Drug Design for Alzheimer's Disease: Biologics vs. Small Molecules.

There shall probably be no "magic bullet" for Alzheimer's; rather, we should be pursuing a "magic shotgun blast" that will target multiple complementary therapeutic receptors. Although protein misfolding/oligomerization will probably be one of these targets, this alone is insufficient and will require the co-administration of other therapeutic entities engaging targets, such as immunopathy, gliopathy, mitochondriopathy, synaptotoxicity or others. Although polypharmacy is emerging as the preferred therapeutic route, many questions remain unanswered. Should this be a cocktail of biologics, a concoction of small molecules, or a judicious combination of both? Biologics and small molecule drugs display both strengths and weaknesses. When addressing a disease as complex and globally important as Alzheimer's, there should be room for the continuing development of both of these therapeutic classes. Each has much to offer, and when used with their advantages and disadvantages in clear focus, an ultimate solution will probably require contributions from both.

Cancer and Alzheimer's Inverse Correlation: an Immunogenetic Analysis.

Numerous studies have demonstrated an inverse link between cancer and Alzheimer's disease (AD), with data suggesting that people with Alzheimer's have a decreased risk of cancer and vice versa. Although other studies have investigated mechanisms to explain this relationship, the connection between these two diseases remains largely unexplained. Processes seen in cancer, such as decreased apoptosis and increased cell proliferation, seem to be reversed in AD. Given the need for effective therapeutic strategies for AD, comparisons with cancer could yield valuable insights into the disease process and perhaps result in new treatments. Here, through a review of existing literature, we compared the expressions of genes involved in cell proliferation and apoptosis to establish a genetic basis for the reciprocal association between AD and cancer. We discuss an array of genes involved in the aforementioned processes, their relevance to both diseases, and how changes in those genes produce varying effects in either disease.

Anti-Inflammatory Anthranilate Analogue Enhances Autophagy through mTOR and Promotes ER-Turnover through TEX264 during Alzheimer-Associated Neuroinflammation.

Autophagy degrades impaired organelles and toxic proteins to maintain cellular homeostasis. Dysregulated autophagy is a pathogenic participant in Alzheimer's disease (AD) progression. In early-stage AD, autophagy is beneficially initiated by mild endoplasmic reticulum (ER) stress to alleviate cellular damage and inflammation. However, chronic overproduction of toxic Aß oligomers eventually causes Ca2+ dysregulation in the ER, subsequently elevating ER-stress and impairing autophagy. Our previous work showed that a novel anthranilate analogue (SI-W052) inhibited lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α and interleukin (IL)-6 on microglia. To investigate its mechanism of action, herein, we postulate that SI-W052 exhibits anti-inflammatory activity through ER-stress-mediated autophagy. We initially demonstrate that autophagy inhibits inflammation, but it becomes impaired during acute inflammation. SI-W052 significantly induces the conversion ratio of LC3 II/I and inhibits LPS-upregulated p-mTOR, thereby restoring impaired autophagy to modulate inflammation. Our signaling study further indicates that SI-W052 inhibits the upregulation of ER-stress marker genes, including Atf4 and sXbp1/tXbp1, explaining compound activity against IL-6. This evidence encouraged us to evaluate ER-stress-triggered ER-phagy using TEX264. ER-phagy mediates ER-turnover by the degradation of ER fragments to maintain homeostasis. TEX264 is an important ER-phagy receptor involved in ATF4-mediated ER-phagy under ER-stress. In our study, elevated TEX264 degradation is identified during inflammation; SI-W052 enhances TEX264 expression, producing a positive effect in ER-turnover. Our knockdown experiment further verifies the important role of TEX264 in SI-W052 activity against IL-6 and ER-stress. In conclusion, this study demonstrates that an anthranilate analogue is a novel neuroinflammation agent functioning through ER-stress-mediated autophagy and ER-phagy mechanisms.

Ferulic acid amide derivatives with varying inhibition of amyloid-ß oligomerization and fibrillization.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized, in part, by the misfolding, oligomerization and fibrillization of amyloid-ß (Aß). Evidence suggests that the mechanisms underpinning Aß oligomerization and subsequent fibrillization are distinct, and may therefore require equally distinct therapeutic approaches. Prior studies have suggested that amide derivatives of ferulic acid, a natural polyphenol, may combat multiple AD pathologies, though its impact on Aß aggregation is controversial. We designed and synthesized a systematic library of amide derivatives of ferulic acid and evaluated their anti-oligomeric and anti-fibrillary capacities independently. Azetidine tethered, triphenyl derivatives were the most potent anti-oligomeric agents (compound 2i: IC50 = 1.8 µM ± 0.73 µM); notably these were only modest anti-fibrillary agents (20.57% inhibition of fibrillization), and exemplify the poor correlation between anti-oligomeric/fibrillary activities. These data were subsequently codified in an in silico QSAR model, which yielded a strong predictive model of anti-Aß oligomeric activity (κ = 0.919 for test set; κ = 0.737 for validation set).

A Series of 2-((1-Phenyl-1H-imidazol-5-yl)methyl)-1H-indoles as Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitors.

Indoleamine 2,3-dioxygenase 1 (IDO1) is a promising therapeutic target in cancer immunotherapy and neurological disease. Thus, searching for highly active inhibitors for use in human cancers is now a focus of widespread research and development efforts. In this study, we report the structure-based design of 2-(5-imidazolyl)indole derivatives, a series of novel IDO1 inhibitors which have been designed and synthesized based on our previous study using N1-substituted 5-indoleimidazoles. Among these, we have identified one with a strong IDO1 inhibitory activity (IC50 =0.16 µM, EC50 =0.3 µM). Structural-activity relationship (SAR) and computational docking simulations suggest that a hydroxyl group favorably interacts with a proximal Ser167 residue in Pocket A, improving IDO1 inhibitory potency. The brain penetrance of potent compounds was estimated by calculation of the Blood Brain Barrier (BBB) Score and Brain Exposure Efficiency (BEE) Score. Many compounds had favorable scores and the two most promising compounds were advanced to a pharmacokinetic study which demonstrated that both compounds were brain penetrant. We have thus discovered a flexible scaffold for brain penetrant IDO1 inhibitors, exemplified by several potent, brain penetrant, agents. With this promising scaffold, we provide herein a basis for further development of brain penetrant IDO1 inhibitors.

Identification of Potent Indoleamine 2,3-Dioxygenase 1 (IDO1) Inhibitors Based on a Phenylimidazole Scaffold.

Inhibition of indoleamine 2,3-dioxygenase (IDO1) is an attractive immunotherapeutic approach for the treatment of a variety of cancers. Dysregulation of this enzyme has also been implicated in other disorders including Alzheimer's disease and arthritis. Herein, we report the structure-based design of two related series of molecules: N1-substituted 5-indoleimidazoles and N1-substituted 5-phenylimidazoles. The latter (and more potent) series was accessed through an unexpected rearrangement of an imine intermediate during a Van Leusen imidazole synthesis reaction. Evidence for the binding modes for both inhibitor series is supported by computational and structure-activity relationship studies.

Susceptibility to hippocampal kindling seizures is increased in aging C57 black mice.

The incidence of seizures increases with old age. Stroke, dementia and brain tumors are recognized risk factors for new-onset seizures in the aging populations and the incidence of these conditions also increased with age. Whether aging is associated with higher seizure susceptibility in the absence of the above pathologies remains unclear. We used classic kindling to explore this issue as the kindling model is highly reproducible and allows close monitoring of electrographic and motor seizure activities in individual animals. We kindled male young and aging mice (C57BL/6 strain, 2-3 and 18-22 months of age) via daily hippocampal CA3 stimulation and monitored seizure activity via video and electroencephalographic recordings. The aging mice needed fewer stimuli to evoke stage-5 motor seizures and exhibited longer hippocampal afterdischarges and more frequent hippocampal spikes relative to the young mice, but afterdischarge thresholds and cumulative afterdischarge durations to stage 5 motor seizures were not different between the two age groups. While hippocampal injury and structural alterations at cellular and micro-circuitry levels remain to be examined in the kindled mice, our present observations suggest that susceptibility to hippocampal CA3 kindling seizures is increased with aging in male C57 black mice.

Impact of protecting ligands on surface structure and antibacterial activity of silver nanoparticles.

Silver nanoparticles (Ag NPs) have attracted much attention in the past decade because of their unique physicochemical properties and notable antibacterial activities. In particular, thiol-protected Ag NPs have come to the forefront of metal nanoparticle studies, as they have been shown to possess high stability and interesting structure-property relationships. However, a clear correlation between thiol-protecting ligands, the resulting Ag NP surface structure, and their antibacterial properties has yet to be determined. Here, a multielement (Ag and S), multi-edge (Ag K-edge, Ag L3-edge, S K-edge) X-ray absorption spectroscopy (XAS) methodology was used to identify the structure and composition of Ag NPs protected with cysteine. XAS characterization was carried out on similar-sized Ag NPs protected with poly(vinylpyrrolidone) (PVP), in order to provide a valid comparison of the ligand effect on surface structure. The PVP-Ag NPs showed a metallic Ag surface and composition, consistent with metal NPs protected by weak protecting ligands. On the other hand, the Cys-Ag NPs exhibited a distinct surface shell of silver sulfide, which is remarkably different than previously studied Cys-Ag NPs. The minimum inhibitory concentration (MIC) of both types of Ag NPs against Gram-positive (+) and Gram-negative (-) bacteria were tested, including Staphylococcus aureus (+), Escherichia coli (-), and Pseudomonas aeruginosa (-). It was found that the MICs of the Cys-Ag NPs were significantly lower than the PVP-Ag NPs for each bacteria, implicating the influence of the sulfidized surface structure. Overall, this work shows the effect of ligand on the surface structure of Ag NPs, as well as the importance of surface structure in controlling antibacterial activity.

Pharmacoresistant epilepsy: unmet needs in solving the puzzle(s).

Pharmacoresistant epilepsy is a significant medical problem. The 2nd Halifax International Epilepsy Conference & Retreat identified crucial needs, which if successfully addressed, will aid in paving the way to improved lives for people with pharmacoresistant epilepsy. These are needs: (1) for an evidence-based and dynamic definition of pharmacoresistant epilepsy; (2) for a comprehensive description of the natural history of pharmacoresistant epilepsy; (3) for a comprehensive description of the complications and comorbidities of pharmacoresistant epilepsy; (4) for a rigorous delineation of the epidemiology and socioeconomic impact of pharmacoresistant epilepsy; (5) for clinically meaningful diagnostic and prognostic physiologically based electroencephalography (EEG) biomarkers; (6) for clinically meaningful diagnostic and prognostic anatomically based (MRI Imaging) biomarkers; (7) for biomolecular/biochemical mechanistic understanding of etiopathogenesis for pharmacoresistant epilepsy; (8) for representative animal models of pharmacoresistant epilepsy; (9) for new and effective drugs or other novel treatments for pharmacoresistant epilepsy; and (10) to promote continuing research and research funding targeting pharmacoresistant epilepsy.

Recent advances in research on radiofrequency fields and health: 2001-2003.

The widespread use of wireless telecommunications devices, particularly mobile phones, has resulted in increased human exposure to radiofrequency (RF) fields. Although national and international agencies have established safety guidelines for exposure to RF fields, concerns remain about the potential for adverse health outcomes to occur in relation to RF field exposure. The extensive literature on RF fields and health has been reviewed by a number of authorities, including the Royal Society of Canada (1999), the European Commission's Scientific Committee on Toxicity, Ecotoxicity, and the Environment (CSTEE, 2001), the British Medical Association (2001), the Swedish Radiation Protection Authority (Boice & McLaughlin, 2002), and the Health Council of The Netherlands (2002). This report provides an update on recent research results on the potential health risks of RF fields since the publication of the Royal Society of Canada report in 1999 (See Krewski et al., 2001a) and our previous 2001 update (Krewski et al., 2001b), covering the period 2001-2003. The present report examines new data on dosimetry and exposure assessment, biological effects such as enzyme induction, and toxicological effects, including genotoxicity, carcinogenicity, and testicular and reproductive outcomes. Epidemiological studies of mobile phone users and occupationally exposed populations are examined, along with human and animal studies of neurological and behavioral effects. All of the authoritative reviews completed within the last 2 yr have concluded that there is no clear evidence of adverse health effects associated with RF fields. However, following a recent review of nine epidemiological studies of mobile phones and cancer, Kundi et al. (2004) concluded that the possibility of an enhanced cancer risk cannot be excluded. These same reviews support the need for further research to clarify the possible associations between RF fields and adverse health outcomes that have appeared in some reports. The results of the ongoing World Health Organization (WHO) study of mobile phones will provide important new information in this regard.

Pruned receptor surface models and pharmacophores for three-dimensional database searching.

A pharmacophore represents the 3D arrangement of chemical features that are shared by molecules exhibiting activity at a protein receptor. Pharmacophores are routinely used in 3D database searching for identifying potential lead compounds. The lack of shape constraints causes the query to identify compounds that could not fit into the active site. In the absence of structural information, a receptor surface model (RSM) can be used to represent the active site. The RSM consists of a surface that envelops a set of known actives after these have been aligned using their common features. When used for database searching, a RSM is overconstraining as it restricts access to regions that could be occupied by ligands, such as the solvent-protein interface or unexplored pockets. We describe a protocol for developing pruned RSMs using information gleaned from 3D quantitative structure-activity relationship (QSAR) models. We examined the performance of queries that consist of pharmacophores used alone or with pruned or unpruned RSMs by performing searches on six databases containing known actives distributed among inactives. The pruned RSMs yield an average selectivity 1.8 times greater than that for pharmacophore queries, compared to 1.6 times for unpruned RSMs. However, the pruned RSMs retrieve on average 73% of the actives identified using the pharmacophores, compared to 40% for the unpruned RSMs. As such, pruned RSMs represent a useful compromise between the high sensitivity of pharmacophores and the high selectivity of unpruned RSMs.

Spline-fitting with a genetic algorithm: a method for developing classification structure-activity relationships.

Classification methods allow for the development of structure-activity relationship models when the target property is categorical rather than continuous. We describe a classification method which fits descriptor splines to activities, with descriptors selected using a genetic algorithm. This method, which we identify as SFGA, is compared to the well-established techniques of recursive partitioning (RP) and soft independent modeling by class analogy (SIMCA) using five series of compounds: cyclooxygenase-2 (COX-2) inhibitors, benzodiazepine receptor (BZR) ligands, estrogen receptor (ER) ligands, dihydrofolate reductase (DHFR) inhibitors, and monoamine oxidase (MAO) inhibitors. Only 1-D and 2-D descriptors were used. Approximately 40% of compounds in each series were assigned to a test set, "cherry-picked" from the complete set such that they lie outside the training set as much as possible. SFGA produced models that were more predictive for all but the DHFR set, for which SIMCA was most predictive. RP gave the least predictive models for all but the MAO set. A similar trend was observed when using training and test sets to which compounds were randomly assigned and when gradually eliminating compounds from the (designed) training set. The stability of models was examined for the random and reduced sets, where stability means that classification statistics and the selected descriptors are similar for models derived from different sets. Here, SIMCA produced the most stable models, followed by SFGA and RP. We show that a consensus approach that combines all three methods outperforms the single best model for all data sets.