NMR spectroscopy and multivariate statistical analysis of metabonomic changes in Allium macrostemon Bunge extracts induced by different drying methods

Abstract

Phytomedicines are mostly dried, in different ways, before they are processed and used, which may induce metabolic changes and even lead to some changes in drug efficiency. In this study, we used NMR spectroscopy coupled with multivariate statistical analysis to investigate the metabolic consequences of Allium macrostemon Bunge (AMB) extracts induced by different drying methods, including freeze drying, shade drying, and sun drying. More than 30 metabolites have been detected in AMB extracts, among which two compounds have not been assigned yet. Multivariate statistical analysis showed that different drying methods gave rise to metabolite variations. As a plant osmoprotectant, the proline content was higher in three drying extracts than in the fresh extract. As plant-regulating agents, sugars and amino acids changed differently in each drying extract. Membrane degradation, putrescine formation, tricarboxylic acid cycle, gluconeogenesis and metabolisms mediated by shikimate were also influenced by drying processes. The result indicated that freeze drying may be the appropriate drying method for AMB because of the higher N-trans-feruloyltyramine content, which was a potential effective component of AMB.