scholarly journals Interplay between epigallocatechin-3-gallate and ionic strength during amyloid aggregation

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12381
Author(s):  
Mantas Ziaunys ◽  
Kamile Mikalauskaite ◽  
Andrius Sakalauskas ◽  
Vytautas Smirnovas
Keyword(s):  
Ionic Strength ◽  
Amyloid Beta ◽  
Inhibitory Effect ◽  
Alpha Synuclein ◽  
Amyloid Aggregation ◽  
Solution Ionic Strength ◽  
Fibril Structure ◽  
Amyloid Aggregates ◽  
Aggregation Inhibitor

The formation and accumulation of protein amyloid aggregates is linked with multiple amyloidoses, including neurodegenerative Alzheimer’s or Parkinson’s disease. The mechanism of such fibril formation is impacted by various environmental conditions, which greatly complicates the search for potential anti-amyloid compounds. One of these factors is solution ionic strength, which varies between different aggregation protocols during in vitro drug screenings. In this work, we examine the interplay between ionic strength and a well-known protein aggregation inhibitor—epigallocatechin-3-gallate. We show that changes in solution ionic strength have a major impact on the compound’s inhibitory effect, reflected in both aggregation times and final fibril structure. We also observe that this effect is unique to different amyloid-forming proteins, such as insulin, alpha-synuclein and amyloid-beta.

scholarly journals Simultaneous Occurrence of Bioactive Compounds (Melatonin, Protocatechuic Acid and Hydroxytyrosol) Increases Their Neuroprotective Effects Against Alpha-Synuclein-Induced Proteotoxicity

2018 ◽  
Author(s):  
Marta Gallardo-Fernández ◽  
Ruth Hornedo-Ortega ◽  
Ana B Cerezo ◽  
Ana M Troncoso ◽  
Mª Carmen Garcia-Parrilla
Keyword(s):  
Bioactive Compounds ◽  
Protocatechuic Acid ◽  
Lewy Bodies ◽  
Initial Step ◽  
Inhibitory Effect ◽  
Alpha Synuclein ◽  
Simultaneous Occurrence ◽  
Neuroprotective Effects ◽  
In Vitro Techniques

The abnormal assembly of α-synuclein (α-Syn) is an initial step in the formation of Lewy bodies in the brain, which finally causes the neuronal death, being considered as a pathological hallmark in Parkinson’s disease (PD). Certain food bioactives or their metabolites at very low concentrations can trespass the blood brain barrier (BBB) that might, thereafter, act simultaneously. The aim of this work was to evaluate the inhibitory and destabilising capacities on α-Syn kinetics and the neuroprotective effects of three well-known bioactive compounds able to cross the BBB and present in foods; melatonin (MEL), protocatechuic acid (PCA) and hydroxytyrosol (HT), and their combinations. For this purpose, different in vitro techniques (Thioflavin T (ThT), Transmission Electronic Microscopy (TEM), electrophoresis and MTT assay) were used. All tested compounds and their combinations were able to abolish the toxicity induced by α-Syn. In addition, the combination of PCA (100 µM) +HT (100 µM) showed the highest inhibitory effect against α-Syn fibril formation and destabilises α-Syn fibrils (88 and 62%, respectively). This is the first time that MEL, PCA and HT prove a joint effect against α-Syn aggregation and toxicity when they are tested together.

scholarly journals Dialysis Unmasks the Fungicidal Properties of Glandular Salivary Secretions

2004 ◽  
Vol 72 (5) ◽  
pp. 2703-2709 ◽  
Author(s):  
Eva J. Helmerhorst ◽  
Bianca Flora ◽  
Robert F. Troxler ◽  
Frank G. Oppenheim
Keyword(s):  
Molecular Weight ◽  
Candida Albicans ◽  
Ionic Strength ◽  
Gel Electrophoresis ◽  
Fungicidal Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Inhibitory Effect ◽  
Salivary Proteins ◽  
Dose Dependent

ABSTRACT Several salivary proteins exhibit fungicidal activity against the opportunistic oral pathogen Candida albicans when they are tested as pure proteins in vitro. However, salivary secretions that are examined by the same assays either lack or exhibit very low candidacidal activity. Since ionic strength is known to have an inhibitory effect on the fungicidal activities of some proteins, parotid secretion was subjected to dialysis with membranes having molecular weight cutoffs (MWCOs) of 500, 1,000, 10,000, and 25,000. Dialysis with membranes with MWCOs of ≥1,000 promoted fungicidal activity of parotid secretion, and this activity was dose dependent. The addition of sodium chloride to dialyzed, fungicidal parotid secretion abolished this activity, indicating that the fungicidal component was salt sensitive. Similar results were obtained with submandibular and sublingual secretions. Polyacrylamide gel electrophoresis under native and denaturing conditions was used to analyze the composition of the dialysate. Unexpectedly, proteins with MWs much lower than the nominal MWCOs of the membranes were not lost during dialysis. Among the retained proteins, the two fractions with MWs of approximately 17,000 and 4,000 exhibited fungicidal activity. These results are consistent with the presence of lysozyme and histatins, respectively, which may represent the major candidacidal capacity of dialyzed parotid secretion.

Inhibition of Alzheimer Amyloid Aggregation with Sulfate Glycopolymers

2008 ◽  
Vol 57 ◽  
pp. 166-169 ◽  
Author(s):  
Yoshiko Miura ◽  
Kiyofumi Yamamoto ◽  
Kikuko Yasuda ◽  
Yoshihiro Nishida ◽  
Kazukiyo Kobayashi
Keyword(s):  
Amyloid Beta ◽  
Amyloid Fibrils ◽  
Inhibitory Effect ◽  
Cd Spectra ◽  
Amyloid Beta Peptides ◽  
Vitro Assay ◽  
Neutralization Activity ◽  
Beta Peptides ◽  
Β Sheet

Glycopolymers carrying sulfate saccharides were found to suppress the formation of amyloid fibrils by amyloid beta peptides, as evaluated by fluorescence assay of thioflavin T and AFM. CD spectra showed that the conformation of amyloid beta peptides was changed from beta peptides depended on the glycopolymer additives, and that the glycopolymer additives reduced the β-sheet contents. Neutralization activity was confirmed by in vitro assay with HeLa cells. The sulfate group and the appropriate sugar contents were essential for the inhibitory effect.

Fucosterol from Sargassum horridum as an amyloid-beta (Aβ1-42) aggregation inhibitor: in vitro and in silico studies

2020 ◽  
pp. 1-13
Author(s):  
Elena Sthephanie Castro-Silva ◽  
Martiniano Bello ◽  
Martha Cecilia Rosales-Hernández ◽  
José Correa-Basurto ◽  
Maricarmen Hernández-Rodríguez ◽  
...  
Keyword(s):  
Amyloid Beta ◽  
In Silico ◽  
In Silico Studies ◽  
Aggregation Inhibitor

scholarly journals Targeting alpha synuclein and amyloid beta by a multifunctional, brain-penetrant dopamine D2/D3 agonist D-520: Potential therapeutic application in Parkinson’s disease with dementia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Deepthi Yedlapudi ◽  
Liping Xu ◽  
Dan Luo ◽  
Gregory B. Marsh ◽  
Sokol V. Todi ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amyloid Beta ◽  
Alpha Synuclein ◽  
Motor Dysfunction ◽  
Dopamine D2 ◽  
Potential Therapeutic Application ◽  
Aβ Aggregation

AbstractA significant number of people with Parkinson’s disease (PD) develop dementia in addition to cognitive dysfunction and are diagnosed as PD with dementia (PDD). This is characterized by cortical and limbic alpha synuclein (α-syn) accumulation, and high levels of diffuse amyloid beta (Aβ) plaques in the striatum and neocortical areas. In this regard, we evaluated the effect of a brain-penetrant, novel multifunctional dopamine D2/D3 agonist, D-520 on the inhibition of Aβ aggregation and disintegration of α-syn and Aβ aggregates in vitro using purified proteins and in a cell culture model that produces intracellular Aβ-induced toxicity. We further evaluated the effect of D-520 in a Drosophila model of Aβ1-42 toxicity. We report that D-520 inhibits the formation of Aβ aggregates in vitro and promotes the disaggregation of both α-syn and Aβ aggregates. Finally, in an in vivo Drosophila model of Aβ1-42 dependent toxicity, D-520 exhibited efficacy by rescuing fly eyes from retinal degeneration caused by Aβ toxicity. Our data indicate the potential therapeutic applicability of D-520 in addressing motor dysfunction and neuroprotection in PD and PDD, as well as attenuating dementia in people with PDD.

scholarly journals Polymorphism of Alpha-Synuclein Amyloid Fibrils Depends on Ionic Strength and Protein Concentration

2021 ◽  
Vol 22 (22) ◽  
pp. 12382
Author(s):  
Mantas Ziaunys ◽  
Andrius Sakalauskas ◽  
Kamile Mikalauskaite ◽  
Vytautas Smirnovas
Keyword(s):  
Ionic Strength ◽  
Protein Concentration ◽  
Amyloid Fibrils ◽  
Alpha Synuclein ◽  
Fibrillar Structure ◽  
Large Sample Size ◽  
Structural Variations ◽  
Protein Aggregate ◽  
Parkinson’S Diseases

Protein aggregate formation is linked with multiple amyloidoses, including Alzheimer‘s and Parkinson‘s diseases. Currently, the understanding of such fibrillar structure formation and propagation is still not sufficient, the outcome of which is a lack of potent, anti-amyloid drugs. The environmental conditions used during in vitro protein aggregation assays play an important role in determining both the aggregation kinetic parameters, as well as resulting fibril structure. In the case of alpha-synuclein, ionic strength has been shown as a crucial factor in its amyloid aggregation. In this work, we examine a large sample size of alpha-synuclein aggregation reactions under thirty different ionic strength and protein concentration combinations and determine the resulting fibril structural variations using their dye-binding properties, secondary structure and morphology. We show that both ionic strength and protein concentration determine the structural variability of alpha-synuclein amyloid fibrils and that sometimes even identical conditions can result in up to four distinct types of aggregates.

scholarly journals A novel approach to evaluate alpha-synuclein seeding shows a wide heterogeneity in multiple system atrophy

2021 ◽  
Author(s):  
Ivan Martinez-Valbuena ◽  
Naomi P. Visanji ◽  
Ain Kim ◽  
Heather H. C. Lau ◽  
Raphaella W. L. So ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Multiple System Atrophy ◽  
Parkinson Disease ◽  
Real Time ◽  
Brain Regions ◽  
Alpha Synuclein ◽  
Novel Approach ◽  
Reliable Detection

Several in vitro and in vivo findings have consistently shown that alpha-synuclein derived from multiple system atrophy (MSA) subjects has more seeding capacity than Parkinson disease-derived alpha-synuclein. However, reliable detection of alpha-synuclein derived from MSA using seeded amplification assays, such as the Real-Time Quaking-induced Conversion, has remained challenging. Here we demonstrate that the interaction of the Thioflavin T dye with alpha-synuclein from MSA and Parkinson disease patients can be modulated by the type of salt, pH, and ionic strength used to generate strain-specific reaction buffers. Employing this novel approach, we have generated a streamlined Real-Time Quaking-induced Conversion assay capable of categorizing MSA brains according to their alpha-synuclein seeding behavior, and to unravel a previously unrecognized heterogeneity in seeding activity between different brain regions of a given individual that goes beyond immunohistochemical observations and provide a framework for future molecular subtyping of MSA.

scholarly journals α-Synuclein polymorphism determines oligodendroglial dysfunction

2021 ◽  
Author(s):  
Benedikt Frieg ◽  
James A Geraets ◽  
Timo Strohaeker ◽  
Christian Dienemann ◽  
Panagiota Mavroeidi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Brain Tissue ◽  
Ex Vivo ◽  
Neurological Diseases ◽  
Alpha Synuclein ◽  
Published Data ◽  
Cryo Electron Microscopy ◽  
Fibril Structure ◽  
Potential Biomarker

Synucleinopathies, such as Parkinson's disease (PD) and Multiple System Atrophy (MSA) are progressive and unremitting neurological diseases. For both PD and MSA, alpha-synuclein fibril inclusions inside brain cells are neuropathological hallmarks. In addition, amplification of alpha-synuclein fibrils from body fluids is a potential biomarker distinguishing PD from MSA. However, little is known about the structure of alpha-synuclein fibrils amplified from human samples and its connection to alpha-synuclein fibril structure in the human brain. Here we amplified alpha-synuclein fibrils from PD and MSA brain tissue, characterized its seeding potential in oligodendroglia, and determined the 3D structures by cryo-electron microscopy. We show that the alpha-synuclein fibrils from a MSA patient are more potent in recruiting the endogenous alpha-synuclein and evoking a redistribution of TPPP/p25alpha protein in mouse primary oligodendroglial cultures compared to those amplified from a PD patient. Cryo-electron microscopy shows that the PD- and MSA-amplified alpha-synuclein fibrils share a similar protofilament fold but differ in their inter-protofilament interface. The structures of the brain-tissue amplified alpha-synuclein fibrils are also similar to other in vitro and ex vivo alpha-synuclein fibrils. Together with published data, our results suggest that aSyn fibrils differ between PD and MSA in their quaternary arrangement and could further vary between different forms of PD and MSA.

Effect of Dipyridamole on Spontaneous Platelet Aggregation in Whole Blood Decreases with the Time After Venepuncture: Evidence for the Role of ADP

1987 ◽  
Vol 58 (02) ◽  
pp. 744-748 ◽  
Author(s):  
A R Saniabadi ◽  
G D O Lowe ◽  
J C Barbenel ◽  
C D Forbes
Keyword(s):  
Platelet Aggregation ◽  
Correlation Coefficient ◽  
Whole Blood ◽  
Blood Platelet ◽  
Inhibitory Effect ◽  
Time Interval ◽  
Adp Receptor ◽  
Spontaneous Platelet Aggregation

SummarySpontaneous platelet aggregation (SPA) was studied in human whole blood at 3, 5, 10, 20, 30, 40 and 60 minutes after venepuncture. Using a whole blood platelet counter, SPA was quantified by measuring the fall in single platelet count upon rollermixing aliquots of citrated blood at 37° C. The extent of SPA increased with the time after venepuncture, with a correlation coefficient of 0.819. The inhibitory effect of dipyridamole (Dipy) on SPA was studied: (a) 10 μM at each time interval; (b) 0.5-100 μM at 3 and 30 minutes and (c) 15 μM in combination with 100 μM adenosine, 8 μM 2-chloroadenosine (2ClAd, an ADP receptor blocker) and 50 μM aspirin. There was a rapid decrease in the inhibitory effect of Dipy with the time after venepuncture; the correlation coefficient was -0.533. At all the concentrations studied, Dipy was more effective at 3 minutes than at 30 minutes after venepuncture. A combination of Dipy with adenosine, 2ClAd or aspirin was a more effective inhibitor of SPA than either drug alone. However, when 15 μM Dipy and 10 μM Ad were added together, the inhibitory effect of Dipy was not increased significantly, suggesting that Dipy inhibits platelet aggregation independent of Ad. The increase in SPA with the time after venepuncture was abolished when blood was taken directly into the anticoagulant containing 5 μM 2ClAd. It is suggested that ADP released from the red blood cells is responsible for the increased platelet aggregability with the time after venepuncture and makes a serious contribution to the artifacts of in vitro platelet function studies.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

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