SAR studies of epoxycurcuphenol derivatives on leukemia CT-CD4 cells.

Bioactive natural products are a potential source of new pharmaceuticals since they offer new modes of action and more specific activities. The use of derivatization also enables the optimal structure for their biological activity to be determined. In this study several epoxycurcuphenol derivatives were synthesized. The substitution pattern on the aromatic and oxirane rings was varied along with that at the benzylic position and the length of the side chain was altered. These changes were made in order to gain a deeper understanding of the structural requirements for activity. The biological activities of these compounds were evaluated on the human leukemia cell line Jurkat using an antiproliferative assay. The activity results and structural requirements are discussed.

Evolution and current status of ecological phytochemistry.

Phytochemical studies have experienced a great deal of change during the last century, not only regarding the number of compounds described, but also in the concept of phytochemistry itself. This change has mainly been related to two key points: the methodologies used in phytochemical studies and the questions regarding 'why secondary metabolites appeared in plants and in other living organisms?' and 'what is their role?'. This transformation in the field has led to new questions concerning such different subjects as evolution, paleobotany, biochemistry, plant physiology and ethnography. However, the main issue is to clarify the role that secondary metabolites play in the plant (and other organisms) and whether the resources invested in their production (C and N allocation, genes encoding their biogenetic pathways, specific enzymes, energy-rich molecules such as ATP and NADPH) have or lack a reasonable reward in terms of advantages for survival. Consequently, in this review the main emphasis will be placed on two subjects related to the evolution of phytochemical studies. The first aim is to describe briefly the influence that the development of the methodologies needed for compound isolation and structure elucidation have had on the field of phytochemistry. The second area to be covered concerns the new theories addressing the role of secondary metabolites from an ecological point of view: co-evolution of plants and their potential enemies (phytophagous insects, microbes, herbivores and other plants), chemical plant defence, adaptative strategies of phytophagues to plant toxins (among them sequestration will be briefly mentioned), and models and theories for carbon and nitrogen allocation. Some final remarks are made to summarize our opinion about the immediate future of phytochemical ecology and phytochemical studies.

Heliespirones B and C: two new plant heliespiranes with a novel spiro heterocyclic sesquiterpene skeleton.

From the medium, polar bioactive fractions of leaf aqueous extract of Helianthus annuus L., heliespirones B (2) and C (3) have been isolated. The structural elucidation was based on extensive spectral studies. A probable biogenesis of heliespirone skeleton is proposed and discussed. The structure of heliespirone B has been confirmed by X-ray diffraction analysis.

Bioactive terpenoids from sunflower leaves cv. Peredovick.

The CH(2)Cl(2) extract of dried leaves of Helianthus annuus L. cv. Peredovick(R) has yielded, in addition to the known sesquiterpene lactones annuolide E and leptocarpin, and the sesquiterpenes heliannuols A, C, D, F, G, H, I, the new bisnorsesquiterpene, annuionone E, and the new sesquiterpenes heliannuol L, helibisabonol A and helibisabonol B. Structural elucidation was based on extensive spectral (one and two-dimensional NMR experiments) and theoretical studies. The sesquiterpenes heliannuol A and helibisabonol A and the sesquiterpene lactone leptocarpin inhibited the growth of etiolated wheat coleoptiles.