Month/Year of Graduation

5-2019

Degree Name

Bachelor of Science in Biotechnology (BTCH)

Department

Biology

First Advisor

Douglas Stack

Abstract

o-Quinones are toxic electrophiles that can disrupt cellular macromolecules. Whether endogenous or xenobiotic, o-quinones are reactive compounds that are difficult to isolate. This work uses the o-quinone of bisphenol(BPA), bisphenol A-3,4-quinone(BPAQ), which can be efficiently synthesized and isolated, to study the electrochemical properties of o-quinones and their sulfur adducts in order to understand their metabolic fate. Cyclic voltammetry and equilibrium analysis were used to determine the relative oxidation potential of the BPA catechol and adducts, formed by reacting glutathione(GSH) and N-acetylcysteine(NAC) with BPAQ. BPAQ-sulfur adducts with 5-position substitution displayed lower oxidation potentials when compared to the 2-subsituted isomers, E1/2=293 and 378 eV, respectively. Oxidation of the adducts is a prerequisite for further sulfur adduction and exchange reactions, both linked to the toxicity of sulfur adducted o-quinones. 5-NAC-BPAQ was used to probe exchange reactions with GSH to determine the effects of sulfur substitution on BPAQ-sulfur chemistry. When reacted with an excess of GSH, three new disubstituted sulfur adducts were formed, 6-GSH-5-NAC-OHBPA, 2-GSH-5-NAC-3-OHBPA, and 5,6-diGSH-3-OHBPA. 5,6-diGSH-3-OHBPA is formed from 6-GHS-5-NAC-OHBPA through oxidation followed by S-aryl exchange. These results show that substitution pattern of o-quinones sulfur adducts has a dramatic effect on downstream chemistries and the resulting toxicity of the sulfur adducts.

Available for download on Saturday, April 23, 2022

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