5. New Medical Applications of Plant Secondary Metabolites

Summary

In the last years, only a limited number of structurally new plant secondary metabolites have entered the scene to attract high medical interest. In contrast, the development of new techniques in the fields of biochemistry, cell biology and molecular biology, e.g. new assay techniques, which are also applicable in the field of natural products chemistry, allowed the finding of several new insights into the molecular mode of action and the pharmacological characterization of known plant secondary metabolites. Accordingly, the pharmacological or clinical characterization of several known plant-derived compounds like the taxanes, artemisinin derivatives or boswellic acids was significantly broadened. Furthermore, new and important medical applications or pharmacological mechanisms of known compounds were found like the antiviral activity of betulinic acid derivatives or the inhibition of tubulin polymerization by combretastatin A-4. Recently, a strong interest has evolved in natural products exhibiting chemopreventive activity. Consequently, the role of several plant polyphenols, like curcumin and xanthohumol, as protective and pharmacologically active, dietary constituents has become an increasingly important area of research. Besides the investigation of single compounds, there is still a growing interest in the application of standardized extracts, complex phytochemical mixtures with a well-defined content of the bioactive constituents. Therefore, new insights concerning the application of extracts from Ginkgo biloba and Hypericum perforatum are also discussed.