Antioxidant activity of spirostanol saponins from Allii Macrostemonis Bulbus and their contents in different origins and processed products

Allii Macrostemonis Bulbus (AMB), a traditional Chinese edible and medicinal plant, is considered beneficial to health. In this study, we isolated and purified nine steroidal saponins (compounds 1–9) from AMB. Their structures were characterized using physicochemical properties, HR-ESI-MS, 1D and 2D NMR spectroscopy. Among these compounds, compounds 1–5 were newly discovered named macrostemonoside U-Y, respectively. We assessed the in vitro antioxidant properties of the nine steroidal saponins through free radical scavenging and reducing power assays. This provides options for developing natural antioxidants. Additionally, an HPLC-ELSD quantitative analysis method was developed for the nine saponins in 12 batches of AMB from different origins and processing methods. The results showed that the contents of the nine steroidal saponins in AMB varied greatly among different growing environments and processing methods.