Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


As part of a biochemical systematic investigation of the tribe Helianteae (Compositae) for their secondary metabolites, Calea deltophylla Cowan from the subtribe Galinsoginae, Squamopappus skutchii (S. F. Blake) Jansen, Harriman and Urbatsch, from the Ecliptinae, and Podachaenium eminens (Lagasca) Shultz-Bip. from the Verbesininae were chemically investigated. Calea deltophylla provided the known compounds ageratochromene and eupatarone and three new compounds, 3-methoxy-4-hydroxyseneciophenone, caldeltophyllide and deltophyllin. Squamopappus skutchii yielded the known sesquiterpenoid (beta)-eudesmol, two new guaianolides, skutchiolides A and B, and the new eudesmanolide chapinolin. P. eminens provided three known guaianolides. The structures of the compounds were established by chemical and spectroscopic methods including MS, IR, CD, ('1)H NMR and ('13)C NMR techniques and single crystal X-ray diffraction analysis. The chemical data support the taxonomical classification of C. deltophylla and P. eminens and justify the removal of S. skutchii from the genera Calea and Podachaenium, and its placement into the subtribe Ecliptinae. Terpenoid extracts of thirty plants from the Composite family were tested for their molluscicidal activity against Biomphalaria glabrata snails. Nearly 50% of the extracts exhibited molluscicidal activity, the most active being those of Podachaenium eminens from Mexico and Ambrosia confertiflora from Nuevo Leon, Mexico, and Texas, with LC(,100) (24 hrs) of 50, 100 and 100ppm, respectively. Confertiflorin from A. confertiflora DC provided upon treatment with p-toluensulfonic acid a mixture of desacetylconfertiflorin and allodesacetylconfertiflorin. Treatment of confertiflorin with phenylselenyl chloride followed by hydrogen peroxide oxidation yielded a mixture of 8(alpha)-acetoxyambrosin and 2,3-dehydro-8(alpha)-acetoxypsilostachin C. The structures of the new compounds were inferred from spectral data. Forty sesquiterpene lactones were tested for their molluscicidal activity against B. glabrata snails. The most active of the compounds was 7(alpha)-hydroxy-3-desoxyzaluzanin C with an LC(,100) (24 hrs) = 1.0 ppm. Ten sesquiterpene lactones, four guaianolides and six pseudoguaianolides, were tested for their inhibitory activity toward the enzyme phosphofructokinase. All compounds were found to be active as inhibitors. The most active of the guaianolides was 7(alpha)-hydroxy-3-desoxyzaluzanin C and allodesacetylconfertiflorin the most active pseudoguaianolide with apparent K(,i) values of 0.07 and 3.24 mM, respectively.