Therapeutic Application against α-Synuclein Aggregation Byrne.… · Preparation and...
Transcript of Therapeutic Application against α-Synuclein Aggregation Byrne.… · Preparation and...
Preparation and Characterization of Manganese (II) Complexes with Potential
Therapeutic Application against α-Synuclein Aggregation
Kate Byrne
BSc Medicinal Chemistry & Pharmaceutical Science
Year 3 Project
Overview
• Aim of the Project
• Parkinson’s Disease and Etiology
• α-Synuclein and Lewy Bodies
• Project Rationale and Objectives
• Synthesis of the compounds
• Characterisation of the compounds
• Conclusion
Aim
The aim of this project was to synthesize, purify and characterise three manganese(II) complexes as part of a structure-activity relationship (SAR) study of a potential
therapeutic system for Parkinson’s disease
Parkinson’s Disease Parkinson’s disease, (PD) is a progressive neurological
disease which is a result of the loss of dopamine producing brain cells
Parkinson’s disease is named after Dr. James Parkinson who first reported symptoms of the disease in 1817 when
it was referred to as “Paralysis Agitans”
Etiology Idiopathic
Figure 1: Dr. James Parkinson
Statistics
• Parkinson’s disease affects 6.3 million people worldwide.
• Over 9,000 of those affected by the disease are Irish.
• The disease typically develops at the age of 65 however people can develop “early-onset” parkinson’s before reaching 50 years.
• Current life expectancy: 81 years
• Projected Life expectancy 2030: 90+ years
α-Synuclein α-Synuclein is a protein that is abundant in the human brain.
In the early stages of Parkinson’s disease misfolded α-synuclein
proteins are converted to pathological oligomers and higher
order aggregates that form fibrils leading to the formation of
Lewy Bodies.
Figure 2: α-Synuclein aggregation stages
Emil Paleek, et al., Changes in interfacial properties of α-synuclein preceding its aggregation, Analyst, 2008, 133, 76.
Lewy bodies are abnormal α-Synuclein protein aggregates that develop in nerve cells in regions of the brain that are
involved in motor control.
The presence of the Lewy Body protein aggregates in the
brain is a pathological hallmark of Parkinson’s Disease.1
Inhibiting α-Synuclein aggregation offers a therapeutic target for Parkinson’s Disease and evidence in the literature
suggests a role for inorganic medicinal chemistry2
1. He-Jin Lee, et al., Extracellular α-synuclein a novel and crucial factor in Lewy body diseases, Nature Reviews Neurology, 2014, 10, 92-98. 2. D.J. Haynes, S. Lim, P.S. Donnelly, Metal complexes designed to bind to amyloid-β for diagnosis and treatment of Alzheimer’s disease, Chem. Soc. Rev., 2014, 43, 6701-6715.
Lewy bodies and Parkinson’s Disease
Lead Compound
The complex salt, MD1 has been shown to be an excellent lead compound for the prevention of α-Synuclein aggregation.
MD1:
[Mn2(oda)(phen)4(H2O)2][Mn2(oda)(phen)4(oda)2]4H2O
Where; odaH2 = octanedioic acid; phen = 1,10-phenanthroline
Figure 4: Structures of MD1 and Octanedioic Acid
• Comprised of bi-nuclear Cationic and Anionic components (Complex salt).1
• Bridging and terminal octanedioate ligands, deprotonated octanedioic acid
• Highly water soluble.
• Exhibits antioxidant capability.2
• Reduces α-Synuclein aggregation in fungal (saccharomyces cerevisiae) and mammalian (HEK293) cellular models.2
1. M. McCann, M. Devereux, et al. Synthesis and structure of the Mn2 (II,II) complex salt [Mn2(oda)(phen)4(H2O)2] [Mn2(oda)2(phen)4] (odaH2 = octanedioic acid): a catalyst for H2O2 disproportionation., J. Chem. Soc., Chem. Commun., 1994, 2643. 2. T. Ribeiro, M. McCann, M. Devereux, M. Pereira, et al., Evaluation of antioxidant activity of a Mn2+complex salt and its potential therapeutic use against alpha—synuclein aggregation. Manuscript in preparation. (Target Journal: Nature Communications)
Research question
What are the structural aspects of MD1 that are important for its
α-Synuclein aggregation inhibitory properties?
Objective of the Structure-Activity Relationship Study
To investigate analogues of MD1 to determine how variations in structure influence the α-Synuclein aggregation inhibitory potential of this class of
manganese(II) complex.
Note: The analogues were varied in terms of the number of Manganese centres in the complex as well as the charge
on the complex
Key Objectives
To synthesise and characterise three known analogues of MD1 with variations in structure achieved by replacing the octanedioate ligands with aliphatic
dicarboxylic acid ligands of varying chain length
[Mn(hxda)(phen)2(H2O)].7H2O 1
[Mn(pda)(phen)]2
[Mn2(bda)2(phen)2(H2O)].2H2O3
Hexanedioic acid (hxdaH2)
Pentanedioic acid (pdaH2)
Butanedioic acid (bdaH2)
1. M. McCann, M. Devereux, et al., Manganese(II) complexes of hexanedioic and heptanedioic acids: X-ray crystal structure of [Mn(hxda)(phen)2(H2O)].7H2O and [Mn(phen)2(H2O)][Mn(hpda)(phen)2(H2O)](hpda) .12.5H2O, Polyhedron, 1997, 16, 2741.
2. Martin Curran, PhD Thesis, DIT/NUIM 1996.
3. M. McCann, M. Devereux, et al., Synthesis, X-ray crystal structure and catalytic activities of manganese(II) butanedioic acid complexes [Mn(bda)(phen)2(H2O)4].2H2O and {[Mn(bda)(bipy2(H2O)2].H2O }n, Polyhedron, 1997, 16, 2547.
Octanedioic acid (odaH2)
Structure of the Analogue Complexes
[Mn(hxda)(phen)2(H2O)].7H2O : Mononuclear (1 manganese centre), 2 phens per manganese, neutral charge
[Mn(pda)(phen)]: Polymeric, 1 phen per manganese, neutral
charge.
[Mn2(bda)2(phen)2(H2O)].2H2O: Binuclear (2 manganese centres), 1 phen per
manganese, neutral charge
Synthetic Scheme Stage One: Generation of the manganese(II) dicarboxylate
precursors
Where; R = -(CH2)4 - or -(CH2)3 -or -(CH2)2 -
Synthetic Scheme Stage Two: Reaction of the precursor complexes with 1,10-
phenanthroline to produce the analogues of MD1
{Mn(OOC-(CH2)n-COO)}x + 4 phen → [Mn(hxda)(phen)2(H2O)].7H2O (where n = 4) [Mn(pda)(phen)] (where n = 3) [Mn2(bda)2(phen)2(H2O)].2H2O (where n = 2)
EtOH
Reflux
Characterisation
The three precursor complexes and the three analogue complexes were characterised using the following
techniques:
• Infra-Red (IR) Spectroscopy
• Magnetic Susceptibility Analysis
• Inductively-Coupled Mass Spectrometry (ICP-MS)
Infrared Spectroscopy An IR spectrum was recorded of:
• The Ligand
• The Precursor Complex
• The Final Complex
Each of the spectra was then overlayed
Hexanedioic Acid
[Mn(hxda)].H2O
[Mn(hxda)(phen)2(H2O)].7H2O
Hexanedioic Acid Spectra Overlay
Infrared Spectroscopy
Precursor Complex and Analogue Complex Similarities
Characteristic Carbonyl Peak
• Asymmetric Stretch 1590-1547cm-1
• Symmetric Stretch 1400-1420cm-1
Determination of [Mn] Using ICP
y = 66202x + 5669.9
R² = 0.9999
0
100000
200000
300000
400000
500000
600000
-1 0 1 2 3 4 5 6 7 8 9
Intensity
Concentration (ppm)
ICP Standards
Mn2+ Analysis Name of Complex Theoretical
Concentration
(ppm)
Experimental
Concentration
(ppm)
[Mn(bda)].2H2O 5.3 4.647
[Mn(pda)].H2O 5.36 4.001
[Mn(hxda)].H2O 5 3.468
Drug 1,
[Mn2(bda)2(phen)2(H2O)].2
H2O
5.4 9.5
4.75 x 2
Drug 2, [Mn(pda)(phen)] 5.45 4.325
Drug 3,
[Mn(hxda)(phen)2(H2O)].7
H2O
4.68 1.468
Magnetic Susceptibility Balance
µ𝑠 .𝑜. = 𝑛(𝑛 + 2)
Where;
N = number of unpaired electrons, n=5
µ𝑠 .𝑜. = 5(5 + 2) = 35 = 5.92
µs.o. = 5.92B.M.
Gram Magnetic Susceptibility Calculation
Χg = c ∗ l ∗ (R − R0)
109 ∗ m
C= calibration constant, 1.05
L= sample length, cm
R= reading taken of sample
R0 = reading taken with no sample
M= sample mass (g)
𝛸𝑀 = 𝛸𝑔 ∗ 𝑀
Where;
𝛸𝑀 = Molar Magetic Susceptibility
𝛸𝑔= Gram Magnetic Susceptibility (cm3 g-1)
M= Molar Mass (g mol-1)
Molar Magnetic Susceptibility
Effective Magnetic Moment
µEFF = 2.828 𝑇𝑋𝑀
µEFF = effective magnetic moment, B.M.
T= Temperature (K), 292K
XM = Molar magnetic Susceptibility, cm3 mol-1
Name of Substance Theoretical Value
B.M.
Experimental
Value B.M.
[Mn(bda)].2H2O 5.92 5.87
[Mn(pda)].H2O 5.92 6.16
[Mn(hxda)].H2O 5.92 3.09
Drug 1,
[Mn2(bda)2(phen)2(H2O)].
2H2O
5.92 8.91
4.455 x 2
Drug 2, [Mn(pda)(phen)] 5.92 6.36
Drug 3,
[Mn(hxda)(phen)2(H2O)].
7H2O
5.92 8.62
Conclusion
1. The complex salt [Mn2(oda)(phen)4(H2O)2] [Mn2(oda)(phen)4(oda)2]4H2O (MD1) is an excellent lead candidate for the prevention of α-Synuclein aggregation.
2. Three known analogues of MD1 {[Mn(hxda)(phen)2(H2O)].7H2O; [Mn(pda)(phen)]; and [Mn2(bda)2(phen)2(H2O)].2H2O along with their precursor manganese(II) dicarboxylate complexes have been synthesised using methods previously published
3. All six complexes have been characterised using a range of analytical techniques.
4. Further work is required to purify the complexes in preparation for their use in a structure-activity relationship study.
Acknowledgements
I would like to thank my supervisors Professor Michael Devereux and Dr. Patricia Ennis for their help and support
when carrying out this project.
I would also like to thank the School of Chemical & Pharmaceutical Sciences for allowing me to use their
equipment.
Thank You