A new arylsulfanyl-benzo-2,1,3-thiadiazoles derivative produces an anti-amnesic effect in mice by modulating acetylcholinesterase activity.

The aim of the present study was investigate the binding affinity of 5-((4-methoxyphenyl)thio)benzo[c][1,2,5]thiadiazole (MTDZ) with acetylcholinesterase (AChE). We also evaluated the effect of MTDZ against scopolamine (SCO)-induced amnesia in mice and we looked at the toxicological potential of this compound in mice. The binding affinity of MTDZ with AChE was investigated by molecular docking analyses. For an experimental model, male Swiss mice were treated daily with MTDZ (10 mg/kg, intragastrically (i.g.)) or canola oil (10 ml/kg, i.g.), and induced, 30 min later, with injection of SCO (0.4 mg/kg, intraperitoneally (i.p.)) or saline (0.9%, 5 ml/kg, i.p.) daily. From day 1 to day 10, mice were submitted to the behavioral tasks (Barnes maze, open-field, object recognition and location, Y-maze and step-down inhibitory avoidance tasks), 30 min after induction with SCO. On the tenth day, the animals were euthanized and blood was collected for the analysis of biochemical markers (creatinine, aspartate (AST), and alanine (ALT) aminotransferase). MTDZ interacts with residues of the AChE active site. SCO caused amnesia in mice by changing behavioral tasks. MTDZ treatment attenuated the behavioral changes caused by SCO. In ex vivo assay, MTDZ also protected against the alteration of AChE activity, reactive species (RS) levels, thiobarbituric acid reative species (TBARS) levels, catalase (CAT) activity in tissues, as well as in transaminase activities of plasma caused by SCO in mice. In conclusion, MTDZ presented anti-amnesic action through modulation of the cholinergic system and provided protection from kidney and liver damage caused by SCO.

Structure-Based Design and Optimization of FPPQ, a Dual-Acting 5-HT3 and 5-HT6 Receptor Antagonist with Antipsychotic and Procognitive Properties.

In line with recent clinical trials demonstrating that ondansetron, a 5-HT3 receptor (5-HT3R) antagonist, ameliorates cognitive deficits of schizophrenia and the known procognitive effects of 5-HT6 receptor (5-HT6R) antagonists, we applied the hybridization strategy to design dual-acting 5-HT3/5-HT6R antagonists. We identified the first-in-class compound FPPQ, which behaves as a 5-HT3R antagonist and a neutral antagonist 5-HT6R of the Gs pathway. FPPQ shows selectivity over 87 targets and decent brain penetration. Likewise, FPPQ inhibits phencyclidine (PCP)-induced hyperactivity and displays procognitive properties in the novel object recognition task. In contrast to FPPQ, neither 5-HT6R inverse agonist SB399885 nor neutral 5-HT6R antagonist CPPQ reversed (PCP)-induced hyperactivity. Thus, combination of 5-HT3R antagonism and 5-HT6R antagonism, exemplified by FPPQ, contributes to alleviating the positive-like symptoms. Present findings reveal critical structural features useful in a rational polypharmacological approach to target 5-HT3/5-HT6 receptors and encourage further studies on dual-acting 5-HT3/5-HT6R antagonists for the treatment of psychiatric disorders.

Drotaverine Inhibitor of PDE4: Reverses the Streptozotocin Induced Alzheimer's Disease in Mice.

Alzheimer's disease (AD) is a progressive neurodegenerative disease associated with decline in memory and cognitive impairments. Phosphodiesterase IV (PDE4) protein, an intracellular cAMP levels regulator, when inhibited act as potent neuroprotective agents by virtue of ceasing the activity of Pro-inflammatory mediators. The complexity of AD etiology has ever since compelled the researchers to discover multifunctional compounds to combat the AD and neurodegeneration. The aim of this study was to probe into role of drotaverine a PDE4 inhibitor in the management of AD. Albino mice were divided into seven groups (n = 10). Group 1 control group received carboxy methyl cellulose (CMC 1 mL/kg), group II diseased group treated with streptozotocin (STZ 3 mg/kg) by intracerebroventricular (ICV) route, group III administered standard drug Piracetam 200 mg/kg and groups IV-VII were given drotaverine (10, 20, 40, and 80 mg/kg i/p respectively). Groups II-VII were given STZ (3 mg/kg, ICV) on 1st and 3rd day of treatment to induce AD. All the groups were given their respective treatments for 23 days. Improvement in learning and memory was evaluated by using behavioral tests like open field test, elevated plus maze test, Morris water maze test and passive avoidance test. Furthermore, brain levels of biochemical markers of oxidative stress, neurotransmitters, ß-amyloid and tau protein were also measured. Drotaverine showed statistically significant dose dependent improvement in behavioral and biochemical markers of AD: the maximum response was achieved at a dose level of 80 mg/kg. The Study concluded that drotaverine ameliorates cognitive impairment and as well as exhibited modulated the brain levels of neurotransmitters.

Discovery of new phenyl sulfonyl-pyrimidine carboxylate derivatives as the potential multi-target drugs with effective anti-Alzheimer's action: Design, synthesis, crystal structure and in-vitro biological evaluation.

Alzheimer's disease (AD) is multifactorial, progressive neurodegeneration with impaired behavioural and cognitive functions. The multitarget-directed ligand (MTDL) strategies are promising paradigm in drug development, potentially leading to new possible therapy options for complex AD. Herein, a series of novel MTDLs phenylsulfonyl-pyrimidine carboxylate (BS-1 to BS-24) derivatives were designed and synthesized for AD treatment. All the synthesized compounds were validated by 1HNMR, 13CNMR, HRMS, and BS-19 were structurally validated by X-Ray single diffraction analysis. To evaluate the plausible binding affinity of designed compounds, molecular docking study was performed, and the result revealed their significant interaction with active sites of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The synthesized compounds displayed moderate to excellent in vitro enzyme inhibitory activity against AChE and BuChE at nanomolar (nM) concentration. Among 24 compounds (BS-1 to BS-24), the optimal compounds (BS-10 and BS-22) displayed potential inhibition against AChE; IC50 = 47.33 ± 0.02 nM and 51.36 ± 0.04 nM and moderate inhibition against BuChE; IC50 = 159.43 ± 0.72 nM and 153.3 ± 0.74 nM respectively. In the enzyme kinetics study, the compound BS-10 displayed non-competitive inhibition of AChE with Ki = 8 nM. Respective compounds BS-10 and BS-22 inhibited AChE-induced Aß1-42 aggregation in thioflavin T-assay at 10 µM and 20 µM, but BS-10 at 10 µM and 20 µM concentrations are found more potent than BS-22. In addition, the aggregation properties were determined by the dynamic light scattering (DLS) and was found that BS-10 and BS-22 could significantly inhibit self-induced as well as AChE-induced Aß1-42 aggregation. The effect of compounds (BS-10 and BS-22) on the viability of MC65 neuroblastoma cells and their capability to cross the blood-brain barrier (BBB) in PAMPA-BBB were further studied. Further, in silico approach was applied to analyze physicochemical and pharmacokinetics properties of the designed compounds via the SwissADME and PreADMET server. Hence, the novel phenylsulfonyl-pyrimidine carboxylate derivatives can act as promising leads in the development of AChE inhibitors and Aß disaggregator for the treatment of AD.

Amyloid Peptide Scaffolds Coordinate with Alzheimer's Disease Drugs.

Functional amyloid materials can combine the self-assembly of peptide scaffolds into amyloid fibrils with binding capacities for ions or compounds of pharmaceutical interest, endowed by mutable non-ß-sheet-forming residues at the termini. Herein, we report the first to our knowledge amyloid materials, encompassing a GAIIG amyloidogenic core, which bind to Alzheimer's disease (AD) drugs, by mimicking the mechanism by which the same AD drugs bind to enzymes according to experimentally resolved structures, including the target enzyme acetylcholinesterase (AChE). The computationally designed amyloid scaffolds are experimentally shown to coordinate with AD drugs, using two techniques, both in dilute solutions and at higher peptide concentrations, with a higher binding capacity for donepezil and tacrine compared to that for memantine and galantamine. The binding for some of the AD drugs is strong and stable even after extensive subsequent aqueous washings, denoting high capturing efficiency by the designed biomaterials, even after incubation under physiological conditions. Our findings constitute starting points to design novel drug delivery carriers binding to one or combinations of AD drugs (e.g., NMDA and cholinesterase inhibitors).

Biphenyl-3-oxo-1,2,4-triazine linked piperazine derivatives as potential cholinesterase inhibitors with anti-oxidant property to improve the learning and memory.

A series of novel piperazine tethered biphenyl-3-oxo-1,2,4-triazine derivatives were designed, and synthesized. Amongst the synthesized analogs, compound 6g showed significant non-competitive inhibitory potential against acetylcholinesterase (AChE, IC50; 0.2 ±â€¯0.01 µM) compared to standard donepezil (AChE, IC50: 0.1 ±â€¯0.002 µM). Compound 6g also exhibited significant displacement of propidium iodide from the peripheral anionic site (PAS) of AChE (22.22 ±â€¯1.11%) and showed good CNS permeability in PAMPA-BBB assay (Pe(exp), 6.93 ±â€¯0.46). The in vivo behavioral studies of compound 6g indicated significant improvement in cognitive dysfunctions against scopolamine-induced amnesia mouse models. Further, ex vivo studies showed a significant AChE inhibition and reversal of the scopolamine-induced oxidative stress by compound 6g. Moreover, molecular docking and dynamics simulations of compound 6g showed a consensual binding affinity and active site interactions with the PAS and active catalytic site (CAS) residues of AChE.

Novel tacrine-coumarin hybrids linked to 1,2,3-triazole as anti-Alzheimer's compounds: In vitro and in vivo biological evaluation and docking study.

A new series of tacrine-coumarin hybrids linked to 1,2,3-triazole were designed, synthesized, and tested as potent dual binding site cholinesterase inhibitors (ChEIs) for the treatment of Alzheimer's disease (AD). Among them, compound 8e was the most potent anti-AChE derivative (IC50 = 27 nM) and compound 8m displayed the best anti-BChE activity (IC50 = 6 nM) much more active than tacrine and donepezil as the reference drugs. Compound 8e was also evaluated for its BACE1 inhibitory activity and neuroprotectivity against PC12 cells exposed to Aß25-35 which indicated low activity. Finally, in vivo studies by Morris water maze task showed that compound 8e significantly reversed scopolamine-induced memory deficit in rats.

Across the blood-brain barrier: Neurotherapeutic screening and characterization of naringenin as a novel CRMP-2 inhibitor in the treatment of Alzheimer's disease using bioinformatics and computational tools.

The discovery and developmental processes of CNS drugs have been limited by the inability of potential drug molecules to pass through the blood-brain barrier (BBB). This presents a significant setback in the treatment of neurodegenerative disorders such as Alzheimer's disease (AD), hence the need for compounds that can adhere strictly to the selective criteria of suitable CNS drugs. Collapsin response mediator protein-2 (CRMP-2) has been recently identified as a viable target in neurotherapeutics due to its involvement in the etiology of AD. As shown in previous studies, Naringenin (NAR), a small molecule derivative of Drynaria rhizome (DR) extract, specifically binds CRMP-2 and reduces its phosphorylation. This was shown to facilitate axonal regrowth, with improvement in cognition and learning. Herein, we report the first account of the use of cheminformatics techniques to define the CNS drug-suitability of NAR using selective criteria, coupled with the prediction of possible biological activities and toxicities. Also, we evaluated the mechanistic activity of NAR by modeling its molecular interaction with human CRMP-2 (hCRMP-2). Physicochemical analyses revealed the suitability of NAR as a CNS drug and its ability to transverse the BBB. Possible neurogenic, anti-carcinogenic and cardioprotective activities were also predicted. NAR exhibited favorable binding to CRMP-2 and formed strong bonds with active site residues, which accounts for its stabilization and affinity. Moreover, NAR induced notable conformational changes in CRMP-2, an occurrence that could possibly disrupt kinase-mediated phosphorylation. These findings will aid in the optimization of NAR and improve its neurotherapeutic activities in the treatment of AD.

Epigallocatechin Gallate Reduces Amyloid ß-Induced Neurotoxicity via Inhibiting Endoplasmic Reticulum Stress-Mediated Apoptosis.

SCOPE: We investigated the role of endoplasmic reticulum (ER) stress in the protective effects of EGCG against the neuronal apoptosis in Aß1-42 -induced SH-SY5Y cells and APP/PS1 transgenic mice. METHODS AND RESULTS: Cell viability (CCK8 assay), flow cytometry, Hoechst 33258 staining, immunohistochemistry, transmission electron microscopy (TEM), and western blotting were used. EGCG prevented Aß1-42-induced toxicity in SH-SY5Y cells, increased cell viability, and decreased apoptosis in a dose-dependent manner. In a subsequent mechanism study, it was found that this effect contributed to the down-regulation of GRP78, CHOP, cleaved-caspase-12 and -3. Moreover, EGCG also reduced the cytotoxicity induced by tunicamycin (TM) and thapsigargin (TG), two ER stress activators. Consistent with the in vitro study, EGCG inhibited neuronal apoptosis in the cortex of APP/PS1 transgenic mice, with the mitigation of ER abnormal ultrastructural swelling and the downregulation of ER-stress-associated proteins. CONCLUSION: These results indicate that EGCG attenuates the neurotoxicity in Alzheimer's disease (AD) via a novel mechanism that involves inhibition of ER-stress-associated neuronal apoptosis in vitro and in vivo, suggesting the tremendous potential of EGCG for use in a nutritional preventive strategy against AD.

Molecular Pharmacology of Rosmarinic and Salvianolic Acids: Potential Seeds for Alzheimer's and Vascular Dementia Drugs.

Both caffeic acid and 3,4-dihydroxyphenyllactic acid (danshensu) are synthesized through two distinct routs of the shikimic acid biosynthesis pathway. In many plants, especially the rosemary and sage family of Lamiaceae, these two compounds are joined through an ester linkage to form rosmarinic acid (RA). A further structural diversity of RA derivatives in some plants such as Salvia miltiorrhiza Bunge is a form of RA dimer, salvianolic acid-B (SA-B), that further give rise to diverse salvianolic acid derivatives. This review provides a comprehensive perspective on the chemistry and pharmacology of these compounds related to their potential therapeutic applications to dementia. The two common causes of dementia, Alzheimer's disease (AD) and stroke, are employed to scrutinize the effects of these compounds in vitro and in animal models of dementia. Key pharmacological mechanisms beyond the common antioxidant and anti-inflammatory effects of polyphenols are highlighted with emphasis given to amyloid beta (Aß) pathologies among others and neuronal regeneration from stem cells.

Gaining Insights into Specific Drug Formulation Additives for Solubilizing a Potential Anti-Alzheimer Disease Drug B4A1.

The pharmacological profiles of small molecule drugs are often challenged by their poor water solubility. Sequence-defined peptides attached to poly(ethylene glycol) (PEG) offer opportunities to overcome these difficulties by acting as drug-specific formulation additives. The peptide-PEG conjugates enable specific, noncovalent drug binding via tailored peptide/drug interactions as well as provide water solubility and drug shielding by well-solvated PEG-blocks. A systematic set of specific solubilizers for B4A1 as a potential anti-Alzheimer disease drug is synthesized and variations involve the length of the PEG-blocks as well as the sequences of the peptidic drug-binding domain. The solubilizer/B4A1 complexes are studied in order to understand contributions of both PEG and peptide segments on drug payload capacities, drug/carrier aggregate sizes, and influences on inhibition of the Tau-protein aggregation in an in vitro assay.

Natural product-based amyloid inhibitors.

Many chronic human diseases, including multiple neurodegenerative diseases, are associated with deleterious protein aggregates, also called protein amyloids. One common therapeutic strategy is to develop protein aggregation inhibitors that can slow down, prevent, or remodel toxic amyloids. Natural products are a major class of amyloid inhibitors, and several dozens of natural product-based amyloid inhibitors have been identified and characterized in recent years. These plant- or microorganism-extracted compounds have shown significant therapeutic potential from in vitro studies as well as in vivo animal tests. Despite the technical challenges of intrinsic disordered or partially unfolded amyloid proteins that are less amenable to characterizations by structural biology, a significant amount of research has been performed, yielding biochemical and pharmacological insights into how inhibitors function. This review aims to summarize recent progress in natural product-based amyloid inhibitors and to analyze their mechanisms of inhibition in vitro. Major classes of natural product inhibitors and how they were identified are described. Our analyses comprehensively address the molecular interactions between the inhibitors and relevant amyloidogenic proteins. These interactions are delineated at molecular and atomic levels, which include covalent, non-covalent, and metal-mediated mechanisms. In vivo animal studies and clinical trials have been summarized as an extension. To enhance natural product bioavailability in vivo, emerging work using nanocarriers for delivery has also been described. Finally, issues and challenges as well as future development of such inhibitors are envisioned.

Intravenous Administration of Stable-Labeled N-Acetylcysteine Demonstrates an Indirect Mechanism for Boosting Glutathione and Improving Redox Status.

There is an increasing interest in using N-acetylcysteine (NAC) as a treatment for neurodegenerative disorders to increase glutathione (GSH) levels and its redox status. The purpose of this study was to characterize the biosynthesis of NAC to GSH using a novel stable isotope-labeled technique, and investigate the pharmacodynamics of NAC in vivo. Female wild-type mice were given a single intravenous bolus dose of 150 mg kg(-1) stable-labeled NAC. Plasma, red blood cells (RBC), and brain tissues were collected at predesignated time points. Stable-labeled NAC and its metabolite GSH (both labeled and unlabeled forms) were quantified in blood and brain samples. Molar ratios of the reduced and oxidized forms of GSH (GSH divided by glutathione disulfide, redox ratio) were also determined. The elimination phase half-life of NAC was approximately 34 min. Both labeled and unlabeled GSH in RBC were found to increase; however, the area under the curve above baseline (AUCb0-280 ) of labeled GSH was only 1% of the unlabeled form. These data indicate that NAC is not a direct precursor of GSH. In addition, NAC has prolonged effects in brain even when the drug has been eliminated from systemic circulation.

Anthocyanins do not influence long-chain n-3 fatty acid status: studies in cells, rodents and humans.

Increased tissue status of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular and cognitive benefits. Limited epidemiological and animal data suggest that flavonoids, and specifically anthocyanins, may increase EPA and DHA levels, potentially by increasing their synthesis from the shorter-chain n-3 PUFA, α-linolenic acid. Using complimentary cell, rodent and human studies we investigated the impact of anthocyanins and anthocyanin-rich foods/extracts on plasma and tissue EPA and DHA levels and on the expression of fatty acid desaturase 2 (FADS2), which represents the rate limiting enzymes in EPA and DHA synthesis. In experiment 1, rats were fed a standard diet containing either palm oil or rapeseed oil supplemented with pure anthocyanins for 8 weeks. Retrospective fatty acid analysis was conducted on plasma samples collected from a human randomized controlled trial where participants consumed an elderberry extract for 12 weeks (experiment 2). HepG2 cells were cultured with α-linolenic acid with or without select anthocyanins and their in vivo metabolites for 24 h and 48 h (experiment 3). The fatty acid composition of the cell membranes, plasma and liver tissues were analyzed by gas chromatography. Anthocyanins and anthocyanin-rich food intake had no significant impact on EPA or DHA status or FADS2 gene expression in any model system. These data indicate little impact of dietary anthocyanins on n-3 PUFA distribution and suggest that the increasingly recognized benefits of anthocyanins are unlikely to be the result of a beneficial impact on tissue fatty acid status.

Rats given linseed oil in microemulsion forms enriches the brain synaptic membrane with docosahexaenoic acid and enhances the neurotransmitter levels in the brain.

Long chain n-3 fatty acids such as docosahexaenoic acid (DHA) are essential for the normal functioning of the brain. The vegetarian sections of the population get only alpha-linolenic acid (ALA) through their diet as a source of n-3 fatty acids. Hence, in this group of the population, the ALAs need to be converted to DHA through the action of the desaturase and the elongase enzymes. However, the conversion of the ALA to the DHA is very minimal (<2%) in mammals. Our recent studies have shown that the conversion of the ALA to the DHA can be enhanced significantly when given in the microemulsion forms. This work was undertaken to study the feasibility of enriching the synaptic membranes of rat brain with the DHA by providing the microemulsions of linseed oil (LSO) containing ALA. The rats were fed LSO as microemulsions in whey protein or in lipoid for 60 days through gavage. The rats given LSO microemulsions in lipoid showed higher levels of the DHA in the brain synaptic membrane when compared to rats given LSO without emulsion formation. This decreased the n-6/n-3 fatty acid ratio of the brain synaptic membrane. This also increased the membrane fluidity, Na⁺-K⁺ ATPase activity, and acetylcholine esterase activity in the synaptic membranes. Furthermore, Ca²âº-Mg²âº ATPase activity, monoamine oxidase A and monoamine oxidase B activity was lowered in the rats given LSO in the microemulsion form. The dopamine and the serotonin levels in the brain were increased in the rats given LSO in the microemulsion form with lipoid as compared to those given LSO without the preemulsion formation. This study indicates that the LSO microemulsions in the lipoid can enhance the synaptic membrane DHA levels and influence the functions associated with the brain in a beneficial manner.

Effects of resveratrol alone or in combination with piperine on cerebral blood flow parameters and cognitive performance in human subjects: a randomised, double-blind, placebo-controlled, cross-over investigation.

Previous research has shown that resveratrol can increase cerebral blood flow (CBF) in the absence of improved cognitive performance in healthy, young human subjects during the performance of cognitively demanding tasks. This lack of cognitive effects may be due to low bioavailability and, in turn, reduced bioefficacy of resveratrol in vivo. Piperine can alter polyphenol pharmacokinetics, but previous studies have not investigated whether this affects the efficacy of the target compound. Therefore, the objective of the present study was to ascertain whether co-supplementation of piperine with resveratrol affects the bioavailability and efficacy of resveratrol with regard to cognition and CBF. The present study utilised a randomised, double-blind, placebo-controlled, within-subjects design, where twenty-three adults were given placebo, trans-resveratrol (250 mg) and trans-resveratrol with 20 mg piperine on separate days at least a week apart. After a 40 min rest/absorption period, the participants performed a selection of cognitive tasks and CBF was assessed throughout the period, in the frontal cortex, using near-IR spectroscopy. The presence of resveratrol and its conjugates in the plasma was confirmed by liquid chromatography-MS analysis carried out following the administration of the same doses in a separate cohort (n 6). The results indicated that when co-supplemented, piperine and resveratrol significantly augmented CBF during task performance in comparison with placebo and resveratrol alone. Cognitive function, mood and blood pressure were not affected. The plasma concentrations of resveratrol and its metabolites were not significantly different between the treatments, which indicates that co-supplementation of piperine with resveratrol enhances the bioefficacy of resveratrol with regard to CBF effects, but not cognitive performance, and does this without altering bioavailability.

Preparation and characterization of methylene blue nanoparticles for Alzheimer's disease and other tauopathies.

Methylene blue (MB) has been shown to slow down the progression of the Alzheimer's disease (AD) and other tauopathies; however distribution of MB into the brain is limited due its high hydrophilicity. In this study, we aimed to prepare novel hydrophobic glutathione coated PLGA nanoparticles to improve bioavailability of MB in the brain. Glutathione coated poly-(lactide-co-glycolide) (PLGA-b-PEG) nanoparticles (NPs) were prepared and tested in two different cell culture models of AD expressing microtubule associated protein tau (tau). The NPs showed a particle size averaging 136.5±4.4nm, which is suitable for the blood brain barrier (BBB) permeation. The in vitro release profile of the NPs exhibited no initial burst release and showed sustained drug release for up to 144 hours. Interestingly, treatment of newly formulated MB-NPs showed a potent reduction in both endogenous and over expressed tau protein levels in human neuroblastoma SHSY-5Y cells expressing endogenous tau and transfected HeLa cells over-expressing tau protein, respectively. Furthermore, in vitro BBB Transwell™ study showed significantly higher permeation of MB-NP compared to the MB solution through the co culture of rat brain endothelial 4 (RBE4) and C6 astrocytoma cells (p<0.05). The proposed MB loaded nanoparticles could provide a more effective treatment option for AD and many other related disorders.

The BRICHOS domain, amyloid fibril formation, and their relationship.

Amyloid diseases are defined by tissue deposition of insoluble, fibrillar ß-sheet polymers of specific proteins, but it appears that toxic oligomeric species rather than the fibrils are the main cause of tissue degeneration. Many proteins can form amyloid-like fibrils in vitro, but only ~30 proteins have been found to cause mammalian amyloid disease, suggesting that physiological mechanisms that protect against amyloid formation exist. The transmembrane region of lung surfactant protein C precursor (proSP-C) forms amyloid-like fibrils in vitro, and SP-C amyloid has been found in lung tissue from patients with interstitial lung disease (ILD). ProSP-C contains a BRICHOS domain, in which many ILD-associated mutations are localized, and the BRICHOS domain can prevent SP-C from forming amyloid-like fibrils. Recent data suggest that recombinant BRICHOS domains from proSP-C and Bri2 (associated with familial dementia and amyloid formation) interact with peptides with a strong propensity to form ß-sheet structures, including amyloid ß-peptide associated with Alzheimer's disease. Such interactions efficiently delay formation of fibrils and oligomers. The BRICHOS domain is defined at the sequence level and is found in ~10 distantly related proprotein families. These have widely different or unknown functions, but several of the proteins are associated with human disease. Structural modeling of various BRICHOS domains, based on the X-ray structure of the proSP-C BRICHOS domain, identifies a conserved region that is structurally complementary to the ß-sheet- and/or amyloid-prone regions in the BRICHOS domain-containing proproteins. These observations make the BRICHOS domain the first example of a chaperone-like domain with specificity for ß-prone regions.

Semagacestat, a γ-secretase inhibitor, activates the growth hormone secretagogue (GHS-R1a) receptor.

OBJECTIVES: Semagacestat, is a γ-secretase inhibitor, which belongs to a class of drugs that are being developed as therapeutic agents for Alzheimer's disease (AD). This study aims to evaluate another potential effect of semagacestat, namely its ability to stimulate the growth hormone secretagogue receptor (GHS-R1a), which may also contribute to its therapeutic efficacy. METHODS: The GHS-R1a-activating potential of semagacestat and its synthetic precursor was assessed in an in vitro calcium mobilization assay in cells expressing the GHS-R1a receptor and compared with that of the endogenous peptide GHS-R1a agonist, acyl-ghrelin, as well as the non-peptidyl synthetic GHS-R1a agonist, MK0677. In addition, semagacestat-mediated cellular trafficking of the GHS-R1a receptor, expressed as an enhanced green fluorescent protein tagged fusion protein, was analysed. KEY FINDINGS: Semagacestat and its precursor were shown to activate the GHS-R1a receptor, as demonstrated by an increased GHS-R1a-mediated intracellular calcium influx. Moreover, a synergistic GHS-R1a receptor activation was shown following a combined exposure to ghrelin and semagacestat. In addition, GHS-R1a receptor internalization was observed upon exposure to semagacestat and its precursor. CONCLUSION: These data suggest a novel molecular mechanism of action for semagacestat via modest GHS-R1a receptor activation. Studies focusing on the relative functional consequence of such effects in vivo are now warranted.

Long-lasting efficacy of the cognitive enhancer cytotoxic necrotizing factor 1.

Rho GTPases are key regulators of the activity-dependent changes of neural circuits. Besides being involved in nervous system development and repair, this neural structural plasticity is believed to constitute the cellular basis of learning and memory. Here we report that concurrent modulation of cerebral Rho GTPases, including Rac, Rho and Cdc42 subfamilies, by Cytotoxic Necrotizing Factor 1 (CNF1, 10 fmol/kg intracerebroventricularly) improves object recognition in both C57BL/6J and CD1 mice. The improvement is long lasting, as it is still observed 90 days post treatment. At this time, the treatment is associated with enhancement of neurotransmission and long-term potentiation. The effects depend on changes in Rho GTPase status, since the recombinant molecule CNF1 C866S, in which the enzymatic activity was abolished through substitution of serine to cysteine at position 866, is ineffective. The study confirms the role of Rho GTPases in learning and suggests that a single administration of CNF1 is effective for a long time after administration. In general, the long-lasting cognition enhancing effect of CNF1 might be beneficial for the treatment of CNS disorders. This article is part of a Special Issue entitled 'Cognitive Enhancers'.