Mass spectrometry as a tool for the dereplication of saponins from Ampelozizyphus amazonicus Ducke bark and wood.

INTRODUCTION Mass spectrometry in natural products research has been used as a first step to identify possible chemical structures and to guide subsequent efforts to isolate novel compounds. Preparations of Ampelozizyphus amazonicus Ducke (AA) are known for their high content of saponins, especially dammarane-type triterpenoid aglycones. In the Amazon, where it is known as "saracura-mira", roots and bark are widely used for the treatment and prevention of malaria, while the wood is discarded. The extract prepared from the wood is also saponin-rich, but its exact chemical composition has not been described. OBJECTIVE This study provides information on the chemical profiling and tentative structural identification of the major compounds (saponins) present in aqueous and ethanol extracts of bark and wood of AA by mass spectrometry. METHODS The strategy used to identify compounds present in all samples was ultra-high-performance liquid chromatography with an ultraviolet detector coupled to tandem mass spectrometry (UHPLC-UV-MS/MS) for the analysis of fragmentation patterns through product ion scan using MZmine 2 software. Also, direct sample injection and electrospray ionisation combined with high-resolution mass spectrometry (DI-ESI-HRMS) measurements were performed. RESULTS The extracts showed chemical similarity, and 95 saponins were tentatively identified in AA wood and bark, including 73 which are described for the first time as tentative structures for this plant species. CONCLUSION This research describes a useful method for the fast and simultaneous tentative identification of major saponins in AA, contributing to the study of the chemical properties of this genus and family. Furthermore, it demonstrates the importance of the qualitative dereplication process, allowing a straightforward way to propose the tentative identification of compounds.