Development of an oxidatively-releasable caged biosensor system and application to the release of antioxidants and fluorescent probes.

摘要

Reactive oxygen species and reactive nitrogen species, produced as a result of normal oxidative metabolism, are implicated in the progression of numerous diseases by the deleterious effects they impose on biological molecules. This research focuses on the development of a new type of caging concept and technique: oxidatively-releasable caging. Based on the fundamental concept of the photoremovable caging group, where biomolecules are masked by a covalent linkage and the release is triggered by an external stimulus, the caging technique developed in the Branchaud lab has been designed to release molecules in response to oxidative activity by reactive species rather than photolysis. This dissertation discusses the design, synthesis, and characterization of the oxidatively-releasable caging system and its application to the release of an antioxidant, alpha-tocopherol, and the common fluorescent probe, fluorescein. Structure-activity studies on the caging system have led to the optimization of its properties and provide flexibility to "tune" the caging system depending on the molecule to be released and the reactive species that triggers its release. alpha-Tocopherol, although a powerful lipid soluble antioxidant, has been found to act as a prooxidant and initiate lipid peroxidation in vitro. This research has aimed to address this issue by application of the oxidatively-releasable caging technique to alpha-tocopherol in order to diminish its undesirable prooxidant activity while maintaining its antioxidant action. An oxidatively-releasable caged alpha-tocopherol compound in preliminary model studies diminishes lipid peroxidation of a lipid model compound. Further examination of this caged antioxidant may be beneficial as a potential therapeutic. In addition, the oxidatively-releasable caging system has been applied to the fluorescent compound fluorescein as a sophisticated approach for the detection of reactive species. So far, oxidatively-releasable caged fluorescent probes have been found to have interesting reactivity to only a couple reactive oxygen and nitrogen species. Therefore, further development of this technique may provide a route for the selective detection of reactive oxygen and nitrogen species. The oxidatively-releasable caging system has practical utility as a new biosensor technique that could be applied for the release of a wide variety of biomolecules.