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Aggregated forms of different proteins are common hallmarks for several neurodegenerative diseases, including Alzheimer's disease, and ligands that selectively detect specific protein aggregates are vital. Herein, we investigate the molecular requirements of thiophene‐vinyl‐benzothiazole based ligands to detect a specific type of Aβ deposits found in individuals with dominantly inherited Alzheimer's disease caused by the Arctic APP E693G mutation. The staining of these Aβ deposits was alternated when switching the terminal heterocyclic moiety attached to the thiophene‐vinyl‐benzothiazole scaffold. The most prevalent staining was observed for ligands having a terminal 3‐methyl‐1H‐indazole moiety or a terminal 1,2‐dimethoxybenzene moiety, verifying that specific molecular interactions between these ligands and the aggregates were necessary. The synthesis of additional thiophene‐vinyl‐benzothiazole ligands aided in pinpointing additional crucial chemical determinants, such as positioning of nitrogen atoms and methyl substituents, for achieving optimal staining of Aβ aggregates. When combining the optimized thiophene‐vinyl‐benzothiazole based ligands with a conventional ligand, CN‐PiB, distinct staining patterns were observed for sporadic Alzheimer's disease versus dominantly inherited Alzheimer's disease caused by the Arctic APP E693G mutation. Our findings provide chemical insights for developing novel ligands that allow for a more precise assignment of Aβ deposits, and might also aid in creating novel agents for clinical imaging of distinct Aβ aggregates in AD. [ABSTRACT FROM AUTHOR]

Author(s): Mohammad Shahnawaz [sup.1] , Abhisek Mukherjee [sup.1] , Sandra Pritzkow [sup.1] , Nicolas Mendez [sup.1] , Prakruti Rabadia [sup.1] , Xiangan Liu [sup.2] , Bo Hu [sup.2] , Ann [...], Synucleinopathies are neurodegenerative diseases that are associated with the misfolding and aggregation of [alpha]-synuclein, including Parkinson's disease, dementia with Lewy bodies and multiple system atrophy.sup.1. Clinically, it is challenging to differentiate Parkinson's disease and multiple system atrophy, especially at the early stages of disease.sup.2. Aggregates of [alpha]-synuclein in distinct synucleinopathies have been proposed to represent different conformational strains of [alpha]-synuclein that can self-propagate and spread from cell to cell.sup.3-6. Protein misfolding cyclic amplification (PMCA) is a technique that has previously been used to detect [alpha]-synuclein aggregates in samples of cerebrospinal fluid with high sensitivity and specificity.sup.7,8. Here we show that the [alpha]-synuclein-PMCA assay can discriminate between samples of cerebrospinal fluid from patients diagnosed with Parkinson's disease and samples from patients with multiple system atrophy, with an overall sensitivity of 95.4%. We used a combination of biochemical, biophysical and biological methods to analyse the product of [alpha]-synuclein-PMCA, and found that the characteristics of the [alpha]-synuclein aggregates in the cerebrospinal fluid could be used to readily distinguish between Parkinson's disease and multiple system atrophy. We also found that the properties of aggregates that were amplified from the cerebrospinal fluid were similar to those of aggregates that were amplified from the brain. These findings suggest that [alpha]-synuclein aggregates that are associated with Parkinson's disease and multiple system atrophy correspond to different conformational strains of [alpha]-synuclein, which can be amplified and detected by [alpha]-synuclein-PMCA. Our results may help to improve our understanding of the mechanism of [alpha]-synuclein misfolding and the structures of the aggregates that are implicated in different synucleinopathies, and may also enable the development of a biochemical assay to discriminate between Parkinson's disease and multiple system atrophy. Protein misfolding cyclic amplification (PMCA) technology can discriminate between patients with Parkinson's disease and patients with multiple system atrophy on the basis of the characteristics of the [alpha]-synuclein aggregates in the cerebrospinal fluid.

Distinct aggregated proteins are correlated with numerous neurodegenerative diseases and the development of ligands that selectively detect these pathological hallmarks is vital. Recently, the synthesis of thiophene‐based optical ligands, denoted bi‐thiophene‐vinyl‐benzothiazoles (bTVBTs), that could be utilized for selective assignment of tau pathology in brain tissue with Alzheimer's disease (AD) pathology, was reported. Herein, we investigate the ability of these ligands to selectively distinguish tau deposits from aggregated amyloid‐β (Aβ), the second AD associated pathological hallmark, when replacing the terminal thiophene moiety with other heterocyclic motifs. The selectivity for tau pathology was reduced when introducing specific heterocyclic motifs, verifying that specific molecular interactions between the ligands and the aggregates are necessary for selective detection of tau deposits. In addition, ligands having certain heterocyclic moieties attached to the central thiophene‐vinylene building block displayed selectivity to aggregated Aβ pathology. Our findings provide chemical insights for the development of ligands that can distinguish between aggregated proteinaceous species consisting of different proteins and might also aid in creating novel agents for clinical imaging of tau pathology in AD. [ABSTRACT FROM AUTHOR]

The aggregation and accumulation of proteins in the brain is the defining feature of many devastating neurodegenerative diseases. The development of fluorescent ligands that bind to these accumulations, or deposits, is essential for the characterization of these neuropathological lesions. We report the synthesis of donor‐acceptor‐donor (D‐A‐D) thiophene‐based ligands with different emission properties. The D‐A‐D ligands displayed selectivity towards distinct disease‐associated protein deposits in histological sections from postmortem brain tissue of individuals affected by Alzheimer's disease (AD). The ability of the ligands to selectively identify AD‐associated pathological alterations, such as deposits composed of aggregates of the amyloid‐β (Aβ) peptide or tau, was reduced when the chemical composition of the ligands was altered. When combining the D‐A‐D ligands with conventional thiophene‐based ligands, superior spectral separation of distinct protein aggregates in AD tissue sections was obtained. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between aggregated proteinaceous species, as well as offer novel strategies for developing multiplex fluorescence detection of protein aggregates in tissue sections. [ABSTRACT FROM AUTHOR]

Many efforts targeting amyloid‐β (Aβ) plaques for the treatment of Alzheimer's Disease thus far have resulted in failures during clinical trials. Regional and temporal heterogeneity of efficacy and dependence on plaque maturity may have contributed to these disappointing outcomes. In this study, we mapped the regional and temporal specificity of various anti‐Aβ treatments through high‐resolution light‐sheet imaging of electrophoretically cleared brains. We assessed the effect on amyloid plaque formation and growth in Thy1‐APP/PS1 mice subjected to β‐secretase inhibitors, polythiophenes, or anti‐Aβ antibodies. Each treatment showed unique spatiotemporal Aβ clearance, with polythiophenes emerging as a potent anti‐Aβ compound. Furthermore, aligning with a spatial‐transcriptomic atlas revealed transcripts that correlate with the efficacy of each Aβ therapy. As observed in this study, there is a striking dependence of specific treatments on the location and maturity of Aβ plaques. This may also contribute to the clinical trial failures of Aβ‐therapies, suggesting that combinatorial regimens may be significantly more effective in clearing amyloid deposition. Synopsis: The brain is highly compartmentalized with many distinct regions. It is unknown how drugs for treating Alzheimer's Disease (AD) work across brain regions and disease stages. We developed a technology to quantify the effects of different AD drugs throughout the brain at different time points. A novel technology was developed for high‐throughput optical mouse brain clarification and staining of Aβ plaques, followed by lightsheet imaging, brain atlas registration, and plaque morphology quantification.Mice were treated with either a BACE1 inhibitor, a polythiophene for stabilizing amyloid fibrils, or an anti‐Aβ antibody.Quantitative results show distinct Aβ plaque modification and removal across brain regions and disease stage.Spatial efficacy profiles of anti‐Aβ therapies were correlated with gene expression maps using a spatial transcriptomics brain atlas. [ABSTRACT FROM AUTHOR]

Protein deposits are associated with many devastating diseases and fluorescent ligands able to visualize these pathological entities are essential. Here, we report the synthesis of thiophene‐based donor–acceptor–donor heptameric ligands that can be utilized for spectral assignment of distinct amyloid‐β (Aβ) aggregates, one of the pathological hallmarks in Alzheimer's disease. The ability of the ligands to selectively distinguish Aβ deposits was abolished when the chemical composition of the ligands was altered. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between aggregated proteinaceous species consisting of the same peptide or protein. In addition, such ligands might aid in interpreting the potential role of polymorphic Aβ deposits in the pathogenesis of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

A new strategy is described for preparing dibenzo[b,f]thiepins and related fused systems, which has featured ortho-metalation of aromatic or heterocyclic aldehyde acetals. They are treated with bis(phenylsulfonul)sulfide for constructing the bis(aryl)- or bis(heteroaryl) sulfide precursors, which are subjected to deacetalization and finally McMurray coupling as the ring-forming step.

Synucleinopathies are neurodegenerative diseases that are associated with the misfolding and aggregation of α-synuclein, including Parkinson's disease, dementia with Lewy bodies and multiple system atrophy1. Clinically, it is challenging to differentiate Parkinson's disease and multiple system atrophy, especially at the early stages of disease2. Aggregates of α-synuclein in distinct synucleinopathies have been proposed to represent different conformational strains of α-synuclein that can self-propagate and spread from cell to cell3–6. Protein misfolding cyclic amplification (PMCA) is a technique that has previously been used to detect α-synuclein aggregates in samples of cerebrospinal fluid with high sensitivity and specificity7,8. Here we show that the α-synuclein-PMCA assay can discriminate between samples of cerebrospinal fluid from patients diagnosed with Parkinson's disease and samples from patients with multiple system atrophy, with an overall sensitivity of 95.4%. We used a combination of biochemical, biophysical and biological methods to analyse the product of α-synuclein-PMCA, and found that the characteristics of the α-synuclein aggregates in the cerebrospinal fluid could be used to readily distinguish between Parkinson's disease and multiple system atrophy. We also found that the properties of aggregates that were amplified from the cerebrospinal fluid were similar to those of aggregates that were amplified from the brain. These findings suggest that α-synuclein aggregates that are associated with Parkinson's disease and multiple system atrophy correspond to different conformational strains of α-synuclein, which can be amplified and detected by α-synuclein-PMCA. Our results may help to improve our understanding of the mechanism of α-synuclein misfolding and the structures of the aggregates that are implicated in different synucleinopathies, and may also enable the development of a biochemical assay to discriminate between Parkinson's disease and multiple system atrophy. Protein misfolding cyclic amplification (PMCA) technology can discriminate between patients with Parkinson's disease and patients with multiple system atrophy on the basis of the characteristics of the α-synuclein aggregates in the cerebrospinal fluid. [ABSTRACT FROM AUTHOR]

The accumulation of protein aggregates is associated with many devastating neurodegenerative diseases and the development of molecular ligands able to detect these pathological hallmarks is essential. Here, the synthesis of thiophene based optical ligands, denoted bi-thiophene-vinyl-benzothiazoles (bTVBTs) that can be utilized for selective assignment of tau aggregates in brain tissue with Alzheimer's disease (AD) pathology is reported. The ability of the ligands to selectively distinguish tau deposits from the other AD associated pathological hallmark, senile plaques consisting of aggregated amyloid-β (Aβ) peptide, was reduced when the chemical composition of the ligands was altered, verifying that specific molecular interactions between the ligands and the aggregates are necessary for the selective detection of tau deposits. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between aggregated proteinaceous species consisting of different proteins. In addition, the bTVBT scaffold might be utilized to create powerful practical research tools for studying the underlying molecular events of tau aggregation and for creating novel agents for clinical imaging of tau pathology in AD. [ABSTRACT FROM AUTHOR]

By replacing the central thiophene unit of an anionic pentameric oligothiophene with other heterocyclic moities, a palette of pentameric thiophene-based ligands with distinct fluorescent properties were synthesized. All ligands displayed superior selectivity towards recombinant amyloid fibrils as well as disease-associated protein aggregates in tissue sections. [ABSTRACT FROM AUTHOR]

The article offers information on a study which explored the antiprion properties of luminescent conjugated polythiophenes (LCPs). Topics discussed include results of solid-state nuclear magnetic resonance analyses and molecular dynamics simulations; intraventricular infusion of four distinct LCPs in prion-infected mice; and relationship between treatment and prion protein (PrP) aggregation states.

The accumulation of protein aggregates is associated with many devastating neurodegenerative diseases and the existence of distinct aggregated morphotypes has been suggested to explain the heterogeneous phenotype reported for these diseases. Thus, the development of molecular probes able to distinguish such morphotypes is essential. We report an anionic tetrameric oligothiophene compound that can be utilized for spectral assignment of different morphotypes of β-amyloid or tau aggregates present in transgenic mice at distinct ages. The ability of the ligand to spectrally distinguish between the aggregated morphotypes was reduced when the spacing between the anionic substituents along the conjugated thiophene backbone was altered, which verified that specific molecular interactions between the ligand and the protein aggregate are necessary to detect aggregate polymorphism. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between different morphotypes of protein aggregates. [ABSTRACT FROM AUTHOR]

A wide range of neurodegenerative diseases are characterized by the deposition of multiple protein aggregates. Ligands for molecular characterization and discrimination of these pathological hallmarks are thus important for understanding their potential role in pathogenesis as well as for clinical diagnosis of the disease. In this regard, luminescent conjugated oligothiophenes (LCOs) have proven useful for spectral discrimination of amyloid-beta (Aβ) and tau neurofibrillary tangles (NFTs), two of the pathological hallmarks associated with Alzheimer's disease. Herein, the solvatochromism of a library of anionic pentameric thiophene-based ligands, as well as their ability to spectrally discriminate Aβ and tau aggregates, were investigated. Overall, the results from this study identified distinct solvatochromic and viscosity-dependent behavior of thiophene-based ligands that can be applied as indices to direct the chemical design of improved LCOs for spectral separation of Aβ and tau aggregates in brain tissue sections. The results also suggest that the observed spectral transitions of the ligands are due to their ability to conform by induced fit to specific microenvironments within the binding interface of each particular protein aggregate. We foresee that these findings might aid in the chemical design of thiophene-based ligands that are increasingly selective for distinct disease-associated protein aggregates. [ABSTRACT FROM AUTHOR]

Protein misfolding diseases are characterized by deposition of protein aggregates, and optical ligands for molecular characterization of these disease-associated structures are important for understanding their potential role in the pathogenesis of the disease. Luminescent conjugated oligothiophenes (LCOs) have proven useful for optical identification of a broader subset of disease-associated protein aggregates than conventional ligands, such as thioflavin T and Congo red. Herein, the molecular requirements for achieving LCOs able to detect nonthioflavinophilic Aβ aggregates or non-congophilic prion aggregates, as well as spectrally discriminate Aβ and tau aggregates, were investigated. An anionic pentameric LCO was subjected to chemical engineering by: 1) replacing thiophene units with selenophene or phenylene moieties, or 2) alternating the anionic substituents along the thiophene backbone. In addition, two asymmetric tetrameric ligands were generated. Overall, the results from this study identified conformational freedom and extended conjugation of the conjugated backbone as crucial determinants for obtaining superior thiophene-based optical ligands for sensitive detection and spectral assignment of disease-associated protein aggregates. [ABSTRACT FROM AUTHOR]

The aim of this work was to synthesize morphine-3- O-sulfate and morphine-6- O-sulfate for use as reference substances, and to determine the sulfate conjugates as possible heroin and morphine metabolites in plasma and urine by a validated LC-MS/MS method. Morphine-6- O-sulfate and morphine-3- O-sulfate were prepared as dihydrates from morphine hydrochloride, in overall yields of 41 and 39% with product purities of >99.5% and >98%, respectively. For bioanalysis, the chromatographic system consisted of a reversed-phase column and gradient elution. The tandem mass spectrometer was operated in the positive electrospray mode using selected reaction monitoring, of transition m/ z 366.15 to 286.40. The measuring range was 5-500 ng/mL for morphine-3- O-sulfate and 4.5-454 ng/mL for morphine-6- O-sulfate in plasma. In urine, the measuring range was 50-5000 ng/mL for morphine-3- O-sulfate and 45.4-4544 ng/mL for morphine-6- O-sulfate. The intra-assay and total imprecision (coefficient of variation) was below 11% for both analytes in urine and plasma. Quantifiable levels of morphine-3- O-sulfate in authentic urine and plasma samples were found. Only one authentic urine sample contained a detectable level of morphine-6- O-sulfate, while no detectable morphine-6- O-sulfate was found in plasma samples. [ABSTRACT FROM AUTHOR]