Functional molecules to test the free radical theory of ageing

McQuaker, Stephen (2013) Functional molecules to test the free radical theory of ageing. PhD thesis, University of Glasgow.

Abstract

Oxidative stress at a cellular level resulting from reactive oxygen species (ROS) has been implicated as a key factor in the ageing process and the development of age-related diseases. Mitochondria are the primary source of endogenously generated ROS through the leakage of electrons from the respiratory chain to molecular oxygen. Therefore there is a lot of interest in investigating ROS production and their biological impacts on both a cellular level and whole organism level.

A mitochondria-targeted hydrogen peroxide (H2O2) probe (MitoB) i and a mitochondria-targeted nitric oxide (•NO) probe (MitoDA) iii have been prepared to allow the detection and quantification of mitochondrial concentrations of these species in vitro and in vivo. These utilise the selective reactivity of boronic acids with H2O2 and 1,2-dianilines with the combination of •NO and oxygen respectively to afford specific reaction products. These conversions are readily detectable by ESI-MS and quantified using deuterated internal standards.

The mitochondrial membrane potential (ΔΨm) is directly linked to levels of ROS production, with an elevated ΔΨm resulting in increased ROS production. Mitochondrial membrane potential moderators that release uncoupling molecules from caged precursors selectively in the presence of H2O2 were developed. Two untargeted analogues, DNP-SUM v and FCCP-SUM viii were prepared to release 2,4-dinitrophenoxyl anions (DNP–, vi) or carbonyl cyanide-p-trifluoromethoxyphenylhydrazonyl anions (FCCP–, ix) respectively and their pseudo-first order kinetics assessed.

Two mitochondria-targeted analogues, MitoDNP-SUM(1) x and MitoDNP-SUM(2) xi designed to release DNP– vi inside the mitochondrial matrix were prepared. Their abilities to lower the ΔΨm and therefore the ROS producing capabilities in isolated rat skeletal muscle mitochondria in response to endogenously generated H2O2 were assessed.

Work was also conducted towards the development of mitochondria-targeted photo-activatable probes that could potentially release small functional bioactive compounds from caged precursors inside individual mitochondria upon selective irradiation.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Free radical theory of ageing, mitochondria, oxidative stress, functional molecules
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Hartley, Dr. Richard
• Date of Award: 2013
• Depositing User: Mr Stephen McQuaker
• Unique ID: glathesis:2013-4211
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 25 Apr 2013 14:21
• Last Modified: 03 Jan 2019 09:14
• URI: https://theses.gla.ac.uk/id/eprint/4211