Copper Complexes as Reactive Oxygen Species DonatorsHannah Kiser and Tom E. Bitterwolf

Department of Chemistry, University of Idaho, Moscow, ID

•Synthesis:

(PPh3)3CuCl +

•Nuclear Magnetic Resonance (NMR): Structure Confirmation

- Low Temperature 31Phosphorous -Solid State 31Posphorous and 63Copper

•UV-Visibility: Copper Complex + tert-Butyl-SN=O to track RSN=O breakdown to NO.

Abstract

Background Information

Materials and Methods

Discussion

Conclusion

Hypothesis

1. Mani, Katrin, Fang Cheng, et al. "Prion, Amyloid β-derived Cu(II) Ions, or Free Zn(II) Ions Support S-Nitroso-dependent Autocleavage of Glypican-1 Heparan Sulfate." Journal Of Biological Chemistry. 278.40 (2003): 38956-38965. Web. 2 Aug. 2012.

Images: www.marinebio.org , journals.prous.com , http://en.wikipedia.org/wiki/Heparan_sulfate

References

Results

1. Copper ions nitrosylate HSPG thiol group2. Reducing agent oxidizes Cu(II)Cu(I)3. Nitric Oxide release4. Autocatalyzes deaminative cleavage1

Can we synthesize a model copper compound capable of releasing NO for application of HSPG breakdown and β-amyloid decomposition?

Synthesize a copper sulfur bridging compound that will serve as a model nitric oxide donor by breakdown of tert-Butyl-SN=O compound.

•Alzheimer’s Disease (AD) is characterized by the accumulation of β-amyloid deposits (senile plaques)• Amyloid precursor protein (APP) undergoes proteolysis

a. P3 Peptide and α-secretase Cu(I) APP Cu homeostasis regulation, normal process

b. β-Amyloid peptide pathogenic plaques•β-amyloid uses Cu+2 and Zn+2 and Heparan Sulfate Proteoglycans (HSPG) to aggregate and form plaques

- β- amyloid + Cu(II) Reactive Oxygen Species, cytotoxic Future Work

•Continue to synthesize copper complex models for RSNO decomposition

•Elucidate PPh3 + RSN=O PPh3=N-S-tBu +PPh3O reaction mechanism

a. Nitrogen NMRb. Synthesize selenium analog (PPh3=NSe-tBu)

77Se NMR to track intermediates and product growth

Our objective was to develop model copper complexes with the ability to decompose a tert-Butyl-SN=O compound and release nitric oxide. We confirmed the structure of our copper complex, (PPh3)4Cu2S2(C7H7), with low temperature and solid state NMR techniques. Upon addition of tert-Butyl-SN=O, UV-Visibility studies showed no decomposition; however, low temperature NMR revealed some reaction taking place. While exploring the possible products of the reaction we stumbled upon the reaction PPh3 + t-Bu-SN=O PPh3S=NR. We took some of the first phosphorous NMR data of the reaction and are currently taking steps to elucidate the reaction mechanism.

c.

a. Free PPh3 rapidly exchanges at +30C and overpowers spectrum, as temperature drops exchange slows and two resonances of interest appear. b. Phosphorous coupling with Copper (63Cu and 65Cu nuclei exhibiting 2:1 abundance) gives two overlapping quartets. The 63Cu NMR shows a puzzling two peaks, perhaps two different arrangements of benzyl groups (up-down or both up/down).

Free PPh3

PPh3PO

•Synthesized copper complex, NMR confirmed

•Cu complex failed to decompose tert-butyl-SNO by UV- Visibility

•Puzzling NMR data of copper complex + tert-RSNO, lead us to test reaction of PPh3 + RSNO

•This reaction produces PPh3=NSR and PPh3O

First Phosphorous NMR on such reaction

Mechanism of reaction unknown, current research to elucidate!

Acknowledgments •This publication was made possible by the INBRE Program, NIH Grant Nos. P20 RR016454 (National Center for Research Resources) and P20 GM103408 (National Institute of General Medical Sciences).•Thanks to my lab mates for their help and patience and Alex Blumenfeld for NMR data.

a. Copper Complex 31P Low Temperature NMR +30C, -40C, -84C

b. Solid State 31P NMR

c. 31P NMR of Copper Complex + tert-Butyl-SN=O. Phosphine is in equilibrium between free (0 to -7ppm) and bound (31ppm and 17ppm). The nature of the bound site is not yet clear.

d. 31P NMR of PPh3+ tert-Butyl-SN=O. Bottom: PPh3 in D-Toluene. Middle: minutes after addition of tert-Butyl-SN=O. Top: reaction completion, 15 minutes after addition. PPh3 (-5ppm) and trace PPh3O (25ppm) before addition of SNO. As reaction takes place PPh3O peak grows as well as PPh3=N-S-t-Bu peak growth (19ppm).

d.

PPh3O

PPh3=N-S-t-Bu

PPh3

DecomposedProduced

Solid State 63Cu NMR