Lipid Peroxidation and its Inhibition: Mechanisms and Molecules

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Autoxidation is primarily responsible for the deterioration of all hydrocarbon-based products and is implicated in aging, cancer and degenerative disease (DD). Accordingly, antioxidants are indispensable product additives, and are believed to play key preventive roles in human health. In the last grant period, we developed new methods to study autoxidation, and used them to elucidate mechanisms and design novel molecules to better control it. In the next grant period, we propose to parlay this expertise to better understand the role of lipid peroxidation (LPO) and its inhibition in oxidative cell death (ferroptosis) and associated DD. The first part of the proposal involves the development of new tools for studying LPO and its inhibition. Specifically, we propose to develop a new approach for the high-throughput characterization of inhibitors of LPO (a second generation of our previously reported Fluorescence-Enabled Inhibited autoxidation, or FENIX, methodology), a new initiating system for use with this approach as well as initiating LPO directly in the cell, and to develop new tools for imaging LPO in live cells using confocal microscopy. These tools will enable mechanistic studies of ferroptosis induction, execution and suppression and greatly aid in the development of drugs for DD. The second part of the proposal involves the study of new molecules and new mechanisms to combat LPO and associated cell death. Specifically, we propose to use our FENIX methods to counter-screen hits from a cell-rescue screen of a 40,000-compound library and carry out mechanistic studies on potent hits which are likely to operate via new mechanisms. We further propose to explore the unique mechanism of CuATSM and related neuroprotective agents, and lastly, propose to illustrate the rational design of a ferroptosis inhibitor based upon reactivity considerations to determine if further gains in RTA activity and anti-ferroptotic potency are generally possible, or if there are intrinsic - or extrinsic - limitations. This research will uncover new mechanisms and provide new molecules to enable further characterization of ferroptosis, and which can be exploited for the future design of preventive and/or therapeutic agents for DD. The final part of the proposal involves studies on the autoxidation of alkenyl ethers, in general, and plasmalogen lipids (PLs), in particular. Despite their abundance, PLs are poorly studied, and have paradoxically been ascribed both protective (i.e. antioxidant) and pathogenic roles. Specifically, we propose to determine the kinetics, mechanism(s) and products of alkenyl ether autoxidation, elucidate the mechanism(s) by which PLs inhibit LPO, and systematically explore the impact of PLs on ferroptotic cell death. This research will establish the kinetics and mechanism of alkenyl ether autoxidation, which is necessary to understand the role of PLs on LPO and ferroptosis and how it contributes to DD in tissues where PLs are abundant.