A Study of the Antioxidant Versus Pro-Oxidant Nature of the Amyloid Beta Peptide and an Analysis of the Natural Products, Isorhamnetin and Narignenin, as Antioxidants

Author

Kaylee HolmesFollow

Date of Award

Spring 4-29-2020

Document Type

Undergraduate Thesis

Department

Chemistry and Biochemistry

First Advisor

Saumen Chakraborty

Second Advisor

Susan Pedigo

Third Advisor

James Cizdziel

Relational Format

Dissertation/Thesis

Abstract

Alzheimer’s disease is a neurodegenerative disorder with no cure. Due to the widespread effects of this disease, abundant research efforts have gone towards finding a cure. The amyloid beta (Ab) peptide has been shown to be a potential cause of the disease due to destructive effects on tissues that it can have both by itself and through reactive oxygen species (ROS) generation. This study was performed in order to assess the structural properties of Ab₄₂monomers, fibrils and oligomers, to assess the antioxidant versus pro-oxidant behavior of the Ab peptide, and to assess the antioxidant nature of the natural products isorhamnetin and naringenin. Several different ROS assays were performed in order to gain insight into the nature of Ab₄₂, isorhamnetin, and naringenin. It was found that the oligomeric form of the peptide behaved solely as a pro-oxidant and generated much more ROS than the monomers and fibrils. The monomers and fibrils, however, showed antioxidant behavior as they decreased the amount of ROS generated by free copper under oxidative conditions. Isorhamnetin was far more successful at reducing ROS generation in all forms of the peptide than naringenin. After performing a copper titration, it was determined that two isorhamnetin molecules are able to bind one copper. These results indicate that Ab₄₂ oligomers behave as pro-oxidants while Ab₄₂ monomers and fibrils behave as antioxidants. The results also indicate that isorhamnetin is a better antioxidant than naringenin.

Recommended Citation

Holmes, Kaylee, "A Study of the Antioxidant Versus Pro-Oxidant Nature of the Amyloid Beta Peptide and an Analysis of the Natural Products, Isorhamnetin and Narignenin, as Antioxidants" (2020). Honors Theses. 1402.
https://egrove.olemiss.edu/hon_thesis/1402

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