Tacrine - Benzothiazoles: Novel class of potential multitarget anti-Alzheimers drugs dealing with cholinergic, amyloid and mitochondrial systems.

A series of tacrine - benzothiazole hybrids incorporate inhibitors of acetylcholinesterase (AChE), amyloid ß (Aß) aggregation and mitochondrial enzyme ABAD, whose interaction with Aß leads to mitochondrial dysfunction, into a single molecule. In vitro, several of 25 final compounds exerted excellent anti-AChE properties and interesting capabilities to block Aß aggregation. The best derivative of the series could be considered 10w that was found to be highly potent and selective towards AChE with the IC50 value in nanomolar range. Moreover, the same drug candidate exerted absolutely the best results of the series against ABAD, decreasing its activity by 23% at 100 µM concentration. Regarding the cytotoxicity profile of highlighted compound, it roughly matched that of its parent compound - 6-chlorotacrine. Finally, 10w was forwarded for in vivo scopolamine-induced amnesia experiment consisting of Morris Water Maze test, where it demonstrated mild procognitive effect. Taking into account all in vitro and in vivo data, highlighted derivative 10w could be considered as the lead structure worthy of further investigation.

Neuroprotective actions of leptin facilitated through balancing mitochondrial morphology and improving mitochondrial function.

Mitochondrial dysfunction has a recognised role in the progression of Alzheimer's disease (AD) pathophysiology. Cerebral perfusion becomes increasingly inefficient throughout ageing, leading to unbalanced mitochondrial dynamics. This effect is exaggerated by amyloid ß (Aß) and phosphorylated tau, two hallmark proteins of AD pathology. A neuroprotective role for the adipose-derived hormone, leptin, has been demonstrated in neuronal cells. However, its effects with relation to mitochondrial function in AD remain largely unknown. To address this question, we have used both a glucose-serum-deprived (CGSD) model of ischaemic stroke in SH-SY5Y cells and a Aß1-42 -treatment model of AD in differentiated hippocampal cells. Using a combination of 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) and MitoRed staining techniques, we show that leptin prevents depolarisation of the mitochondrial membrane and excessive mitochondrial fragmentation induced by both CGSD and Aß1-42 . Thereafter, we used ELISAs and a number of activity assays to reveal the biochemical underpinnings of these processes. Specifically, leptin was seen to inhibit up-regulation of the mitochondrial fission protein Fis1 and down-regulation of the mitochondrial fusion protein, Mfn2. Furthermore, leptin was seen to up-regulate the expression and activity of the antioxidant enzyme, monoamine oxidase B. Herein we provide the first demonstration that leptin is sufficient to protect against aberrant mitochondrial dynamics and resulting loss of function induced by both CGSD and Aß1-42 . We conclude that the established neuroprotective actions of leptin may be facilitated through regulation of mitochondrial dynamics.

Benzothiazolyl Ureas are Low Micromolar and Uncompetitive Inhibitors of 17ß-HSD10 with Implications to Alzheimer's Disease Treatment.

Human 17ß-hydroxysteroid dehydrogenase type 10 is a multifunctional protein involved in many enzymatic and structural processes within mitochondria. This enzyme was suggested to be involved in several neurological diseases, e.g., mental retardation, Parkinson's disease, or Alzheimer's disease, in which it was shown to interact with the amyloid-beta peptide. We prepared approximately 60 new compounds based on a benzothiazolyl scaffold and evaluated their inhibitory ability and mechanism of action. The most potent inhibitors contained 3-chloro and 4-hydroxy substitution on the phenyl ring moiety, a small substituent at position 6 on the benzothiazole moiety, and the two moieties were connected via a urea linker (4at, 4bb, and 4bg). These compounds exhibited IC50 values of 1-2 µM and showed an uncompetitive mechanism of action with respect to the substrate, acetoacetyl-CoA. These uncompetitive benzothiazolyl inhibitors of 17ß-hydroxysteroid dehydrogenase type 10 are promising compounds for potential drugs for neurodegenerative diseases that warrant further research and development.

Novel Benzothiazole-based Ureas as 17ß-HSD10 Inhibitors, A Potential Alzheimer's Disease Treatment.

: It has long been established that mitochondrial dysfunction in Alzheimer's disease (AD) patients can trigger pathological changes in cell metabolism by altering metabolic enzymes such as the mitochondrial 17ß-hydroxysteroid dehydrogenase type 10 (17ß-HSD10), also known as amyloid-binding alcohol dehydrogenase (ABAD). We and others have shown that frentizole and riluzole derivatives can inhibit 17ß-HSD10 and that this inhibition is beneficial and holds therapeutic merit for the treatment of AD. Here we evaluate several novel series based on benzothiazolylurea scaffold evaluating key structural and activity relationships required for the inhibition of 17ß-HSD10. Results show that the most promising of these compounds have markedly increased potency on our previously published inhibitors, with the most promising exhibiting advantageous features like low cytotoxicity and target engagement in living cells.

1-(Benzo[d]thiazol-2-yl)-3-phenylureas as dual inhibitors of casein kinase 1 and ABAD enzymes for treatment of neurodegenerative disorders.

Several neurodegenerative disorders including Alzheimer's disease (AD) have been connected with deregulation of casein kinase 1 (CK1) activity. Inhibition of CK1 therefore presents a potential therapeutic strategy against such pathologies. Recently, novel class of CK1-specific inhibitors with N-(benzo[d]thiazol-2-yl)-2-phenylacetamide structural scaffold has been discovered. 1-(benzo[d]thiazol-2-yl)-3-phenylureas, on the other hand, are known inhibitors amyloid-beta binding alcohol dehydrogenase (ABAD), an enzyme also involved in pathophysiology of AD. Based on their tight structural similarity, we decided to evaluate series of previously published benzothiazolylphenylureas, originally designed as ABAD inhibitors, for their inhibitory activity towards CK1. Several compounds were found to be submicromolar CK1 inhibitors. Moreover, two compounds were found to inhibit both, ABAD and CK1. Such dual-activity could be of advantage for AD treatment, as it would simultaneously target two distinct pathological processes involved in disease's progression. Based on PAMPA testing both compounds were suggested to permeate the blood-brain barrier, which makes them, together with their unique dual activity, interesting lead compounds for further development.

Synthesis and evaluation of frentizole-based indolyl thiourea analogues as MAO/ABAD inhibitors for Alzheimer's disease treatment.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with an excessive accumulation of amyloid-beta peptide (Aß). Based on the multifactorial nature of AD, preparation of multi-target-directed ligands presents a viable option to address more pathological events at one time. A novel class of asymmetrical disubstituted indolyl thioureas have been designed and synthesized to interact with monoamine oxidase (MAO) and/or amyloid-binding alcohol dehydrogenase (ABAD). The design combines the features of known MAO inhibitors scaffolds (e.g. rasagiline or ladostigil) and a frentizole moiety with potential to interact with ABAD. Evaluation against MAO identified several compounds that inhibited in the low to moderate micromolar range. The most promising compound (19) inhibited human MAO-A and MAO-B with IC50 values of 6.34µM and 0.30µM, respectively. ABAD activity evaluation did not show any highly potent compound, but the compound series allowed identification of structural features to assist the future development of ABAD inhibitors. Finally, several of the compounds were found to be potent inhibitors of horseradish peroxidase (HRP), preventing the use of the Amplex™ Red assay to detect hydrogen peroxide produced by MAO, highlighting the need for serious precautions when using an enzyme-coupled assay.

Morphology-Specific Inhibition of ß-Amyloid Aggregates by 17ß-Hydroxysteroid Dehydrogenase Type 10.

A major hallmark of Alzheimer's disease (AD) is the formation of toxic aggregates of the ß-amyloid peptide (Aß). Given that Aß peptides are known to localise within mitochondria and interact with 17ß-HSD10, a mitochondrial protein expressed at high levels in AD brains, we investigated the inhibitory potential of 17ß-HSD10 against Aß aggregation under a range of physiological conditions. Fluorescence self-quenching (FSQ) of Aß(1-42) labelled with HiLyte Fluor 555 was used to evaluate the inhibitory effect under conditions established to grow distinct Aß morphologies. 17ß-HSD10 preferentially inhibits the formation of globular and fibrillar-like structures but has no effect on the growth of amorphous plaque-like aggregates at endosomal pH 6. This work provides insights into the dependence of the Aß-17ß-HSD10 interaction with the morphology of Aß aggregates and how this impacts enzymatic function.

Design, synthesis and in vitro evaluation of benzothiazole-based ureas as potential ABAD/17ß-HSD10 modulators for Alzheimer's disease treatment.

Amyloid-beta peptide (Aß) has been recognized to interact with numerous proteins, which may lead to pathological changes in cell metabolism of Alzheimer's disease (AD) patients. One such known metabolic enzyme is mitochondrial amyloid-binding alcohol dehydrogenase (ABAD), also known as 17ß-hydroxysteroid dehydrogenase type 10 (17ß-HSD10). Altered enzyme function caused by the Aß-ABAD interaction, was previously shown to cause mitochondrial distress and a consequent cytotoxic effect, therefore providing a feasible target in AD drug development. Based on previous frentizole derivatives studies, we report two novel series of benzothiazolyl ureas along with novel insights into the structure and activity relationships for inhibition of ABAD. Two compounds (37, 39) were identified as potent ABAD inhibitors, where compound 39 exhibited comparable cytotoxicity with the frentizole standard; however, one-fold higher cytotoxicity than the parent riluzole standard. The calculated and experimental physical chemical properties of the most potent compounds showed promising features for blood-brain barrier penetration.

Development of submicromolar 17ß-HSD10 inhibitors and their in vitro and in vivo evaluation.

17ß-hydroxysteroid dehydrogenase type 10 (17ß-HSD10) is a multifunctional mitochondrial enzyme and putative drug target for the treatment of various pathologies including Alzheimer's disease or some types of hormone-dependent cancer. In this study, a series of new benzothiazolylurea-based inhibitors were developed based on the structure-activity relationship (SAR) study of previously published compounds and predictions of their physico-chemical properties. This led to the identification of several submicromolar inhibitors (IC50 ∼0.3 µM), the most potent compounds within the benzothiazolylurea class known to date. The positive interaction with 17ß-HSD10 was further confirmed by differential scanning fluorimetry and the best molecules were found to be cell penetrable. In addition, the best compounds weren't found to have additional effects for mitochondrial off-targets and cytotoxic or neurotoxic effects. The two most potent inhibitors 9 and 11 were selected for in vivo pharmacokinetic study after intravenous and peroral administration. Although the pharmacokinetic results were not fully conclusive, it seemed that compound 9 was bioavailable after peroral administration and could penetrate into the brain (brain-plasma ratio 0.56).

The Psychological Distress and Quality of Life of Breast Cancer Survivors in Sydney, Australia.

In Australia, breast cancer is one of the most common cancers affecting women. Between 1987-1991 and 2012-2016, the five-year survival rate improved from 75% to 91%. The increased chance of survival due to early detection and treatment interventions has resulted in more women living with the diagnosis. This qualitative study was designed to analyse the journey of breast cancer survivors, their experience of psychological distress and changes in quality of life (QOL) due to the increased prevalence amongst Australian women. In-depth interviews were conducted; they lasted over 45 min and comprised 15 participants. The main topics discussed were knowledge of breast cancer prior to diagnosis, psychological distress, QOL and experience of use of healthcare services. The results showed that the process of diagnosis, undergoing treatment and isolation post-treatment resulted in high amounts of psychological distress. A reduction in QOL was also experienced due to treatment and medication side effects, fatigue, cognitive changes, and body-image perception. These findings can assist researchers in providing evidence-based frameworks for policy changes and for further investigation into effective healthcare interventions.

Willin/FRMD6 Mediates Mitochondrial Dysfunction Relevant to Neuronal Aß Toxicity.

Willin/FRMD6 has been reported as a potential Alzheimer's disease (AD) risk gene in a series of genome-wide association and neuroimaging studies; however, the mechanisms underlying its potential role in AD pathogenesis remain unknown. Here, we demonstrate the direct effects of Aß on Willin/FRMD6 expression and position mitochondrial oxidative stress as a novel potential mechanism underlying the role of Willin/FRMD6 in AD pathogenesis. Specifically, using mouse hippocampal HT-22 cells and primary mouse neurons, we show that Aß induces downregulation of Willin/FRMD6 protein expression. Furthermore, we demonstrate that Willin/FRMD6 knockdown leads to mitochondrial dysfunction and fragmentation, as well as upregulation of ERK1/2 signaling, both of which are reported to be key early features of AD pathogenesis. Importantly, increasing Willin/FRMD6 expression was able to rescue Aß-induced abnormalities in mitochondrial morphology, function, and energetics. Thus, enhancing Willin/FRMD6 expression holds potential as a therapeutic strategy for protecting against Aß-induced mitochondrial and neuronal dysfunction.

Mitochondrial ß-amyloid in Alzheimer's disease.

It is well established that the intracellular accumulation of Aß (amyloid ß-peptide) is associated with AD (Alzheimer's disease) and that this accumulation is toxic to neurons. The precise mechanism by which this toxicity occurs is not well understood; however, identifying the causes of this toxicity is an essential step towards developing treatments for AD. One intracellular location where the accumulation of Aß can have a major effect is within mitochondria, where mitochondrial proteins have been identified that act as binding sites for Aß, and when binding occurs, a toxic response results. At one of these identified sites, an enzyme known as ABAD (amyloid-binding alcohol dehydrogenase), we have identified changes in gene expression in the brain cortex, following Aß accumulation within mitochondria. Specifically, we have identified two proteins that are up-regulated not only in the brains of transgenic animal models of AD but also in those of human sufferers. The increased expression of these proteins demonstrates the complex and counteracting pathways that are activated in AD. Previous studies have identified approximate contact sites between ABAD and Aß; on basis of these observations, we have shown that by using a modified peptide approach it is possible to reverse the expression of these two proteins in living transgenic animals and also to recover mitochondrial and behavioural deficits. This indicates that the ABAD-Aß interaction is potentially an interesting target for therapeutic intervention. To explore this further we used a fluorescing substrate mimic to measure the activity of ABAD within living cells, and in addition we have identified chemical fragments that bind to ABAD, using a thermal shift assay.

The consequences of mitochondrial amyloid beta-peptide in Alzheimer's disease.

The Abeta (amyloid-beta peptide) has long been associated with Alzheimer's disease, originally in the form of extracellular plaques. However, in the present paper we review the growing evidence for the role of soluble intracellular Abeta in the disease progression, with particular reference to Abeta found within the mitochondria. Once inside the cell, Abeta is able to interact with a number of targets, including the mitochondrial proteins ABAD (amyloid-binding alcohol dehydrogenase) and CypD (cyclophilin D), which is a component of the mitochondrial permeability transition pore. Interference with the normal functions of these proteins results in disruption of cell homoeostasis and ultimately cell death. The present review explores the possible mechanisms by which cell death occurs, considering the evidence presented on a molecular, cellular and in vivo level.

Willin/FRMD6: A Multi-Functional Neuronal Protein Associated with Alzheimer's Disease.

The FERM domain-containing protein 6 (FRMD6), also known as Willin, is an upstream regulator of Hippo signaling that has recently been shown to modulate actin cytoskeleton dynamics and mechanical phenotype of neuronal cells through ERK signaling. Physiological functions of Willin/FRMD6 in the nervous system include neuronal differentiation, myelination, nerve injury repair, and vesicle exocytosis. The newly established neuronal role of Willin/FRMD6 is of particular interest given the mounting evidence suggesting a role for Willin/FRMD6 in Alzheimer's disease (AD), including a series of genome wide association studies that position Willin/FRMD6 as a novel AD risk gene. Here we describe recent findings regarding the role of Willin/FRMD6 in the nervous system and its actions in cellular perturbations related to the pathogenesis of AD.

Identification, characterization and deduced amino acid sequence of the dominant protease from Kudoa paniformis and K. thyrsites: a unique cytoplasmic cysteine protease.

Kudoa paniformis and Kudoa thyrsites (Myxozoa: Myxosporea) infections are associated with severe proteolysis of host muscle tissue post-mortem. The present study was undertaken to identify and characterize the protease responsible for myoliquefaction and determine mechanisms controlling protease function in vivo. N-terminal sequence analysis of partially purified protease from hake muscle infected with K. paniformis and K. thyrsites revealed a 23 amino acid sequence that aligned with cysteine proteases. Enzyme inhibition assays confirmed the presence of an essential active site cysteine residue. Using the above K. paniformis amino acid sequence data, a corresponding cDNA sequence from K. thyrsites plasmodia was elucidated revealing a cathepsin L proenzyme (Kth-CL). The translated amino acid sequence lacked a signal sequence characteristic of lysosomal and secreted proteins suggesting a unique cytoplasmic location. Only the proenzyme form of Kth-CL was present in Atlantic salmon muscle anti-mortem but this form became processed in vivo when infected muscle was stored at 4 degrees C. The proenzyme of Kth-CL showed uninhibited activity at pH 6.0, negligible activity at pH 6.5 and no measurable activity at pH 7.0 whilst the processed protease showed stability and function over a broad pH range (pH 4.5-8.8). The pH dependent processing and function of Kth-CL was consistent with histidine residues in the proregion playing a critical role in the regulation of Kth-CL.

6-benzothiazolyl ureas, thioureas and guanidines are potent inhibitors of ABAD/17ß-HSD10 and potential drugs for Alzheimer's disease treatment: Design, synthesis and in vitro evaluation.

BACKGROUND: The mitochondrial enzyme amyloid beta-binding alcohol dehydrogenase (ABAD) also known as 17ß-hydroxysteroid dehydrogenase type 10 (17ß-HSD10) has been connected with the pathogenesis of Alzheimer's disease (AD). ABAD/ 17ß-HSD10 is a binding site for the amyloid-beta peptide (Aß) inside the mitochondrial matrix where it exacerbates Aß toxicity. Interaction between these two proteins triggers a series of events leading to mitochondrial dysfunction as seen in AD. METHODS: As ABAD's enzymatic activity is required for mediating Aß toxicity, its inhibition presents a promising strategy for AD treatment. In this study, a series of new benzothiazolylurea analogues have been prepared and evaluated in vitro for their potency to inhibit ABAD/ 17ß-HSD10 enzymatic activity. The most potent compounds have also been tested for their cytotoxic properties and their ability to permeate through blood-brain barrier has been predicted. To explain the structure-activity relationship QSAR and pharmacophore studies have been performed. RESULTS AND CONCLUSIONS: Compound 12 was identified being the most promising hit compound with good inhibitory activity (IC50 = 3.06 ± 0.40µM) and acceptable cytotoxicity profile comparable to the parent compound of frentizole. The satisfactory physical-chemical properties suggesting its capability to permeate through BBB make compound 12 a novel lead structure for further development and biological assessment.

In Vitro Assay Development and HTS of Small-Molecule Human ABAD/17ß-HSD10 Inhibitors as Therapeutics in Alzheimer's Disease.

A major hallmark of Alzheimer's disease (AD) is the formation of neurotoxic aggregates composed of the amyloid-ß peptide (Aß). Aß has been recognized to interact with numerous proteins, resulting in pathological changes to the metabolism of patients with AD. One such mitochondrial metabolic enzyme is amyloid-binding alcohol dehydrogenase (ABAD), where altered enzyme function caused by the Aß-ABAD interaction is known to cause mitochondrial distress and cytotoxic effects, providing a feasible therapeutic target for AD drug development. Here we have established a high-throughput screening platform for the identification of modulators to the ABAD enzyme. A pilot screen with a total of 6759 compounds from the NIH Clinical Collections (NCC) and SelleckChem libraries and a selection of compounds from the BioAscent diversity collection have allowed validation and robustness to be optimized. The pilot screen revealed 16 potential inhibitors in the low µM range against ABAD with favorable physicochemical properties for blood-brain barrier penetration.

Benzothiazoles - scaffold of interest for CNS targeted drugs.

Benzothiazole compounds represent heterocyclic systems comprising a benzene ring fused with a thiazole ring containing nitrogen and sulphur in its structure. Besides the presence of a benzothiazole core in naturally occurring molecules, synthesized compounds containing a benzothiazole moiety in their structure proved to be a significant class of potential therapeutics, as they exhibit biological effects such as antitumor, antibacterial, antitubercular, antiviral, anthelmintic, antidiabetic and many others. Apart from the aforementioned peripheral or microbial active sites, benzothiazole analogues are also biologically active compounds in the central nervous system, where some approved drugs containing a benzothiazole moiety have already been identified and are used in the treatment of various neurological disorders. New benzothiazole molecules are currently under development and are being evaluated for several uses including diagnostics and as therapeutic drug candidates for the treatment of epilepsy and neurodegenerative diseases such as Alzheimer's disease, Huntington's disease and amyotrophic lateral sclerosis amongst others.

A Direct Interaction Between Mitochondrial Proteins and Amyloid-ß Peptide and its Significance for the Progression and Treatment of Alzheimer's Disease

The amyloid-ß peptide (Aß) has been associated with Alzheimer's disease (AD) for decades. The original amyloid cascade hypothesis declared that the insoluble extracellular plaques were responsible for Aß toxicity. Later, this hypothesis has been updated and soluble intracellular Aß forms and their effects within the cell have come into focus.Mitochondrial dysfunction plays an important role in the pathophysiology of AD. Aß was detected inside mitochondria and several mitochondrial proteins were found to interact directly with Aß. Such interactionscan affecta protein's function and cause damage to the mitochondria and finally to the whole cell.This review summarizes the current knowledge of mitochondrial proteins directly interacting with Aß and discusses their significance for the development of therapeutics in the treatment of AD.

Is amyloid binding alcohol dehydrogenase a drug target for treating Alzheimer's disease?

Current strategies for the treatment of Alzheimer's disease (AD) involve tackling the formation or clearance of the amyloid-beta peptide (Aß) and/or hyper-phosphorylated tau, or the support and stabilization of the remaining neuronal networks. However, as we gain a clearer idea of the large number of molecular mechanisms at work in this disease, it is becoming clearer that the treatment of AD should take a combined approach of dealing with several aspects of the pathology. The concept that we also need to protect specific sensitive targets within the cell should also be considered. In particular the role of protecting the function of a specific mitochondrial protein, amyloid binding alcohol dehydrogenase (ABAD), will be the focus of this review. Mitochondrial dysfunction is a well-recognized fact in the progression of AD, though until recently the mechanisms involved could only be loosely labeled as changes in 'metabolism'. The discovery that Aß can be present within the mitochondria and specifically bind to ABAD, has opened up a new area of AD research. Here we review the evidence that the prevention of Aß binding to ABAD is a drug target for the treatment of AD.