Oxidatively releasable caged antioxidants and fluorescent probes

ORGN 670

Kari A. Trumbull and Bruce P. Branchaud, bbranch@uoregon.edu. Department of Chemistry, University of Oregon, Eugene, OR 97403-1253
Lipid peroxidation is implicated in the progression of numerous diseases, particularly cardiovascular disease. The common antioxidant α-tocopherol has been well known to hinder lipid peroxidation by scavenging lipid peroxyl radicals. However, recent evidence has found that α-tocopherol can act as a pro-oxidant to initiate lipid peroxidation. We have developed a new technique to potentially diminish this undesirable pro-oxidant activity of α-tocopherol. Our technique uses a xanthenyl based caging group sensitive to reactive oxygen species (ROS) that can release the reactive caged molecule under lipid peroxidation conditions. The oxidatively-releasable xanthenyl caging group has a weak C-H bond that has been shown to be more susceptible to radical abstraction than model lipids. Attachment of the caged group to α-tocopherol should completely mask its pro-oxidant and antioxidant activity. In the presence of ROS generated under lipid peroxidation conditions a radical is diverted to the caging group which then releases α-tocopherol. In addition, the oxidatively-releasable caging system has been bound to a fluorescent probe, fluorescein, to potentially be used as a tool to visualize sites of oxidative stress in cells. The development, synthesis and characterization of the oxidatively-releasable caged antioxidants and fluorescent probes will be discussed.