development of a photochromic nitroxyl delivery system david spivey mentor: dr. kevin p. schultz...
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DEVELOPMENT OF A PHOTOCHROMIC NITROXYL DELIVERY SYSTEM
David Spivey
Mentor: Dr. Kevin P. Schultz
Goucher College
Nitroxyl (HNO)
HNO has been found to have pharmacological effects: Positive cardiac inotropy Vasodilation Inhibits breast cancer tumor growth
Potential therapeutic agent for heart disease
Downside: highly unstable in physiological conditions
Current HNO Donors
A stable and controllable nitroxyl donor is needed to further study its therapeutic benefits and potential usefulness as a drug
Chromism
A process that induces a reversible color change in compounds
Types of chromism: Photochromism - color change caused by light Thermochromism - color change caused by heat Electrochromism - color change caused by an
electrical current Solvatochromism - color change caused by
solvent polarity Tribochromism - color change caused by
mechanical friction
Photochromism
The reversible transformation of a chemical species between two forms by the absorption of electromagnetic radiation, where the two forms have different absorption spectra.
Electrocyclic ring closing reaction
Diene Synthesis
Nitroxyl Binding and Release
UV/Vis Studies of Photochromic Transformation
First compound used produced results indicative of degradation
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0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
3 sec A6 sec A11 sec A16 sec A26 sec A36 sec A56 sec A
Wavelength (nm)
Absorb
ance
UV/Vis of New Compound
Photostationary State
The equilibrium chemical composition under a specific kind of electromagnetic radiation
0 10 20 30 40 50 60 700
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
440 nm Peak
Time (s)
Absorb
ance
0 10 20 30 40 50 60 703.6
3.8
4
4.2
4.4
4.6
4.8
5
237 nm Peak
Time (s)
Absorb
ance
Parallel vs. Antiparallel
UV light
Monitoring Closing by NMR
Open form
After 10 min of irradiation
Isolation of Closed Isomer
Nitroxyl Release
Tried heating open ring form in xylene/water at 140° C
Future Plans
Optimize retro-Diels Alder reaction and HNO release
Optimize side groups to obtain a higher percent in the closed conformation
References
Fukuto, J.M.; Dutton, A.S.; Houk, K.N. “The chemistry and biology of nitroxyl (HNO): a chemically unique species with novel and important biological activity,” Chembiochem, 2005, 6, 612–619.
Lopez, B. E.; Shinyashiki, M.; Han, T. H.; Fukuto, J. M. “Antioxidant actions of nitroxyl (HNO),” Free Radical Biol. Med. 2007, 42, 482–91.
Atkinson, R. N.; Storey, B. M.; King, S. B. “Reactions of Acyl Nitroso Compounds with Amines : Production of Nitroxyl (HNO) with the Preparation of Amides” Tetrahedron Lett. 1996, 37, 9287–9290.
Irie, M., “Diarylethenes for Memories and Switches,” Chem. Rev. 2000, 100, 1685–1716.
Lemieux, V.; Gauthier, S.; Branda, N. R. “Selective and sequential photorelease using molecular switches,” Ang. Chem. Int. Ed. 2006, 45, 6820–6824.
Erno, Z.; Asadirad, A. M.; Lemieux, V.; Branda, N. R. “Using light and a molecular switch to “lock” and “unlock” the Diels-Alder reaction,” Org. Biomol. Chem. 2012, 10, 2787–2792.
Acknowledgements
Kevin Schultz, Ph.D Goucher Chemistry Department Claasen Summer Research Fund Kirkbride Loya Jaclyn Kellon Kat Flanagan Marie McConville