Characterization of saponin biotransformation driven by intrinsic proteins in Aralia elata leaves

Aralia elata (Miq.) Seem. a nutrient-rich wild vegetable widely consumed in Northeast Asia, is abundant in triterpenoid saponins. While methanol and water are commonly used for phytochemical extraction and food processing, respectively. Although solvent-dependent changes in saponin composition have been reported in Panax leaves, similar effects in A. elata leaves (AEL), another member of the Araliaceae family, remain unclear. In this study, an UPLC–Q–TOF MS method was developed to profile saponins in methanolic and aqueous extracts of AEL. A total of 78 saponins were identified and 22 quantified, including one new compound. Major saponins in methanolic extracts were converted in aqueous extracts into corresponding deglucosylated forms via selective hydrolysis at the C-28 position. This transformation was mediated by intrinsic proteins during aqueous extraction. One transformed product was isolated and identified by NMR as a new saponin. These findings reveal protein-mediated, solvent-dependent saponin biotransformation during AEL processing.