Metabolomics analysis of major metabolites in medicinal herbs

Abstract

A metabolomics approach with a platform consisting of GC-MS, ¹H NMR and HPLC-UV was used to investigate the regulatory mechanisms of metabolic pathways in Stevia rebaudiana and Coptidis rhizoma. The data suggested that glycolysis and the oxidative pentose phosphate pathway (OPPP) remained as the main components of plant respiration in these botanicals. However, the absence of citrate, succinic acids, glutamate and fumarate in Stevia suggested that the tricarboxylic acid (TCA) cycle was not required extensively to synthesize its bioactive diterpene glycosides. The results further suggested that the carbon flow was directed between the shikimic acid and methylerythritol 4-phosphate (MEP) pathway. For the Coptidis, the use of an alternative biosynthesis route with proline, phenylalanine, catechollactate and 2-mono-isobutyrin was proposed to synthesize its major bioactive alkaloids. It was observed that different fatty acids might be needed to modulate the biosynthesis of the bioactive secondary metabolites in the medicinal herbs. Concurrently, primary and secondary metabolite profiling was studied by unsupervised multivariate Principal Component Analysis (PCA) to discriminate and assign the different phenotypes under various cultivation conditions. Hence, the simultaneous profiling of primary and secondary metabolites could significantly aid the existing functional genomics approaches to study the biosynthesis function in medicinal herbs.