Untargeted metabolite analysis-based UHPLC-Q-TOF-MS reveals significant enrichment of p-hydroxybenzyl dimers of citric acids in fresh beige-scape Gastrodia elata (Wutianma).

In order to comprehensively elucidate the chemical biosynthesis process of the beige-scape Gastrodia elata Blume (Wutianma) as a traditional herbal medicines, the untargeted analysis-based UHPLC-PDA-ESI-Q-TOF-MS reveals the metabolites ranging from the skeletons to novel dimers of citric acids in fresh and dried immature/mature stem tubers. Interestingly, two novel types of dimers for citric acids with the anhydride groups at sn-1 and/or sn-5 were discovered in fresh samples. Moreover, the classical mono- versus novel di-mers, and the aglycons versus the glycosides could be easily discriminated by signature fragmentation patterns and some novel adduct ions. The heat map of contents demonstrated more p-hydroxybenzyl metabolites than gastroxyl ones were determined in fresh Wutianma revealing a significant specificity with the lack of the sufficient gastrodin and gastroxyl products in biosynthetic pathway.