Date of Award

Fall 2008

Project Type

Thesis

Program or Major

Chemistry

Degree Name

Master of Science

Abstract

Chapter 1. Binding properties of tach-3-MeOpyr with Zn(II), Cu(II), Fe(II) and Ni(II) have been studied and compared to other tachpyr family metal complexes. The hypothesis was that weak binding between metals and the tachpyr ligand family might be responsible for its lower cytotoxicity towards cells. However, the electronic and structural data in solution do not demonstrate any signs of weaker binding for Cu(II), Fe(II) and Ni(II) between tach-3-MeOpyr and tach-3-Mepyr. While tachpyr, tach-3-Mepyr and tach-3-MeOpyr all have similar binding properties toward Fe(II) in an oxygen free environment, the rates of oxidative dehydrogenation of their Fe(II) complexes in air are substantially different. The rate of oxidation of the chelators appears related to their mechanism of cytotoxicity because rates of cytotoxicity correlated with the rate of oxidation.

Chapter 2. Two curcumin analogues (2,4-DMCU, 4,4'-DMCU) and curcumin were synthesized via Pabon's method with some modification. These two synthetic derivatives contain the same metal binding motif with different aryl rings. All curcuminoids have shown keto-enol tautomers in solution, characterized by 1H and 13C NMR.

Chapter 3. Upon deprotonation of the beta-diketone structural motif, curcumin will chelate a variety of divalent and trivalent metal ions, Ga(III), In(III), Cu(II), Mn(II), and Fe(III). Depending on the experimental conditions, UV-Vis spectrophotometric titrations showed the formation of iron-curcuminoids complexes with M:L stoichiometries of 1:1, 1:2 or 1:3. A combination of EPR, Evans' method, and spectrophotometric studies indicate that Fe(III) is reduced to Fe(ll) by reaction with curcumin anions under aerobic conditions but not with a synthetic derivative 4,4'-dimethoxycurcumin (4,4'-DMCU). Although curcumin was degraded in pH 7.4 PBS solutions, it was degraded much less when iron was present.

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