additives.

Novel Potent Dopamine-Norepinephrine and Triple Reuptake Uptake Inhibitors Based on Asymmetric Pyran Template and Their Molecular Interactions with Monoamine Transporters.

We have carried out a structural exploration of (2S,4R,5R)-2-(bis(4-fluorophenyl)methyl)-5-((4-methoxybenzyl)amino)tetrahydro-2H-pyran-4-ol (D-473) to investigate the influence of various functional groups on its aromatic ring, the introduction of heterocyclic aromatic rings, and the alteration of the stereochemistry of functional group on the pyran ring. The novel compounds were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting monoamine neurotransmitter uptake. Our studies identified some of the most potent dopamine-norepinephrine reuptake inhibitors known to-date like D-528 and D-529. The studies also led to development of potent triple reuptake inhibitors such as compounds D-544 and D-595. A significant influence from the alteration of the stereochemistry of the hydroxyl group on the pyran ring of D-473 on transporters affinities was observed indicating stereospecific preference for interaction. The inhibitory profiles and structure-activity relationship of lead compounds were further corroborated by molecular docking studies at the primary binding sites of monoamine transporters. The nature of interactions found computationally correlated well with their affinities for the transporters.

D-578, an orally active triple monoamine reuptake inhibitor, displays antidepressant and anti-PTSD like effects in rats.

Significant unmet needs exist for development of better pharmacotherapeutic agents for major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) as the current drugs are inadequate. Our goal in this study is to investigate behavioral pharmacological characterization of a novel triple reuptake inhibitor (TRI) D-578 which exhibits nanomolar potency at all three monoamine transporters (Ki; 16.2. 16.2, 3.23 nM, and 29.6, 20.6, 6.10 nM for the rat brain and cloned human dopamine, serotonin and norepinephrine transporters, respectively) and exhibited little to no affinity for other off-target CNS receptors. In a rat forced swim test, compound D-578 upon oral administration displayed high efficacy and not stimulating in locomotor behavior. The effects of D-578 and paroxetine were next evaluated in a rat model for traumatic stress exposure - the single prolonged stress (SPS) model - which has been shown to have construct, predictive, and behavioral validity in modeling aspects of PTSD. Our results show that SPS had no effect on the acquisition of conditioned fear, but impaired extinction learning and extinction retention of fear behavior compared to sham treatment. D-578, but not paroxetine, attenuated the extinction and extinction-retention deficit induced by SPS. These findings suggest that D-578 has greater efficacy in normalizing traumatic stress-induced extinction-retention learning in a model for PTSD compared to paroxetine. Overall these results suggest that D-578, in addition to producing a robust and efficacious antidepressant effect, may attenuate maladaptive retention of fearful memories and support further testing of this agent for the pharmacotherapy of depression and PTSD.

A one-pot, microwave-influenced synthesis of diverse small molecules by multicomponent reaction cascades.

Small molecule diversity can be achieved in a single synthetic operation from bifunctional substrates in the absence of additives and under the influence of microwaves with complete control of pathway selectivity. The preliminary Ugi four-component coupling products give rise to three structurally distinct scaffolds that are dependent on solvent effects and sterics. 2,5-Diketopiperazines (Type A), 2-azaspiro[4.5]deca-6,9-diene-3,8-diones (Type B), and thiophene-derived Diels-Alder tricyclic lactams (Type C) predominate in this reaction cascade.

Diastereoselective, titanium-mediated cyclization of omega-vinyl tethered imides.

[reaction: see text] Diastereoselective reductive coupling reactions of omega-vinyl tethered cyclic imides are achieved by a preexisting stereocenter at an allylic position. Particularly noteworthy is the effective use of a 1:2 mixture of Ti(O-i-Pr)4 and n-BuLi to afford the N-acylhemiaminal products in good yields.

Triple reuptake inhibitors as potential next-generation antidepressants: a new hope?

The current therapy for depression is less than ideal with remission rates of only 25-35% and a slow onset of action with other associated side effects. The persistence of anhedonia originating from depressed dopaminergic activity is one of the most treatment-resistant symptoms of depression. Therefore, it has been hypothesized that triple reuptake inhibitors (TRIs) with potency to block dopamine reuptake in addition to serotonin and norepinephrine transporters should produce higher efficacy. The current review comprehensively describes the development of TRIs and discusses the importance of evaluation of in vivo transporter occupancy of TRIs, which should correlate with efficacy in humans.

Pharmacological and behavioral characterization of D-473, an orally active triple reuptake inhibitor targeting dopamine, serotonin and norepinephrine transporters.

Major depressive disorder (MDD) is a debilitating disease affecting a wide cross section of people around the world. The current therapy for depression is less than adequate and there is a considerable unmet need for more efficacious treatment. Dopamine has been shown to play a significant role in depression including production of anhedonia which has been one of the untreated symptoms in MDD. It has been hypothesized that drugs acting at all three monoamine transporters including dopamine transporter should provide more efficacious antidepressants activity. This has led to the development of triple reuptake inhibitor D-473 which is a novel pyran based molecule and interacts with all three monoamine transporters. The monoamine uptake inhibition activity in the cloned human transporters expressed in HEK-293 cells (70.4, 9.18 and 39.7 for DAT, SERT and NET, respectively) indicates a serotonin preferring triple reuptake inhibition profile for this drug. The drug D-473 exhibited good brain penetration and produced efficacious activity in rat forced swim test under oral administration. The optimal efficacy dose did not produce any locomotor activation. Microdialysis experiment demonstrated that systemic administration of D-473 elevated extracellular level of the three monoamines DA, 5-HT, and NE efficaciously in the dorsal lateral striatum (DLS) and the medial prefrontal cortex (mPFC) area, indicating in vivo blockade of all three monoamine transporters by D-473. Thus, the current biological data from D-473 indicate potent antidepressant activity of the molecule.

D-512 and D-440 as novel multifunctional dopamine agonists: characterization of neuroprotection properties and evaluation of in vivo efficacy in a Parkinson's disease animal model.

In this article, we have demonstrated the in vivo efficacy of D-512 and D-440 in a 6-OHDA-induced unilaterally lesioned rat model experiment, a Parkinson's disease animal model. D-512 is a novel highly potent D2/D3 agonist, and D-440 is a novel highly selective D3 agonist. We evaluated the neuroprotective properties of D-512 and D-440 in the dopaminergic MN9D cells. Cotreatment of these two drugs with 6-OHDA and MPP+ significantly attenuated and reversed 6-OHDA- and MPP+-induced toxicity in a dose-dependent manner in the dopaminergic MN9D cells. The inhibition of caspase 3/7 and lipid peroxidation activities along with the restoration of tyrosine hydroxylase levels by D-512 in 6-OHDA-treated cells may partially explain the mechanism of its neuroprotective property. Furthermore, studies were carried out to elucidate the time-dependent changes in the pERK1/2 and pAkt, two kinases implicated in cell survival and apoptosis, levels upon treatment with 6-OHDA in presence of D-512. The neuroprotective property exhibited by these drugs was independent of their dopamine-agonist activity, which is consistent with our multifunctional drug-development approach that is focused on the generation of disease-modifying symptomatic-treatment agents for Parkinson's disease.

Interaction of D3 preferring agonist (-)-N6-(2-(4-(biphenyl-4-yl)piperazin-1-yl)ethyl)-N6-propyl-4,5,6,7-tetrahydrobenzo[d]thiazole-2,6-diamine (D-264) with cloned human D2L, D2S, and D3 receptors: potent stimulation of mitogen-activated protein kinases and G protein-coupled inward rectifier potassium channels.

This study aims to determine the effect of the novel D(3) dopamine receptor agonist, D-264, on activation of D(3) and D(2) dopamine receptor signal transduction pathways and cell proliferation. AtT-20 neuroendocrine cells stably expressing human D(2S), D(2L), and D(3) dopamine receptors were treated with D-264 and the coupling of the receptors to mitogen-activated protein kinase (MAPK) and G protein-coupled inward rectifier potassium (GIRK) channels was determined using Western blotting and whole-cell voltage clamp recording, respectively. D-264 potently activated MAPK signaling pathway coupled to D(2S), D(2L), and D(3) dopamine receptors. The activation of MAPK was more pronounced than the reference agonist quinpirole and was longer lasting. D-264 also activated GIRK channels coupled to D(2S), D(2L), and D(3) receptors. In addition, D-264 dose-dependently induced cell proliferation in AtT-D(2L) and AtT-D(3) cells. These results indicate that D-264 robustly activates GIRK channels and MAPK coupled to D(2) and D(3) dopamine receptors in AtT-20 cells. D-264 is also a potent inducer of cell proliferation.

Structural exploration of (3S,6S)-6-benzhydryl-N-benzyltetrahydro-2H-pyran-3-amine analogues: identification of potent triple monoamine reuptake inhibitors as potential antidepressants.

To further explore the basic structural motifs (3S,6S)-6-benzhydryl-N-benzyltetrahydro-2H-pyran-3-amine and (2S,4R,5R)-2-benzhydryl-5-(benzylamino)tetrahydro-2H-pyran-4-ol, developed by our research group, for monoamine transport inhibition, we designed and synthesized various structurally altered analogues. The new compounds were tested for their affinities for the dopamine transporter (DAT), the serotonin transporter (SERT), and the norepinephrine transporter (NET) in rat brain by measuring their capacity to inhibit the uptake of [(3)H]DA, [(3)H]5-HT, and [(3)H]NE, respectively. Our results point to novel compounds with a TUI, DNRI, SNRI, or SSRI profile. Among the TUIs, compound 2 g exhibited a balanced potency for all three monoamine transporters (K(i): 60, 79, and 70.3 nM for DAT, SERT, and NET, respectively). In the rat forced swim test, compound 2 g produced a significant decrease in immobility in drug-treated rats relative to vehicle, indicating a potential antidepressant property.

Further structure-activity relationship studies on 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol: identification of compounds with triple uptake inhibitory activity as potential antidepressant agents.

To investigate structural alterations of the lead triple uptake inhibitor molecule, disubstituted 4-((((3S,6S)-6-benzhydryltetrahydro-2H-pyran-3-yl)amino)methyl)phenol, we have carried out structure-activity relationship (SAR) studies to investigate the effect of alteration of aromatic substitutions and introduction of heterocyclic aromatic moieties on this molecular template. The novel compounds were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting the uptake of [(3)H]DA, [(3)H]5-HT, and [(3)H]NE, respectively. SAR results indicate dopamine norepinephrine reuptake inhibitory (DNRI) type activity in thiophene (10g) and pyrrole (10i) derivatives. On the other hand, 3-hydroxyphenyl derivative 10f and 4-methoxyphenyl derivative 10j exhibited a triple reuptake inhibitory (TUI) activity profile, as these molecules exhibited potent uptake inhibition for all the monoamine transporters (K(i) of 31.3, 40, 38.5 and K(i) of 15.9, 12.9, 29.3 for DAT, SERT, and NET for 10f and 10g, respectively). Compound 10f was further evaluated in the rat forced swim test to evaluate its potential antidepressant effect. The results show significant reduction of immobility by TUI 10f at 10 mg/kg dose, indicating potential antidepressant activity.

A tandem one-pot, microwave-assisted synthesis of regiochemically differentiated 1,2,4,5-tetrahydro-1,4-benzodiazepin-3-ones.

A one-pot, two-step synthesis of the title compounds employs a multicomponent Ugi condensation reaction, microwave irradiation, and Fe(0) as a reductant. Two pathways are accessible; both routes utilize bifunctional, o-nitro-substituted arenes leading to either C2, N4, C5 substitution (A) or C2, N4 substitution (B).