scholarly journals Study on tau-aggregation inhibitors in Alzheimer’s disease of methanol extracts of several medicinal plants collected in the Mekong Delta, Vietnam

2017 ◽  
Vol 1 (T2) ◽  
pp. 21-28
Author(s):  
Dua Kim Nguyen ◽  
Trang Thi Xuan Dai
Keyword(s):  
Tau Protein ◽  
Mekong Delta ◽  
Psidium Guajava ◽  
Nelumbo Nucifera ◽  
Artocarpus Altilis ◽  
Methanol Extracts ◽  
Aerial Parts ◽  
Ipomoea Aquatic ◽  
Tau Aggregation

Tau protein and Aβ-amyloid have been studied as pathological aggregations, which form neurofibrillary tangles and amyloid plaques in Alzheimer’s disease brain. Tau protein plays a critical role in neuron that binds to microtubules and assists with their formation and stabilization. However, unbinding of hyperphosphorylated tau and microtubules leads to unstable and disintegrating state of neuron. The free tau proteins form neurofibrillary tangles. The purpose of this study is to screen in vitro the the tau-aggregation inhibitory activity of nine methanol extracts of Psidium guajava leaf, Nelumbo nucifera leaf; wild Ipomoea aquatic, Cleome rutidosperma aerial parts, Artocarpus altilis leaf, cultivated Ipomoea aquatic, Centella asiatica leaf, Mimosa pudica L. aerial parts, Nelumbo nucifera seed pod collected in the Mekong Delta. Nine herbs were collected, dried and extracted with methanol. The half maximal inhibitory concentration (IC50) of methanol extracts was measured by Thioflavin T assay at various concentrations. Silica gel column chromatography was employed to fractionate the Psidium guajava leaf crude extract. Nine methanol extracts were proved to reduce the tau aggregation in vitro. Extracts from leaves of Psidium guajava, Artocarpus altilis and Nelumbo nucifera impressively inhibited the tau aggregation with IC50 at 0.39 mg/mL, 1.05 mg/mL and 1.24 mg/mL, respectively. Methylene blue was used as a positive control, with IC50 at 1.35 μM. The five examined fractions of guava leaf were proved to inhibit the tau aggregation ranging from 33.70 % to 48.49 %, except the 100 % of hexane fraction showed almost no effect on the tau aggregation inhibitor.

scholarly journals Dextran sulphate-induced tau assemblies cause endogenous tau aggregation and propagation in wild-type mice

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Masami Masuda-Suzukake ◽  
Genjiro Suzuki ◽  
Masato Hosokawa ◽  
Takashi Nonaka ◽  
Michel Goedert ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Tau Protein ◽  
Guanidine Hydrochloride ◽  
Intracerebral Injection ◽  
Dextran Sulphate ◽  
Wild Type ◽  
Synthetic Filament ◽  
Biochemical Analyses ◽  
Tau Aggregation

Abstract Accumulation of assembled tau protein in the central nervous system is characteristic of Alzheimer’s disease and several other neurodegenerative diseases, called tauopathies. Recent studies have revealed that propagation of assembled tau is key to understanding the pathological mechanisms of these diseases. Mouse models of tau propagation are established by injecting human-derived tau seeds intracerebrally; nevertheless, these have a limitation in terms of regulation of availability. To date, no study has shown that synthetic assembled tau induce tau propagation in non-transgenic mice. Here we confirm that dextran sulphate, a sulphated glycosaminoglycan, induces the assembly of recombinant tau protein into filaments in vitro. As compared to tau filaments induced by heparin, those induced by dextran sulphate showed higher thioflavin T fluorescence and lower resistance to guanidine hydrochloride, which suggests that the two types of filaments have distinct conformational features. Unlike other synthetic filament seeds, intracerebral injection of dextran sulphate-induced assemblies of recombinant tau caused aggregation of endogenous murine tau in wild-type mice. AT8-positive tau was present at the injection site 1 month after injection, from where it spread to anatomically connected regions. Induced tau assemblies were also stained by anti-tau antibodies AT100, AT180, 12E8, PHF1, anti-pS396 and anti-pS422. They were thioflavin- and Gallyas-Braak silver-positive, indicative of amyloid. In biochemical analyses, accumulated sarkosyl-insoluble and hyperphosphorylated tau was observed in the injected mice. In conclusion, we revealed that intracerebral injection of synthetic full-length wild-type tau seeds prepared in the presence of dextran sulphate caused tau propagation in non-transgenic mice. These findings establish that propagation of tau assemblies does not require tau to be either mutant and/or overexpressed.

scholarly journals Lysine methylation is an endogenous post-translational modification of tau protein in human brain and a modulator of aggregation propensity

2014 ◽  
Vol 462 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Kristen E. Funk ◽  
Stefani N. Thomas ◽  
Kelsey N. Schafer ◽  
Grace L. Cooper ◽  
Zhongping Liao ◽  
...  
Keyword(s):  
Human Brain ◽  
Tau Protein ◽  
Protein Function ◽  
Lysine Methylation ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Aggregation Propensity ◽  
Normal Human ◽  
Tau Aggregation

Diverse post-translational modifications regulate tau protein function and misfolding. In the present study we identified lysine methylation as a tau post-translational modification in normal human brain, and found it depressed tau aggregation propensity when modelled in vitro.

scholarly journals From Aggregation to Inhibition: N-Amination Converts Amyloidogenic Tau Peptides into Soluble Antagonists of Cellular Seeding

2021 ◽  
Author(s):  
Kamlesh Makwana ◽  
Matthew P. Sarnowski ◽  
Jiyuan Miao ◽  
Yu-Shan Lin ◽  
Juan Del Valle
Keyword(s):  
Small Molecules ◽  
Tau Protein ◽  
Supramolecular Assembly ◽  
Rational Basis ◽  
Protein Assemblies ◽  
Amino Groups ◽  
Minimalist Approach ◽  
Full Complement ◽  
Tau Aggregation

The spread of neurofibrillary tangles resulting from tau protein aggregation is a hallmark of Alzheimer’s and related neurodegenerative diseases. Early oligomerization of tau involves conformational reorganization into parallel b-sheet structures and supramolecular assembly into toxic fibrils. Despite the need for selective inhibitors of tau propagation, b-rich protein assemblies are inherently difficult to target with small molecules. Here, we describe a minimalist approach to mimic the aggregation-prone modules within tau. We carried out a backbone residue scan and show that amide N-amination completely abolishes the tendency of these peptides to self-aggregate, rendering them soluble mimics of ordered b-strands from the tau R2 and R3 domains. Several N-amino peptides (NAPs) inhibit disease-associated tau aggregation and prevent fibril formation <i>in vitro</i>. We further demonstrate that NAPs <b>12</b> and <b>13</b> are effective at blocking the cellular seeding of endogenous tau by interacting with both monomeric or fibrillar forms of extracellular tau. Peptidomimetic <b>12</b> is serum stable, non-toxic to neuronal cells, and selectivity inhibits the aggregation of tau over Ab<sub>­42</sub>. Structural analysis of our lead NAPs shows considerable conformational constraint imposed by the N-amino groups. The enhanced rigidity and full complement of sidechains thus enables NAPs to recognize tau fibrils. The described backbone N-amination approach provides a rational basis for the mimicry of other aggregation-prone peptides that drive pathogenic protein assembly.

scholarly journals From Aggregation to Inhibition: N-Amination Converts Amyloidogenic Tau Peptides into Soluble Antagonists of Cellular Seeding

2021 ◽  
Author(s):  
Kamlesh Makwana ◽  
Matthew P. Sarnowski ◽  
Jiyuan Miao ◽  
Yu-Shan Lin ◽  
Juan Del Valle
Keyword(s):  
Small Molecules ◽  
Tau Protein ◽  
Supramolecular Assembly ◽  
Rational Basis ◽  
Protein Assemblies ◽  
Amino Groups ◽  
Minimalist Approach ◽  
Full Complement ◽  
Tau Aggregation

The spread of neurofibrillary tangles resulting from tau protein aggregation is a hallmark of Alzheimer’s and related neurodegenerative diseases. Early oligomerization of tau involves conformational reorganization into parallel b-sheet structures and supramolecular assembly into toxic fibrils. Despite the need for selective inhibitors of tau propagation, b-rich protein assemblies are inherently difficult to target with small molecules. Here, we describe a minimalist approach to mimic the aggregation-prone modules within tau. We carried out a backbone residue scan and show that amide N-amination completely abolishes the tendency of these peptides to self-aggregate, rendering them soluble mimics of ordered b-strands from the tau R2 and R3 domains. Several N-amino peptides (NAPs) inhibit disease-associated tau aggregation and prevent fibril formation <i>in vitro</i>. We further demonstrate that NAPs <b>12</b> and <b>13</b> are effective at blocking the cellular seeding of endogenous tau by interacting with both monomeric or fibrillar forms of extracellular tau. Peptidomimetic <b>12</b> is serum stable, non-toxic to neuronal cells, and selectivity inhibits the aggregation of tau over Ab<sub>­42</sub>. Structural analysis of our lead NAPs shows considerable conformational constraint imposed by the N-amino groups. The enhanced rigidity and full complement of sidechains thus enables NAPs to recognize tau fibrils. The described backbone N-amination approach provides a rational basis for the mimicry of other aggregation-prone peptides that drive pathogenic protein assembly.

scholarly journals A Comparison of Phytotoxic Potential among the Crude Extracts from Parthenium hysterophorus L. Extracted with Solvents of Increasing Polarity

2015 ◽  
Vol 33 ◽  
pp. 73-81 ◽  
Author(s):  
Ujjal Kumar Pati ◽  
Ashim Chowdhury
Keyword(s):  
Ethyl Acetate ◽  
Weed Management ◽  
Parthenium Hysterophorus ◽  
Weed Species ◽  
Methanol Extracts ◽  
Aerial Parts ◽  
Crude Extracts ◽  
Seed Germination Assay ◽  
Range Test

There is a worldwide search for the safe, effective and eco-friendly compounds of plant origin to combat the weed species and other pests which are responsible for the great impact on the growth and productivity of agricultural crops. In this present study, a comparison was made to evaluate the phytotoxicity potential of sequentially extracted solvent (hexane, ethyl-acetate, methanol) extracts of Parthenium hysterophorus L. (aerial parts) in vitro through bench-top seed germination assay (Vigna radiata L.). One-way analysis of variance (ANOVA) followed by Duncan’s multiple range test (DMRT) were done for statistical analysis of the data. The study reveals that germination, growth and vigour was significantly (P<0.05) reduced by ethyl-acetate and methanol extracts. The present study concluded that phytotoxicity of ethylacetate and methanolic crude extracts of Parthenium hysterophorus could be exploited as potential bioherbicide for future weed management programme and the development of bioherbicide for commercial use.

scholarly journals In vitro anti-urease, antioxidant, anticholinesterase, cytotoxic and in vivo anti-inflammatory potential of Satureja cuneifolia Ten.

2020 ◽  
Vol 12 (2) ◽  
pp. 222-232
Author(s):  
Turgut TASKIN ◽  
Murat DOGAN ◽  
Muhammet E. CAM ◽  
Talip SAHIN ◽  
Ismail SENKARDES
Keyword(s):  
Methanol Extract ◽  
Radical Scavenging ◽  
Inflammatory Activity ◽  
Cytotoxic Activities ◽  
Methanol Extracts ◽  
Aerial Parts ◽  
Direct Methanol ◽  
Anti Inflammatory

Satureja cuneifolia Ten. (wild savoury) belongs to the Lamiaceae family and is used to produce essential oil and aromatic water. This plant is also used as a condiment and herbal tea due to its stimulating, tonic and carminative effects. The in vitro antioxidant, anti-urease, anticholinesterase and cytotoxic activities of the different extracts from the plant’s aerial parts were examined. Besides, the in vivo anti-inflammatory activities of the fraction and direct methanol extracts were determined comparatively. In the current study, fraction methanol extract exhibited the strongest ABTS (52.34 mM trolox/mg extract) radical scavenging and ferric reduction (17.22 mM Fe2+/mg extract) activity. It was also found that the fraction methanol extract had stronger anti-urease (12.52%) and anticholinesterase (69.02%) activity than other extracts.  The XTT results showed that fraction methanol extract had the most cytotoxic activity on MCF-7 cell lines (39.92%).  According to the results of in vivo anti-inflammatory activity, it was found that both fraction and direct methanol extracts exhibited close and significant anti-inflammatory activity. The fact that methanol extracts have significant biological activity suggests that these may be used as a natural source in the future.

scholarly journals Investigation on the Aggregation Behaviors and Filament Morphology of Tau Protein by a Simple 90° Angle Light-Scattering Assay

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Hai-Lin Liao ◽  
Ling-Feng Jiang ◽  
Tian-Ming Yao
Keyword(s):  
Light Scattering ◽  
Tau Protein ◽  
Incident Wavelength ◽  
Angle Dependence ◽  
Critical Concentrations ◽  
Microtubule Binding Domain ◽  
Aggregation Behaviors ◽  
Tau Aggregation ◽  
Micromolar Range

Thein vitroaggregation of tau constructs was monitored by a simple 90° angle light-scattering (LS) approach which was conducted directly on fluorescence instrument. At the optimum incident wavelength (550 nm, unpolarized), the sensitivity of LS was high enough to detect tau aggregation at micromolar range. The nucleation and elongation, different events in the aggregation process of 4RMBD construct (corresponding with the four repeated units of tau Microtubule Binding Domain) could be observed by this approach, as compared with ThS fluorescence assay. The validity of this technique was demonstrated over a range of tau concentrations with different tau filaments. Linear regression of scattering light against concentration yielded thex-intercept, the critical concentrations of tau constructs. The critical concentrations of 4RMBD and its S305N mutant are 5.26 μM and 4.04 μM respectively, indicating point mutation S305N, which is associated with FTDP-17, appear to enhance the heparin-induced tau aggregationin vitro. Furthermore, the slopes of concentration dependence curves, as well as the angle dependence, were discussed based on the filaments morphology examined by electron microscopy and ultrasonication experiment.

scholarly journals Cannabidiol Inhibits Tau Aggregation In Vitro

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3521
Author(s):  
Soha Alali ◽  
Gholamhossein Riazi ◽  
Mohammad Reza Ashrafi-Kooshk ◽  
Sogol Meknatkhah ◽  
Shahin Ahmadian ◽  
...  
Keyword(s):  
Tau Protein ◽  
Cannabis Sativa ◽  
Antioxidant Activities ◽  
Thioflavin T ◽  
Lag Phase ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tau Aggregation ◽  
Quenching Assay

A hallmark of Alzheimer’s disease (AD) is the accumulation of tau protein in the brain. Compelling evidence indicates that the presence of tau aggregates causes irreversible neuronal destruction, eventually leading to synaptic loss. So far, the inhibition of tau aggregation has been recognized as one of the most effective therapeutic strategies. Cannabidiol (CBD), a major component found in Cannabis sativa L., has antioxidant activities as well as numerous neuroprotective features. Therefore, we hypothesize that CBD may serve as a potent substance to hamper tau aggregation in AD. In this study, we aim to investigate the CBD effect on the aggregation of recombinant human tau protein 1N/4R isoform using biochemical methods in vitro and in silico. Using Thioflavin T (ThT) assay, circular dichroism (CD), atomic force microscopy (AFM), we demonstrated that CBD can suppress tau fibrils formation. Moreover, by quenching assay, docking and job’s plot, we further demonstrate that one molecule of CBD interacts with one molecule of tau protein through a spontaneous binding. Experiments performed by quenching assay, docking and Thioflavin T assay further established that the main forces are hydrogenvan der Waals and some non-negligible hydrophobic forces, affecting the lag phase of tau protein kinetics. Taken together, this study provides new insights about a natural substance, CBD, for tau therapy which may offer new hope for the treatment of AD.

In vitro antioxidant potential of spray-dried Psidium guajava L. leaves extracts

Planta Medica ◽  
2013 ◽  
Vol 79 (13) ◽  
Author(s):  
MR Fernandes ◽  
CR Souza ◽  
ML Martinez ◽  
WP Oliveira
Keyword(s):  
Psidium Guajava ◽  
Antioxidant Potential ◽  
Spray Dried
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