Analysis of Combinatorial Natural Products by HPLC and CE

methods such as antisense–cosuppression technologies or overexpression, scientists could tailor medicinal plants to produce pharmaceutically important secondary metabolites by eliminating interfering metabolic steps or by introducing desired steps. For example, to accumulate more of an end product, analysts could block a side pathway that also uses the same precursor (6). A transgene could be introduced to accumulate a compound not normally produced in a particular plant species. An end product can be derivatized — for example, to a more soluble glycoside — by introducing a glycosyl transferase gene. Alternatively, microbes could be used to produce secondary metabolites (7). Short biosynthetic pathways can be functionally expressed in yeast or bacteria to produce a single enzyme for use in a subsequent biomimetic synthesis or even to produce the end product. Catharanthus roseus (vinca rosea) produces widely used alkaloids such as the antihypertensive compounds ajmalicine and serpentine, as well as the anticancer agents vinblastine and vincristine (8). The latter compounds bind specifically to tubulin during mitosis and block the ability of the protein to polymerize into microtubules. Both normal and malignant cells exposed to these alkaloids undergo changes characteristic of apoptosis. Earlier reports about vinca rosea Natural products are among the largest and most diverse groups of plant secondary metabolites. Advances in modern genetic technology have enabled scientists to engineer biosynthetic pathways with the promise of generating novel chemical entities. In this study, the authors used an extensive database of secondary metabolite–related enzymes for cloning and testing Catharanthus roseus and other plant genes of interest. They discuss how they used accelerated solvent extraction, high performance liquid chromatography, and capillary electrophoresis (CE) to monitor changes in combinatorial genetics–mediated secondary metabolite generation. Because of the lower sample requirement and higher sensitivity, the authors found CE to be their preferred separation method in this study. Analysis of Combinatorial Natural Products by HPLC and CE