Current Organic Chemistry - Volume 5, Issue 9, 2001

The genus Aglaia is the source of a unique group of natural products featuring a cyclopenta[b]tetrahydrobenzofuran skeleton. Commonly these compounds, which until now include more than 50 naturally occurring derivatives, are named after the parent compound, rocaglamide, which was described for the first time almost twenty years ago. This review highlights the chemical diversity of rocaglamide derivatives and of biogenetically similar compounds from the genus Aglaia and their remarkable biological activity in the fields of insecticides and cytostatic agents. With a few exceptions, all naturally occurring rocaglamide derivatives exhibit striking insecticidal activity against various pest insects. In addition, they display pronounced cytostatic activity against human cancer cell lines in vitro. Furthermore, it was shown recently that rocaglamide and several of its congeners inhibit NF-kB induced gene activation in human T cells and are able to elicit apoptosis in resistant tumor cells. Taken together, these data make rocaglamide derivatives interesting candidates for possible therapeutic agents primarily in the field of cancer chemotherapy. In some Aglaia species, rocaglamide derivatives co-occur with biogenetically similar natural products of the aglain, aglaforbesin or forbaglin type. These latter compounds differ from rocaglamide and its congeners mainly by the nature of their heterocycle. Furthermore, they seem to be devoid of significant biological activity at least in the areas mentioned above, thereby pointing to the cyclopenta[b]tetrahydrobenzofuran core of the rocaglamide skeleton as one essential structural requirement for the pronounced biological activity of the rocaglamides.

Polysaccharides from plants have been the subject of study for a very long time, but mainly for their physical properties and industrial use based on these properties. Over the last 20 years there has been an ever increasing interest in the biological activity of biomolecules. These studies became possible as a result of the scientific development of isolation, purification and characterisation methods concomi-tant with the development of fairly simple in vitro tests, especially for effects on the immune system. The growing acceptance of the knowledge to be gained by people still using so-called traditional medicine in finding sources worthy of investigation has led to new sources for interesting bioactive plant polysaccharides. This review covers only a small part of the field it focuses primarily on the pectic type polymers and their activity some important neutral polysaccharides like lentinan and acemannan are mentioned as well as methods used for these studies.

Starfish extracts have been reported to exhibit a broad spectrum of pharmacological properties, which are related to the presence of typical steroidal oli-goglycosides. In the animal kingdom, these metabolites have only been found in the marine phylum Echinodermata and particularly in the class Asteroidea (sea stars).This communication offers a general view of steroid oligoglycoside distribution among starfishes and focuses on a number of recent examples, much of these from the authors laboratory, to discuss structural characteristics, biological activities and methods of investigation.

Biotransformation of plants secondary compounds by the variety of organism sometimes afford novel and / or useful compounds. The ability of organism metabolizing those natural products and the metabolic fate of those in nature can also be revealed by this investigation. Lignans and neolignans are well known plants secondary compounds which are widely distributed in terrestrial plants, and have attracted much attention due to the varied biological activities. This review summarizes recent research in to field of biotransformation of lignans and neolignans.