This research will focus on hemiparasitic species of the plant family Scrophulariaceae. It will emphasize the alkaloid and iridoid glycoside chemistry of the plants, how these metabolites may affect insect herbivores whose larvae consume the plants, and how some of the isolated iridoid glycosides can be utilized in the laboratory as chiral synthons. The plant species to be studied are parasitic on the roots of host plants which contain alkaloids. These alkaloids are transferred into the parasites and may themselves affect insect herbivores. Utilization of the alkaloids by the parasites as herbivore defenses will be studied as will specificity of the parasites for certain host plants and alkaloid transport from the host into the parasite. Since insect herbivores which utilize alkaloid- and iridoid-containing plants sequester and /or metabolize the compounds, a study of chemical transformations in insect metabolism of alkaloids and iridoids will be made. Relationships between iridoid glycoside structures and their ease of conversion to pyridine alkaloids will be investigated because, in some plants, iridoids are converted to pyridine monoterpene alkaloids, but pyridine monoterpenes expected from several iridoids found in very high plant concentration have never been isolated. Finally, since iridoids are readily available in multigram quantities from some of the plants under investigation and can be converted in high yield in a one-pot reaction to chiral, pentasubstituted cyclopentanes, a study will be carried out to convert these products to enantiomerically-pure carbocyclic nucleosides. %%% With this award the Synthetic Organic Program of the Chemistry Division will support the research of Dr. Frank R. Stermitz of the Department of Chemistry at Colorado State University. This research will focus on hemiparasitic species of the plant family Scrophularicaeae whose members are parasitic on the roots of host plants which contain alkaloids. These alkaloids are transferred into the parasites and may themselves affect insect herbivores. Utilization of the alkaloids by the parasites as herbivore defenses will be studied as will specificity of the parasites for certain host plants and alkaloid transport from the host into the parasites. These latter two studies have important implications for the biodiversity question that is becoming of crisis proportions as the earth's rainforests are being threatened because simply preserving the genetic pool of plant species may not be enough if secondary metabolite composition is also dependant upon host species.
