The overall objective of the proposed research is to develop a fundamental understanding of the biologically pertinent chemistry of prostaglandin endoperoxides (e.g. PGH2) and the biologically active products derived from these key intermediates in the oxidative metabolism of polyunsaturated fatty acids. We exploit model studies to guide investigations of these structurally complex and chemically reactive molecules, and we exploit efficient total syntheses to provide ample supplies of these compounds for biological evaluation. Our studies led to the important discovery that PGH2 rearranges to new seco prostanoic acid levulinaldehyde derivatives which we named levuglandin (LG) E2 and LGD2. Most recently we discovered that levuglandins are potent and selective inhibitors of the uterotonic actions of prostaglandins, rapidly (in seconds) binding covalently with and extensively cross-linking proteins under extraordinarily mild incubation conditions. Our primary immediate goal is to detect and quantify the natural occurrence of levuglandins or their covalent adducts with various biological nucleophiles, especially proteins and DNA. Techniques to be employed include immunoassay, centrifugal counter current partition chromatographic and HPLC detection and isolation, and spectral characterization. The analytical methods developed will be used to examine several hypotheses about the biological roles of levuglandins, their mechanisms of formation and interconversions. Thus, for example, we propose that levuglandins may be involved in the tissue damage associated with ageing or the burst of fatty acid oxidative metabolism during oxygen reperfusion following the ischemia of heart attacks or stroke. A better understanding of the biochemistry of brain edema is essential to allow the development of more rational therapeutic measures. Extensive further studies of the biological activities of levuglandins are also planned to explore their influence on receptor binding or prostaglandins, on intracellular concentration of calcium, on c- AMP concentration, and on the concentration of inositol phosphates. We will explore the molecular mechanisms of these biological actions inter alia, testing the possibility that dihydroxpyrrolidines are intermediates in the covalent binding and cross-linking of proteins by levuglandins.
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