Inhibition of Butyrylcholinesterase with Fluorobenzylcymserine, An Experimental Alzheimer's Drug Candidate: Validation of Enzoinformatics Results by Classical and Innovative Enzyme Kinetic Analyses.

Background: Selective butyrylcholinesterase (BuChE)-inhibition, increases acetylcholine (ACh) levels. In rodents, this inhibition is known to boost cognition. Also, this occurs without the typical unwanted adverse effects of acetylcholinesterase-inhibitors or AChE-Is.

Cognitive Impairments Induced by Concussive Mild Traumatic Brain Injury in Mouse Are Ameliorated by Treatment with Phenserine via Multiple Non-Cholinergic and Cholinergic Mechanisms.

Traumatic brain injury (TBI), often caused by a concussive impact to the head, affects an estimated 1.7 million Americans annually. With no approved drugs, its pharmacological treatment represents a significant and currently unmet medical need.

(-)-Phenserine attenuates soman-induced neuropathology.

Organophosphorus (OP) nerve agents are deadly chemical weapons that pose an alarming threat to military and civilian populations. The irreversible inhibition of the critical cholinergic degradative enzyme acetylcholinesterase (AChE) by OP nerve agents leads to cholinergic crisis. Resulting excessive synaptic acetylcholine levels leads to status epilepticus that, in turn, results in brain damage.

Selective acetyl- and butyrylcholinesterase inhibitors reduce amyloid-β ex vivo activation of peripheral chemo-cytokines from Alzheimer's disease subjects: exploring the cholinergic anti-inflammatory pathway.

Increasing evidence suggests that elevated production and/or reduced clearance of amyloid-β peptide (Aβ) drives the early pathogenesis of Alzheimer's disease (AD). Aβ soluble oligomers trigger a neurotoxic cascade that leads to neuronal dysfunction, neurodegeneration and, ultimately, clinical dementia. Inflammation, both within brain and systemically, together with a deficiency in the neurotransmitter acetylcholine (ACh) that underpinned the development of anticholinesterases for AD symptomatic treatment, are invariable hallmarks of the disease.

Cognitive impairments accompanying rodent mild traumatic brain injury involve p53-dependent neuronal cell death and are ameliorated by the tetrahydrobenzothiazole PFT-α.

With parallels to concussive mild traumatic brain injury (mTBI) occurring in humans, anesthetized mice subjected to a single 30 g weight drop mTBI event to the right parietal cortex exhibited significant diffuse neuronal degeneration that was accompanied by delayed impairments in recognition and spatial memory. To elucidate the involvement of reversible p53-dependent apoptosis in this neuronal loss and associated cognitive deficits, mice were subjected to experimental mTBI followed by the systemic administration of the tetrahydrobenzothiazole p53 inactivator, PFT-α, or vehicle. Neuronal loss was quantified immunohistochemically at 72 hr.

Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway.

Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin.

Neurotrophic and neuroprotective actions of (-)- and (+)-phenserine, candidate drugs for Alzheimer's disease.

Neuronal dysfunction and demise together with a reduction in neurogenesis are cardinal features of Alzheimer's disease (AD) induced by a combination of oxidative stress, toxic amyloid-β peptide (Aβ) and a loss of trophic factor support. Amelioration of these was assessed with the Aβ lowering AD experimental drugs (+)-phenserine and (-)-phenserine in neuronal cultures, and actions in mice were evaluated with (+)-phenserine. Both experimental drugs together with the metabolite N1-norphenserine induced neurotrophic actions in human SH-SY5Y cells that were mediated by the protein kinase C (PKC) and extracellular signal-regulated kinases (ERK) pathways, were evident in cells expressing amyloid precursor protein Swedish mutation (APP(SWE)), and retained in the presence of Aβ and oxidative stress challenge.

Synthesis of the Alzheimer drug Posiphen into its primary metabolic products (+)-N1-norPosiphen, (+)-N8-norPosiphen and (+)-N1, N8-bisnorPosiphen, their inhibition of amyloid precursor protein, α-Synuclein synthesis, interleukin-1β release, and cholinergic action.

A major pathological hallmark of Alzheimer disease (AD) is the appearance in the brain of senile plaques that are primarily composed of aggregated forms of β-amyloid peptide (Aβ) that derive from amyloid precursor protein (APP). Posiphen (1) tartrate is an experimental AD drug in current clinical trials that reduces Aβ levels by lowering the rate of APP synthesis without toxicity. To support the clinical development of Posiphen (1) and elucidate its efficacy, its three major metabolic products, (+)-N1-norPosiphen (15), (+)-N8-norPosiphen (17) and (+)-N1, N8-bisnorPosiphen (11), were required in high chemical and optical purity.

Kinetics of Torpedo californica acetylcholinesterase inhibition by bisnorcymserine and crystal structure of the complex with its leaving group.

Natural and synthetic carbamates act as pseudo-irreversible inhibitors of AChE (acetylcholinesterase) as well as BChE (butyrylcholinesterase), two enzymes involved in neuronal function as well as in the development and progression of AD (Alzheimer's disease). The AChE mode of action is characterized by a rapid carbamoylation of the active-site Ser(200) with release of a leaving group followed by a slow regeneration of enzyme action due to subsequent decarbamoylation. The experimental AD therapeutic bisnorcymserine, a synthetic carbamate, shows an interesting activity and selectivity for BChE, and its clinical development is currently being pursued.

Butyrylcholinesterase inhibitors ameliorate cognitive dysfunction induced by amyloid-β peptide in mice.

The cholinesterase inhibitor, rivastigmine, ameliorates cognitive dysfunction and is approved for the treatment of Alzheimer's disease (AD). Rivastigmine is a dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE); however, the impact of BuChE inhibition on cognitive dysfunction remains to be determined. We compared the effects of a selective BuChE inhibitor, N1-phenethyl-norcymserine (PEC), rivastigmine and donepezil (an AChE-selective inhibitor) on cognitive dysfunction induced by amyloid-β peptide (Aβ(1-40)) in mice.

Design, synthesis and biological assessment of novel N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines and 3-substituted 2,6-dioxopiperidines for TNF-α inhibitory activity.

Eight novel 2-(2,6-dioxopiperidin-3-yl)phthalimidine EM-12 dithiocarbamates 9 and 10, N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines 11-14 and 3-substituted 2,6-dioxopiperidines 16 and 18 were synthesized as tumor necrosis factor-α (TNF-α) synthesis inhibitors. Synthesis involved utilization of a novel condensation approach, a one-pot reaction involving addition, iminium rearrangement and elimination, to generate the phthalimidine ring required for the creation of compounds 9-14. Agents were, thereafter, quantitatively assessed for their ability to suppress the synthesis on TNF-α in a lipopolysaccharide (LPS)-challenged mouse macrophage-like cellular screen, utilizing cultured RAW 264.

Preparation and Characterization of Tetrabenazine Enantiomers against Vesicular Monoamine Transporter 2.

As a clinical medication for the treatment of hyperkinetic movement disorders, in conditions such as Huntington's disease, tetrabenazine (TBZ) has been always used in its racemic form. To establish whether or not its beneficial therapeutic actions are enantiospecific, a practical total synthetic route was developed to yield each enantiomeric form to allow their chemical and pharmacological characterization. We briefly summarize the total synthesis of TBZ and report a detailed procedure for resolution of TBZ into its enantiomers, (+)-TBZ and (-)-TBZ.

Long-acting anticholinesterases for myasthenia gravis: synthesis and activities of quaternary phenylcarbamates of neostigmine, pyridostigmine and physostigmine.

The N-monophenylcarbamate analogues of neostigmine methyl sulfate (6) and pyridostigmine bromide (8) together with their precursors (5), (7), and the N(1)-methylammonium analogues of (-)-phenserine (12), (-)-tolserine (14), (-)-cymserine (16) and (-)-phenethylcymserine (18) were synthesized to produce long-acting peripheral inhibitors of acetylcholinesterase or butyrylcholinesterase. Evaluation of their cholinesterase inhibition against human enzyme ex vivo demonstrated that, whereas compounds 5-8 possessed only marginal activity, 12, 14, 16 and 18 proved to be potent anticholinesterases. An extended duration of cholinesterase inhibition was determined in rodent, making them of potential interest as long-acting agents for myasthenia gravis.

Plumbagin promotes the generation of astrocytes from rat spinal cord neural progenitors via activation of the transcription factor Stat3.

Plumbagin (5-hydroxy-2-methyl-1,4 naphthoquinone) is a naturally occurring low molecular weight lipophilic phytochemical derived from roots of plants of the Plumbago genus. Plumbagin has been reported to have several clinically relevant biological activities in non-neural cells, including anti-atherosclerotic, anticoagulant, anticarcinogenic, antitumor, and bactericidal effects. In a recent screen of a panel of botanical pesticides, we identified plumbagin as having neuroprotective activity.

A synthetic uric acid analog accelerates cutaneous wound healing in mice.

Wound healing is a complex process involving intrinsic dermal and epidermal cells, and infiltrating macrophages and leukocytes. Excessive oxidative stress and associated inflammatory processes can impair wound healing, and antioxidants have been reported to improve wound healing in animal models and human subjects. Uric acid (UA) is an efficient free radical scavenger, but has a very low solubility and poor tissue penetrability.

Plumbagin, a novel Nrf2/ARE activator, protects against cerebral ischemia.

Many phytochemicals function as noxious agents that protect plants against insects and other damaging organisms. However, at subtoxic doses, the same phytochemicals may activate adaptive cellular stress response pathways that can protect cells against a variety of adverse conditions. We screened a panel of botanical pesticides using cultured human and rodent neuronal cell models, and identified plumbagin as a novel potent activator of the nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway.

A cellular model of inflammation for identifying TNF-alpha synthesis inhibitors.

Neuroinflammation is a common facet of both acute and chronic neurodegenerative conditions, exemplified by stroke and by Alzheimer's and Parkinson's disease, and the presence of elevated levels of the proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), has been documented in each. Although initial TNF-alpha generation is associated with a protective compensatory response, its unregulated chronic elevation is generally detrimental and can drive the disease process. In such circumstances, therapeutic strategies that can both gain access to the brain and target the production of TNF-alpha are predicted to be of clinical benefit.

Immobilized butyrylcholinesterase in the characterization of new inhibitors that could ease Alzheimer's disease.

Focus of this work was the development and characterization of a new immobilized enzyme reactor (IMER) containing human recombinant butyrylcholinesterase (rBChE) for the on-line kinetic characterization of specific, pseudo-irreversible and brain-targeted BChE inhibitors as potential drug candidates for Alzheimer's disease (AD). Specifically, a rBChE-IMER containing 0.99 U of covalently bound target enzyme was purposely developed and inserted into a HPLC system connected to a UV-vis detector.

Accommodation of physostigmine and its analogues by acetylcholinesterase is dominated by hydrophobic interactions.

The role of the functional architecture of the HuAChE (human acetylcholinesterase) in reactivity toward the carbamates pyridostigmine, rivastigmine and several analogues of physostigmine, that are currently used or considered for use as drugs for Alzheimer's disease, was analysed using over 20 mutants of residues that constitute the interaction subsites in the active centre. Both steps of the HuAChE carbamylation reaction, formation of the Michaelis complex as well as the nucleophilic process, are sensitive to accommodation of the ligand by the enzyme. For certain carbamate/HuAChE combinations, the mode of inhibition shifted from a covalent to a noncovalent type, according to the balance between dissociation and covalent reaction rates.

Tetrahydrofurobenzofuran cymserine, a potent butyrylcholinesterase inhibitor and experimental Alzheimer drug candidate, enzyme kinetic analysis.

Synaptic loss, particularly related to the forebrain cholinergic system, is considered to be an early event that leads to Alzheimer's disease (AD) and has led to the development of acetylcholinesterase inhibitors (AChE-Is) as the mainstay of treatment for several degenerative disorders that culminate in dementia. The primary dose-limiting toxicities of all clinically available AChE-Is are, similar to useful actions on cognition, cholinergically mediated and they ultimately limit the value of this drug class in achieving anything but symptomatic improvements. In addition, AChE levels in brain areas associated with AD decline with disease progression, which likely ultimately limits the therapeutic utility of this drug class.

Presenilin-1 mutation impairs cholinergic modulation of synaptic plasticity and suppresses NMDA currents in hippocampus slices.

Presenilin-1 (PS1) mutations cause many cases of early-onset inherited Alzheimer's disease, in part, by increasing the production of neurotoxic forms of amyloid beta-peptide (Abeta). However, Abeta-independent effects of mutant PS1 on neuronal Ca(2+) homeostasis and sensitivity to excitatory neurotransmitters have been reported. Here we show that cholinergic modulation of hippocampal synaptic plasticity is impaired in PS1 mutant knockin (PS1KI) mice.

Soluble neuroprotective antioxidant uric acid analogs ameliorate ischemic brain injury in mice.

Uric acid is a major antioxidant in the blood of humans that can protect cultured neurons against oxidative and metabolic insults. However, uric acid has a very low solubility which compromises its potential clinical use for neurodegenerative disorders. Here we describe the synthesis, characterization and preclinical development of neuroprotective methyl- and sulfur-containing analogs of uric acid with increased solubility.

Preclinical investigation of the topical administration of phenserine: transdermal flux, cholinesterase inhibition, and cognitive efficacy.

Phenserine (PS) was designed as a selective acetylcholinesterase (AChE) inhibitor, with a tartrate form (PST) for oral administration in mild to moderate Alzheimer's disease (AD). Recent phase 3 trials of PST in Europe indicate that any clinically relevant activity of PST may be limited by its duration of action. Like many oral drugs, bioavailability and plasma concentrations of PST are regulated by hepatic and gastrointestinal first-pass effects.

The experimental Alzheimer's disease drug posiphen [(+)-phenserine] lowers amyloid-beta peptide levels in cell culture and mice.

Major characteristics of Alzheimer's disease (AD) are synaptic loss, cholinergic dysfunction, and abnormal protein depositions in the brain. The amyloid beta-peptide (Abeta), a proteolytic fragment of amyloid beta precursor protein (APP), aggregates to form neuritic plaques and has a causative role in AD. A present focus of AD research is to develop safe Abeta-lowering drugs.