This volume is a compilation of plenary lectures presented at the IOCD/CYTED Symposium held in Panama City, Panama in 1997, and covers different aspects of research into plants from North, South and Central America. The topics treated all revolve around the chemistry, pharmacology, and biology of these plants. The importance of pharmaceuticals derived from plant sources is described, together with the potential of ethnomedicine for providing new leads in the search for bioactive constituents. The biodiversity of the Americas is underlined and an idea is given of the urgency with which the flora must be studied.

Over the past few years, increasing attention has been paid to the search for bioactive compounds from natural sources. The success of plant-derived products such as paclitaxel (Taxol) in tumor therapy or artemisinin in the treatment of malaria has provided the impetus for the introduction of numerous research programmes, especially in Industry. A great deal of effort is being expended in the generation of novel lead molecules of vegetable, marine and microbial origin by the use of high throughput screening protocols. When interesting hits are found, it is essen tial to have methods available for the rapid isolation of target compounds. For this reason, both industry and academia need efficient preparative chromatographic separation techniques and experience in their application. Purified natural products are required for complete spectro scopic identification and full characterization of new compo unds, for biological testing and for the supply of pharmaceuti cals, standards, and starting materials for synthetic work. Obtaining pure products from an extract can be a very long, te dious and expensive undertaking, involving many steps. Sometimes only minute amounts of the desired compounds are at hand and these entities may be labile. Thus it is an advantage to have access to as many different methods as possible in order to aid the isolation process. Although a certain amount of trial and error may be involved, nowadays there is the possibility of devising suitable rapid separation schemes by a judicious choice of the different techniques available."